[2/3] api: odp_timer.h: updated API, lock-less implementation

Message ID 1418078986-24980-3-git-send-email-ola.liljedahl@linaro.org
State New
Headers show

Commit Message

Ola Liljedahl Dec. 8, 2014, 10:49 p.m.
Signed-off-by: Ola Liljedahl <ola.liljedahl@linaro.org>
---
(This document/code contribution attached is provided under the terms of
agreement LES-LTM-21309)
The timer API is updated according to https://docs.google.com/a/linaro.org/document/d/1bfY_J8ecLJPsFTmYftb0NVmGnB9qkEc_NpcJ87yfaD8
A major change is that timers are allocated and freed separately from timeouts
being set and cancelled. The life-length of a timer normally corresponds to the
life-length of the associated stateful flow while the life-length of a timeout
corresponds to individual packets being transmitted and received.
The reference timer implementation is lock-less for platforms with support
for 128-bit (16-byte) atomic exchange and CAS operations. Otherwise a lock-based
implementation (using as many locks as desired) is used but some operations
(e.g. reset re-using existing timeout buffer) may still be lock-less.
Updated the example example/timer/odp_timer_test.c.

 example/timer/odp_timer_test.c                     |  165 ++-
 platform/linux-generic/include/api/odp_timer.h     |  474 +++++++--
 .../linux-generic/include/odp_timer_internal.h     |   69 +-
 platform/linux-generic/odp_timer.c                 | 1083 ++++++++++++++------
 4 files changed, 1311 insertions(+), 480 deletions(-)

Comments

Mike Holmes Dec. 9, 2014, 10:55 p.m. | #1
On 8 December 2014 at 17:49, Ola Liljedahl <ola.liljedahl@linaro.org> wrote:

> Signed-off-by: Ola Liljedahl <ola.liljedahl@linaro.org>
> ---
> (This document/code contribution attached is provided under the terms of
> agreement LES-LTM-21309)
> The timer API is updated according to
> https://docs.google.com/a/linaro.org/document/d/1bfY_J8ecLJPsFTmYftb0NVmGnB9qkEc_NpcJ87yfaD8
> A major change is that timers are allocated and freed separately from
> timeouts
> being set and cancelled. The life-length of a timer normally corresponds
> to the
> life-length of the associated stateful flow while the life-length of a
> timeout
> corresponds to individual packets being transmitted and received.
> The reference timer implementation is lock-less for platforms with support
> for 128-bit (16-byte) atomic exchange and CAS operations. Otherwise a
> lock-based
> implementation (using as many locks as desired) is used but some operations
> (e.g. reset re-using existing timeout buffer) may still be lock-less.
> Updated the example example/timer/odp_timer_test.c.
>
>
This valuable description should be saved in the git history by moving it
ablove ---

Also checkpatch has issues

Using patch:
/home/mike/incoming/lng-odp_PATCH_2-3_api_odp_timer.h_updated_API,_
git am /home/mike/incoming/lng-odp_PATCH_2-3_api_odp_timer.h_updated_API,_
  Patch applied, building...
WARNING: line over 80 characters
#148: FILE: example/timer/odp_timer_test.c:138:
+ EXAMPLE_ABORT("Unexpected timeout received (timer %x, tick %"PRIu64",
expected %"PRIu64")\n",

total: 0 errors, 1 warnings, 0 checks, 2098 lines checked

NOTE: Ignored message types: DEPRECATED_VARIABLE NEW_TYPEDEFS

0001-api-odp_timer.h-updated-API-lock-less-implementation.patch has style
problems, please review.







>  example/timer/odp_timer_test.c                     |  165 ++-
>  platform/linux-generic/include/api/odp_timer.h     |  474 +++++++--
>  .../linux-generic/include/odp_timer_internal.h     |   69 +-
>  platform/linux-generic/odp_timer.c                 | 1083
> ++++++++++++++------
>  4 files changed, 1311 insertions(+), 480 deletions(-)
>
> diff --git a/example/timer/odp_timer_test.c
> b/example/timer/odp_timer_test.c
> index 9968bfe..b71e3f1 100644
> --- a/example/timer/odp_timer_test.c
> +++ b/example/timer/odp_timer_test.c
> @@ -43,67 +43,116 @@ typedef struct {
>  /** @private Barrier for test synchronisation */
>  static odp_barrier_t test_barrier;
>
> -/** @private Timer handle*/
> -static odp_timer_t test_timer;
> +/** @private Buffer pool handle */
> +static odp_buffer_pool_t pool;
>
> +/** @private Timer pool handle */
> +static odp_timer_pool_t tp;
> +
> +/** @private Timeout status ASCII strings */
> +static const char *const status2str[] = {
> +       "fresh", "stale", "orphaned"
> +};
> +
> +/** @private Timer set status ASCII strings */
> +static const char *timerset2str(uint64_t val)
> +{
> +       switch (val) {
> +       case ODP_TICK_TOOEARLY:
> +               return "tooearly";
> +       case ODP_TICK_TOOLATE:
> +               return "toolate";
> +       case ODP_TICK_INVALID:
> +               return "error";
> +       default:
> +               return "success";
> +       }
> +};
> +
> +/** @private Helper struct for timers */
> +struct test_timer {
> +       odp_timer_t tim;
> +       odp_buffer_t buf;
> +       uint64_t tick;
> +};
> +
> +/** @private Array of all timer helper structs */
> +static struct test_timer tt[256];
>
>  /** @private test timeout */
>  static void test_abs_timeouts(int thr, test_args_t *args)
>  {
> -       uint64_t tick;
>         uint64_t period;
>         uint64_t period_ns;
>         odp_queue_t queue;
> -       odp_buffer_t buf;
> -       int num;
> +       int remain = args->tmo_count;
> +       uint64_t tick;
> +       struct test_timer *ttp;
>
>         EXAMPLE_DBG("  [%i] test_timeouts\n", thr);
>
>         queue = odp_queue_lookup("timer_queue");
>
>         period_ns = args->period_us*ODP_TIME_USEC;
> -       period    = odp_timer_ns_to_tick(test_timer, period_ns);
> +       period    = odp_timer_ns_to_tick(tp, period_ns);
>
>         EXAMPLE_DBG("  [%i] period %"PRIu64" ticks,  %"PRIu64" ns\n", thr,
>                     period, period_ns);
>
> -       tick = odp_timer_current_tick(test_timer);
> +       EXAMPLE_DBG("  [%i] current tick %"PRIu64"\n", thr,
> +                   odp_timer_current_tick(tp));
>
> -       EXAMPLE_DBG("  [%i] current tick %"PRIu64"\n", thr, tick);
> -
> -       tick += period;
> -
> -       if (odp_timer_absolute_tmo(test_timer, tick, queue,
> ODP_BUFFER_INVALID)
> -           == ODP_TIMER_TMO_INVALID){
> -               EXAMPLE_DBG("Timeout request failed\n");
> +       ttp = &tt[thr - 1]; /* Thread starts at 1 */
> +       ttp->tim = odp_timer_alloc(tp, queue, ttp);
> +       if (ttp->tim == ODP_TIMER_INVALID) {
> +               EXAMPLE_ERR("Failed to allocate timer\n");
>                 return;
>         }
> +       ttp->buf = odp_buffer_alloc(pool);
> +       if (ttp->buf == ODP_BUFFER_INVALID) {
> +               EXAMPLE_ERR("Failed to allocate buffer\n");
> +               return;
> +       }
> +       tick = odp_timer_current_tick(tp);
>
> -       num = args->tmo_count;
> -
> -       while (1) {
> -               odp_timeout_t tmo;
> -
> -               buf = odp_schedule_one(&queue, ODP_SCHED_WAIT);
> -
> -               tmo  = odp_timeout_from_buffer(buf);
> -               tick = odp_timeout_tick(tmo);
> -
> -               EXAMPLE_DBG("  [%i] timeout, tick %"PRIu64"\n", thr, tick);
> -
> -               odp_buffer_free(buf);
> -
> -               num--;
> -
> -               if (num == 0)
> -                       break;
> +       while (remain != 0) {
> +               odp_buffer_t buf;
>
>                 tick += period;
> +               ttp->tick = odp_timer_set_abs(ttp->tim, tick, &ttp->buf);
> +               if (odp_unlikely(ttp->tick == ODP_TICK_TOOEARLY ||
> +                                ttp->tick == ODP_TICK_TOOLATE ||
> +                                ttp->tick == ODP_TICK_INVALID)) {
> +                       /* Too early or too late timeout requested */
> +                       EXAMPLE_ABORT("odp_timer_set_abs() failed: %s\n",
> +                                     timerset2str(ttp->tick));
> +               }
>
> -               odp_timer_absolute_tmo(test_timer, tick,
> -                                      queue, ODP_BUFFER_INVALID);
> +               /* Get the next expired timeout */
> +               buf = odp_schedule_one(&queue, ODP_SCHED_WAIT);
> +               if (odp_timer_tmo_metadata(buf, NULL, &tick, (void
> **)&ttp)) {
> +                       ttp->buf = buf;
> +                       if (odp_likely(tick != ttp->tick)) {
> +                               /* Not the expected expiration tick, timer
> has
> +                                * been reset or cancelled or freed */
> +                               EXAMPLE_ABORT("Unexpected timeout received
> (timer %x, tick %"PRIu64", expected %"PRIu64")\n",
> +                                             ttp->tim, tick, ttp->tick);
> +                       }
> +                       EXAMPLE_DBG("  [%i] timeout, tick %"PRIu64"\n",
> +                                   thr, tick);
> +                       remain--;
> +               } else {
> +                       /* Not a default timeout buffer */
> +                       EXAMPLE_ABORT("Unexpected buffer type (%u)
> received\n",
> +                                     odp_buffer_type(buf));
> +               }
>         }
>
> +       /* Free last timer used */
> +       ttp->tick = odp_timer_free(ttp->tim, &ttp->buf);
> +       if (ttp->buf != ODP_BUFFER_INVALID)
> +               odp_buffer_free(ttp->buf);
> +
>         if (odp_queue_sched_type(queue) == ODP_SCHED_SYNC_ATOMIC)
>                 odp_schedule_release_atomic();
>  }
> @@ -192,14 +241,14 @@ static void parse_args(int argc, char *argv[],
> test_args_t *args)
>         /* defaults */
>         args->core_count    = 0; /* all cores */
>         args->resolution_us = 10000;
> -       args->min_us        = args->resolution_us;
> +       args->min_us        = 0;
>         args->max_us        = 10000000;
>         args->period_us     = 1000000;
>         args->tmo_count     = 30;
>
>         while (1) {
>                 opt = getopt_long(argc, argv, "+c:r:m:x:p:t:h",
> -                                longopts, &long_index);
> +                                 longopts, &long_index);
>
>                 if (opt == -1)
>                         break;  /* No more options */
> @@ -243,13 +292,13 @@ int main(int argc, char *argv[])
>         odph_linux_pthread_t thread_tbl[MAX_WORKERS];
>         test_args_t args;
>         int num_workers;
> -       odp_buffer_pool_t pool;
>         void *pool_base;
>         odp_queue_t queue;
>         int first_core;
>         uint64_t cycles, ns;
>         odp_queue_param_t param;
>         odp_shm_t shm;
> +       odp_timer_pool_info_t tpinfo;
>
>         printf("\nODP timer example starts\n");
>
> @@ -309,7 +358,7 @@ int main(int argc, char *argv[])
>         printf("timeouts:           %i\n", args.tmo_count);
>
>         /*
> -        * Create message pool
> +        * Create buffer pool for timeouts
>          */
>         shm = odp_shm_reserve("msg_pool",
>                               MSG_POOL_SIZE, ODP_CACHE_LINE_SIZE, 0);
> @@ -321,9 +370,32 @@ int main(int argc, char *argv[])
>                                       ODP_BUFFER_TYPE_TIMEOUT);
>
>         if (pool == ODP_BUFFER_POOL_INVALID) {
> -               EXAMPLE_ERR("Pool create failed.\n");
> +               EXAMPLE_ERR("Buffer pool create failed.\n");
> +               return -1;
> +       }
> +
> +       tp = odp_timer_pool_create("timer_pool", pool,
> +                                  args.resolution_us*ODP_TIME_USEC,
> +                                  args.min_us*ODP_TIME_USEC,
> +                                  args.max_us*ODP_TIME_USEC,
> +                                  num_workers, /* One timer per worker */
> +                                  true,
> +                                  ODP_CLOCK_CPU);
> +       if (tp == ODP_TIMER_POOL_INVALID) {
> +               EXAMPLE_ERR("Timer pool create failed.\n");
>                 return -1;
>         }
> +       odp_timer_pool_start();
> +
> +       odp_shm_print_all();
> +       (void)odp_timer_pool_info(tp, &tpinfo, sizeof(tpinfo));
> +       printf("Timer pool\n");
> +       printf("----------\n");
> +       printf("  name: %s\n", tpinfo.name);
> +       printf("  resolution: %"PRIu64" ns\n", tpinfo.resolution);
> +       printf("  min tmo: %"PRIu64" ticks\n", tpinfo.min_tmo);
> +       printf("  max tmo: %"PRIu64" ticks\n", tpinfo.max_tmo);
> +       printf("\n");
>
>         /*
>          * Create a queue for timer test
> @@ -340,20 +412,7 @@ int main(int argc, char *argv[])
>                 return -1;
>         }
>
> -       test_timer = odp_timer_create("test_timer", pool,
> -                                     args.resolution_us*ODP_TIME_USEC,
> -                                     args.min_us*ODP_TIME_USEC,
> -                                     args.max_us*ODP_TIME_USEC);
> -
> -       if (test_timer == ODP_TIMER_INVALID) {
> -               EXAMPLE_ERR("Timer create failed.\n");
> -               return -1;
> -       }
> -
> -
> -       odp_shm_print_all();
> -
> -       printf("CPU freq %"PRIu64" hz\n", odp_sys_cpu_hz());
> +       printf("CPU freq %"PRIu64" Hz\n", odp_sys_cpu_hz());
>         printf("Cycles vs nanoseconds:\n");
>         ns = 0;
>         cycles = odp_time_ns_to_cycles(ns);
> diff --git a/platform/linux-generic/include/api/odp_timer.h
> b/platform/linux-generic/include/api/odp_timer.h
> index 6cca27c..f8ecf64 100644
> --- a/platform/linux-generic/include/api/odp_timer.h
> +++ b/platform/linux-generic/include/api/odp_timer.h
> @@ -8,9 +8,211 @@
>  /**
>   * @file
>   *
> - * ODP timer
> + * ODP timer service
>   */
>
> +/** Example #1 Retransmission timer (e.g. for reliable connections)
> + @code
> +
> +//Create timer pool for reliable connections
> +#define SEC 1000000000ULL //1s expressed in nanoseconds
> +odp_timer_pool_t tcp_tpid =
> +    odp_timer_pool_create("TCP",
> +                         buffer_pool,
> +                         1000000,//resolution 1ms
> +                         0,//min tmo
> +                         7200 * SEC,//max tmo length 2hours
> +                         40000,//num_timers
> +                         true,//shared
> +                         ODP_CLOCK_CPU
> +                        );
> +if (tcp_tpid == ODP_TIMER_POOL_INVALID)
> +{
> +       //Failed to create timer pool => fatal error
> +}
> +
> +
> +//Setting up a new connection
> +//Allocate retransmission timeout (identical for supervision timeout)
> +//The user pointer points back to the connection context
> +conn->ret_tim = odp_timer_alloc(tcp_tpid, queue, conn);
> +//Check if all resources were successfully allocated
> +if (conn->ret_tim == ODP_TIMER_INVALID)
> +{
> +       //Failed to allocate all resources for connection => tear down
> +       //Tear down connection
> +       ...
> +       return false;
> +}
> +//All necessary resources successfully allocated
> +//Compute initial retransmission length in timer ticks
> +conn->ret_len = odp_timer_ns_to_tick(tcp_tpid, 3 * SEC);//Per RFC1122
> +//Allocate a timeout buffer
> +conn->tmo_buf = odp_buffer_alloc(buffer_pool);
> +if (conn->tmo_buf == ODP_BUFFER_INVALID)
> +       ODP_ABORT("Failed to allocate timeout buffer\n");
> +//Arm the timer with our timeout
> +conn->expected = odp_timer_set_rel(conn->ret_tim, conn->ret_len,
> +                                  &conn->tmo_buf);
> +//Check return value for too early or too late expiration tick
> +return true;
> +
> +
> +//A packet for the connection has just been transmitted
> +//Reset the retransmission timer, reusing the previously specified timeout
> +conn->expected = odp_timer_set_rel(conn->ret_tim, conn->ret_len, NULL);
> +if (conn->expected == ODP_TICK_INVALID) {
> +       //Timer has expired
> +       //We could allocate another timeout buffer and reset the timer
> with it
> +       ...
> +}
> +//Else check return value for too early or too late expiration tick
> +
> +
> +//Check if the buffer is a system timeout buffer
> +if (!odp_timer_tmo_metadata(&buf, NULL, &exp_tick, (void**)&conn)) {
> +       //Not a system timeout buffer
> +       ...
> +}
> +//A retransmission timeout buffer for the connection has been received
> +conn->tmo_buf = buf;
> +//Check if timeout is fresh or stale, for stale timeouts we need to reset
> the
> +//timer
> +if (conn->expected == exp_tick) {
> +       //Fresh timeout, last transmitted packet not acked in time =>
> +         retransmit
> +       //Retransmit last packet (e.g. TCP segment)
> +       ...
> +       //Re-arm timer using original delta value
> +       odp_timer_set_rel(conn->ret_tim, conn->ret_len, &conn->tmo_buf);
> +} else {
> +       //Timeout does not have the expected expiration tick, timer has
> been
> +       //reset or cancelled
> +       //We can ignore the timeout or reset the timer to the expected tick
> +       if (conn->expected != ODP_TICK_INVALID)
> +               (void)odp_timer_set_abs(conn->ret_tim, conn->expected,
> +                                       &conn->tmo_buf);
> +}
> +
> + @endcode
> +*/
> +
> +/** Example #2 Periodic tick
> + @code
> +
> +//Create timer pool for periodic ticks
> +odp_timer_pool_t per_tpid =
> +    odp_timer_pool_create("periodic-tick",
> +                         buffer_pool,
> +                         1,//resolution 1ns
> +                         1,//minimum timeout length 1ns
> +                         1000000000,//maximum timeout length 1s
> +                         10,//num_timers
> +                         false,//not shared
> +                         ODP_CLOCK_CPU
> +                        );
> +if (per_tpid == ODP_TIMER_POOL_INVALID)
> +{
> +       //Failed to create timer pool => fatal error
> +}
> +
> +
> +//Allocate periodic timer
> +tim_1733 = odp_timer_alloc(per_tpid, queue, NULL);
> +//Check if all resources were successfully allocated
> +if (tim_1733 == ODP_TIMER_INVALID)
> +{
> +       //Failed to allocate all resources => tear down
> +       //Tear down other state
> +       ...
> +       return false;
> +}
> +//All necessary resources successfully allocated
> +//Compute tick period in timer ticks
> +period_1733 = odp_timer_ns_to_tick(per_tpid, 1000000000U / 1733U);//1733Hz
> +//Compute when next tick should expire
> +next_1733 = odp_timer_current_tick(per_tpid) + period_1733;
> +//Allocate a timeout buffer
> +buf_1733 = odp_buffer_alloc(buffer_pool);
> +if (buf_1733 == ODP_BUFFER_INVALID)
> +       ODP_ABORT("Failed to allocate timeout buffer\n");
> +//Arm the periodic timer
> +(void)odp_timer_set_abs(tim_1733, next_1733, &buf_1733);
> +return true;
> +
> +
> +
> +//Check if the buffer is a system timeout buffer
> +if (!odp_timer_tmo_metadata(&buf, &timer, NULL, NULL)) {
> +       //Not a system timeout buffer
> +       ...
> +}
> +if (timer != tim_1733) {
> +       //Not our periodic timer
> +       ...
> +}
> +//A periodic timer timeout has been received
> +//Do processing driven by timeout *before*
> +...
> +do {
> +       //Compute when the timer should expire next
> +       next_1733 += period_1733;
> +       //Check that this is in the future
> +       if (likely(next_1733 > odp_timer_current_tick(per_tpid))
> +               break;//Yes, done
> +       //Else we missed a timeout
> +       //Optionally attempt some recovery and/or logging of the problem
> +       ...
> +} while (1);
> +//Re-arm periodic timer
> +(void)odp_timer_set_abs(tim_1733, next_1733, &buf);
> +//Or do processing driven by timeout *after*
> +...
> +return;
> +
> + @endcode
> +*/
> +
> +/** Example #3 Tear down of flow
> + @code
> +//ctx points to flow context data structure owned by application
> +//Free the timer, cancelling any timeout
> +ctx->expected = odp_timer_free(ctx->timer, &ctx->tmo_buf);
> +//Invalidate our save timer handle
> +ctx->timer = ODP_TIMER_INVALID;
> +if (ctx->tmo_buf != ODP_BUFFER_INVALID) {
> +       //Tear down the flow
> +       ...
> +       odp_buffer_free(ctx->tmo_buf);
> +       //Free flow context
> +       ..
> +       //Teardown complete
> +} else {
> +       //Timer had already expired and timeout enqueued
> +       //Continue teardown when receiving timeout
> +       ctx->teardown_in_progress = true;
> +}
> +return;
> +
> +//A buffer has been received, check type
> +if (!odp_timer_tmo_metadata(buf, &timer, NULL, (void**)&ctx)) {
> +       //Not a system timeout buffer
> +       ...
> +}
> +ctx->tmo_buf = buf;
> +//Check if we are tearing down flow
> +if (ctx->teardown_in_progress) {
> +       //Continue tearing down the flow
> +       //Free the timeout buffer
> +       odp_buffer_free(ctx->tmo_buf));
> +       //Free the context
> +       ...
> +       //Teardown complete
> +}
> +
> + @endcode
> +*/
> +
>  #ifndef ODP_TIMER_H_
>  #define ODP_TIMER_H_
>
> @@ -18,6 +220,7 @@
>  extern "C" {
>  #endif
>
> +#include <stdlib.h>
>  #include <odp_std_types.h>
>  #include <odp_buffer.h>
>  #include <odp_buffer_pool.h>
> @@ -27,138 +230,283 @@ extern "C" {
>   *  @{
>   */
>
> -/**
> - * ODP timer handle
> - */
> -typedef uint32_t odp_timer_t;
> -
> -/** Invalid timer */
> -#define ODP_TIMER_INVALID 0
> +struct odp_timer_pool_s; /**< Forward declaration */
>
> +/**
> +* ODP timer pool handle (platform dependent)
> +*/
> +typedef struct odp_timer_pool_s *odp_timer_pool_t;
>
>  /**
> - * ODP timeout handle
> + * Invalid timer pool handle (platform dependent).
>   */
> -typedef odp_buffer_t odp_timer_tmo_t;
> +#define ODP_TIMER_POOL_INVALID NULL
>
> -/** Invalid timeout */
> -#define ODP_TIMER_TMO_INVALID 0
> +/**
> + * Clock sources for timers in timer pool.
> + */
> +typedef enum odp_timer_clk_src_e {
> +       /** Use CPU clock as clock source for timers */
> +       ODP_CLOCK_CPU,
> +       /** Use external clock as clock source for timers */
> +       ODP_CLOCK_EXT
> +       /* Platform dependent which other clock sources exist */
> +} odp_timer_clk_src_t;
>
> +/**
> +* ODP timer handle (platform dependent).
> +*/
> +typedef uint32_t odp_timer_t;
>
>  /**
> - * Timeout notification
> + * Invalid timer handle (platform dependent).
>   */
> -typedef odp_buffer_t odp_timeout_t;
> +#define ODP_TIMER_INVALID ((uint32_t)~0U)
>
> +/**
> + * Return values of timer set calls.
> + */
> +/**
> + * Timer set operation failed, expiration too early.
> + * Either retry with a later expiration time or process the timeout
> + * immediately. */
> +#define ODP_TICK_TOOEARLY 0xFFFFFFFFFFFFFFFDULL
> +/**
> + * Timer set operation failed, expiration too late.
> + * Truncate the expiration time against the maximum timeout for the
> + * timer pool. */
> +#define ODP_TICK_TOOLATE  0xFFFFFFFFFFFFFFFEULL
> +/**
> + * Timer set operation failed because not timeout buffer present or
> specified.
> + * This value is also return from odp_timer_cancel() and odp_timer_free().
> + */
> +#define ODP_TICK_INVALID  0xFFFFFFFFFFFFFFFFULL
>
>  /**
> - * Create a timer
> + * Create a timer pool
>   *
> - * Creates a new timer with requested properties.
> + * Create a new timer pool.
>   *
>   * @param name       Name
> - * @param pool       Buffer pool for allocating timeout notifications
> + * @param buf_pool   Buffer pool for allocating timeouts (and only
> timeouts)
>   * @param resolution Timeout resolution in nanoseconds
> - * @param min_tmo    Minimum timeout duration in nanoseconds
> - * @param max_tmo    Maximum timeout duration in nanoseconds
> + * @param min_tmo    Minimum relative timeout in nanoseconds
> + * @param max_tmo    Maximum relative timeout in nanoseconds
> + * @param num_timers Number of supported timers (minimum)
> + * @param shared     Shared or private timer pool.
> + *                Operations on shared timers will include the necessary
> + *                mutual exclusion, operations on private timers may not
> + *                (mutual exclusion is the responsibility of the caller).
> + * @param clk_src    Clock source to use
> + *
> + * @return Timer pool handle if successful, otherwise
> ODP_TIMER_POOL_INVALID
> + * and errno set
> + */
> +odp_timer_pool_t
> +odp_timer_pool_create(const char *name,
> +                     odp_buffer_pool_t buf_pool,
> +                     uint64_t resolution,
> +                     uint64_t min_tmo,
> +                     uint64_t max_tmo,
> +                     uint32_t num_timers,
> +                     int shared,
> +                     odp_timer_clk_src_t clk_src);
> +
> +/**
> + * Start a timer pool
> + *
> + * Start all created timer pools, enabling the allocation of timers.
> + * The purpose of this call is to coordinate the creation of multiple
> timer
> + * pools that may use the same underlying HW resources.
> + * This function may be called multiple times.
> + */
> +void odp_timer_pool_start(void);
> +
> +/**
> + * Destroy a timer pool
>   *
> - * @return Timer handle if successful, otherwise ODP_TIMER_INVALID
> + * Destroy a timer pool, freeing all resources.
> + * All timers must have been freed.
> + *
> + * @param tpid  Timer pool identifier
>   */
> -odp_timer_t odp_timer_create(const char *name, odp_buffer_pool_t pool,
> -                            uint64_t resolution, uint64_t min_tmo,
> -                            uint64_t max_tmo);
> +void odp_timer_pool_destroy(odp_timer_pool_t tpid);
>
>  /**
>   * Convert timer ticks to nanoseconds
>   *
> - * @param timer Timer
> + * @param tpid  Timer pool identifier
>   * @param ticks Timer ticks
>   *
>   * @return Nanoseconds
>   */
> -uint64_t odp_timer_tick_to_ns(odp_timer_t timer, uint64_t ticks);
> +uint64_t odp_timer_tick_to_ns(odp_timer_pool_t tpid, uint64_t ticks);
>
>  /**
>   * Convert nanoseconds to timer ticks
>   *
> - * @param timer Timer
> + * @param tpid  Timer pool identifier
>   * @param ns    Nanoseconds
>   *
>   * @return Timer ticks
>   */
> -uint64_t odp_timer_ns_to_tick(odp_timer_t timer, uint64_t ns);
> +uint64_t odp_timer_ns_to_tick(odp_timer_pool_t tpid, uint64_t ns);
>
>  /**
> - * Timer resolution in nanoseconds
> + * Current tick value
>   *
> - * @param timer Timer
> + * @param tpid Timer pool identifier
>   *
> - * @return Resolution in nanoseconds
> + * @return Current time in timer ticks
>   */
> -uint64_t odp_timer_resolution(odp_timer_t timer);
> +uint64_t odp_timer_current_tick(odp_timer_pool_t tpid);
>
>  /**
> - * Maximum timeout in timer ticks
> + * ODP timer pool information and configuration
> + */
> +
> +typedef struct odp_timer_pool_info_s {
> +       uint64_t resolution;/**< Timer resolution (in ns) */
> +       uint64_t min_tmo;   /**< Min supported relative timeout (in
> ticks)*/
> +       uint64_t max_tmo;   /**< Max supported relative timeout (in
> ticks)*/
> +       uint32_t num_timers;/**< Number of supported timers */
> +       uint32_t cur_timers;/**< Number of currently allocated timers */
> +       uint32_t hwm_timers;/**< Number of used timers high watermark */
> +       int shared;         /**< Shared flag */
> +       char name[80];      /**< Name of timer pool */
> +} odp_timer_pool_info_t;
> +
> +/**
> + * Query timer pool information and configuration
> + *  Timer resolution in nanoseconds
> + *  Minimum and maximum (relative) timeouts in timer ticks
> + *  Number of supported timers
> + *  Nunber of timers in use
> + *  Nunber of timers in use - high watermark
> + *  Shared or private timer pool
> + *  Name of timer pool.
>   *
> - * @param timer Timer
> + * @param tpid Timer pool identifier
> + * @param buf Pointer to information buffer
> + * @param buf_size Size of information buffer
>   *
> - * @return Maximum timeout in timer ticks
> + * @return Actual size written
>   */
> -uint64_t odp_timer_maximum_tmo(odp_timer_t timer);
> +size_t odp_timer_pool_info(odp_timer_pool_t tpid,
> +                          odp_timer_pool_info_t *buf,
> +                          size_t buf_size);
>
>  /**
> - * Current timer tick
> + * Allocate a timer
>   *
> - * @param timer Timer
> + * Create a timer (allocating all necessary resources e.g. timeout event)
> from
> + * the timer pool. The user_ptr is copied to timeouts and can be retrieved
> + * using the odp_timer_userptr() call.
>   *
> - * @return Current time in timer ticks
> + * @param tpid     Timer pool identifier
> + * @param queue    Destination queue for timeout notifications
> + * @param user_ptr User defined pointer or NULL to be copied to timeouts
> + *
> + * @return Timer handle if successful, otherwise ODP_TIMER_INVALID and
> + *        errno set.
> + */
> +odp_timer_t odp_timer_alloc(odp_timer_pool_t tpid,
> +                           odp_queue_t queue,
> +                           void *user_ptr);
> +
> +/**
> + * Free a timer
> + *
> + * Free (destroy) a timer, freeing associated resources.
> + * The timeout buffer for an active timer will be returned.
> + * An expired and enqueued timeout buffer will not be freed.
> + * It is the responsibility of the application to free this timeout when
> it
> + * is received.
> + *
> + * @param tim      Timer handle
> + * @param tmo_buf Reference to a buffer variable which will be written
> with
> + * the buffer handle of any present timeout buffer (e.g. for an active
> timer).
> + * @return       A tick value which will not match any valid expiration
> tick.
>   */
> -uint64_t odp_timer_current_tick(odp_timer_t timer);
> +uint64_t odp_timer_free(odp_timer_t tim, odp_buffer_t *tmo_buf);
>
>  /**
> - * Request timeout with an absolute timer tick
> + * Set a timer (absolute time) with a user-provided timeout buffer
> + *
> + * Set (arm) the timer to expire at specific time. The timeout
> + * buffer will be enqueued when the timer expires.
>   *
> - * When tick reaches tmo_tick, the timer enqueues the timeout
> notification into
> - * the destination queue.
> + * Note: any invalid parameters will be treated as programming errors and
> will
> + * cause the application to abort.
>   *
> - * @param timer    Timer
> - * @param tmo_tick Absolute timer tick value which triggers the timeout
> - * @param queue    Destination queue for the timeout notification
> - * @param buf      User defined timeout notification buffer. When
> - *                 ODP_BUFFER_INVALID, default timeout notification is
> used.
> + * @param tim      Timer
> + * @param abs_tck  Expiration time in absolute timer ticks
> + * @param tmo_buf  Reference to a buffer variable that points to timeout
> buffer
> + * or NULL to reuse the existing timeout buffer
>   *
> - * @return Timeout handle if successful, otherwise ODP_TIMER_TMO_INVALID
> + * @return The expiration tick or ODP_TICK_TOOEARLY, ODP_TICK_TOOLATE or
> + * ODP_TICK_INVALID (timer not active and no timeout buffer to reuse).
>   */
> -odp_timer_tmo_t odp_timer_absolute_tmo(odp_timer_t timer, uint64_t
> tmo_tick,
> -                                      odp_queue_t queue, odp_buffer_t
> buf);
> +uint64_t odp_timer_set_abs(odp_timer_t tim,
> +                          uint64_t abs_tck,
> +                          odp_buffer_t *tmo_buf);
>
>  /**
> - * Cancel a timeout
> + * Set a timer with a relative expiration time and user-provided buffer.
>   *
> - * @param timer Timer
> - * @param tmo   Timeout to cancel
> + * Set (arm) the timer to expire at a relative future time.
>   *
> - * @return 0 if successful
> + * Note: any invalid parameters will be treated as programming errors and
> will
> + * cause the application to abort.
> + *
> + * @param tim      Timer
> + * @param rel_tck  Expiration time in timer ticks relative to current
> time of
> + *                the timer pool the timer belongs to
> + * @param tmo_buf  Reference to a buffer variable that points to timeout
> buffer
> + * or NULL to reuse the existing timeout buffer
> + *
> + * @return The expiration tick or ODP_TICK_TOOEARLY, ODP_TICK_TOOLATE or
> + * ODP_TICK_INVALID (timer not active and no timeout buffer to reuse).
>   */
> -int odp_timer_cancel_tmo(odp_timer_t timer, odp_timer_tmo_t tmo);
> +uint64_t odp_timer_set_rel(odp_timer_t tim,
> +                          uint64_t rel_tck,
> +                          odp_buffer_t *tmo_buf);
>
>  /**
> - * Convert buffer handle to timeout handle
> + * Cancel a timer
> + *
> + * Cancel a timer, preventing future expiration and delivery. Return any
> + * present timeout buffer.
> + *
> + * A timer that has already expired may be impossible to cancel and the
> timeout
> + * will instead be delivered to the destination queue.
>   *
> - * @param buf  Buffer handle
> + * Note: any invalid parameters will be treated as programming errors and
> will
> + * cause the application to abort.
>   *
> - * @return Timeout buffer handle
> + * @param tim     Timer
> + * @param tmo_buf Reference to a buffer variable which will be written
> with
> + * the buffer handle of any present timeout buffer (e.g. for an active
> timer).
> + * @return       A tick value which will not match any valid expiration
> tick.
>   */
> -odp_timeout_t odp_timeout_from_buffer(odp_buffer_t buf);
> +uint64_t odp_timer_cancel(odp_timer_t tim, odp_buffer_t *tmo_buf);
>
>  /**
> - * Return absolute timeout tick
> + * Get metadata from system timeout buffer
>   *
> - * @param tmo Timeout buffer handle
> + * @param buf A timeout buffer
> + * @param hdl NULL or a pointer where the timer handle will be written.
> + * @param exp_tck NULL or a pointer where the expiration tick will be
> written.
> + * @param user_ptr NULL or a pointer where the user pointer will be
> written.
>   *
> - * @return Absolute timeout tick
> + * @return True (1) if timeout buffer is of type ODP_BUFFER_TYPE_TIMEOUT
> and
> + *         metadata variables have been updated from the timeout.
> + *         False (0) if timeout buffer is not of type
> ODP_BUFFER_TYPE_TIMEOUT.
>   */
> -uint64_t odp_timeout_tick(odp_timeout_t tmo);
> +int odp_timer_tmo_metadata(odp_buffer_t buf,
> +               odp_timer_t *hdl,
> +               uint64_t *exp_tck,
> +               void **user_ptr);
>
>  /**
>   * @}
> diff --git a/platform/linux-generic/include/odp_timer_internal.h
> b/platform/linux-generic/include/odp_timer_internal.h
> index ad28f53..0e0cf48 100644
> --- a/platform/linux-generic/include/odp_timer_internal.h
> +++ b/platform/linux-generic/include/odp_timer_internal.h
> @@ -1,4 +1,4 @@
> -/* Copyright (c) 2013, Linaro Limited
> +/* Copyright (c) 2014, Linaro Limited
>   * All rights reserved.
>   *
>   * SPDX-License-Identifier:     BSD-3-Clause
> @@ -8,72 +8,49 @@
>  /**
>   * @file
>   *
> - * ODP timer timeout descriptor - implementation internal
> + * ODP timeout descriptor - implementation internal
>   */
>
>  #ifndef ODP_TIMER_INTERNAL_H_
>  #define ODP_TIMER_INTERNAL_H_
>
> -#ifdef __cplusplus
> -extern "C" {
> -#endif
> -
> -#include <odp_std_types.h>
> -#include <odp_queue.h>
> -#include <odp_buffer.h>
> +#include <odp_align.h>
> +#include <odp_debug.h>
>  #include <odp_buffer_internal.h>
>  #include <odp_buffer_pool_internal.h>
>  #include <odp_timer.h>
>
> -struct timeout_t;
> -
> -typedef struct timeout_t {
> -       struct timeout_t *next;
> -       int               timer_id;
> -       int               tick;
> -       uint64_t          tmo_tick;
> -       odp_queue_t       queue;
> -       odp_buffer_t      buf;
> -       odp_buffer_t      tmo_buf;
> -} timeout_t;
> -
> -
> -struct odp_timeout_hdr_t;
> -
>  /**
> - * Timeout notification header
> + * Internal Timeout header
>   */
> -typedef struct odp_timeout_hdr_t {
> +typedef struct {
> +       /* common buffer header */
>         odp_buffer_hdr_t buf_hdr;
>
> -       timeout_t meta;
> -
> -       uint8_t buf_data[];
> +       /* Requested expiration time */
> +       uint64_t expiration;
> +       /* User ptr inherited from parent timer */
> +       void *user_ptr;
> +       /* Parent timer */
> +       odp_timer_t timer;
> +#if __SIZEOF_POINTER__ != 4
> +       uint32_t pad32;
> +#endif
> +       uint8_t buf_data[0];
>  } odp_timeout_hdr_t;
>
> -
> -
>  ODP_STATIC_ASSERT(sizeof(odp_timeout_hdr_t) ==
> -          ODP_OFFSETOF(odp_timeout_hdr_t, buf_data),
> -          "ODP_TIMEOUT_HDR_T__SIZE_ERR");
> -
> +                 ODP_OFFSETOF(odp_timeout_hdr_t, buf_data),
> +                 "sizeof(odp_timeout_hdr_t) ==
> ODP_OFFSETOF(odp_timeout_hdr_t, buf_data)");
>  ODP_STATIC_ASSERT(sizeof(odp_timeout_hdr_t) % sizeof(uint64_t) == 0,
> -          "ODP_TIMEOUT_HDR_T__SIZE_ERR2");
> -
> +                 "sizeof(odp_timeout_hdr_t) % sizeof(uint64_t) == 0");
>
>  /**
> - * Return timeout header
> + * Return the timeout header
>   */
> -static inline odp_timeout_hdr_t *odp_timeout_hdr(odp_timeout_t tmo)
> +static inline odp_timeout_hdr_t *odp_timeout_hdr(odp_buffer_t buf)
>  {
> -       odp_buffer_hdr_t *buf_hdr = odp_buf_to_hdr((odp_buffer_t)tmo);
> -       return (odp_timeout_hdr_t *)(uintptr_t)buf_hdr;
> -}
> -
> -
> -
> -#ifdef __cplusplus
> +       return (odp_timeout_hdr_t *)odp_buf_to_hdr(buf);
>  }
> -#endif
>
>  #endif
> diff --git a/platform/linux-generic/odp_timer.c
> b/platform/linux-generic/odp_timer.c
> index a4fef58..02a460b 100644
> --- a/platform/linux-generic/odp_timer.c
> +++ b/platform/linux-generic/odp_timer.c
> @@ -4,428 +4,875 @@
>   * SPDX-License-Identifier:     BSD-3-Clause
>   */
>
> -#include <odp_timer.h>
> -#include <odp_timer_internal.h>
> -#include <odp_time.h>
> -#include <odp_buffer_pool_internal.h>
> -#include <odp_internal.h>
> +/**
> + * @file
> + *
> + * ODP timer service
> + *
> + */
> +
> +/* Check if compiler supports 16-byte atomics. GCC needs -mcx16 flag */
> +/* Using spin lock actually seems faster on Core2 */
> +#ifdef ODP_ATOMIC_U128
> +/* TB_NEEDS_PAD defined if sizeof(odp_buffer_t) != 8 */
> +#define TB_NEEDS_PAD
> +#define TB_SET_PAD(x) ((x).pad = 0)
> +#else
> +#define TB_SET_PAD(x) (void)(x)
> +#endif
> +
> +#include <assert.h>
> +#include <errno.h>
> +#include <string.h>
> +#include <stdlib.h>
> +#include <time.h>
> +#include <signal.h>
>  #include <odp_atomic.h>
> +#include <odp_atomic_internal.h>
> +#include <odp_std_types.h>
> +#include <odp_buffer.h>
> +#include <odp_buffer_pool.h>
> +#include <odp_queue.h>
> +#include <odp_hints.h>
>  #include <odp_spinlock.h>
>  #include <odp_sync.h>
>  #include <odp_debug_internal.h>
> +#include <odp_debug.h>
> +#include <odp_align.h>
> +#include <odp_align_internal.h>
> +#include <odp_shared_memory.h>
> +#include <odp_hints.h>
> +#include <odp_internal.h>
> +#include <odp_time.h>
> +#include <odp_timer.h>
> +#include <odp_timer_internal.h>
>
> -#include <signal.h>
> -#include <time.h>
> +#define TMO_UNUSED   ((uint64_t)0xFFFFFFFFFFFFFFFF)
> +#define TMO_INACTIVE ((uint64_t)0xFFFFFFFFFFFFFFFE)
>
> -#include <string.h>
> +#ifdef __ARM_ARCH
> +#define PREFETCH(ptr) __builtin_prefetch((ptr), 0, 0)
> +#else
> +#define PREFETCH(ptr) (void)(ptr)
> +#endif
>
> -#define NUM_TIMERS    1
> -#define MAX_TICKS     1024
> -#define MAX_RES       ODP_TIME_SEC
> -#define MIN_RES       (100*ODP_TIME_USEC)
>
> +/******************************************************************************
> + * Mutual exclusion in the absence of CAS16
> +
> *****************************************************************************/
>
> +#ifndef ODP_ATOMIC_U128
> +#define NUM_LOCKS 1024
> +static _odp_atomic_flag_t locks[NUM_LOCKS]; /* Multiple locks per cache
> line! */
> +#define IDX2LOCK(idx) (&locks[(idx) % NUM_LOCKS])
> +#endif
>
> -typedef struct {
> -       odp_spinlock_t lock;
> -       timeout_t      *list;
> -} tick_t;
> -
> -typedef struct {
> -       int               allocated;
> -       volatile int      active;
> -       volatile uint64_t cur_tick;
> -       timer_t           timerid;
> -       odp_timer_t       timer_hdl;
> -       odp_buffer_pool_t pool;
> -       uint64_t          resolution_ns;
> -       uint64_t          max_ticks;
> -       tick_t            tick[MAX_TICKS];
> -
> -} timer_ring_t;
> -
> -typedef struct {
> -       odp_spinlock_t lock;
> -       int            num_timers;
> -       timer_ring_t   timer[NUM_TIMERS];
> -
> -} timer_global_t;
>
> +/******************************************************************************
> + * Translation between timeout and timeout header
> +
> *****************************************************************************/
>
> -/* Global */
> -static timer_global_t odp_timer;
> +/**
> + * System timeout buffer (ODP_BUFFER_TYPE_TIEMOUT)
> + */
> +typedef odp_buffer_t odp_timer_tmo_t;
>
> -static void add_tmo(tick_t *tick, timeout_t *tmo)
> +/** Translate from generic buffer to timeout */
> +static inline odp_timer_tmo_t odp_tmo_from_buffer(odp_buffer_t buf)
>  {
> -       odp_spinlock_lock(&tick->lock);
> -
> -       tmo->next  = tick->list;
> -       tick->list = tmo;
> -
> -       odp_spinlock_unlock(&tick->lock);
> +       /* In this implementation, timeout == buffer */
> +       return (odp_timer_tmo_t)buf;
>  }
>
> -static timeout_t *rem_tmo(tick_t *tick)
> +/** Translate from timeout to generic buffer */
> +static inline odp_buffer_t odp_buffer_from_tmo(odp_timer_tmo_t tmo)
>  {
> -       timeout_t *tmo;
> +       /* In this implementation, buffer == timeout */
> +       return (odp_buffer_t)tmo;
> +}
>
> -       odp_spinlock_lock(&tick->lock);
> +static inline odp_timeout_hdr_t *odp_tmo_to_hdr(odp_timer_tmo_t tmo)
> +{
> +       odp_buffer_t buf = odp_buffer_from_tmo(tmo);
> +       odp_timeout_hdr_t *tmo_hdr = (odp_timeout_hdr_t
> *)odp_buf_to_hdr(buf);
> +       return tmo_hdr;
> +}
>
> -       tmo = tick->list;
>
> +/******************************************************************************
> + * odp_timer abstract datatype
> +
> *****************************************************************************/
> +
> +typedef struct tick_buf_s {
> +       odp_atomic_u64_t exp_tck;/* Expiration tick or TMO_xxx */
> +       odp_buffer_t tmo_buf;/* ODP_BUFFER_INVALID if timer not active */
> +#ifdef TB_NEEDS_PAD
> +       uint32_t pad;/* Need to be able to access padding for successful
> CAS */
> +#endif
> +} tick_buf_t
> +#ifdef ODP_ATOMIC_U128
> +ODP_ALIGNED(16) /* 16-byte atomic operations need properly aligned
> addresses */
> +#endif
> +;
> +
> +ODP_STATIC_ASSERT(sizeof(tick_buf_t) == 16, "sizeof(tick_buf_t) == 16");
> +
> +typedef struct odp_timer_s {
> +       void *user_ptr; /* User-defined pointer for odp_timer_tmo_t
> buffers */
> +       odp_queue_t queue;/* Used for free list when timer is free */
> +} odp_timer;
> +
> +static void timer_init(odp_timer *tim,
> +               tick_buf_t *tb,
> +               odp_queue_t _q,
> +               void *_up)
> +{
> +       tim->queue = _q;
> +       tim->user_ptr = _up;
> +       tb->tmo_buf = ODP_BUFFER_INVALID;
> +       /* All pad fields need a defined and constant value */
> +       TB_SET_PAD(*tb);
> +       /* Release the timer by setting timer state to inactive */
> +       _odp_atomic_u64_store_mm(&tb->exp_tck, TMO_INACTIVE,
> _ODP_MEMMODEL_RLS);
> +}
>
> -       if (tmo)
> -               tick->list = tmo->next;
> +/* Teardown when timer is freed */
> +static void timer_fini(odp_timer *tim, tick_buf_t *tb)
> +{
> +       assert(tb->exp_tck.v == TMO_UNUSED);
> +       assert(tb->tmo_buf == ODP_BUFFER_INVALID);
> +       tim->queue = ODP_QUEUE_INVALID;
> +       tim->user_ptr = NULL;
> +}
>
> -       odp_spinlock_unlock(&tick->lock);
> +static inline uint32_t get_next_free(odp_timer *tim)
> +{
> +       /* Reusing 'queue' for next free index */
> +       return tim->queue;
> +}
>
> -       if (tmo)
> -               tmo->next = NULL;
> +static inline void set_next_free(odp_timer *tim, uint32_t nf)
> +{
> +       assert(tim->queue == ODP_QUEUE_INVALID);
> +       /* Reusing 'queue' for next free index */
> +       tim->queue = nf;
> +}
>
> -       return tmo;
>
> +/******************************************************************************
> + * odp_timer_pool abstract datatype
> + * Inludes alloc and free timer
> +
> *****************************************************************************/
> +
> +typedef struct odp_timer_pool_s {
> +/* Put frequently accessed fields in the first cache line */
> +       odp_atomic_u64_t cur_tick;/* Current tick value */
> +       uint64_t min_rel_tck;
> +       uint64_t max_rel_tck;
> +       uint64_t resolution_ns;
> +       tick_buf_t *tick_buf; /* Expiration tick and timeout buffer */
> +       odp_timer *timers; /* User pointer and queue handle (and lock) */
> +       odp_atomic_u32_t high_wm;/* High watermark of allocated timers */
> +       odp_spinlock_t itimer_running;
> +       odp_spinlock_t lock;
> +       bool shared;
> +       uint32_t num_alloc;/* Current number of allocated timers */
> +       uint32_t max_timers;/* Max number of timers */
> +       uint32_t first_free;/* 0..max_timers-1 => free timer */
> +       uint32_t tp_idx;/* Index into timer_pool array */
> +       const char *name;
> +       odp_buffer_pool_t buf_pool;
> +       odp_shm_t shm;
> +       timer_t timerid;
> +       odp_timer_clk_src_t clk_src;
> +} odp_timer_pool;
> +
> +#define MAX_TIMER_POOLS 255 /* Leave one for ODP_TIMER_INVALID */
> +#define INDEX_BITS 24
> +static odp_atomic_u32_t num_timer_pools;
> +static odp_timer_pool *timer_pool[MAX_TIMER_POOLS];
> +
> +static inline odp_timer_pool *handle_to_tp(odp_timer_t hdl)
> +{
> +       uint32_t tp_idx = hdl >> INDEX_BITS;
> +       if (odp_likely(tp_idx < MAX_TIMER_POOLS)) {
> +               odp_timer_pool *tp = timer_pool[tp_idx];
> +               if (odp_likely(tp != NULL))
> +                       return timer_pool[tp_idx];
> +       }
> +       ODP_ABORT("Invalid timer handle %#x\n", hdl);
>  }
>
> -/**
> - * Search and delete tmo entry from timeout list
> - * return -1 : on error.. handle not in list
> - *             0 : success
> - */
> -static int find_and_del_tmo(timeout_t **tmo, odp_timer_tmo_t handle)
> +static inline uint32_t handle_to_idx(odp_timer_t hdl,
> +               struct odp_timer_pool_s *tp)
>  {
> -       timeout_t *cur, *prev;
> -       prev = NULL;
> +       uint32_t idx = hdl & ((1U << INDEX_BITS) - 1U);
> +       PREFETCH(&tp->tick_buf[idx]);
> +       if (odp_likely(idx < odp_atomic_load_u32(&tp->high_wm)))
> +               return idx;
> +       ODP_ABORT("Invalid timer handle %#x\n", hdl);
> +}
>
> -       for (cur = *tmo; cur != NULL; prev = cur, cur = cur->next) {
> -               if (cur->tmo_buf == handle) {
> -                       if (prev == NULL)
> -                               *tmo = cur->next;
> -                       else
> -                               prev->next = cur->next;
> +static inline odp_timer_t tp_idx_to_handle(struct odp_timer_pool_s *tp,
> +               uint32_t idx)
> +{
> +       assert(idx < (1U << INDEX_BITS));
> +       return (tp->tp_idx << INDEX_BITS) | idx;
> +}
>
> -                       break;
> -               }
> +/* Forward declarations */
> +static void itimer_init(odp_timer_pool *tp);
> +static void itimer_fini(odp_timer_pool *tp);
> +
> +static odp_timer_pool *odp_timer_pool_new(
> +       const char *_name,
> +       odp_buffer_pool_t _bp,
> +       uint64_t _res,
> +       uint64_t _mintmo,
> +       uint64_t _maxtmo,
> +       uint32_t _maxtim,
> +       bool _sh,
> +       odp_timer_clk_src_t _cs)
> +{
> +       uint32_t tp_idx = odp_atomic_fetch_add_u32(&num_timer_pools, 1);
> +       if (odp_unlikely(tp_idx >= MAX_TIMER_POOLS)) {
> +               /* Restore the previous value */
> +               odp_atomic_sub_u32(&num_timer_pools, 1);
> +               errno = ENFILE; /* Table overflow */
> +               return NULL;
>         }
> +       size_t sz0 = ODP_ALIGN_ROUNDUP(sizeof(odp_timer_pool),
> +                       ODP_CACHE_LINE_SIZE);
> +       size_t sz1 = ODP_ALIGN_ROUNDUP(sizeof(tick_buf_t) * _maxtim,
> +                       ODP_CACHE_LINE_SIZE);
> +       size_t sz2 = ODP_ALIGN_ROUNDUP(sizeof(odp_timer) * _maxtim,
> +                       ODP_CACHE_LINE_SIZE);
> +       odp_shm_t shm = odp_shm_reserve(_name, sz0 + sz1 + sz2,
> +                       ODP_CACHE_LINE_SIZE, ODP_SHM_SW_ONLY);
> +       if (odp_unlikely(shm == ODP_SHM_INVALID))
> +               ODP_ABORT("%s: timer pool shm-alloc(%zuKB) failed\n",
> +                         _name, (sz0 + sz1 + sz2) / 1024);
> +       odp_timer_pool *tp = (odp_timer_pool *)odp_shm_addr(shm);
> +       odp_atomic_init_u64(&tp->cur_tick, 0);
> +       tp->name = strdup(_name);
> +       tp->shm = shm;
> +       tp->buf_pool = _bp;
> +       tp->resolution_ns = _res;
> +       tp->min_rel_tck = odp_timer_ns_to_tick(tp, _mintmo);
> +       tp->max_rel_tck = odp_timer_ns_to_tick(tp, _maxtmo);
> +       tp->num_alloc = 0;
> +       odp_atomic_init_u32(&tp->high_wm, 0);
> +       tp->max_timers = _maxtim;
> +       tp->first_free = 0;
> +       tp->shared = _sh;
> +       tp->clk_src = _cs;
> +       tp->tick_buf = (void *)((char *)odp_shm_addr(shm) + sz0);
> +       tp->timers = (void *)((char *)odp_shm_addr(shm) + sz0 + sz1);
> +       /* Initialize all odp_timer entries */
> +       uint32_t i;
> +       for (i = 0; i < tp->max_timers; i++) {
> +               set_next_free(&tp->timers[i], i + 1);
> +               tp->timers[i].user_ptr = NULL;
> +       }
> +       tp->tp_idx = tp_idx;
> +       odp_spinlock_init(&tp->lock);
> +       odp_spinlock_init(&tp->itimer_running);
> +       timer_pool[tp_idx] = tp;
> +       if (tp->clk_src == ODP_CLOCK_CPU)
> +               itimer_init(tp);
> +       return tp;
> +}
>
> -       if (!cur)
> -               /* couldn't find tmo in list */
> -               return -1;
> -
> -       /* application to free tmo_buf provided by absolute_tmo call */
> -       return 0;
> +static void odp_timer_pool_del(odp_timer_pool *tp)
> +{
> +       odp_spinlock_lock(&tp->lock);
> +       timer_pool[tp->tp_idx] = NULL;
> +       /* Wait for itimer thread to stop running */
> +       odp_spinlock_lock(&tp->itimer_running);
> +       if (tp->num_alloc != 0) {
> +               /* It's a programming error to attempt to destroy a */
> +               /* timer pool which is still in use */
> +               ODP_ABORT("%s: timers in use\n", tp->name);
> +       }
> +       if (tp->clk_src == ODP_CLOCK_CPU)
> +               itimer_fini(tp);
> +       int rc = odp_shm_free(tp->shm);
> +       if (rc != 0)
> +               ODP_ABORT("Failed to free shared memory (%d)\n", rc);
>  }
>
> -int odp_timer_cancel_tmo(odp_timer_t timer_hdl, odp_timer_tmo_t tmo)
> +static inline odp_timer_t timer_alloc(odp_timer_pool *tp,
> +                                     odp_queue_t queue,
> +                                     void *user_ptr)
>  {
> -       int id;
> -       int tick_idx;
> -       timeout_t *cancel_tmo;
> -       odp_timeout_hdr_t *tmo_hdr;
> -       tick_t *tick;
> +       odp_timer_t hdl;
> +       odp_spinlock_lock(&tp->lock);
> +       if (odp_likely(tp->num_alloc < tp->max_timers)) {
> +               tp->num_alloc++;
> +               /* Remove first unused timer from free list */
> +               assert(tp->first_free != tp->max_timers);
> +               uint32_t idx = tp->first_free;
> +               odp_timer *tim = &tp->timers[idx];
> +               tp->first_free = get_next_free(tim);
> +               /* Initialize timer */
> +               timer_init(tim, &tp->tick_buf[idx], queue, user_ptr);
> +               if (odp_unlikely(tp->num_alloc >
> +                                odp_atomic_load_u32(&tp->high_wm)))
> +                       /* Update high_wm last with release model to
> +                        * ensure timer initialization is visible */
> +                       _odp_atomic_u32_store_mm(&tp->high_wm,
> +                                                tp->num_alloc,
> +                                                _ODP_MEMMODEL_RLS);
> +               hdl = tp_idx_to_handle(tp, idx);
> +       } else {
> +               errno = ENFILE; /* Reusing file table overflow */
> +               hdl = ODP_TIMER_INVALID;
> +       }
> +       odp_spinlock_unlock(&tp->lock);
> +       return hdl;
> +}
>
> -       /* get id */
> -       id = (int)timer_hdl - 1;
> +static odp_buffer_t timer_cancel(odp_timer_pool *tp,
> +               uint32_t idx,
> +               uint64_t new_state);
>
> -       tmo_hdr = odp_timeout_hdr((odp_timeout_t) tmo);
> -       /* get tmo_buf to cancel */
> -       cancel_tmo = &tmo_hdr->meta;
> +static inline odp_buffer_t timer_free(odp_timer_pool *tp, uint32_t idx)
> +{
> +       odp_timer *tim = &tp->timers[idx];
>
> -       tick_idx = cancel_tmo->tick;
> -       tick = &odp_timer.timer[id].tick[tick_idx];
> +       /* Free the timer by setting timer state to unused and
> +        * grab any timeout buffer */
> +       odp_buffer_t old_buf = timer_cancel(tp, idx, TMO_UNUSED);
>
> -       odp_spinlock_lock(&tick->lock);
> -       /* search and delete tmo from tick list */
> -       if (find_and_del_tmo(&tick->list, tmo) != 0) {
> -               odp_spinlock_unlock(&tick->lock);
> -               ODP_DBG("Couldn't find the tmo (%d) in tick list\n",
> (int)tmo);
> -               return -1;
> -       }
> -       odp_spinlock_unlock(&tick->lock);
> +       /* Destroy timer */
> +       timer_fini(tim, &tp->tick_buf[idx]);
>
> -       return 0;
> +       /* Insert timer into free list */
> +       odp_spinlock_lock(&tp->lock);
> +       set_next_free(tim, tp->first_free);
> +       tp->first_free = idx;
> +       assert(tp->num_alloc != 0);
> +       tp->num_alloc--;
> +       odp_spinlock_unlock(&tp->lock);
> +
> +       return old_buf;
>  }
>
> -static void notify_function(union sigval sigval)
> -{
> -       uint64_t cur_tick;
> -       timeout_t *tmo;
> -       tick_t *tick;
> -       timer_ring_t *timer;
>
> +/******************************************************************************
> + * Operations on timers
> + * expire/reset/cancel timer
> +
> *****************************************************************************/
>
> -       timer = sigval.sival_ptr;
> +static bool timer_reset(uint32_t idx,
> +               uint64_t abs_tck,
> +               odp_buffer_t *tmo_buf,
> +               odp_timer_pool *tp)
> +{
> +       bool success = true;
> +       tick_buf_t *tb = &tp->tick_buf[idx];
> +
> +       if (tmo_buf == NULL || *tmo_buf == ODP_BUFFER_INVALID) {
> +#ifdef ODP_ATOMIC_U128
> +               tick_buf_t new, old;
> +               do {
> +                       /* Relaxed and non-atomic read of current values */
> +                       old.exp_tck.v = tb->exp_tck.v;
> +                       old.tmo_buf = tb->tmo_buf;
> +                       TB_SET_PAD(old);
> +                       /* Check if there actually is a timeout buffer
> +                        * present */
> +                       if (old.tmo_buf == ODP_BUFFER_INVALID) {
> +                               /* Cannot reset a timer with neither old
> nor
> +                                * new timeout buffer */
> +                               success = false;
> +                               break;
> +                       }
> +                       /* Set up new values */
> +                       new.exp_tck.v = abs_tck;
> +                       new.tmo_buf = old.tmo_buf;
> +                       TB_SET_PAD(new);
> +                       /* Atomic CAS will fail if we experienced torn
> reads,
> +                        * retry update sequence until CAS succeeds */
> +               } while (!_odp_atomic_u128_cmp_xchg_mm(
> +                                       (_odp_atomic_u128_t *)tb,
> +                                       (_uint128_t *)&old,
> +                                       (_uint128_t *)&new,
> +                                       _ODP_MEMMODEL_RLS,
> +                                       _ODP_MEMMODEL_RLX));
> +#else
> +#ifdef __ARM_ARCH
> +               /* Since barriers are not good for C-A15, we take an
> +                * alternative approach using relaxed memory model */
> +               uint64_t old;
> +               /* Swap in new expiration tick, get back old tick which
> +                * will indicate active/inactive timer state */
> +               old = _odp_atomic_u64_xchg_mm(&tb->exp_tck, abs_tck,
> +                       _ODP_MEMMODEL_RLX);
> +               if (old == TMO_INACTIVE) {
> +                       /* Timer was inactive (cancelled or expired),
> +                        * we can't reset a timer without a timeout buffer.
> +                        * Attempt to restore inactive state, we don't
> +                        * want this timer to continue as active without
> +                        * timeout as this will trigger unnecessary and
> +                        * aborted expiration attempts.
> +                        * We don't care if we fail, then some other thread
> +                        * reset or cancelled the timer. Without any
> +                        * synchronization between the threads, we have a
> +                        * data race and the behavior is undefined */
> +                       (void)_odp_atomic_u64_cmp_xchg_strong_mm(
> +                                       &tb->exp_tck,
> +                                       &abs_tck,
> +                                       TMO_INACTIVE,
> +                                       _ODP_MEMMODEL_RLX,
> +                                       _ODP_MEMMODEL_RLX);
> +                       success = false;
> +               }
> +#else
> +               /* Take a related lock */
> +               while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
> +                       (void)0;
> +
> +               /* Only if there is a timeout buffer can be reset the
> timer */
> +               if (odp_likely(tb->tmo_buf != ODP_BUFFER_INVALID)) {
> +                       /* Write the new expiration tick */
> +                       tb->exp_tck.v = abs_tck;
> +               } else {
> +                       /* Cannot reset a timer with neither old nor new
> +                        * timeout buffer */
> +                       success = false;
> +               }
>
> -       if (timer->active == 0) {
> -               ODP_DBG("Timer (%u) not active\n", timer->timer_hdl);
> -               return;
> +               /* Release the lock */
> +               _odp_atomic_flag_clear(IDX2LOCK(idx));
> +#endif
> +#endif
> +       } else {
> +               /* We have a new timeout buffer which replaces any old one
> */
> +               odp_buffer_t old_buf = ODP_BUFFER_INVALID;
> +#ifdef ODP_ATOMIC_U128
> +               tick_buf_t new, old;
> +               new.exp_tck.v = abs_tck;
> +               new.tmo_buf = *tmo_buf;
> +               TB_SET_PAD(new);
> +               /* We are releasing the new timeout buffer to some other
> +                * thread */
> +               _odp_atomic_u128_xchg_mm((_odp_atomic_u128_t *)tb,
> +                                        (_uint128_t *)&new,
> +                                        (_uint128_t *)&old,
> +                                        _ODP_MEMMODEL_ACQ_RLS);
> +               old_buf = old.tmo_buf;
> +#else
> +               /* Take a related lock */
> +               while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
> +                       (void)0;
> +
> +               /* Swap in new buffer, save any old buffer */
> +               old_buf = tb->tmo_buf;
> +               tb->tmo_buf = *tmo_buf;
> +
> +               /* Write the new expiration tick */
> +               tb->exp_tck.v = abs_tck;
> +
> +               /* Release the lock */
> +               _odp_atomic_flag_clear(IDX2LOCK(idx));
> +#endif
> +               /* Return old timeout buffer */
> +               *tmo_buf = old_buf;
>         }
> +       return success;
> +}
>
> -       /* ODP_DBG("Tick\n"); */
> -
> -       cur_tick = timer->cur_tick++;
> -
> -       odp_sync_stores();
> -
> -       tick = &timer->tick[cur_tick % MAX_TICKS];
> +static odp_buffer_t timer_cancel(odp_timer_pool *tp,
> +               uint32_t idx,
> +               uint64_t new_state)
> +{
> +       tick_buf_t *tb = &tp->tick_buf[idx];
> +       odp_buffer_t old_buf;
> +
> +#ifdef ODP_ATOMIC_U128
> +       tick_buf_t new, old;
> +       /* Update the timer state (e.g. cancel the current timeout) */
> +       new.exp_tck.v = new_state;
> +       /* Swap out the old buffer */
> +       new.tmo_buf = ODP_BUFFER_INVALID;
> +       TB_SET_PAD(new);
> +       _odp_atomic_u128_xchg_mm((_odp_atomic_u128_t *)tb,
> +                                (_uint128_t *)&new, (_uint128_t *)&old,
> +                                _ODP_MEMMODEL_RLX);
> +       old_buf = old.tmo_buf;
> +#else
> +       /* Take a related lock */
> +       while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
> +               (void)0;
> +
> +       /* Update the timer state (e.g. cancel the current timeout) */
> +       tb->exp_tck.v = new_state;
> +
> +       /* Swap out the old buffer */
> +       old_buf = tb->tmo_buf;
> +       tb->tmo_buf = ODP_BUFFER_INVALID;
> +
> +       /* Release the lock */
> +       _odp_atomic_flag_clear(IDX2LOCK(idx));
> +#endif
> +       /* Return the old buffer */
> +       return old_buf;
> +}
>
> -       while ((tmo = rem_tmo(tick)) != NULL) {
> -               odp_queue_t  queue;
> -               odp_buffer_t buf;
> +static unsigned timer_expire(odp_timer_pool *tp, uint32_t idx, uint64_t
> tick)
> +{
> +       odp_timer *tim = &tp->timers[idx];
> +       tick_buf_t *tb = &tp->tick_buf[idx];
> +       odp_buffer_t tmo_buf = ODP_BUFFER_INVALID;
> +       uint64_t exp_tck;
> +#ifdef ODP_ATOMIC_U128
> +       /* Atomic re-read for correctness */
> +       exp_tck = _odp_atomic_u64_load_mm(&tb->exp_tck, _ODP_MEMMODEL_RLX);
> +       /* Re-check exp_tck */
> +       if (odp_likely(exp_tck <= tick)) {
> +               /* Attempt to grab timeout buffer, replace with inactive
> timer
> +                * and invalid buffer */
> +               tick_buf_t new, old;
> +               old.exp_tck.v = exp_tck;
> +               old.tmo_buf = tb->tmo_buf;
> +               TB_SET_PAD(old);
> +               new.exp_tck.v = TMO_INACTIVE;
> +               new.tmo_buf = ODP_BUFFER_INVALID;
> +               TB_SET_PAD(new);
> +               int succ = _odp_atomic_u128_cmp_xchg_mm(
> +                               (_odp_atomic_u128_t *)tb,
> +                               (_uint128_t *)&old, (_uint128_t *)&new,
> +                               _ODP_MEMMODEL_RLS, _ODP_MEMMODEL_RLX);
> +               if (succ)
> +                       tmo_buf = old.tmo_buf;
> +               /* Else CAS failed, something changed => skip timer
> +                * this tick, it will be checked again next tick */
> +       }
> +       /* Else false positive, ignore */
> +#else
> +       /* Take a related lock */
> +       while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
> +               (void)0;
> +       /* Proper check for timer expired */
> +       exp_tck = tb->exp_tck.v;
> +       if (odp_likely(exp_tck <= tick)) {
> +               /* Verify that there is a timeout buffer */
> +               if (odp_likely(tb->tmo_buf != ODP_BUFFER_INVALID)) {
> +                       /* Grab timeout buffer, replace with inactive timer
> +                        * and invalid buffer */
> +                       tmo_buf = tb->tmo_buf;
> +                       tb->tmo_buf = ODP_BUFFER_INVALID;
> +                       tb->exp_tck.v = TMO_INACTIVE;
> +               }
> +               /* Else somehow active timer without user buffer */
> +       }
> +       /* Else false positive, ignore */
> +       /* Release the lock */
> +       _odp_atomic_flag_clear(IDX2LOCK(idx));
> +#endif
> +       if (odp_likely(tmo_buf != ODP_BUFFER_INVALID)) {
> +               /* Fill in metadata fields in system timeout buffer */
> +               if (odp_buffer_type(tmo_buf) == ODP_BUFFER_TYPE_TIMEOUT) {
> +                       /* Convert from buffer to timeout hdr */
> +                       odp_timeout_hdr_t *tmo_hdr =
> +
>  odp_tmo_to_hdr(odp_tmo_from_buffer(tmo_buf));
> +                       tmo_hdr->timer = tp_idx_to_handle(tp, idx);
> +                       tmo_hdr->expiration = exp_tck;
> +                       tmo_hdr->user_ptr = tim->user_ptr;
> +               }
> +               /* Else ignore buffers of other types */
> +               /* Post the timeout to the destination queue */
> +               int rc = odp_queue_enq(tim->queue, tmo_buf);
> +               if (odp_unlikely(rc != 0))
> +                       ODP_ABORT("Failed to enqueue timeout buffer
> (%d)\n",
> +                                 rc);
> +               return 1;
> +       } else {
> +               /* Else false positive, ignore */
> +               return 0;
> +       }
> +}
>
> -               queue = tmo->queue;
> -               buf   = tmo->buf;
> +static unsigned odp_timer_pool_expire(odp_timer_pool_t tpid, uint64_t
> tick)
> +{
> +       tick_buf_t *array = &tpid->tick_buf[0];
> +       uint32_t high_wm = _odp_atomic_u32_load_mm(&tpid->high_wm,
> +                       _ODP_MEMMODEL_ACQ);
> +       unsigned nexp = 0;
> +       uint32_t i;
> +
> +       for (i = 0; i < high_wm;) {
> +#ifdef __ARM_ARCH
> +               /* As a rare occurence, we can outsmart the HW prefetcher
> +                * and the compiler (GCC -fprefetch-loop-arrays) with some
> +                * tuned manual prefetching (32x16=512B ahead), seems to
> +                * give 30% better performance on ARM C-A15 */
> +               PREFETCH(&array[i + 32]);
> +#endif
> +               /* Non-atomic read for speed */
> +               uint64_t exp_tck = array[i++].exp_tck.v;
> +               if (odp_unlikely(exp_tck <= tick)) {
> +                       /* Attempt to expire timer */
> +                       nexp += timer_expire(tpid, i - 1, tick);
> +               }
> +       }
> +       return nexp;
> +}
>
> -               if (buf != tmo->tmo_buf)
> -                       odp_buffer_free(tmo->tmo_buf);
>
> +/******************************************************************************
> + * POSIX timer support
> + * Functions that use Linux/POSIX per-process timers and related
> facilities
> +
> *****************************************************************************/
>
> -               odp_queue_enq(queue, buf);
> +static void timer_notify(sigval_t sigval)
> +{
> +       odp_timer_pool *tp = (odp_timer_pool *)sigval.sival_ptr;
> +#ifdef __ARM_ARCH
> +       odp_timer *array = &tp->timers[0];
> +       uint32_t i;
> +       /* Prefetch initial cache lines (match 32 above) */
> +       for (i = 0; i < 32; i += ODP_CACHE_LINE_SIZE / sizeof(array[0]))
> +               PREFETCH(&array[i]);
> +#endif
> +       uint64_t prev_tick = odp_atomic_fetch_inc_u64(&tp->cur_tick);
> +       /* Attempt to acquire the lock, check if the old value was clear */
> +       if (odp_spinlock_trylock(&tp->itimer_running)) {
> +               /* Scan timer array, looking for timers to expire */
> +               (void)odp_timer_pool_expire(tp, prev_tick);
> +               odp_spinlock_unlock(&tp->itimer_running);
>         }
> +       /* Else skip scan of timers. cur_tick was updated and next itimer
> +        * invocation will process older expiration ticks as well */
>  }
>
> -static void timer_start(timer_ring_t *timer)
> +static void itimer_init(odp_timer_pool *tp)
>  {
>         struct sigevent   sigev;
>         struct itimerspec ispec;
>         uint64_t res, sec, nsec;
>
> -       ODP_DBG("\nTimer (%u) starts\n", timer->timer_hdl);
> +       ODP_DBG("Creating POSIX timer for timer pool %s, period %"
> +               PRIu64" ns\n", tp->name, tp->resolution_ns);
>
>         memset(&sigev, 0, sizeof(sigev));
>         memset(&ispec, 0, sizeof(ispec));
>
>         sigev.sigev_notify          = SIGEV_THREAD;
> -       sigev.sigev_notify_function = notify_function;
> -       sigev.sigev_value.sival_ptr = timer;
> +       sigev.sigev_notify_function = timer_notify;
> +       sigev.sigev_value.sival_ptr = tp;
>
> -       if (timer_create(CLOCK_MONOTONIC, &sigev, &timer->timerid)) {
> -               ODP_DBG("Timer create failed\n");
> -               return;
> -       }
> +       if (timer_create(CLOCK_MONOTONIC, &sigev, &tp->timerid))
> +               ODP_ABORT("timer_create() returned error %s\n",
> +                         strerror(errno));
>
> -       res  = timer->resolution_ns;
> +       res  = tp->resolution_ns;
>         sec  = res / ODP_TIME_SEC;
> -       nsec = res - sec*ODP_TIME_SEC;
> +       nsec = res - sec * ODP_TIME_SEC;
>
>         ispec.it_interval.tv_sec  = (time_t)sec;
>         ispec.it_interval.tv_nsec = (long)nsec;
>         ispec.it_value.tv_sec     = (time_t)sec;
>         ispec.it_value.tv_nsec    = (long)nsec;
>
> -       if (timer_settime(timer->timerid, 0, &ispec, NULL)) {
> -               ODP_DBG("Timer set failed\n");
> -               return;
> -       }
> -
> -       return;
> +       if (timer_settime(&tp->timerid, 0, &ispec, NULL))
> +               ODP_ABORT("timer_settime() returned error %s\n",
> +                         strerror(errno));
>  }
>
> -int odp_timer_init_global(void)
> +static void itimer_fini(odp_timer_pool *tp)
>  {
> -       ODP_DBG("Timer init ...");
> -
> -       memset(&odp_timer, 0, sizeof(timer_global_t));
> -
> -       odp_spinlock_init(&odp_timer.lock);
> -
> -       ODP_DBG("done\n");
> -
> -       return 0;
> +       if (timer_delete(tp->timerid) != 0)
> +               ODP_ABORT("timer_delete() returned error %s\n",
> +                         strerror(errno));
>  }
>
> -int odp_timer_disarm_all(void)
>
> +/******************************************************************************
> + * Public API functions
> + * Some parameter checks and error messages
> + * No modificatios of internal state
> +
> *****************************************************************************/
> +odp_timer_pool_t
> +odp_timer_pool_create(const char *name,
> +                     odp_buffer_pool_t buf_pool,
> +                     uint64_t resolution_ns,
> +                     uint64_t min_timeout,
> +                     uint64_t max_timeout,
> +                     uint32_t num_timers,
> +                     int shared,
> +                     odp_timer_clk_src_t clk_src)
>  {
> -       int timers;
> -       struct itimerspec ispec;
> -
> -       odp_spinlock_lock(&odp_timer.lock);
> -
> -       timers = odp_timer.num_timers;
> -
> -       ispec.it_interval.tv_sec  = 0;
> -       ispec.it_interval.tv_nsec = 0;
> -       ispec.it_value.tv_sec     = 0;
> -       ispec.it_value.tv_nsec    = 0;
> -
> -       for (; timers >= 0; timers--) {
> -               if (timer_settime(odp_timer.timer[timers].timerid,
> -                                 0, &ispec, NULL)) {
> -                       ODP_DBG("Timer reset failed\n");
> -                       odp_spinlock_unlock(&odp_timer.lock);
> -                       return -1;
> -               }
> -               odp_timer.num_timers--;
> -       }
> -
> -       odp_spinlock_unlock(&odp_timer.lock);
> -
> -       return 0;
> +       /* Verify that buffer pool can be used for timeouts */
> +       odp_buffer_t buf = odp_buffer_alloc(buf_pool);
> +       if (buf == ODP_BUFFER_INVALID)
> +               ODP_ABORT("%s: Failed to allocate buffer\n", name);
> +       if (odp_buffer_type(buf) != ODP_BUFFER_TYPE_TIMEOUT)
> +               ODP_ABORT("%s: Buffer pool wrong type\n", name);
> +       odp_buffer_free(buf);
> +       odp_timer_pool_t tp = odp_timer_pool_new(name, buf_pool,
> resolution_ns,
> +                             min_timeout, max_timeout, num_timers, shared,
> +                             clk_src);
> +       return tp;
>  }
>
> -odp_timer_t odp_timer_create(const char *name, odp_buffer_pool_t pool,
> -                            uint64_t resolution_ns, uint64_t min_ns,
> -                            uint64_t max_ns)
> +void odp_timer_pool_start(void)
>  {
> -       uint32_t id;
> -       timer_ring_t *timer;
> -       odp_timer_t timer_hdl;
> -       int i;
> -       uint64_t max_ticks;
> -       (void) name;
> -
> -       if (resolution_ns < MIN_RES)
> -               resolution_ns = MIN_RES;
> -
> -       if (resolution_ns > MAX_RES)
> -               resolution_ns = MAX_RES;
> -
> -       max_ticks = max_ns / resolution_ns;
> -
> -       if (max_ticks > MAX_TICKS) {
> -               ODP_DBG("Maximum timeout too long: %"PRIu64" ticks\n",
> -                       max_ticks);
> -               return ODP_TIMER_INVALID;
> -       }
> -
> -       if (min_ns < resolution_ns) {
> -               ODP_DBG("Min timeout %"PRIu64" ns < resolution %"PRIu64"
> ns\n",
> -                       min_ns, resolution_ns);
> -               return ODP_TIMER_INVALID;
> -       }
> -
> -       odp_spinlock_lock(&odp_timer.lock);
> -
> -       if (odp_timer.num_timers >= NUM_TIMERS) {
> -               odp_spinlock_unlock(&odp_timer.lock);
> -               ODP_DBG("All timers allocated\n");
> -               return ODP_TIMER_INVALID;
> -       }
> -
> -       for (id = 0; id < NUM_TIMERS; id++) {
> -               if (odp_timer.timer[id].allocated == 0)
> -                       break;
> -       }
> -
> -       timer = &odp_timer.timer[id];
> -       timer->allocated = 1;
> -       odp_timer.num_timers++;
> -
> -       odp_spinlock_unlock(&odp_timer.lock);
> -
> -       timer_hdl = id + 1;
> -
> -       timer->timer_hdl     = timer_hdl;
> -       timer->pool          = pool;
> -       timer->resolution_ns = resolution_ns;
> -       timer->max_ticks     = MAX_TICKS;
> -
> -       for (i = 0; i < MAX_TICKS; i++) {
> -               odp_spinlock_init(&timer->tick[i].lock);
> -               timer->tick[i].list = NULL;
> -       }
> -
> -       timer->active = 1;
> -       odp_sync_stores();
> -
> -       timer_start(timer);
> -
> -       return timer_hdl;
> +       /* Nothing to do here, timer pools are started by the create call
> */
>  }
>
> -odp_timer_tmo_t odp_timer_absolute_tmo(odp_timer_t timer_hdl, uint64_t
> tmo_tick,
> -                                      odp_queue_t queue, odp_buffer_t buf)
> +void odp_timer_pool_destroy(odp_timer_pool_t tpid)
>  {
> -       int id;
> -       uint64_t tick;
> -       uint64_t cur_tick;
> -       timeout_t *new_tmo;
> -       odp_buffer_t tmo_buf;
> -       odp_timeout_hdr_t *tmo_hdr;
> -       timer_ring_t *timer;
> -
> -       id = (int)timer_hdl - 1;
> -       timer = &odp_timer.timer[id];
> +       odp_timer_pool_del(tpid);
> +}
>
> -       cur_tick = timer->cur_tick;
> -       if (tmo_tick <= cur_tick) {
> -               ODP_DBG("timeout too close\n");
> -               return ODP_TIMER_TMO_INVALID;
> -       }
> +uint64_t odp_timer_tick_to_ns(odp_timer_pool_t tpid, uint64_t ticks)
> +{
> +       return ticks * tpid->resolution_ns;
> +}
>
> -       if ((tmo_tick - cur_tick) > MAX_TICKS) {
> -               ODP_DBG("timeout too far: cur %"PRIu64" tmo %"PRIu64"\n",
> -                       cur_tick, tmo_tick);
> -               return ODP_TIMER_TMO_INVALID;
> -       }
> +uint64_t odp_timer_ns_to_tick(odp_timer_pool_t tpid, uint64_t ns)
> +{
> +       return (uint64_t)(ns / tpid->resolution_ns);
> +}
>
> -       tick = tmo_tick % MAX_TICKS;
> +uint64_t odp_timer_current_tick(odp_timer_pool_t tpid)
> +{
> +       /* Relaxed atomic read for lowest overhead */
> +       return odp_atomic_load_u64(&tpid->cur_tick);
> +}
>
> -       tmo_buf = odp_buffer_alloc(timer->pool);
> -       if (tmo_buf == ODP_BUFFER_INVALID) {
> -               ODP_DBG("tmo buffer alloc failed\n");
> -               return ODP_TIMER_TMO_INVALID;
> +size_t odp_timer_pool_info(odp_timer_pool_t tpid,
> +                          odp_timer_pool_info_t *buf,
> +                          size_t buf_size)
> +{
> +       size_t needs;
> +       buf->resolution = tpid->resolution_ns;
> +       buf->min_tmo = tpid->min_rel_tck;
> +       buf->max_tmo = tpid->max_rel_tck;
> +       buf->num_timers = tpid->max_timers;
> +       buf->cur_timers = tpid->num_alloc;
> +       buf->hwm_timers = odp_atomic_load_u32(&tpid->high_wm);
> +       buf->shared = tpid->shared;
> +       /* Compute how large buffer is needed */
> +       needs = offsetof(struct odp_timer_pool_info_s, name) +
> +               strlen(tpid->name) + 1;
> +       if (buf_size >= needs) {
> +               /* Provided buffer is large enough */
> +               strcpy(buf->name, tpid->name);
> +               return needs;
> +       } else {
> +               /* Provided buffer is too small */
> +               size_t siz = sizeof(buf->name);
> +               /* Truncate name when copying into buffer */
> +               strncpy(buf->name, tpid->name, siz - 1);
> +               buf->name[siz] = 0;
> +               return buf_size;
>         }
> -
> -       tmo_hdr = odp_timeout_hdr((odp_timeout_t) tmo_buf);
> -       new_tmo = &tmo_hdr->meta;
> -
> -       new_tmo->timer_id = id;
> -       new_tmo->tick     = (int)tick;
> -       new_tmo->tmo_tick = tmo_tick;
> -       new_tmo->queue    = queue;
> -       new_tmo->tmo_buf  = tmo_buf;
> -
> -       if (buf != ODP_BUFFER_INVALID)
> -               new_tmo->buf = buf;
> -       else
> -               new_tmo->buf = tmo_buf;
> -
> -       add_tmo(&timer->tick[tick], new_tmo);
> -
> -       return tmo_buf;
>  }
>
> -uint64_t odp_timer_tick_to_ns(odp_timer_t timer_hdl, uint64_t ticks)
> +odp_timer_t odp_timer_alloc(odp_timer_pool_t tpid,
> +                           odp_queue_t queue,
> +                           void *user_ptr)
>  {
> -       uint32_t id;
> -
> -       id = timer_hdl - 1;
> -       return ticks * odp_timer.timer[id].resolution_ns;
> +       if (odp_unlikely(queue == ODP_QUEUE_INVALID))
> +               ODP_ABORT("%s: Invalid queue handle\n", tpid->name);
> +       /* We don't care about the validity of user_ptr because we will not
> +        * attempt to dereference it */
> +       odp_timer_t hdl = timer_alloc(tpid, queue, user_ptr);
> +       if (odp_likely(hdl != ODP_TIMER_INVALID)) {
> +               /* Success */
> +               return hdl;
> +       }
> +       /* errno set by timer_alloc() */
> +       return ODP_TIMER_INVALID;
>  }
>
> -uint64_t odp_timer_ns_to_tick(odp_timer_t timer_hdl, uint64_t ns)
> +uint64_t odp_timer_free(odp_timer_t hdl, odp_buffer_t *tmo_buf)
>  {
> -       uint32_t id;
> -
> -       id = timer_hdl - 1;
> -       return ns / odp_timer.timer[id].resolution_ns;
> +       odp_timer_pool *tp = handle_to_tp(hdl);
> +       uint32_t idx = handle_to_idx(hdl, tp);
> +       odp_buffer_t old_buf = timer_free(tp, idx);
> +       /* Only overwrite *tmo_buf if we are actually returning a timeout
> +        * buffer */
> +       if (old_buf != ODP_BUFFER_INVALID)
> +               *tmo_buf = old_buf;
> +       /* Return a special value that will not match any timeout
> expiration
> +        * tick and thus help identify stale timeouts */
> +       return ODP_TICK_INVALID;
>  }
>
> -uint64_t odp_timer_resolution(odp_timer_t timer_hdl)
> +uint64_t odp_timer_set_abs(odp_timer_t hdl,
> +                          uint64_t abs_tck,
> +                          odp_buffer_t *tmo_buf)
>  {
> -       uint32_t id;
> -
> -       id = timer_hdl - 1;
> -       return odp_timer.timer[id].resolution_ns;
> +       odp_timer_pool *tp = handle_to_tp(hdl);
> +       uint32_t idx = handle_to_idx(hdl, tp);
> +       uint64_t cur_tick = odp_atomic_load_u64(&tp->cur_tick);
> +       if (odp_unlikely(abs_tck < cur_tick + tp->min_rel_tck))
> +               return ODP_TICK_TOOEARLY;
> +       if (odp_unlikely(abs_tck > cur_tick + tp->max_rel_tck))
> +               return ODP_TICK_TOOLATE;
> +       /* Return either the requested tick value when successful or a
> special
> +        * value that will not match any timeout for errors */
> +       return timer_reset(idx, abs_tck, tmo_buf, tp) ?
> +               abs_tck : ODP_TICK_INVALID;
>  }
>
> -uint64_t odp_timer_maximum_tmo(odp_timer_t timer_hdl)
> +uint64_t odp_timer_set_rel(odp_timer_t hdl,
> +                          uint64_t rel_tck,
> +                          odp_buffer_t *tmo_buf)
>  {
> -       uint32_t id;
> -
> -       id = timer_hdl - 1;
> -       return odp_timer.timer[id].max_ticks;
> +       odp_timer_pool *tp = handle_to_tp(hdl);
> +       uint32_t idx = handle_to_idx(hdl, tp);
> +       if (odp_unlikely(rel_tck < tp->min_rel_tck))
> +               return ODP_TICK_TOOEARLY;
> +       if (odp_unlikely(rel_tck > tp->max_rel_tck))
> +               return ODP_TICK_TOOLATE;
> +       uint64_t abs_tck = odp_atomic_load_u64(&tp->cur_tick) + rel_tck;
> +       /* Return either the requested tick value when successful or a
> special
> +        * value that will not match any timeout for errors */
> +       return timer_reset(idx, abs_tck, tmo_buf, tp) ?
> +               abs_tck : ODP_TICK_INVALID;
>  }
>
> -uint64_t odp_timer_current_tick(odp_timer_t timer_hdl)
> +uint64_t odp_timer_cancel(odp_timer_t hdl, odp_buffer_t *tmo_buf)
>  {
> -       uint32_t id;
> -
> -       id = timer_hdl - 1;
> -       return odp_timer.timer[id].cur_tick;
> +       odp_timer_pool *tp = handle_to_tp(hdl);
> +       uint32_t idx = handle_to_idx(hdl, tp);
> +       *tmo_buf = timer_cancel(tp, idx, TMO_INACTIVE);
> +       /* Return a special value that will not match any timeout
> expiration
> +        * tick and thus help identify stale timeouts */
> +       return ODP_TICK_INVALID;
>  }
>
> -odp_timeout_t odp_timeout_from_buffer(odp_buffer_t buf)
> +int odp_timer_tmo_metadata(odp_buffer_t buf,
> +               odp_timer_t *hdl_p,
> +               uint64_t *exp_tck_p,
> +               void **user_ptr_p)
>  {
> -       return (odp_timeout_t) buf;
> +       if (odp_likely(odp_buffer_type(buf) == ODP_BUFFER_TYPE_TIMEOUT)) {
> +               odp_timeout_hdr_t *tmo_hdr =
> +                       odp_tmo_to_hdr(odp_tmo_from_buffer(buf));
> +               odp_timer_t timer = tmo_hdr->timer;
> +               uint64_t expiration = tmo_hdr->expiration;
> +               void *user_ptr = tmo_hdr->user_ptr;
> +               if (odp_likely(hdl_p != NULL))
> +                       *hdl_p = timer;
> +               if (odp_likely(exp_tck_p != NULL))
> +                       *exp_tck_p = expiration;
> +               if (odp_likely(user_ptr_p != NULL))
> +                       *user_ptr_p = user_ptr;
> +               return 1;
> +       } else {
> +               /* Not a buffer of the appropriate type */
> +               return 0;
> +       }
>  }
>
> -uint64_t odp_timeout_tick(odp_timeout_t tmo)
> +int odp_timer_init_global(void)
>  {
> -       odp_timeout_hdr_t *tmo_hdr = odp_timeout_hdr(tmo);
> -       return tmo_hdr->meta.tmo_tick;
> +#ifndef ODP_ATOMIC_U128
> +       uint32_t i;
> +       for (i = 0; i < NUM_LOCKS; i++)
> +               _odp_atomic_flag_clear(&locks[i]);
> +#else
> +       ODP_DBG("Using lock-less timer implementation\n");
> +#endif
> +       odp_atomic_init_u32(&num_timer_pools, 0);
> +       return 0;
>  }
> --
> 1.9.1
>
>
> _______________________________________________
> lng-odp mailing list
> lng-odp@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/lng-odp
>

Patch

diff --git a/example/timer/odp_timer_test.c b/example/timer/odp_timer_test.c
index 9968bfe..b71e3f1 100644
--- a/example/timer/odp_timer_test.c
+++ b/example/timer/odp_timer_test.c
@@ -43,67 +43,116 @@  typedef struct {
 /** @private Barrier for test synchronisation */
 static odp_barrier_t test_barrier;
 
-/** @private Timer handle*/
-static odp_timer_t test_timer;
+/** @private Buffer pool handle */
+static odp_buffer_pool_t pool;
 
+/** @private Timer pool handle */
+static odp_timer_pool_t tp;
+
+/** @private Timeout status ASCII strings */
+static const char *const status2str[] = {
+	"fresh", "stale", "orphaned"
+};
+
+/** @private Timer set status ASCII strings */
+static const char *timerset2str(uint64_t val)
+{
+	switch (val) {
+	case ODP_TICK_TOOEARLY:
+		return "tooearly";
+	case ODP_TICK_TOOLATE:
+		return "toolate";
+	case ODP_TICK_INVALID:
+		return "error";
+	default:
+		return "success";
+	}
+};
+
+/** @private Helper struct for timers */
+struct test_timer {
+	odp_timer_t tim;
+	odp_buffer_t buf;
+	uint64_t tick;
+};
+
+/** @private Array of all timer helper structs */
+static struct test_timer tt[256];
 
 /** @private test timeout */
 static void test_abs_timeouts(int thr, test_args_t *args)
 {
-	uint64_t tick;
 	uint64_t period;
 	uint64_t period_ns;
 	odp_queue_t queue;
-	odp_buffer_t buf;
-	int num;
+	int remain = args->tmo_count;
+	uint64_t tick;
+	struct test_timer *ttp;
 
 	EXAMPLE_DBG("  [%i] test_timeouts\n", thr);
 
 	queue = odp_queue_lookup("timer_queue");
 
 	period_ns = args->period_us*ODP_TIME_USEC;
-	period    = odp_timer_ns_to_tick(test_timer, period_ns);
+	period    = odp_timer_ns_to_tick(tp, period_ns);
 
 	EXAMPLE_DBG("  [%i] period %"PRIu64" ticks,  %"PRIu64" ns\n", thr,
 		    period, period_ns);
 
-	tick = odp_timer_current_tick(test_timer);
+	EXAMPLE_DBG("  [%i] current tick %"PRIu64"\n", thr,
+		    odp_timer_current_tick(tp));
 
-	EXAMPLE_DBG("  [%i] current tick %"PRIu64"\n", thr, tick);
-
-	tick += period;
-
-	if (odp_timer_absolute_tmo(test_timer, tick, queue, ODP_BUFFER_INVALID)
-	    == ODP_TIMER_TMO_INVALID){
-		EXAMPLE_DBG("Timeout request failed\n");
+	ttp = &tt[thr - 1]; /* Thread starts at 1 */
+	ttp->tim = odp_timer_alloc(tp, queue, ttp);
+	if (ttp->tim == ODP_TIMER_INVALID) {
+		EXAMPLE_ERR("Failed to allocate timer\n");
 		return;
 	}
+	ttp->buf = odp_buffer_alloc(pool);
+	if (ttp->buf == ODP_BUFFER_INVALID) {
+		EXAMPLE_ERR("Failed to allocate buffer\n");
+		return;
+	}
+	tick = odp_timer_current_tick(tp);
 
-	num = args->tmo_count;
-
-	while (1) {
-		odp_timeout_t tmo;
-
-		buf = odp_schedule_one(&queue, ODP_SCHED_WAIT);
-
-		tmo  = odp_timeout_from_buffer(buf);
-		tick = odp_timeout_tick(tmo);
-
-		EXAMPLE_DBG("  [%i] timeout, tick %"PRIu64"\n", thr, tick);
-
-		odp_buffer_free(buf);
-
-		num--;
-
-		if (num == 0)
-			break;
+	while (remain != 0) {
+		odp_buffer_t buf;
 
 		tick += period;
+		ttp->tick = odp_timer_set_abs(ttp->tim, tick, &ttp->buf);
+		if (odp_unlikely(ttp->tick == ODP_TICK_TOOEARLY ||
+				 ttp->tick == ODP_TICK_TOOLATE ||
+				 ttp->tick == ODP_TICK_INVALID)) {
+			/* Too early or too late timeout requested */
+			EXAMPLE_ABORT("odp_timer_set_abs() failed: %s\n",
+				      timerset2str(ttp->tick));
+		}
 
-		odp_timer_absolute_tmo(test_timer, tick,
-				       queue, ODP_BUFFER_INVALID);
+		/* Get the next expired timeout */
+		buf = odp_schedule_one(&queue, ODP_SCHED_WAIT);
+		if (odp_timer_tmo_metadata(buf, NULL, &tick, (void **)&ttp)) {
+			ttp->buf = buf;
+			if (odp_likely(tick != ttp->tick)) {
+				/* Not the expected expiration tick, timer has
+				 * been reset or cancelled or freed */
+				EXAMPLE_ABORT("Unexpected timeout received (timer %x, tick %"PRIu64", expected %"PRIu64")\n",
+					      ttp->tim, tick, ttp->tick);
+			}
+			EXAMPLE_DBG("  [%i] timeout, tick %"PRIu64"\n",
+				    thr, tick);
+			remain--;
+		} else {
+			/* Not a default timeout buffer */
+			EXAMPLE_ABORT("Unexpected buffer type (%u) received\n",
+				      odp_buffer_type(buf));
+		}
 	}
 
+	/* Free last timer used */
+	ttp->tick = odp_timer_free(ttp->tim, &ttp->buf);
+	if (ttp->buf != ODP_BUFFER_INVALID)
+		odp_buffer_free(ttp->buf);
+
 	if (odp_queue_sched_type(queue) == ODP_SCHED_SYNC_ATOMIC)
 		odp_schedule_release_atomic();
 }
@@ -192,14 +241,14 @@  static void parse_args(int argc, char *argv[], test_args_t *args)
 	/* defaults */
 	args->core_count    = 0; /* all cores */
 	args->resolution_us = 10000;
-	args->min_us        = args->resolution_us;
+	args->min_us        = 0;
 	args->max_us        = 10000000;
 	args->period_us     = 1000000;
 	args->tmo_count     = 30;
 
 	while (1) {
 		opt = getopt_long(argc, argv, "+c:r:m:x:p:t:h",
-				 longopts, &long_index);
+				  longopts, &long_index);
 
 		if (opt == -1)
 			break;	/* No more options */
@@ -243,13 +292,13 @@  int main(int argc, char *argv[])
 	odph_linux_pthread_t thread_tbl[MAX_WORKERS];
 	test_args_t args;
 	int num_workers;
-	odp_buffer_pool_t pool;
 	void *pool_base;
 	odp_queue_t queue;
 	int first_core;
 	uint64_t cycles, ns;
 	odp_queue_param_t param;
 	odp_shm_t shm;
+	odp_timer_pool_info_t tpinfo;
 
 	printf("\nODP timer example starts\n");
 
@@ -309,7 +358,7 @@  int main(int argc, char *argv[])
 	printf("timeouts:           %i\n", args.tmo_count);
 
 	/*
-	 * Create message pool
+	 * Create buffer pool for timeouts
 	 */
 	shm = odp_shm_reserve("msg_pool",
 			      MSG_POOL_SIZE, ODP_CACHE_LINE_SIZE, 0);
@@ -321,9 +370,32 @@  int main(int argc, char *argv[])
 				      ODP_BUFFER_TYPE_TIMEOUT);
 
 	if (pool == ODP_BUFFER_POOL_INVALID) {
-		EXAMPLE_ERR("Pool create failed.\n");
+		EXAMPLE_ERR("Buffer pool create failed.\n");
+		return -1;
+	}
+
+	tp = odp_timer_pool_create("timer_pool", pool,
+				   args.resolution_us*ODP_TIME_USEC,
+				   args.min_us*ODP_TIME_USEC,
+				   args.max_us*ODP_TIME_USEC,
+				   num_workers, /* One timer per worker */
+				   true,
+				   ODP_CLOCK_CPU);
+	if (tp == ODP_TIMER_POOL_INVALID) {
+		EXAMPLE_ERR("Timer pool create failed.\n");
 		return -1;
 	}
+	odp_timer_pool_start();
+
+	odp_shm_print_all();
+	(void)odp_timer_pool_info(tp, &tpinfo, sizeof(tpinfo));
+	printf("Timer pool\n");
+	printf("----------\n");
+	printf("  name: %s\n", tpinfo.name);
+	printf("  resolution: %"PRIu64" ns\n", tpinfo.resolution);
+	printf("  min tmo: %"PRIu64" ticks\n", tpinfo.min_tmo);
+	printf("  max tmo: %"PRIu64" ticks\n", tpinfo.max_tmo);
+	printf("\n");
 
 	/*
 	 * Create a queue for timer test
@@ -340,20 +412,7 @@  int main(int argc, char *argv[])
 		return -1;
 	}
 
-	test_timer = odp_timer_create("test_timer", pool,
-				      args.resolution_us*ODP_TIME_USEC,
-				      args.min_us*ODP_TIME_USEC,
-				      args.max_us*ODP_TIME_USEC);
-
-	if (test_timer == ODP_TIMER_INVALID) {
-		EXAMPLE_ERR("Timer create failed.\n");
-		return -1;
-	}
-
-
-	odp_shm_print_all();
-
-	printf("CPU freq %"PRIu64" hz\n", odp_sys_cpu_hz());
+	printf("CPU freq %"PRIu64" Hz\n", odp_sys_cpu_hz());
 	printf("Cycles vs nanoseconds:\n");
 	ns = 0;
 	cycles = odp_time_ns_to_cycles(ns);
diff --git a/platform/linux-generic/include/api/odp_timer.h b/platform/linux-generic/include/api/odp_timer.h
index 6cca27c..f8ecf64 100644
--- a/platform/linux-generic/include/api/odp_timer.h
+++ b/platform/linux-generic/include/api/odp_timer.h
@@ -8,9 +8,211 @@ 
 /**
  * @file
  *
- * ODP timer
+ * ODP timer service
  */
 
+/** Example #1 Retransmission timer (e.g. for reliable connections)
+ @code
+
+//Create timer pool for reliable connections
+#define SEC 1000000000ULL //1s expressed in nanoseconds
+odp_timer_pool_t tcp_tpid =
+    odp_timer_pool_create("TCP",
+			  buffer_pool,
+			  1000000,//resolution 1ms
+			  0,//min tmo
+			  7200 * SEC,//max tmo length 2hours
+			  40000,//num_timers
+			  true,//shared
+			  ODP_CLOCK_CPU
+			 );
+if (tcp_tpid == ODP_TIMER_POOL_INVALID)
+{
+	//Failed to create timer pool => fatal error
+}
+
+
+//Setting up a new connection
+//Allocate retransmission timeout (identical for supervision timeout)
+//The user pointer points back to the connection context
+conn->ret_tim = odp_timer_alloc(tcp_tpid, queue, conn);
+//Check if all resources were successfully allocated
+if (conn->ret_tim == ODP_TIMER_INVALID)
+{
+	//Failed to allocate all resources for connection => tear down
+	//Tear down connection
+	...
+	return false;
+}
+//All necessary resources successfully allocated
+//Compute initial retransmission length in timer ticks
+conn->ret_len = odp_timer_ns_to_tick(tcp_tpid, 3 * SEC);//Per RFC1122
+//Allocate a timeout buffer
+conn->tmo_buf = odp_buffer_alloc(buffer_pool);
+if (conn->tmo_buf == ODP_BUFFER_INVALID)
+	ODP_ABORT("Failed to allocate timeout buffer\n");
+//Arm the timer with our timeout
+conn->expected = odp_timer_set_rel(conn->ret_tim, conn->ret_len,
+				   &conn->tmo_buf);
+//Check return value for too early or too late expiration tick
+return true;
+
+
+//A packet for the connection has just been transmitted
+//Reset the retransmission timer, reusing the previously specified timeout
+conn->expected = odp_timer_set_rel(conn->ret_tim, conn->ret_len, NULL);
+if (conn->expected == ODP_TICK_INVALID) {
+	//Timer has expired
+	//We could allocate another timeout buffer and reset the timer with it
+	...
+}
+//Else check return value for too early or too late expiration tick
+
+
+//Check if the buffer is a system timeout buffer
+if (!odp_timer_tmo_metadata(&buf, NULL, &exp_tick, (void**)&conn)) {
+	//Not a system timeout buffer
+	...
+}
+//A retransmission timeout buffer for the connection has been received
+conn->tmo_buf = buf;
+//Check if timeout is fresh or stale, for stale timeouts we need to reset the
+//timer
+if (conn->expected == exp_tick) {
+	//Fresh timeout, last transmitted packet not acked in time =>
+	  retransmit
+	//Retransmit last packet (e.g. TCP segment)
+	...
+	//Re-arm timer using original delta value
+	odp_timer_set_rel(conn->ret_tim, conn->ret_len, &conn->tmo_buf);
+} else {
+	//Timeout does not have the expected expiration tick, timer has been
+	//reset or cancelled
+	//We can ignore the timeout or reset the timer to the expected tick
+	if (conn->expected != ODP_TICK_INVALID)
+		(void)odp_timer_set_abs(conn->ret_tim, conn->expected,
+					&conn->tmo_buf);
+}
+
+ @endcode
+*/
+
+/** Example #2 Periodic tick
+ @code
+
+//Create timer pool for periodic ticks
+odp_timer_pool_t per_tpid =
+    odp_timer_pool_create("periodic-tick",
+			  buffer_pool,
+			  1,//resolution 1ns
+			  1,//minimum timeout length 1ns
+			  1000000000,//maximum timeout length 1s
+			  10,//num_timers
+			  false,//not shared
+			  ODP_CLOCK_CPU
+			 );
+if (per_tpid == ODP_TIMER_POOL_INVALID)
+{
+	//Failed to create timer pool => fatal error
+}
+
+
+//Allocate periodic timer
+tim_1733 = odp_timer_alloc(per_tpid, queue, NULL);
+//Check if all resources were successfully allocated
+if (tim_1733 == ODP_TIMER_INVALID)
+{
+	//Failed to allocate all resources => tear down
+	//Tear down other state
+	...
+	return false;
+}
+//All necessary resources successfully allocated
+//Compute tick period in timer ticks
+period_1733 = odp_timer_ns_to_tick(per_tpid, 1000000000U / 1733U);//1733Hz
+//Compute when next tick should expire
+next_1733 = odp_timer_current_tick(per_tpid) + period_1733;
+//Allocate a timeout buffer
+buf_1733 = odp_buffer_alloc(buffer_pool);
+if (buf_1733 == ODP_BUFFER_INVALID)
+	ODP_ABORT("Failed to allocate timeout buffer\n");
+//Arm the periodic timer
+(void)odp_timer_set_abs(tim_1733, next_1733, &buf_1733);
+return true;
+
+
+
+//Check if the buffer is a system timeout buffer
+if (!odp_timer_tmo_metadata(&buf, &timer, NULL, NULL)) {
+	//Not a system timeout buffer
+	...
+}
+if (timer != tim_1733) {
+	//Not our periodic timer
+	...
+}
+//A periodic timer timeout has been received
+//Do processing driven by timeout *before*
+...
+do {
+	//Compute when the timer should expire next
+	next_1733 += period_1733;
+	//Check that this is in the future
+	if (likely(next_1733 > odp_timer_current_tick(per_tpid))
+		break;//Yes, done
+	//Else we missed a timeout
+	//Optionally attempt some recovery and/or logging of the problem
+	...
+} while (1);
+//Re-arm periodic timer
+(void)odp_timer_set_abs(tim_1733, next_1733, &buf);
+//Or do processing driven by timeout *after*
+...
+return;
+
+ @endcode
+*/
+
+/** Example #3 Tear down of flow
+ @code
+//ctx points to flow context data structure owned by application
+//Free the timer, cancelling any timeout
+ctx->expected = odp_timer_free(ctx->timer, &ctx->tmo_buf);
+//Invalidate our save timer handle
+ctx->timer = ODP_TIMER_INVALID;
+if (ctx->tmo_buf != ODP_BUFFER_INVALID) {
+	//Tear down the flow
+	...
+	odp_buffer_free(ctx->tmo_buf);
+	//Free flow context
+	..
+	//Teardown complete
+} else {
+	//Timer had already expired and timeout enqueued
+	//Continue teardown when receiving timeout
+	ctx->teardown_in_progress = true;
+}
+return;
+
+//A buffer has been received, check type
+if (!odp_timer_tmo_metadata(buf, &timer, NULL, (void**)&ctx)) {
+	//Not a system timeout buffer
+	...
+}
+ctx->tmo_buf = buf;
+//Check if we are tearing down flow
+if (ctx->teardown_in_progress) {
+	//Continue tearing down the flow
+	//Free the timeout buffer
+	odp_buffer_free(ctx->tmo_buf));
+	//Free the context
+	...
+	//Teardown complete
+}
+
+ @endcode
+*/
+
 #ifndef ODP_TIMER_H_
 #define ODP_TIMER_H_
 
@@ -18,6 +220,7 @@ 
 extern "C" {
 #endif
 
+#include <stdlib.h>
 #include <odp_std_types.h>
 #include <odp_buffer.h>
 #include <odp_buffer_pool.h>
@@ -27,138 +230,283 @@  extern "C" {
  *  @{
  */
 
-/**
- * ODP timer handle
- */
-typedef uint32_t odp_timer_t;
-
-/** Invalid timer */
-#define ODP_TIMER_INVALID 0
+struct odp_timer_pool_s; /**< Forward declaration */
 
+/**
+* ODP timer pool handle (platform dependent)
+*/
+typedef struct odp_timer_pool_s *odp_timer_pool_t;
 
 /**
- * ODP timeout handle
+ * Invalid timer pool handle (platform dependent).
  */
-typedef odp_buffer_t odp_timer_tmo_t;
+#define ODP_TIMER_POOL_INVALID NULL
 
-/** Invalid timeout */
-#define ODP_TIMER_TMO_INVALID 0
+/**
+ * Clock sources for timers in timer pool.
+ */
+typedef enum odp_timer_clk_src_e {
+	/** Use CPU clock as clock source for timers */
+	ODP_CLOCK_CPU,
+	/** Use external clock as clock source for timers */
+	ODP_CLOCK_EXT
+	/* Platform dependent which other clock sources exist */
+} odp_timer_clk_src_t;
 
+/**
+* ODP timer handle (platform dependent).
+*/
+typedef uint32_t odp_timer_t;
 
 /**
- * Timeout notification
+ * Invalid timer handle (platform dependent).
  */
-typedef odp_buffer_t odp_timeout_t;
+#define ODP_TIMER_INVALID ((uint32_t)~0U)
 
+/**
+ * Return values of timer set calls.
+ */
+/**
+ * Timer set operation failed, expiration too early.
+ * Either retry with a later expiration time or process the timeout
+ * immediately. */
+#define ODP_TICK_TOOEARLY 0xFFFFFFFFFFFFFFFDULL
+/**
+ * Timer set operation failed, expiration too late.
+ * Truncate the expiration time against the maximum timeout for the
+ * timer pool. */
+#define ODP_TICK_TOOLATE  0xFFFFFFFFFFFFFFFEULL
+/**
+ * Timer set operation failed because not timeout buffer present or specified.
+ * This value is also return from odp_timer_cancel() and odp_timer_free().
+ */
+#define ODP_TICK_INVALID  0xFFFFFFFFFFFFFFFFULL
 
 /**
- * Create a timer
+ * Create a timer pool
  *
- * Creates a new timer with requested properties.
+ * Create a new timer pool.
  *
  * @param name       Name
- * @param pool       Buffer pool for allocating timeout notifications
+ * @param buf_pool   Buffer pool for allocating timeouts (and only timeouts)
  * @param resolution Timeout resolution in nanoseconds
- * @param min_tmo    Minimum timeout duration in nanoseconds
- * @param max_tmo    Maximum timeout duration in nanoseconds
+ * @param min_tmo    Minimum relative timeout in nanoseconds
+ * @param max_tmo    Maximum relative timeout in nanoseconds
+ * @param num_timers Number of supported timers (minimum)
+ * @param shared     Shared or private timer pool.
+ *		   Operations on shared timers will include the necessary
+ *		   mutual exclusion, operations on private timers may not
+ *		   (mutual exclusion is the responsibility of the caller).
+ * @param clk_src    Clock source to use
+ *
+ * @return Timer pool handle if successful, otherwise ODP_TIMER_POOL_INVALID
+ * and errno set
+ */
+odp_timer_pool_t
+odp_timer_pool_create(const char *name,
+		      odp_buffer_pool_t buf_pool,
+		      uint64_t resolution,
+		      uint64_t min_tmo,
+		      uint64_t max_tmo,
+		      uint32_t num_timers,
+		      int shared,
+		      odp_timer_clk_src_t clk_src);
+
+/**
+ * Start a timer pool
+ *
+ * Start all created timer pools, enabling the allocation of timers.
+ * The purpose of this call is to coordinate the creation of multiple timer
+ * pools that may use the same underlying HW resources.
+ * This function may be called multiple times.
+ */
+void odp_timer_pool_start(void);
+
+/**
+ * Destroy a timer pool
  *
- * @return Timer handle if successful, otherwise ODP_TIMER_INVALID
+ * Destroy a timer pool, freeing all resources.
+ * All timers must have been freed.
+ *
+ * @param tpid  Timer pool identifier
  */
-odp_timer_t odp_timer_create(const char *name, odp_buffer_pool_t pool,
-			     uint64_t resolution, uint64_t min_tmo,
-			     uint64_t max_tmo);
+void odp_timer_pool_destroy(odp_timer_pool_t tpid);
 
 /**
  * Convert timer ticks to nanoseconds
  *
- * @param timer Timer
+ * @param tpid  Timer pool identifier
  * @param ticks Timer ticks
  *
  * @return Nanoseconds
  */
-uint64_t odp_timer_tick_to_ns(odp_timer_t timer, uint64_t ticks);
+uint64_t odp_timer_tick_to_ns(odp_timer_pool_t tpid, uint64_t ticks);
 
 /**
  * Convert nanoseconds to timer ticks
  *
- * @param timer Timer
+ * @param tpid  Timer pool identifier
  * @param ns    Nanoseconds
  *
  * @return Timer ticks
  */
-uint64_t odp_timer_ns_to_tick(odp_timer_t timer, uint64_t ns);
+uint64_t odp_timer_ns_to_tick(odp_timer_pool_t tpid, uint64_t ns);
 
 /**
- * Timer resolution in nanoseconds
+ * Current tick value
  *
- * @param timer Timer
+ * @param tpid Timer pool identifier
  *
- * @return Resolution in nanoseconds
+ * @return Current time in timer ticks
  */
-uint64_t odp_timer_resolution(odp_timer_t timer);
+uint64_t odp_timer_current_tick(odp_timer_pool_t tpid);
 
 /**
- * Maximum timeout in timer ticks
+ * ODP timer pool information and configuration
+ */
+
+typedef struct odp_timer_pool_info_s {
+	uint64_t resolution;/**< Timer resolution (in ns) */
+	uint64_t min_tmo;   /**< Min supported relative timeout (in ticks)*/
+	uint64_t max_tmo;   /**< Max supported relative timeout (in ticks)*/
+	uint32_t num_timers;/**< Number of supported timers */
+	uint32_t cur_timers;/**< Number of currently allocated timers */
+	uint32_t hwm_timers;/**< Number of used timers high watermark */
+	int shared;         /**< Shared flag */
+	char name[80];      /**< Name of timer pool */
+} odp_timer_pool_info_t;
+
+/**
+ * Query timer pool information and configuration
+ *  Timer resolution in nanoseconds
+ *  Minimum and maximum (relative) timeouts in timer ticks
+ *  Number of supported timers
+ *  Nunber of timers in use
+ *  Nunber of timers in use - high watermark
+ *  Shared or private timer pool
+ *  Name of timer pool.
  *
- * @param timer Timer
+ * @param tpid Timer pool identifier
+ * @param buf Pointer to information buffer
+ * @param buf_size Size of information buffer
  *
- * @return Maximum timeout in timer ticks
+ * @return Actual size written
  */
-uint64_t odp_timer_maximum_tmo(odp_timer_t timer);
+size_t odp_timer_pool_info(odp_timer_pool_t tpid,
+			   odp_timer_pool_info_t *buf,
+			   size_t buf_size);
 
 /**
- * Current timer tick
+ * Allocate a timer
  *
- * @param timer Timer
+ * Create a timer (allocating all necessary resources e.g. timeout event) from
+ * the timer pool. The user_ptr is copied to timeouts and can be retrieved
+ * using the odp_timer_userptr() call.
  *
- * @return Current time in timer ticks
+ * @param tpid     Timer pool identifier
+ * @param queue    Destination queue for timeout notifications
+ * @param user_ptr User defined pointer or NULL to be copied to timeouts
+ *
+ * @return Timer handle if successful, otherwise ODP_TIMER_INVALID and
+ *	   errno set.
+ */
+odp_timer_t odp_timer_alloc(odp_timer_pool_t tpid,
+			    odp_queue_t queue,
+			    void *user_ptr);
+
+/**
+ * Free a timer
+ *
+ * Free (destroy) a timer, freeing associated resources.
+ * The timeout buffer for an active timer will be returned.
+ * An expired and enqueued timeout buffer will not be freed.
+ * It is the responsibility of the application to free this timeout when it
+ * is received.
+ *
+ * @param tim      Timer handle
+ * @param tmo_buf Reference to a buffer variable which will be written with
+ * the buffer handle of any present timeout buffer (e.g. for an active timer).
+ * @return       A tick value which will not match any valid expiration tick.
  */
-uint64_t odp_timer_current_tick(odp_timer_t timer);
+uint64_t odp_timer_free(odp_timer_t tim, odp_buffer_t *tmo_buf);
 
 /**
- * Request timeout with an absolute timer tick
+ * Set a timer (absolute time) with a user-provided timeout buffer
+ *
+ * Set (arm) the timer to expire at specific time. The timeout
+ * buffer will be enqueued when the timer expires.
  *
- * When tick reaches tmo_tick, the timer enqueues the timeout notification into
- * the destination queue.
+ * Note: any invalid parameters will be treated as programming errors and will
+ * cause the application to abort.
  *
- * @param timer    Timer
- * @param tmo_tick Absolute timer tick value which triggers the timeout
- * @param queue    Destination queue for the timeout notification
- * @param buf      User defined timeout notification buffer. When
- *                 ODP_BUFFER_INVALID, default timeout notification is used.
+ * @param tim      Timer
+ * @param abs_tck  Expiration time in absolute timer ticks
+ * @param tmo_buf  Reference to a buffer variable that points to timeout buffer
+ * or NULL to reuse the existing timeout buffer
  *
- * @return Timeout handle if successful, otherwise ODP_TIMER_TMO_INVALID
+ * @return The expiration tick or ODP_TICK_TOOEARLY, ODP_TICK_TOOLATE or
+ * ODP_TICK_INVALID (timer not active and no timeout buffer to reuse).
  */
-odp_timer_tmo_t odp_timer_absolute_tmo(odp_timer_t timer, uint64_t tmo_tick,
-				       odp_queue_t queue, odp_buffer_t buf);
+uint64_t odp_timer_set_abs(odp_timer_t tim,
+			   uint64_t abs_tck,
+			   odp_buffer_t *tmo_buf);
 
 /**
- * Cancel a timeout
+ * Set a timer with a relative expiration time and user-provided buffer.
  *
- * @param timer Timer
- * @param tmo   Timeout to cancel
+ * Set (arm) the timer to expire at a relative future time.
  *
- * @return 0 if successful
+ * Note: any invalid parameters will be treated as programming errors and will
+ * cause the application to abort.
+ *
+ * @param tim      Timer
+ * @param rel_tck  Expiration time in timer ticks relative to current time of
+ *		   the timer pool the timer belongs to
+ * @param tmo_buf  Reference to a buffer variable that points to timeout buffer
+ * or NULL to reuse the existing timeout buffer
+ *
+ * @return The expiration tick or ODP_TICK_TOOEARLY, ODP_TICK_TOOLATE or
+ * ODP_TICK_INVALID (timer not active and no timeout buffer to reuse).
  */
-int odp_timer_cancel_tmo(odp_timer_t timer, odp_timer_tmo_t tmo);
+uint64_t odp_timer_set_rel(odp_timer_t tim,
+			   uint64_t rel_tck,
+			   odp_buffer_t *tmo_buf);
 
 /**
- * Convert buffer handle to timeout handle
+ * Cancel a timer
+ *
+ * Cancel a timer, preventing future expiration and delivery. Return any
+ * present timeout buffer.
+ *
+ * A timer that has already expired may be impossible to cancel and the timeout
+ * will instead be delivered to the destination queue.
  *
- * @param buf  Buffer handle
+ * Note: any invalid parameters will be treated as programming errors and will
+ * cause the application to abort.
  *
- * @return Timeout buffer handle
+ * @param tim     Timer
+ * @param tmo_buf Reference to a buffer variable which will be written with
+ * the buffer handle of any present timeout buffer (e.g. for an active timer).
+ * @return       A tick value which will not match any valid expiration tick.
  */
-odp_timeout_t odp_timeout_from_buffer(odp_buffer_t buf);
+uint64_t odp_timer_cancel(odp_timer_t tim, odp_buffer_t *tmo_buf);
 
 /**
- * Return absolute timeout tick
+ * Get metadata from system timeout buffer
  *
- * @param tmo Timeout buffer handle
+ * @param buf A timeout buffer
+ * @param hdl NULL or a pointer where the timer handle will be written.
+ * @param exp_tck NULL or a pointer where the expiration tick will be written.
+ * @param user_ptr NULL or a pointer where the user pointer will be written.
  *
- * @return Absolute timeout tick
+ * @return True (1) if timeout buffer is of type ODP_BUFFER_TYPE_TIMEOUT and
+ *         metadata variables have been updated from the timeout.
+ *         False (0) if timeout buffer is not of type ODP_BUFFER_TYPE_TIMEOUT.
  */
-uint64_t odp_timeout_tick(odp_timeout_t tmo);
+int odp_timer_tmo_metadata(odp_buffer_t buf,
+		odp_timer_t *hdl,
+		uint64_t *exp_tck,
+		void **user_ptr);
 
 /**
  * @}
diff --git a/platform/linux-generic/include/odp_timer_internal.h b/platform/linux-generic/include/odp_timer_internal.h
index ad28f53..0e0cf48 100644
--- a/platform/linux-generic/include/odp_timer_internal.h
+++ b/platform/linux-generic/include/odp_timer_internal.h
@@ -1,4 +1,4 @@ 
-/* Copyright (c) 2013, Linaro Limited
+/* Copyright (c) 2014, Linaro Limited
  * All rights reserved.
  *
  * SPDX-License-Identifier:     BSD-3-Clause
@@ -8,72 +8,49 @@ 
 /**
  * @file
  *
- * ODP timer timeout descriptor - implementation internal
+ * ODP timeout descriptor - implementation internal
  */
 
 #ifndef ODP_TIMER_INTERNAL_H_
 #define ODP_TIMER_INTERNAL_H_
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include <odp_std_types.h>
-#include <odp_queue.h>
-#include <odp_buffer.h>
+#include <odp_align.h>
+#include <odp_debug.h>
 #include <odp_buffer_internal.h>
 #include <odp_buffer_pool_internal.h>
 #include <odp_timer.h>
 
-struct timeout_t;
-
-typedef struct timeout_t {
-	struct timeout_t *next;
-	int               timer_id;
-	int               tick;
-	uint64_t          tmo_tick;
-	odp_queue_t       queue;
-	odp_buffer_t      buf;
-	odp_buffer_t      tmo_buf;
-} timeout_t;
-
-
-struct odp_timeout_hdr_t;
-
 /**
- * Timeout notification header
+ * Internal Timeout header
  */
-typedef struct odp_timeout_hdr_t {
+typedef struct {
+	/* common buffer header */
 	odp_buffer_hdr_t buf_hdr;
 
-	timeout_t meta;
-
-	uint8_t buf_data[];
+	/* Requested expiration time */
+	uint64_t expiration;
+	/* User ptr inherited from parent timer */
+	void *user_ptr;
+	/* Parent timer */
+	odp_timer_t timer;
+#if __SIZEOF_POINTER__ != 4
+	uint32_t pad32;
+#endif
+	uint8_t buf_data[0];
 } odp_timeout_hdr_t;
 
-
-
 ODP_STATIC_ASSERT(sizeof(odp_timeout_hdr_t) ==
-	   ODP_OFFSETOF(odp_timeout_hdr_t, buf_data),
-	   "ODP_TIMEOUT_HDR_T__SIZE_ERR");
-
+		  ODP_OFFSETOF(odp_timeout_hdr_t, buf_data),
+		  "sizeof(odp_timeout_hdr_t) == ODP_OFFSETOF(odp_timeout_hdr_t, buf_data)");
 ODP_STATIC_ASSERT(sizeof(odp_timeout_hdr_t) % sizeof(uint64_t) == 0,
-	   "ODP_TIMEOUT_HDR_T__SIZE_ERR2");
-
+		  "sizeof(odp_timeout_hdr_t) % sizeof(uint64_t) == 0");
 
 /**
- * Return timeout header
+ * Return the timeout header
  */
-static inline odp_timeout_hdr_t *odp_timeout_hdr(odp_timeout_t tmo)
+static inline odp_timeout_hdr_t *odp_timeout_hdr(odp_buffer_t buf)
 {
-	odp_buffer_hdr_t *buf_hdr = odp_buf_to_hdr((odp_buffer_t)tmo);
-	return (odp_timeout_hdr_t *)(uintptr_t)buf_hdr;
-}
-
-
-
-#ifdef __cplusplus
+	return (odp_timeout_hdr_t *)odp_buf_to_hdr(buf);
 }
-#endif
 
 #endif
diff --git a/platform/linux-generic/odp_timer.c b/platform/linux-generic/odp_timer.c
index a4fef58..02a460b 100644
--- a/platform/linux-generic/odp_timer.c
+++ b/platform/linux-generic/odp_timer.c
@@ -4,428 +4,875 @@ 
  * SPDX-License-Identifier:     BSD-3-Clause
  */
 
-#include <odp_timer.h>
-#include <odp_timer_internal.h>
-#include <odp_time.h>
-#include <odp_buffer_pool_internal.h>
-#include <odp_internal.h>
+/**
+ * @file
+ *
+ * ODP timer service
+ *
+ */
+
+/* Check if compiler supports 16-byte atomics. GCC needs -mcx16 flag */
+/* Using spin lock actually seems faster on Core2 */
+#ifdef ODP_ATOMIC_U128
+/* TB_NEEDS_PAD defined if sizeof(odp_buffer_t) != 8 */
+#define TB_NEEDS_PAD
+#define TB_SET_PAD(x) ((x).pad = 0)
+#else
+#define TB_SET_PAD(x) (void)(x)
+#endif
+
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <time.h>
+#include <signal.h>
 #include <odp_atomic.h>
+#include <odp_atomic_internal.h>
+#include <odp_std_types.h>
+#include <odp_buffer.h>
+#include <odp_buffer_pool.h>
+#include <odp_queue.h>
+#include <odp_hints.h>
 #include <odp_spinlock.h>
 #include <odp_sync.h>
 #include <odp_debug_internal.h>
+#include <odp_debug.h>
+#include <odp_align.h>
+#include <odp_align_internal.h>
+#include <odp_shared_memory.h>
+#include <odp_hints.h>
+#include <odp_internal.h>
+#include <odp_time.h>
+#include <odp_timer.h>
+#include <odp_timer_internal.h>
 
-#include <signal.h>
-#include <time.h>
+#define TMO_UNUSED   ((uint64_t)0xFFFFFFFFFFFFFFFF)
+#define TMO_INACTIVE ((uint64_t)0xFFFFFFFFFFFFFFFE)
 
-#include <string.h>
+#ifdef __ARM_ARCH
+#define PREFETCH(ptr) __builtin_prefetch((ptr), 0, 0)
+#else
+#define PREFETCH(ptr) (void)(ptr)
+#endif
 
-#define NUM_TIMERS    1
-#define MAX_TICKS     1024
-#define MAX_RES       ODP_TIME_SEC
-#define MIN_RES       (100*ODP_TIME_USEC)
+/******************************************************************************
+ * Mutual exclusion in the absence of CAS16
+ *****************************************************************************/
 
+#ifndef ODP_ATOMIC_U128
+#define NUM_LOCKS 1024
+static _odp_atomic_flag_t locks[NUM_LOCKS]; /* Multiple locks per cache line! */
+#define IDX2LOCK(idx) (&locks[(idx) % NUM_LOCKS])
+#endif
 
-typedef struct {
-	odp_spinlock_t lock;
-	timeout_t      *list;
-} tick_t;
-
-typedef struct {
-	int               allocated;
-	volatile int      active;
-	volatile uint64_t cur_tick;
-	timer_t           timerid;
-	odp_timer_t       timer_hdl;
-	odp_buffer_pool_t pool;
-	uint64_t          resolution_ns;
-	uint64_t          max_ticks;
-	tick_t            tick[MAX_TICKS];
-
-} timer_ring_t;
-
-typedef struct {
-	odp_spinlock_t lock;
-	int            num_timers;
-	timer_ring_t   timer[NUM_TIMERS];
-
-} timer_global_t;
+/******************************************************************************
+ * Translation between timeout and timeout header
+ *****************************************************************************/
 
-/* Global */
-static timer_global_t odp_timer;
+/**
+ * System timeout buffer (ODP_BUFFER_TYPE_TIEMOUT)
+ */
+typedef odp_buffer_t odp_timer_tmo_t;
 
-static void add_tmo(tick_t *tick, timeout_t *tmo)
+/** Translate from generic buffer to timeout */
+static inline odp_timer_tmo_t odp_tmo_from_buffer(odp_buffer_t buf)
 {
-	odp_spinlock_lock(&tick->lock);
-
-	tmo->next  = tick->list;
-	tick->list = tmo;
-
-	odp_spinlock_unlock(&tick->lock);
+	/* In this implementation, timeout == buffer */
+	return (odp_timer_tmo_t)buf;
 }
 
-static timeout_t *rem_tmo(tick_t *tick)
+/** Translate from timeout to generic buffer */
+static inline odp_buffer_t odp_buffer_from_tmo(odp_timer_tmo_t tmo)
 {
-	timeout_t *tmo;
+	/* In this implementation, buffer == timeout */
+	return (odp_buffer_t)tmo;
+}
 
-	odp_spinlock_lock(&tick->lock);
+static inline odp_timeout_hdr_t *odp_tmo_to_hdr(odp_timer_tmo_t tmo)
+{
+	odp_buffer_t buf = odp_buffer_from_tmo(tmo);
+	odp_timeout_hdr_t *tmo_hdr = (odp_timeout_hdr_t *)odp_buf_to_hdr(buf);
+	return tmo_hdr;
+}
 
-	tmo = tick->list;
+/******************************************************************************
+ * odp_timer abstract datatype
+ *****************************************************************************/
+
+typedef struct tick_buf_s {
+	odp_atomic_u64_t exp_tck;/* Expiration tick or TMO_xxx */
+	odp_buffer_t tmo_buf;/* ODP_BUFFER_INVALID if timer not active */
+#ifdef TB_NEEDS_PAD
+	uint32_t pad;/* Need to be able to access padding for successful CAS */
+#endif
+} tick_buf_t
+#ifdef ODP_ATOMIC_U128
+ODP_ALIGNED(16) /* 16-byte atomic operations need properly aligned addresses */
+#endif
+;
+
+ODP_STATIC_ASSERT(sizeof(tick_buf_t) == 16, "sizeof(tick_buf_t) == 16");
+
+typedef struct odp_timer_s {
+	void *user_ptr; /* User-defined pointer for odp_timer_tmo_t buffers */
+	odp_queue_t queue;/* Used for free list when timer is free */
+} odp_timer;
+
+static void timer_init(odp_timer *tim,
+		tick_buf_t *tb,
+		odp_queue_t _q,
+		void *_up)
+{
+	tim->queue = _q;
+	tim->user_ptr = _up;
+	tb->tmo_buf = ODP_BUFFER_INVALID;
+	/* All pad fields need a defined and constant value */
+	TB_SET_PAD(*tb);
+	/* Release the timer by setting timer state to inactive */
+	_odp_atomic_u64_store_mm(&tb->exp_tck, TMO_INACTIVE, _ODP_MEMMODEL_RLS);
+}
 
-	if (tmo)
-		tick->list = tmo->next;
+/* Teardown when timer is freed */
+static void timer_fini(odp_timer *tim, tick_buf_t *tb)
+{
+	assert(tb->exp_tck.v == TMO_UNUSED);
+	assert(tb->tmo_buf == ODP_BUFFER_INVALID);
+	tim->queue = ODP_QUEUE_INVALID;
+	tim->user_ptr = NULL;
+}
 
-	odp_spinlock_unlock(&tick->lock);
+static inline uint32_t get_next_free(odp_timer *tim)
+{
+	/* Reusing 'queue' for next free index */
+	return tim->queue;
+}
 
-	if (tmo)
-		tmo->next = NULL;
+static inline void set_next_free(odp_timer *tim, uint32_t nf)
+{
+	assert(tim->queue == ODP_QUEUE_INVALID);
+	/* Reusing 'queue' for next free index */
+	tim->queue = nf;
+}
 
-	return tmo;
+/******************************************************************************
+ * odp_timer_pool abstract datatype
+ * Inludes alloc and free timer
+ *****************************************************************************/
+
+typedef struct odp_timer_pool_s {
+/* Put frequently accessed fields in the first cache line */
+	odp_atomic_u64_t cur_tick;/* Current tick value */
+	uint64_t min_rel_tck;
+	uint64_t max_rel_tck;
+	uint64_t resolution_ns;
+	tick_buf_t *tick_buf; /* Expiration tick and timeout buffer */
+	odp_timer *timers; /* User pointer and queue handle (and lock) */
+	odp_atomic_u32_t high_wm;/* High watermark of allocated timers */
+	odp_spinlock_t itimer_running;
+	odp_spinlock_t lock;
+	bool shared;
+	uint32_t num_alloc;/* Current number of allocated timers */
+	uint32_t max_timers;/* Max number of timers */
+	uint32_t first_free;/* 0..max_timers-1 => free timer */
+	uint32_t tp_idx;/* Index into timer_pool array */
+	const char *name;
+	odp_buffer_pool_t buf_pool;
+	odp_shm_t shm;
+	timer_t timerid;
+	odp_timer_clk_src_t clk_src;
+} odp_timer_pool;
+
+#define MAX_TIMER_POOLS 255 /* Leave one for ODP_TIMER_INVALID */
+#define INDEX_BITS 24
+static odp_atomic_u32_t num_timer_pools;
+static odp_timer_pool *timer_pool[MAX_TIMER_POOLS];
+
+static inline odp_timer_pool *handle_to_tp(odp_timer_t hdl)
+{
+	uint32_t tp_idx = hdl >> INDEX_BITS;
+	if (odp_likely(tp_idx < MAX_TIMER_POOLS)) {
+		odp_timer_pool *tp = timer_pool[tp_idx];
+		if (odp_likely(tp != NULL))
+			return timer_pool[tp_idx];
+	}
+	ODP_ABORT("Invalid timer handle %#x\n", hdl);
 }
 
-/**
- * Search and delete tmo entry from timeout list
- * return -1 : on error.. handle not in list
- *		0 : success
- */
-static int find_and_del_tmo(timeout_t **tmo, odp_timer_tmo_t handle)
+static inline uint32_t handle_to_idx(odp_timer_t hdl,
+		struct odp_timer_pool_s *tp)
 {
-	timeout_t *cur, *prev;
-	prev = NULL;
+	uint32_t idx = hdl & ((1U << INDEX_BITS) - 1U);
+	PREFETCH(&tp->tick_buf[idx]);
+	if (odp_likely(idx < odp_atomic_load_u32(&tp->high_wm)))
+		return idx;
+	ODP_ABORT("Invalid timer handle %#x\n", hdl);
+}
 
-	for (cur = *tmo; cur != NULL; prev = cur, cur = cur->next) {
-		if (cur->tmo_buf == handle) {
-			if (prev == NULL)
-				*tmo = cur->next;
-			else
-				prev->next = cur->next;
+static inline odp_timer_t tp_idx_to_handle(struct odp_timer_pool_s *tp,
+		uint32_t idx)
+{
+	assert(idx < (1U << INDEX_BITS));
+	return (tp->tp_idx << INDEX_BITS) | idx;
+}
 
-			break;
-		}
+/* Forward declarations */
+static void itimer_init(odp_timer_pool *tp);
+static void itimer_fini(odp_timer_pool *tp);
+
+static odp_timer_pool *odp_timer_pool_new(
+	const char *_name,
+	odp_buffer_pool_t _bp,
+	uint64_t _res,
+	uint64_t _mintmo,
+	uint64_t _maxtmo,
+	uint32_t _maxtim,
+	bool _sh,
+	odp_timer_clk_src_t _cs)
+{
+	uint32_t tp_idx = odp_atomic_fetch_add_u32(&num_timer_pools, 1);
+	if (odp_unlikely(tp_idx >= MAX_TIMER_POOLS)) {
+		/* Restore the previous value */
+		odp_atomic_sub_u32(&num_timer_pools, 1);
+		errno = ENFILE; /* Table overflow */
+		return NULL;
 	}
+	size_t sz0 = ODP_ALIGN_ROUNDUP(sizeof(odp_timer_pool),
+			ODP_CACHE_LINE_SIZE);
+	size_t sz1 = ODP_ALIGN_ROUNDUP(sizeof(tick_buf_t) * _maxtim,
+			ODP_CACHE_LINE_SIZE);
+	size_t sz2 = ODP_ALIGN_ROUNDUP(sizeof(odp_timer) * _maxtim,
+			ODP_CACHE_LINE_SIZE);
+	odp_shm_t shm = odp_shm_reserve(_name, sz0 + sz1 + sz2,
+			ODP_CACHE_LINE_SIZE, ODP_SHM_SW_ONLY);
+	if (odp_unlikely(shm == ODP_SHM_INVALID))
+		ODP_ABORT("%s: timer pool shm-alloc(%zuKB) failed\n",
+			  _name, (sz0 + sz1 + sz2) / 1024);
+	odp_timer_pool *tp = (odp_timer_pool *)odp_shm_addr(shm);
+	odp_atomic_init_u64(&tp->cur_tick, 0);
+	tp->name = strdup(_name);
+	tp->shm = shm;
+	tp->buf_pool = _bp;
+	tp->resolution_ns = _res;
+	tp->min_rel_tck = odp_timer_ns_to_tick(tp, _mintmo);
+	tp->max_rel_tck = odp_timer_ns_to_tick(tp, _maxtmo);
+	tp->num_alloc = 0;
+	odp_atomic_init_u32(&tp->high_wm, 0);
+	tp->max_timers = _maxtim;
+	tp->first_free = 0;
+	tp->shared = _sh;
+	tp->clk_src = _cs;
+	tp->tick_buf = (void *)((char *)odp_shm_addr(shm) + sz0);
+	tp->timers = (void *)((char *)odp_shm_addr(shm) + sz0 + sz1);
+	/* Initialize all odp_timer entries */
+	uint32_t i;
+	for (i = 0; i < tp->max_timers; i++) {
+		set_next_free(&tp->timers[i], i + 1);
+		tp->timers[i].user_ptr = NULL;
+	}
+	tp->tp_idx = tp_idx;
+	odp_spinlock_init(&tp->lock);
+	odp_spinlock_init(&tp->itimer_running);
+	timer_pool[tp_idx] = tp;
+	if (tp->clk_src == ODP_CLOCK_CPU)
+		itimer_init(tp);
+	return tp;
+}
 
-	if (!cur)
-		/* couldn't find tmo in list */
-		return -1;
-
-	/* application to free tmo_buf provided by absolute_tmo call */
-	return 0;
+static void odp_timer_pool_del(odp_timer_pool *tp)
+{
+	odp_spinlock_lock(&tp->lock);
+	timer_pool[tp->tp_idx] = NULL;
+	/* Wait for itimer thread to stop running */
+	odp_spinlock_lock(&tp->itimer_running);
+	if (tp->num_alloc != 0) {
+		/* It's a programming error to attempt to destroy a */
+		/* timer pool which is still in use */
+		ODP_ABORT("%s: timers in use\n", tp->name);
+	}
+	if (tp->clk_src == ODP_CLOCK_CPU)
+		itimer_fini(tp);
+	int rc = odp_shm_free(tp->shm);
+	if (rc != 0)
+		ODP_ABORT("Failed to free shared memory (%d)\n", rc);
 }
 
-int odp_timer_cancel_tmo(odp_timer_t timer_hdl, odp_timer_tmo_t tmo)
+static inline odp_timer_t timer_alloc(odp_timer_pool *tp,
+				      odp_queue_t queue,
+				      void *user_ptr)
 {
-	int id;
-	int tick_idx;
-	timeout_t *cancel_tmo;
-	odp_timeout_hdr_t *tmo_hdr;
-	tick_t *tick;
+	odp_timer_t hdl;
+	odp_spinlock_lock(&tp->lock);
+	if (odp_likely(tp->num_alloc < tp->max_timers)) {
+		tp->num_alloc++;
+		/* Remove first unused timer from free list */
+		assert(tp->first_free != tp->max_timers);
+		uint32_t idx = tp->first_free;
+		odp_timer *tim = &tp->timers[idx];
+		tp->first_free = get_next_free(tim);
+		/* Initialize timer */
+		timer_init(tim, &tp->tick_buf[idx], queue, user_ptr);
+		if (odp_unlikely(tp->num_alloc >
+				 odp_atomic_load_u32(&tp->high_wm)))
+			/* Update high_wm last with release model to
+			 * ensure timer initialization is visible */
+			_odp_atomic_u32_store_mm(&tp->high_wm,
+						 tp->num_alloc,
+						 _ODP_MEMMODEL_RLS);
+		hdl = tp_idx_to_handle(tp, idx);
+	} else {
+		errno = ENFILE; /* Reusing file table overflow */
+		hdl = ODP_TIMER_INVALID;
+	}
+	odp_spinlock_unlock(&tp->lock);
+	return hdl;
+}
 
-	/* get id */
-	id = (int)timer_hdl - 1;
+static odp_buffer_t timer_cancel(odp_timer_pool *tp,
+		uint32_t idx,
+		uint64_t new_state);
 
-	tmo_hdr = odp_timeout_hdr((odp_timeout_t) tmo);
-	/* get tmo_buf to cancel */
-	cancel_tmo = &tmo_hdr->meta;
+static inline odp_buffer_t timer_free(odp_timer_pool *tp, uint32_t idx)
+{
+	odp_timer *tim = &tp->timers[idx];
 
-	tick_idx = cancel_tmo->tick;
-	tick = &odp_timer.timer[id].tick[tick_idx];
+	/* Free the timer by setting timer state to unused and
+	 * grab any timeout buffer */
+	odp_buffer_t old_buf = timer_cancel(tp, idx, TMO_UNUSED);
 
-	odp_spinlock_lock(&tick->lock);
-	/* search and delete tmo from tick list */
-	if (find_and_del_tmo(&tick->list, tmo) != 0) {
-		odp_spinlock_unlock(&tick->lock);
-		ODP_DBG("Couldn't find the tmo (%d) in tick list\n", (int)tmo);
-		return -1;
-	}
-	odp_spinlock_unlock(&tick->lock);
+	/* Destroy timer */
+	timer_fini(tim, &tp->tick_buf[idx]);
 
-	return 0;
+	/* Insert timer into free list */
+	odp_spinlock_lock(&tp->lock);
+	set_next_free(tim, tp->first_free);
+	tp->first_free = idx;
+	assert(tp->num_alloc != 0);
+	tp->num_alloc--;
+	odp_spinlock_unlock(&tp->lock);
+
+	return old_buf;
 }
 
-static void notify_function(union sigval sigval)
-{
-	uint64_t cur_tick;
-	timeout_t *tmo;
-	tick_t *tick;
-	timer_ring_t *timer;
+/******************************************************************************
+ * Operations on timers
+ * expire/reset/cancel timer
+ *****************************************************************************/
 
-	timer = sigval.sival_ptr;
+static bool timer_reset(uint32_t idx,
+		uint64_t abs_tck,
+		odp_buffer_t *tmo_buf,
+		odp_timer_pool *tp)
+{
+	bool success = true;
+	tick_buf_t *tb = &tp->tick_buf[idx];
+
+	if (tmo_buf == NULL || *tmo_buf == ODP_BUFFER_INVALID) {
+#ifdef ODP_ATOMIC_U128
+		tick_buf_t new, old;
+		do {
+			/* Relaxed and non-atomic read of current values */
+			old.exp_tck.v = tb->exp_tck.v;
+			old.tmo_buf = tb->tmo_buf;
+			TB_SET_PAD(old);
+			/* Check if there actually is a timeout buffer
+			 * present */
+			if (old.tmo_buf == ODP_BUFFER_INVALID) {
+				/* Cannot reset a timer with neither old nor
+				 * new timeout buffer */
+				success = false;
+				break;
+			}
+			/* Set up new values */
+			new.exp_tck.v = abs_tck;
+			new.tmo_buf = old.tmo_buf;
+			TB_SET_PAD(new);
+			/* Atomic CAS will fail if we experienced torn reads,
+			 * retry update sequence until CAS succeeds */
+		} while (!_odp_atomic_u128_cmp_xchg_mm(
+					(_odp_atomic_u128_t *)tb,
+					(_uint128_t *)&old,
+					(_uint128_t *)&new,
+					_ODP_MEMMODEL_RLS,
+					_ODP_MEMMODEL_RLX));
+#else
+#ifdef __ARM_ARCH
+		/* Since barriers are not good for C-A15, we take an
+		 * alternative approach using relaxed memory model */
+		uint64_t old;
+		/* Swap in new expiration tick, get back old tick which
+		 * will indicate active/inactive timer state */
+		old = _odp_atomic_u64_xchg_mm(&tb->exp_tck, abs_tck,
+			_ODP_MEMMODEL_RLX);
+		if (old == TMO_INACTIVE) {
+			/* Timer was inactive (cancelled or expired),
+			 * we can't reset a timer without a timeout buffer.
+			 * Attempt to restore inactive state, we don't
+			 * want this timer to continue as active without
+			 * timeout as this will trigger unnecessary and
+			 * aborted expiration attempts.
+			 * We don't care if we fail, then some other thread
+			 * reset or cancelled the timer. Without any
+			 * synchronization between the threads, we have a
+			 * data race and the behavior is undefined */
+			(void)_odp_atomic_u64_cmp_xchg_strong_mm(
+					&tb->exp_tck,
+					&abs_tck,
+					TMO_INACTIVE,
+					_ODP_MEMMODEL_RLX,
+					_ODP_MEMMODEL_RLX);
+			success = false;
+		}
+#else
+		/* Take a related lock */
+		while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
+			(void)0;
+
+		/* Only if there is a timeout buffer can be reset the timer */
+		if (odp_likely(tb->tmo_buf != ODP_BUFFER_INVALID)) {
+			/* Write the new expiration tick */
+			tb->exp_tck.v = abs_tck;
+		} else {
+			/* Cannot reset a timer with neither old nor new
+			 * timeout buffer */
+			success = false;
+		}
 
-	if (timer->active == 0) {
-		ODP_DBG("Timer (%u) not active\n", timer->timer_hdl);
-		return;
+		/* Release the lock */
+		_odp_atomic_flag_clear(IDX2LOCK(idx));
+#endif
+#endif
+	} else {
+		/* We have a new timeout buffer which replaces any old one */
+		odp_buffer_t old_buf = ODP_BUFFER_INVALID;
+#ifdef ODP_ATOMIC_U128
+		tick_buf_t new, old;
+		new.exp_tck.v = abs_tck;
+		new.tmo_buf = *tmo_buf;
+		TB_SET_PAD(new);
+		/* We are releasing the new timeout buffer to some other
+		 * thread */
+		_odp_atomic_u128_xchg_mm((_odp_atomic_u128_t *)tb,
+					 (_uint128_t *)&new,
+					 (_uint128_t *)&old,
+					 _ODP_MEMMODEL_ACQ_RLS);
+		old_buf = old.tmo_buf;
+#else
+		/* Take a related lock */
+		while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
+			(void)0;
+
+		/* Swap in new buffer, save any old buffer */
+		old_buf = tb->tmo_buf;
+		tb->tmo_buf = *tmo_buf;
+
+		/* Write the new expiration tick */
+		tb->exp_tck.v = abs_tck;
+
+		/* Release the lock */
+		_odp_atomic_flag_clear(IDX2LOCK(idx));
+#endif
+		/* Return old timeout buffer */
+		*tmo_buf = old_buf;
 	}
+	return success;
+}
 
-	/* ODP_DBG("Tick\n"); */
-
-	cur_tick = timer->cur_tick++;
-
-	odp_sync_stores();
-
-	tick = &timer->tick[cur_tick % MAX_TICKS];
+static odp_buffer_t timer_cancel(odp_timer_pool *tp,
+		uint32_t idx,
+		uint64_t new_state)
+{
+	tick_buf_t *tb = &tp->tick_buf[idx];
+	odp_buffer_t old_buf;
+
+#ifdef ODP_ATOMIC_U128
+	tick_buf_t new, old;
+	/* Update the timer state (e.g. cancel the current timeout) */
+	new.exp_tck.v = new_state;
+	/* Swap out the old buffer */
+	new.tmo_buf = ODP_BUFFER_INVALID;
+	TB_SET_PAD(new);
+	_odp_atomic_u128_xchg_mm((_odp_atomic_u128_t *)tb,
+				 (_uint128_t *)&new, (_uint128_t *)&old,
+				 _ODP_MEMMODEL_RLX);
+	old_buf = old.tmo_buf;
+#else
+	/* Take a related lock */
+	while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
+		(void)0;
+
+	/* Update the timer state (e.g. cancel the current timeout) */
+	tb->exp_tck.v = new_state;
+
+	/* Swap out the old buffer */
+	old_buf = tb->tmo_buf;
+	tb->tmo_buf = ODP_BUFFER_INVALID;
+
+	/* Release the lock */
+	_odp_atomic_flag_clear(IDX2LOCK(idx));
+#endif
+	/* Return the old buffer */
+	return old_buf;
+}
 
-	while ((tmo = rem_tmo(tick)) != NULL) {
-		odp_queue_t  queue;
-		odp_buffer_t buf;
+static unsigned timer_expire(odp_timer_pool *tp, uint32_t idx, uint64_t tick)
+{
+	odp_timer *tim = &tp->timers[idx];
+	tick_buf_t *tb = &tp->tick_buf[idx];
+	odp_buffer_t tmo_buf = ODP_BUFFER_INVALID;
+	uint64_t exp_tck;
+#ifdef ODP_ATOMIC_U128
+	/* Atomic re-read for correctness */
+	exp_tck = _odp_atomic_u64_load_mm(&tb->exp_tck, _ODP_MEMMODEL_RLX);
+	/* Re-check exp_tck */
+	if (odp_likely(exp_tck <= tick)) {
+		/* Attempt to grab timeout buffer, replace with inactive timer
+		 * and invalid buffer */
+		tick_buf_t new, old;
+		old.exp_tck.v = exp_tck;
+		old.tmo_buf = tb->tmo_buf;
+		TB_SET_PAD(old);
+		new.exp_tck.v = TMO_INACTIVE;
+		new.tmo_buf = ODP_BUFFER_INVALID;
+		TB_SET_PAD(new);
+		int succ = _odp_atomic_u128_cmp_xchg_mm(
+				(_odp_atomic_u128_t *)tb,
+				(_uint128_t *)&old, (_uint128_t *)&new,
+				_ODP_MEMMODEL_RLS, _ODP_MEMMODEL_RLX);
+		if (succ)
+			tmo_buf = old.tmo_buf;
+		/* Else CAS failed, something changed => skip timer
+		 * this tick, it will be checked again next tick */
+	}
+	/* Else false positive, ignore */
+#else
+	/* Take a related lock */
+	while (_odp_atomic_flag_tas(IDX2LOCK(idx)))
+		(void)0;
+	/* Proper check for timer expired */
+	exp_tck = tb->exp_tck.v;
+	if (odp_likely(exp_tck <= tick)) {
+		/* Verify that there is a timeout buffer */
+		if (odp_likely(tb->tmo_buf != ODP_BUFFER_INVALID)) {
+			/* Grab timeout buffer, replace with inactive timer
+			 * and invalid buffer */
+			tmo_buf = tb->tmo_buf;
+			tb->tmo_buf = ODP_BUFFER_INVALID;
+			tb->exp_tck.v = TMO_INACTIVE;
+		}
+		/* Else somehow active timer without user buffer */
+	}
+	/* Else false positive, ignore */
+	/* Release the lock */
+	_odp_atomic_flag_clear(IDX2LOCK(idx));
+#endif
+	if (odp_likely(tmo_buf != ODP_BUFFER_INVALID)) {
+		/* Fill in metadata fields in system timeout buffer */
+		if (odp_buffer_type(tmo_buf) == ODP_BUFFER_TYPE_TIMEOUT) {
+			/* Convert from buffer to timeout hdr */
+			odp_timeout_hdr_t *tmo_hdr =
+				odp_tmo_to_hdr(odp_tmo_from_buffer(tmo_buf));
+			tmo_hdr->timer = tp_idx_to_handle(tp, idx);
+			tmo_hdr->expiration = exp_tck;
+			tmo_hdr->user_ptr = tim->user_ptr;
+		}
+		/* Else ignore buffers of other types */
+		/* Post the timeout to the destination queue */
+		int rc = odp_queue_enq(tim->queue, tmo_buf);
+		if (odp_unlikely(rc != 0))
+			ODP_ABORT("Failed to enqueue timeout buffer (%d)\n",
+				  rc);
+		return 1;
+	} else {
+		/* Else false positive, ignore */
+		return 0;
+	}
+}
 
-		queue = tmo->queue;
-		buf   = tmo->buf;
+static unsigned odp_timer_pool_expire(odp_timer_pool_t tpid, uint64_t tick)
+{
+	tick_buf_t *array = &tpid->tick_buf[0];
+	uint32_t high_wm = _odp_atomic_u32_load_mm(&tpid->high_wm,
+			_ODP_MEMMODEL_ACQ);
+	unsigned nexp = 0;
+	uint32_t i;
+
+	for (i = 0; i < high_wm;) {
+#ifdef __ARM_ARCH
+		/* As a rare occurence, we can outsmart the HW prefetcher
+		 * and the compiler (GCC -fprefetch-loop-arrays) with some
+		 * tuned manual prefetching (32x16=512B ahead), seems to
+		 * give 30% better performance on ARM C-A15 */
+		PREFETCH(&array[i + 32]);
+#endif
+		/* Non-atomic read for speed */
+		uint64_t exp_tck = array[i++].exp_tck.v;
+		if (odp_unlikely(exp_tck <= tick)) {
+			/* Attempt to expire timer */
+			nexp += timer_expire(tpid, i - 1, tick);
+		}
+	}
+	return nexp;
+}
 
-		if (buf != tmo->tmo_buf)
-			odp_buffer_free(tmo->tmo_buf);
+/******************************************************************************
+ * POSIX timer support
+ * Functions that use Linux/POSIX per-process timers and related facilities
+ *****************************************************************************/
 
-		odp_queue_enq(queue, buf);
+static void timer_notify(sigval_t sigval)
+{
+	odp_timer_pool *tp = (odp_timer_pool *)sigval.sival_ptr;
+#ifdef __ARM_ARCH
+	odp_timer *array = &tp->timers[0];
+	uint32_t i;
+	/* Prefetch initial cache lines (match 32 above) */
+	for (i = 0; i < 32; i += ODP_CACHE_LINE_SIZE / sizeof(array[0]))
+		PREFETCH(&array[i]);
+#endif
+	uint64_t prev_tick = odp_atomic_fetch_inc_u64(&tp->cur_tick);
+	/* Attempt to acquire the lock, check if the old value was clear */
+	if (odp_spinlock_trylock(&tp->itimer_running)) {
+		/* Scan timer array, looking for timers to expire */
+		(void)odp_timer_pool_expire(tp, prev_tick);
+		odp_spinlock_unlock(&tp->itimer_running);
 	}
+	/* Else skip scan of timers. cur_tick was updated and next itimer
+	 * invocation will process older expiration ticks as well */
 }
 
-static void timer_start(timer_ring_t *timer)
+static void itimer_init(odp_timer_pool *tp)
 {
 	struct sigevent   sigev;
 	struct itimerspec ispec;
 	uint64_t res, sec, nsec;
 
-	ODP_DBG("\nTimer (%u) starts\n", timer->timer_hdl);
+	ODP_DBG("Creating POSIX timer for timer pool %s, period %"
+		PRIu64" ns\n", tp->name, tp->resolution_ns);
 
 	memset(&sigev, 0, sizeof(sigev));
 	memset(&ispec, 0, sizeof(ispec));
 
 	sigev.sigev_notify          = SIGEV_THREAD;
-	sigev.sigev_notify_function = notify_function;
-	sigev.sigev_value.sival_ptr = timer;
+	sigev.sigev_notify_function = timer_notify;
+	sigev.sigev_value.sival_ptr = tp;
 
-	if (timer_create(CLOCK_MONOTONIC, &sigev, &timer->timerid)) {
-		ODP_DBG("Timer create failed\n");
-		return;
-	}
+	if (timer_create(CLOCK_MONOTONIC, &sigev, &tp->timerid))
+		ODP_ABORT("timer_create() returned error %s\n",
+			  strerror(errno));
 
-	res  = timer->resolution_ns;
+	res  = tp->resolution_ns;
 	sec  = res / ODP_TIME_SEC;
-	nsec = res - sec*ODP_TIME_SEC;
+	nsec = res - sec * ODP_TIME_SEC;
 
 	ispec.it_interval.tv_sec  = (time_t)sec;
 	ispec.it_interval.tv_nsec = (long)nsec;
 	ispec.it_value.tv_sec     = (time_t)sec;
 	ispec.it_value.tv_nsec    = (long)nsec;
 
-	if (timer_settime(timer->timerid, 0, &ispec, NULL)) {
-		ODP_DBG("Timer set failed\n");
-		return;
-	}
-
-	return;
+	if (timer_settime(&tp->timerid, 0, &ispec, NULL))
+		ODP_ABORT("timer_settime() returned error %s\n",
+			  strerror(errno));
 }
 
-int odp_timer_init_global(void)
+static void itimer_fini(odp_timer_pool *tp)
 {
-	ODP_DBG("Timer init ...");
-
-	memset(&odp_timer, 0, sizeof(timer_global_t));
-
-	odp_spinlock_init(&odp_timer.lock);
-
-	ODP_DBG("done\n");
-
-	return 0;
+	if (timer_delete(tp->timerid) != 0)
+		ODP_ABORT("timer_delete() returned error %s\n",
+			  strerror(errno));
 }
 
-int odp_timer_disarm_all(void)
+/******************************************************************************
+ * Public API functions
+ * Some parameter checks and error messages
+ * No modificatios of internal state
+ *****************************************************************************/
+odp_timer_pool_t
+odp_timer_pool_create(const char *name,
+		      odp_buffer_pool_t buf_pool,
+		      uint64_t resolution_ns,
+		      uint64_t min_timeout,
+		      uint64_t max_timeout,
+		      uint32_t num_timers,
+		      int shared,
+		      odp_timer_clk_src_t clk_src)
 {
-	int timers;
-	struct itimerspec ispec;
-
-	odp_spinlock_lock(&odp_timer.lock);
-
-	timers = odp_timer.num_timers;
-
-	ispec.it_interval.tv_sec  = 0;
-	ispec.it_interval.tv_nsec = 0;
-	ispec.it_value.tv_sec     = 0;
-	ispec.it_value.tv_nsec    = 0;
-
-	for (; timers >= 0; timers--) {
-		if (timer_settime(odp_timer.timer[timers].timerid,
-				  0, &ispec, NULL)) {
-			ODP_DBG("Timer reset failed\n");
-			odp_spinlock_unlock(&odp_timer.lock);
-			return -1;
-		}
-		odp_timer.num_timers--;
-	}
-
-	odp_spinlock_unlock(&odp_timer.lock);
-
-	return 0;
+	/* Verify that buffer pool can be used for timeouts */
+	odp_buffer_t buf = odp_buffer_alloc(buf_pool);
+	if (buf == ODP_BUFFER_INVALID)
+		ODP_ABORT("%s: Failed to allocate buffer\n", name);
+	if (odp_buffer_type(buf) != ODP_BUFFER_TYPE_TIMEOUT)
+		ODP_ABORT("%s: Buffer pool wrong type\n", name);
+	odp_buffer_free(buf);
+	odp_timer_pool_t tp = odp_timer_pool_new(name, buf_pool, resolution_ns,
+			      min_timeout, max_timeout, num_timers, shared,
+			      clk_src);
+	return tp;
 }
 
-odp_timer_t odp_timer_create(const char *name, odp_buffer_pool_t pool,
-			     uint64_t resolution_ns, uint64_t min_ns,
-			     uint64_t max_ns)
+void odp_timer_pool_start(void)
 {
-	uint32_t id;
-	timer_ring_t *timer;
-	odp_timer_t timer_hdl;
-	int i;
-	uint64_t max_ticks;
-	(void) name;
-
-	if (resolution_ns < MIN_RES)
-		resolution_ns = MIN_RES;
-
-	if (resolution_ns > MAX_RES)
-		resolution_ns = MAX_RES;
-
-	max_ticks = max_ns / resolution_ns;
-
-	if (max_ticks > MAX_TICKS) {
-		ODP_DBG("Maximum timeout too long: %"PRIu64" ticks\n",
-			max_ticks);
-		return ODP_TIMER_INVALID;
-	}
-
-	if (min_ns < resolution_ns) {
-		ODP_DBG("Min timeout %"PRIu64" ns < resolution %"PRIu64" ns\n",
-			min_ns, resolution_ns);
-		return ODP_TIMER_INVALID;
-	}
-
-	odp_spinlock_lock(&odp_timer.lock);
-
-	if (odp_timer.num_timers >= NUM_TIMERS) {
-		odp_spinlock_unlock(&odp_timer.lock);
-		ODP_DBG("All timers allocated\n");
-		return ODP_TIMER_INVALID;
-	}
-
-	for (id = 0; id < NUM_TIMERS; id++) {
-		if (odp_timer.timer[id].allocated == 0)
-			break;
-	}
-
-	timer = &odp_timer.timer[id];
-	timer->allocated = 1;
-	odp_timer.num_timers++;
-
-	odp_spinlock_unlock(&odp_timer.lock);
-
-	timer_hdl = id + 1;
-
-	timer->timer_hdl     = timer_hdl;
-	timer->pool          = pool;
-	timer->resolution_ns = resolution_ns;
-	timer->max_ticks     = MAX_TICKS;
-
-	for (i = 0; i < MAX_TICKS; i++) {
-		odp_spinlock_init(&timer->tick[i].lock);
-		timer->tick[i].list = NULL;
-	}
-
-	timer->active = 1;
-	odp_sync_stores();
-
-	timer_start(timer);
-
-	return timer_hdl;
+	/* Nothing to do here, timer pools are started by the create call */
 }
 
-odp_timer_tmo_t odp_timer_absolute_tmo(odp_timer_t timer_hdl, uint64_t tmo_tick,
-				       odp_queue_t queue, odp_buffer_t buf)
+void odp_timer_pool_destroy(odp_timer_pool_t tpid)
 {
-	int id;
-	uint64_t tick;
-	uint64_t cur_tick;
-	timeout_t *new_tmo;
-	odp_buffer_t tmo_buf;
-	odp_timeout_hdr_t *tmo_hdr;
-	timer_ring_t *timer;
-
-	id = (int)timer_hdl - 1;
-	timer = &odp_timer.timer[id];
+	odp_timer_pool_del(tpid);
+}
 
-	cur_tick = timer->cur_tick;
-	if (tmo_tick <= cur_tick) {
-		ODP_DBG("timeout too close\n");
-		return ODP_TIMER_TMO_INVALID;
-	}
+uint64_t odp_timer_tick_to_ns(odp_timer_pool_t tpid, uint64_t ticks)
+{
+	return ticks * tpid->resolution_ns;
+}
 
-	if ((tmo_tick - cur_tick) > MAX_TICKS) {
-		ODP_DBG("timeout too far: cur %"PRIu64" tmo %"PRIu64"\n",
-			cur_tick, tmo_tick);
-		return ODP_TIMER_TMO_INVALID;
-	}
+uint64_t odp_timer_ns_to_tick(odp_timer_pool_t tpid, uint64_t ns)
+{
+	return (uint64_t)(ns / tpid->resolution_ns);
+}
 
-	tick = tmo_tick % MAX_TICKS;
+uint64_t odp_timer_current_tick(odp_timer_pool_t tpid)
+{
+	/* Relaxed atomic read for lowest overhead */
+	return odp_atomic_load_u64(&tpid->cur_tick);
+}
 
-	tmo_buf = odp_buffer_alloc(timer->pool);
-	if (tmo_buf == ODP_BUFFER_INVALID) {
-		ODP_DBG("tmo buffer alloc failed\n");
-		return ODP_TIMER_TMO_INVALID;
+size_t odp_timer_pool_info(odp_timer_pool_t tpid,
+			   odp_timer_pool_info_t *buf,
+			   size_t buf_size)
+{
+	size_t needs;
+	buf->resolution = tpid->resolution_ns;
+	buf->min_tmo = tpid->min_rel_tck;
+	buf->max_tmo = tpid->max_rel_tck;
+	buf->num_timers = tpid->max_timers;
+	buf->cur_timers = tpid->num_alloc;
+	buf->hwm_timers = odp_atomic_load_u32(&tpid->high_wm);
+	buf->shared = tpid->shared;
+	/* Compute how large buffer is needed */
+	needs = offsetof(struct odp_timer_pool_info_s, name) +
+		strlen(tpid->name) + 1;
+	if (buf_size >= needs) {
+		/* Provided buffer is large enough */
+		strcpy(buf->name, tpid->name);
+		return needs;
+	} else {
+		/* Provided buffer is too small */
+		size_t siz = sizeof(buf->name);
+		/* Truncate name when copying into buffer */
+		strncpy(buf->name, tpid->name, siz - 1);
+		buf->name[siz] = 0;
+		return buf_size;
 	}
-
-	tmo_hdr = odp_timeout_hdr((odp_timeout_t) tmo_buf);
-	new_tmo = &tmo_hdr->meta;
-
-	new_tmo->timer_id = id;
-	new_tmo->tick     = (int)tick;
-	new_tmo->tmo_tick = tmo_tick;
-	new_tmo->queue    = queue;
-	new_tmo->tmo_buf  = tmo_buf;
-
-	if (buf != ODP_BUFFER_INVALID)
-		new_tmo->buf = buf;
-	else
-		new_tmo->buf = tmo_buf;
-
-	add_tmo(&timer->tick[tick], new_tmo);
-
-	return tmo_buf;
 }
 
-uint64_t odp_timer_tick_to_ns(odp_timer_t timer_hdl, uint64_t ticks)
+odp_timer_t odp_timer_alloc(odp_timer_pool_t tpid,
+			    odp_queue_t queue,
+			    void *user_ptr)
 {
-	uint32_t id;
-
-	id = timer_hdl - 1;
-	return ticks * odp_timer.timer[id].resolution_ns;
+	if (odp_unlikely(queue == ODP_QUEUE_INVALID))
+		ODP_ABORT("%s: Invalid queue handle\n", tpid->name);
+	/* We don't care about the validity of user_ptr because we will not
+	 * attempt to dereference it */
+	odp_timer_t hdl = timer_alloc(tpid, queue, user_ptr);
+	if (odp_likely(hdl != ODP_TIMER_INVALID)) {
+		/* Success */
+		return hdl;
+	}
+	/* errno set by timer_alloc() */
+	return ODP_TIMER_INVALID;
 }
 
-uint64_t odp_timer_ns_to_tick(odp_timer_t timer_hdl, uint64_t ns)
+uint64_t odp_timer_free(odp_timer_t hdl, odp_buffer_t *tmo_buf)
 {
-	uint32_t id;
-
-	id = timer_hdl - 1;
-	return ns / odp_timer.timer[id].resolution_ns;
+	odp_timer_pool *tp = handle_to_tp(hdl);
+	uint32_t idx = handle_to_idx(hdl, tp);
+	odp_buffer_t old_buf = timer_free(tp, idx);
+	/* Only overwrite *tmo_buf if we are actually returning a timeout
+	 * buffer */
+	if (old_buf != ODP_BUFFER_INVALID)
+		*tmo_buf = old_buf;
+	/* Return a special value that will not match any timeout expiration
+	 * tick and thus help identify stale timeouts */
+	return ODP_TICK_INVALID;
 }
 
-uint64_t odp_timer_resolution(odp_timer_t timer_hdl)
+uint64_t odp_timer_set_abs(odp_timer_t hdl,
+			   uint64_t abs_tck,
+			   odp_buffer_t *tmo_buf)
 {
-	uint32_t id;
-
-	id = timer_hdl - 1;
-	return odp_timer.timer[id].resolution_ns;
+	odp_timer_pool *tp = handle_to_tp(hdl);
+	uint32_t idx = handle_to_idx(hdl, tp);
+	uint64_t cur_tick = odp_atomic_load_u64(&tp->cur_tick);
+	if (odp_unlikely(abs_tck < cur_tick + tp->min_rel_tck))
+		return ODP_TICK_TOOEARLY;
+	if (odp_unlikely(abs_tck > cur_tick + tp->max_rel_tck))
+		return ODP_TICK_TOOLATE;
+	/* Return either the requested tick value when successful or a special
+	 * value that will not match any timeout for errors */
+	return timer_reset(idx, abs_tck, tmo_buf, tp) ?
+		abs_tck : ODP_TICK_INVALID;
 }
 
-uint64_t odp_timer_maximum_tmo(odp_timer_t timer_hdl)
+uint64_t odp_timer_set_rel(odp_timer_t hdl,
+			   uint64_t rel_tck,
+			   odp_buffer_t *tmo_buf)
 {
-	uint32_t id;
-
-	id = timer_hdl - 1;
-	return odp_timer.timer[id].max_ticks;
+	odp_timer_pool *tp = handle_to_tp(hdl);
+	uint32_t idx = handle_to_idx(hdl, tp);
+	if (odp_unlikely(rel_tck < tp->min_rel_tck))
+		return ODP_TICK_TOOEARLY;
+	if (odp_unlikely(rel_tck > tp->max_rel_tck))
+		return ODP_TICK_TOOLATE;
+	uint64_t abs_tck = odp_atomic_load_u64(&tp->cur_tick) + rel_tck;
+	/* Return either the requested tick value when successful or a special
+	 * value that will not match any timeout for errors */
+	return timer_reset(idx, abs_tck, tmo_buf, tp) ?
+		abs_tck : ODP_TICK_INVALID;
 }
 
-uint64_t odp_timer_current_tick(odp_timer_t timer_hdl)
+uint64_t odp_timer_cancel(odp_timer_t hdl, odp_buffer_t *tmo_buf)
 {
-	uint32_t id;
-
-	id = timer_hdl - 1;
-	return odp_timer.timer[id].cur_tick;
+	odp_timer_pool *tp = handle_to_tp(hdl);
+	uint32_t idx = handle_to_idx(hdl, tp);
+	*tmo_buf = timer_cancel(tp, idx, TMO_INACTIVE);
+	/* Return a special value that will not match any timeout expiration
+	 * tick and thus help identify stale timeouts */
+	return ODP_TICK_INVALID;
 }
 
-odp_timeout_t odp_timeout_from_buffer(odp_buffer_t buf)
+int odp_timer_tmo_metadata(odp_buffer_t buf,
+		odp_timer_t *hdl_p,
+		uint64_t *exp_tck_p,
+		void **user_ptr_p)
 {
-	return (odp_timeout_t) buf;
+	if (odp_likely(odp_buffer_type(buf) == ODP_BUFFER_TYPE_TIMEOUT)) {
+		odp_timeout_hdr_t *tmo_hdr =
+			odp_tmo_to_hdr(odp_tmo_from_buffer(buf));
+		odp_timer_t timer = tmo_hdr->timer;
+		uint64_t expiration = tmo_hdr->expiration;
+		void *user_ptr = tmo_hdr->user_ptr;
+		if (odp_likely(hdl_p != NULL))
+			*hdl_p = timer;
+		if (odp_likely(exp_tck_p != NULL))
+			*exp_tck_p = expiration;
+		if (odp_likely(user_ptr_p != NULL))
+			*user_ptr_p = user_ptr;
+		return 1;
+	} else {
+		/* Not a buffer of the appropriate type */
+		return 0;
+	}
 }
 
-uint64_t odp_timeout_tick(odp_timeout_t tmo)
+int odp_timer_init_global(void)
 {
-	odp_timeout_hdr_t *tmo_hdr = odp_timeout_hdr(tmo);
-	return tmo_hdr->meta.tmo_tick;
+#ifndef ODP_ATOMIC_U128
+	uint32_t i;
+	for (i = 0; i < NUM_LOCKS; i++)
+		_odp_atomic_flag_clear(&locks[i]);
+#else
+	ODP_DBG("Using lock-less timer implementation\n");
+#endif
+	odp_atomic_init_u32(&num_timer_pools, 0);
+	return 0;
 }