[v3,2/5] lib/ring: add zero copy APIs

Message ID 20201023044343.13462-3-honnappa.nagarahalli@arm.com
State Superseded
Headers show
Series
  • lib/ring: add zero copy APIs
Related show

Commit Message

Honnappa Nagarahalli Oct. 23, 2020, 4:43 a.m.
Add zero-copy APIs. These APIs provide the capability to
copy the data to/from the ring memory directly, without
having a temporary copy (for ex: an array of mbufs on
the stack). Use cases that involve copying large amount
of data to/from the ring can benefit from these APIs.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>

---
 lib/librte_ring/meson.build        |   1 +
 lib/librte_ring/rte_ring_elem.h    |   1 +
 lib/librte_ring/rte_ring_peek_zc.h | 542 +++++++++++++++++++++++++++++
 3 files changed, 544 insertions(+)
 create mode 100644 lib/librte_ring/rte_ring_peek_zc.h

-- 
2.17.1

Comments

Ananyev, Konstantin Oct. 23, 2020, 1:59 p.m. | #1
> 

> Add zero-copy APIs. These APIs provide the capability to

> copy the data to/from the ring memory directly, without

> having a temporary copy (for ex: an array of mbufs on

> the stack). Use cases that involve copying large amount

> of data to/from the ring can benefit from these APIs.


LGTM in general.
Few nits, see below.

> 

> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

> Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>

> ---

>  lib/librte_ring/meson.build        |   1 +

>  lib/librte_ring/rte_ring_elem.h    |   1 +

>  lib/librte_ring/rte_ring_peek_zc.h | 542 +++++++++++++++++++++++++++++

>  3 files changed, 544 insertions(+)

>  create mode 100644 lib/librte_ring/rte_ring_peek_zc.h


Need to update documentation: PG and RN.

> 

> diff --git a/lib/librte_ring/meson.build b/lib/librte_ring/meson.build

> index 31c0b4649..36fdcb6a5 100644

> --- a/lib/librte_ring/meson.build

> +++ b/lib/librte_ring/meson.build

> @@ -11,5 +11,6 @@ headers = files('rte_ring.h',

>  		'rte_ring_hts_c11_mem.h',

>  		'rte_ring_peek.h',

>  		'rte_ring_peek_c11_mem.h',

> +		'rte_ring_peek_zc.h',

>  		'rte_ring_rts.h',

>  		'rte_ring_rts_c11_mem.h')

> diff --git a/lib/librte_ring/rte_ring_elem.h b/lib/librte_ring/rte_ring_elem.h

> index 938b398fc..7034d29c0 100644

> --- a/lib/librte_ring/rte_ring_elem.h

> +++ b/lib/librte_ring/rte_ring_elem.h

> @@ -1079,6 +1079,7 @@ rte_ring_dequeue_burst_elem(struct rte_ring *r, void *obj_table,

> 

>  #ifdef ALLOW_EXPERIMENTAL_API

>  #include <rte_ring_peek.h>

> +#include <rte_ring_peek_zc.h>

>  #endif

> 

>  #include <rte_ring.h>

> diff --git a/lib/librte_ring/rte_ring_peek_zc.h b/lib/librte_ring/rte_ring_peek_zc.h

> new file mode 100644

> index 000000000..9db2d343f

> --- /dev/null

> +++ b/lib/librte_ring/rte_ring_peek_zc.h

> @@ -0,0 +1,542 @@

> +/* SPDX-License-Identifier: BSD-3-Clause

> + *

> + * Copyright (c) 2020 Arm Limited

> + * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org

> + * All rights reserved.

> + * Derived from FreeBSD's bufring.h

> + * Used as BSD-3 Licensed with permission from Kip Macy.

> + */

> +

> +#ifndef _RTE_RING_PEEK_ZC_H_

> +#define _RTE_RING_PEEK_ZC_H_

> +

> +/**

> + * @file

> + * @b EXPERIMENTAL: this API may change without prior notice

> + * It is not recommended to include this file directly.

> + * Please include <rte_ring_elem.h> instead.

> + *

> + * Ring Peek Zero Copy APIs

> + * These APIs make it possible to split public enqueue/dequeue API

> + * into 3 parts:

> + * - enqueue/dequeue start

> + * - copy data to/from the ring

> + * - enqueue/dequeue finish

> + * Along with the advantages of the peek APIs, these APIs provide the ability

> + * to avoid copying of the data to temporary area (for ex: array of mbufs

> + * on the stack).

> + *

> + * Note that currently these APIs are available only for two sync modes:

> + * 1) Single Producer/Single Consumer (RTE_RING_SYNC_ST)

> + * 2) Serialized Producer/Serialized Consumer (RTE_RING_SYNC_MT_HTS).

> + * It is user's responsibility to create/init ring with appropriate sync

> + * modes selected.

> + *

> + * Following are some examples showing the API usage.

> + * 1)

> + * struct elem_obj {uint64_t a; uint32_t b, c;};

> + * struct elem_obj *obj;

> + *

> + * // Create ring with sync type RTE_RING_SYNC_ST or RTE_RING_SYNC_MT_HTS

> + * // Reserve space on the ring

> + * n = rte_ring_enqueue_zc_bulk_elem_start(r, sizeof(elem_obj), 1, &zcd, NULL);

> + *

> + * // Produce the data directly on the ring memory

> + * obj = (struct elem_obj *)zcd->ptr1;

> + * obj.a = rte_get_a();


As obj is a pointer, should be obj->a = ...
Same for b and c.

> + * obj.b = rte_get_b();

> + * obj.c = rte_get_c();

> + * rte_ring_enqueue_zc_elem_finish(ring, n);

> + *

> + * 2)

> + * // Create ring with sync type RTE_RING_SYNC_ST or RTE_RING_SYNC_MT_HTS

> + * // Reserve space on the ring

> + * n = rte_ring_enqueue_zc_burst_start(r, 32, &zcd, NULL);

> + *

> + * // Pkt I/O core polls packets from the NIC

> + * if (n == 32)

> + *	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, 32);

> + * else

> + *	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, zcd->n1);


Hmm, that doesn't look exactly correct to me.
It could be that n == 32, but we still need to do wrap-around.
Shouldn't it be:

If (n != 0) {
	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, zcd->n1);
	if (nb_rx == zcd->n1 && nb_rx != n)
		nb_rx += rte_eth_rx_burst(portid, queueid, zcd->ptr2, n - nb_rx);
}

> + *

> + * // Provide packets to the packet processing cores

> + * rte_ring_enqueue_zc_finish(r, nb_rx);

> + *

> + * Note that between _start_ and _finish_ none other thread can proceed

> + * with enqueue/dequeue operation till _finish_ completes.

> + */

> +

> +#ifdef __cplusplus

> +extern "C" {

> +#endif

> +

> +#include <rte_ring_peek_c11_mem.h>

> +

> +/**

> + * Ring zero-copy information structure.

> + *

> + * This structure contains the pointers and length of the space

> + * reserved on the ring storage.

> + */

> +struct rte_ring_zc_data {

> +	/* Pointer to the first space in the ring */

> +	void **ptr1;


Why not just 'void *ptr1;'?
Same for ptr2.

> +	/* Pointer to the second space in the ring if there is wrap-around */

> +	void **ptr2;

> +	/* Number of elements in the first pointer. If this is equal to

> +	 * the number of elements requested, then ptr2 is NULL.

> +	 * Otherwise, subtracting n1 from number of elements requested

> +	 * will give the number of elements available at ptr2.

> +	 */

> +	unsigned int n1;

> +} __rte_cache_aligned;

> +

> +static __rte_always_inline void

> +__rte_ring_get_elem_addr(struct rte_ring *r, uint32_t head,

> +	uint32_t esize, uint32_t num, void **dst1, uint32_t *n1, void **dst2)

> +{

> +	uint32_t idx, scale, nr_idx;

> +	uint32_t *ring = (uint32_t *)&r[1];

> +

> +	/* Normalize to uint32_t */

> +	scale = esize / sizeof(uint32_t);

> +	idx = head & r->mask;

> +	nr_idx = idx * scale;

> +

> +	*dst1 = ring + nr_idx;

> +	*n1 = num;

> +

> +	if (idx + num > r->size) {

> +		*n1 = r->size - idx;

> +		*dst2 = ring;

> +	}


Seems like missing:
else {*dst2 = NULL;}

> +}

> +

> +/**

> + * @internal This function moves prod head value.

> + */

> +static __rte_always_inline unsigned int

> +__rte_ring_do_enqueue_zc_elem_start(struct rte_ring *r, unsigned int esize,

> +		uint32_t n, enum rte_ring_queue_behavior behavior,

> +		struct rte_ring_zc_data *zcd, unsigned int *free_space)

> +{

> +	uint32_t free, head, next;

> +

> +	switch (r->prod.sync_type) {

> +	case RTE_RING_SYNC_ST:

> +		n = __rte_ring_move_prod_head(r, RTE_RING_SYNC_ST, n,

> +			behavior, &head, &next, &free);

> +		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd->ptr1,


If you change ptr1, ptr2 to be just 'void *', then probably no extra type-cast
will be needed here. 

> +			&zcd->n1, (void **)&zcd->ptr2);

> +		break;

> +	case RTE_RING_SYNC_MT_HTS:

> +		n = __rte_ring_hts_move_prod_head(r, n, behavior, &head, &free);

> +		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd->ptr1,

> +			&zcd->n1, (void **)&zcd->ptr2);

> +		break;

> +	case RTE_RING_SYNC_MT:

> +	case RTE_RING_SYNC_MT_RTS:

> +	default:

> +		/* unsupported mode, shouldn't be here */

> +		RTE_ASSERT(0);

> +		n = 0;

> +		free = 0;

> +	}


Would it make sense to move __rte_ring_get_elem_addr() here and do it
only when n != 0?
I.E:

if (n != 0)
	__rte_ring_get_elem_addr(...);
	
Same comments for _dequeue_ analog.

> +

> +	if (free_space != NULL)

> +		*free_space = free - n;

> +	return n;

> +}

> +
Honnappa Nagarahalli Oct. 24, 2020, 3:45 p.m. | #2
Hi Konstantin,
	Thank you for the quick comments. Please see the responses inline.

<snip>

> 

> 

> >

> > Add zero-copy APIs. These APIs provide the capability to copy the data

> > to/from the ring memory directly, without having a temporary copy (for

> > ex: an array of mbufs on the stack). Use cases that involve copying

> > large amount of data to/from the ring can benefit from these APIs.

> 

> LGTM in general.

> Few nits, see below.

> 

> >

> > Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

> > Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>

> > ---

> >  lib/librte_ring/meson.build        |   1 +

> >  lib/librte_ring/rte_ring_elem.h    |   1 +

> >  lib/librte_ring/rte_ring_peek_zc.h | 542

> > +++++++++++++++++++++++++++++

> >  3 files changed, 544 insertions(+)

> >  create mode 100644 lib/librte_ring/rte_ring_peek_zc.h

> 

> Need to update documentation: PG and RN.

> 

> >

> > diff --git a/lib/librte_ring/meson.build b/lib/librte_ring/meson.build

> > index 31c0b4649..36fdcb6a5 100644

> > --- a/lib/librte_ring/meson.build

> > +++ b/lib/librte_ring/meson.build

> > @@ -11,5 +11,6 @@ headers = files('rte_ring.h',

> >  		'rte_ring_hts_c11_mem.h',

> >  		'rte_ring_peek.h',

> >  		'rte_ring_peek_c11_mem.h',

> > +		'rte_ring_peek_zc.h',

> >  		'rte_ring_rts.h',

> >  		'rte_ring_rts_c11_mem.h')

> > diff --git a/lib/librte_ring/rte_ring_elem.h

> > b/lib/librte_ring/rte_ring_elem.h index 938b398fc..7034d29c0 100644

> > --- a/lib/librte_ring/rte_ring_elem.h

> > +++ b/lib/librte_ring/rte_ring_elem.h

> > @@ -1079,6 +1079,7 @@ rte_ring_dequeue_burst_elem(struct rte_ring *r,

> > void *obj_table,

> >

> >  #ifdef ALLOW_EXPERIMENTAL_API

> >  #include <rte_ring_peek.h>

> > +#include <rte_ring_peek_zc.h>

> >  #endif

> >

> >  #include <rte_ring.h>

> > diff --git a/lib/librte_ring/rte_ring_peek_zc.h

> > b/lib/librte_ring/rte_ring_peek_zc.h

> > new file mode 100644

> > index 000000000..9db2d343f

> > --- /dev/null

> > +++ b/lib/librte_ring/rte_ring_peek_zc.h

> > @@ -0,0 +1,542 @@

> > +/* SPDX-License-Identifier: BSD-3-Clause

> > + *

> > + * Copyright (c) 2020 Arm Limited

> > + * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org

> > + * All rights reserved.

> > + * Derived from FreeBSD's bufring.h

> > + * Used as BSD-3 Licensed with permission from Kip Macy.

> > + */

> > +

> > +#ifndef _RTE_RING_PEEK_ZC_H_

> > +#define _RTE_RING_PEEK_ZC_H_

> > +

> > +/**

> > + * @file

> > + * @b EXPERIMENTAL: this API may change without prior notice

> > + * It is not recommended to include this file directly.

> > + * Please include <rte_ring_elem.h> instead.

> > + *

> > + * Ring Peek Zero Copy APIs

> > + * These APIs make it possible to split public enqueue/dequeue API

> > + * into 3 parts:

> > + * - enqueue/dequeue start

> > + * - copy data to/from the ring

> > + * - enqueue/dequeue finish

> > + * Along with the advantages of the peek APIs, these APIs provide the

> > +ability

> > + * to avoid copying of the data to temporary area (for ex: array of

> > +mbufs

> > + * on the stack).

> > + *

> > + * Note that currently these APIs are available only for two sync modes:

> > + * 1) Single Producer/Single Consumer (RTE_RING_SYNC_ST)

> > + * 2) Serialized Producer/Serialized Consumer

> (RTE_RING_SYNC_MT_HTS).

> > + * It is user's responsibility to create/init ring with appropriate

> > +sync

> > + * modes selected.

> > + *

> > + * Following are some examples showing the API usage.

> > + * 1)

> > + * struct elem_obj {uint64_t a; uint32_t b, c;};

> > + * struct elem_obj *obj;

> > + *

> > + * // Create ring with sync type RTE_RING_SYNC_ST or

> > +RTE_RING_SYNC_MT_HTS

> > + * // Reserve space on the ring

> > + * n = rte_ring_enqueue_zc_bulk_elem_start(r, sizeof(elem_obj), 1,

> > +&zcd, NULL);

> > + *

> > + * // Produce the data directly on the ring memory

> > + * obj = (struct elem_obj *)zcd->ptr1;

> > + * obj.a = rte_get_a();

> 

> As obj is a pointer, should be obj->a = ...

> Same for b and c.

Will fix.

> 

> > + * obj.b = rte_get_b();

> > + * obj.c = rte_get_c();

> > + * rte_ring_enqueue_zc_elem_finish(ring, n);

> > + *

> > + * 2)

> > + * // Create ring with sync type RTE_RING_SYNC_ST or

> > + RTE_RING_SYNC_MT_HTS

> > + * // Reserve space on the ring

> > + * n = rte_ring_enqueue_zc_burst_start(r, 32, &zcd, NULL);

> > + *

> > + * // Pkt I/O core polls packets from the NIC

> > + * if (n == 32)

> > + *	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, 32);

> > + * else

> > + *	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, zcd->n1);

> 

> Hmm, that doesn't look exactly correct to me.

> It could be that n == 32, but we still need to do wrap-around.

> Shouldn't it be:

> 

> If (n != 0) {

> 	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, zcd->n1);

> 	if (nb_rx == zcd->n1 && nb_rx != n)

> 		nb_rx += rte_eth_rx_burst(portid, queueid, zcd->ptr2, n -

> nb_rx); }

Agree

> 

> > + *

> > + * // Provide packets to the packet processing cores

> > + * rte_ring_enqueue_zc_finish(r, nb_rx);

> > + *

> > + * Note that between _start_ and _finish_ none other thread can

> > + proceed

> > + * with enqueue/dequeue operation till _finish_ completes.

> > + */

> > +

> > +#ifdef __cplusplus

> > +extern "C" {

> > +#endif

> > +

> > +#include <rte_ring_peek_c11_mem.h>

> > +

> > +/**

> > + * Ring zero-copy information structure.

> > + *

> > + * This structure contains the pointers and length of the space

> > + * reserved on the ring storage.

> > + */

> > +struct rte_ring_zc_data {

> > +	/* Pointer to the first space in the ring */

> > +	void **ptr1;

> 

> Why not just 'void *ptr1;'?

> Same for ptr2.

Agree

> 

> > +	/* Pointer to the second space in the ring if there is wrap-around */

> > +	void **ptr2;

> > +	/* Number of elements in the first pointer. If this is equal to

> > +	 * the number of elements requested, then ptr2 is NULL.

> > +	 * Otherwise, subtracting n1 from number of elements requested

> > +	 * will give the number of elements available at ptr2.

> > +	 */

> > +	unsigned int n1;

> > +} __rte_cache_aligned;

> > +

> > +static __rte_always_inline void

> > +__rte_ring_get_elem_addr(struct rte_ring *r, uint32_t head,

> > +	uint32_t esize, uint32_t num, void **dst1, uint32_t *n1, void

> > +**dst2) {

> > +	uint32_t idx, scale, nr_idx;

> > +	uint32_t *ring = (uint32_t *)&r[1];

> > +

> > +	/* Normalize to uint32_t */

> > +	scale = esize / sizeof(uint32_t);

> > +	idx = head & r->mask;

> > +	nr_idx = idx * scale;

> > +

> > +	*dst1 = ring + nr_idx;

> > +	*n1 = num;

> > +

> > +	if (idx + num > r->size) {

> > +		*n1 = r->size - idx;

> > +		*dst2 = ring;

> > +	}

> 

> Seems like missing:

> else {*dst2 = NULL;}

I did not add it since dst2 should be accessed only if there is wrap-around. Will call it out in the struct above.

> 

> > +}

> > +

> > +/**

> > + * @internal This function moves prod head value.

> > + */

> > +static __rte_always_inline unsigned int

> > +__rte_ring_do_enqueue_zc_elem_start(struct rte_ring *r, unsigned int

> esize,

> > +		uint32_t n, enum rte_ring_queue_behavior behavior,

> > +		struct rte_ring_zc_data *zcd, unsigned int *free_space) {

> > +	uint32_t free, head, next;

> > +

> > +	switch (r->prod.sync_type) {

> > +	case RTE_RING_SYNC_ST:

> > +		n = __rte_ring_move_prod_head(r, RTE_RING_SYNC_ST, n,

> > +			behavior, &head, &next, &free);

> > +		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd-

> >ptr1,

> 

> If you change ptr1, ptr2 to be just 'void *', then probably no extra type-cast

> will be needed here.

Thanks for catching this, pointers are out of whack.

> 

> > +			&zcd->n1, (void **)&zcd->ptr2);

> > +		break;

> > +	case RTE_RING_SYNC_MT_HTS:

> > +		n = __rte_ring_hts_move_prod_head(r, n, behavior, &head,

> &free);

> > +		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd-

> >ptr1,

> > +			&zcd->n1, (void **)&zcd->ptr2);

> > +		break;

> > +	case RTE_RING_SYNC_MT:

> > +	case RTE_RING_SYNC_MT_RTS:

> > +	default:

> > +		/* unsupported mode, shouldn't be here */

> > +		RTE_ASSERT(0);

> > +		n = 0;

> > +		free = 0;

> > +	}

> 

> Would it make sense to move __rte_ring_get_elem_addr() here and do it

> only when n != 0?

> I.E:

> 

> if (n != 0)

> 	__rte_ring_get_elem_addr(...);

It adds an 'if' statement. We can add a return to the default case and skip the if statement.

> 

> Same comments for _dequeue_ analog.

> 

> > +

> > +	if (free_space != NULL)

> > +		*free_space = free - n;

> > +	return n;

> > +}

> > +

Patch

diff --git a/lib/librte_ring/meson.build b/lib/librte_ring/meson.build
index 31c0b4649..36fdcb6a5 100644
--- a/lib/librte_ring/meson.build
+++ b/lib/librte_ring/meson.build
@@ -11,5 +11,6 @@  headers = files('rte_ring.h',
 		'rte_ring_hts_c11_mem.h',
 		'rte_ring_peek.h',
 		'rte_ring_peek_c11_mem.h',
+		'rte_ring_peek_zc.h',
 		'rte_ring_rts.h',
 		'rte_ring_rts_c11_mem.h')
diff --git a/lib/librte_ring/rte_ring_elem.h b/lib/librte_ring/rte_ring_elem.h
index 938b398fc..7034d29c0 100644
--- a/lib/librte_ring/rte_ring_elem.h
+++ b/lib/librte_ring/rte_ring_elem.h
@@ -1079,6 +1079,7 @@  rte_ring_dequeue_burst_elem(struct rte_ring *r, void *obj_table,
 
 #ifdef ALLOW_EXPERIMENTAL_API
 #include <rte_ring_peek.h>
+#include <rte_ring_peek_zc.h>
 #endif
 
 #include <rte_ring.h>
diff --git a/lib/librte_ring/rte_ring_peek_zc.h b/lib/librte_ring/rte_ring_peek_zc.h
new file mode 100644
index 000000000..9db2d343f
--- /dev/null
+++ b/lib/librte_ring/rte_ring_peek_zc.h
@@ -0,0 +1,542 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 2020 Arm Limited
+ * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
+ * All rights reserved.
+ * Derived from FreeBSD's bufring.h
+ * Used as BSD-3 Licensed with permission from Kip Macy.
+ */
+
+#ifndef _RTE_RING_PEEK_ZC_H_
+#define _RTE_RING_PEEK_ZC_H_
+
+/**
+ * @file
+ * @b EXPERIMENTAL: this API may change without prior notice
+ * It is not recommended to include this file directly.
+ * Please include <rte_ring_elem.h> instead.
+ *
+ * Ring Peek Zero Copy APIs
+ * These APIs make it possible to split public enqueue/dequeue API
+ * into 3 parts:
+ * - enqueue/dequeue start
+ * - copy data to/from the ring
+ * - enqueue/dequeue finish
+ * Along with the advantages of the peek APIs, these APIs provide the ability
+ * to avoid copying of the data to temporary area (for ex: array of mbufs
+ * on the stack).
+ *
+ * Note that currently these APIs are available only for two sync modes:
+ * 1) Single Producer/Single Consumer (RTE_RING_SYNC_ST)
+ * 2) Serialized Producer/Serialized Consumer (RTE_RING_SYNC_MT_HTS).
+ * It is user's responsibility to create/init ring with appropriate sync
+ * modes selected.
+ *
+ * Following are some examples showing the API usage.
+ * 1)
+ * struct elem_obj {uint64_t a; uint32_t b, c;};
+ * struct elem_obj *obj;
+ *
+ * // Create ring with sync type RTE_RING_SYNC_ST or RTE_RING_SYNC_MT_HTS
+ * // Reserve space on the ring
+ * n = rte_ring_enqueue_zc_bulk_elem_start(r, sizeof(elem_obj), 1, &zcd, NULL);
+ *
+ * // Produce the data directly on the ring memory
+ * obj = (struct elem_obj *)zcd->ptr1;
+ * obj.a = rte_get_a();
+ * obj.b = rte_get_b();
+ * obj.c = rte_get_c();
+ * rte_ring_enqueue_zc_elem_finish(ring, n);
+ *
+ * 2)
+ * // Create ring with sync type RTE_RING_SYNC_ST or RTE_RING_SYNC_MT_HTS
+ * // Reserve space on the ring
+ * n = rte_ring_enqueue_zc_burst_start(r, 32, &zcd, NULL);
+ *
+ * // Pkt I/O core polls packets from the NIC
+ * if (n == 32)
+ *	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, 32);
+ * else
+ *	nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, zcd->n1);
+ *
+ * // Provide packets to the packet processing cores
+ * rte_ring_enqueue_zc_finish(r, nb_rx);
+ *
+ * Note that between _start_ and _finish_ none other thread can proceed
+ * with enqueue/dequeue operation till _finish_ completes.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <rte_ring_peek_c11_mem.h>
+
+/**
+ * Ring zero-copy information structure.
+ *
+ * This structure contains the pointers and length of the space
+ * reserved on the ring storage.
+ */
+struct rte_ring_zc_data {
+	/* Pointer to the first space in the ring */
+	void **ptr1;
+	/* Pointer to the second space in the ring if there is wrap-around */
+	void **ptr2;
+	/* Number of elements in the first pointer. If this is equal to
+	 * the number of elements requested, then ptr2 is NULL.
+	 * Otherwise, subtracting n1 from number of elements requested
+	 * will give the number of elements available at ptr2.
+	 */
+	unsigned int n1;
+} __rte_cache_aligned;
+
+static __rte_always_inline void
+__rte_ring_get_elem_addr(struct rte_ring *r, uint32_t head,
+	uint32_t esize, uint32_t num, void **dst1, uint32_t *n1, void **dst2)
+{
+	uint32_t idx, scale, nr_idx;
+	uint32_t *ring = (uint32_t *)&r[1];
+
+	/* Normalize to uint32_t */
+	scale = esize / sizeof(uint32_t);
+	idx = head & r->mask;
+	nr_idx = idx * scale;
+
+	*dst1 = ring + nr_idx;
+	*n1 = num;
+
+	if (idx + num > r->size) {
+		*n1 = r->size - idx;
+		*dst2 = ring;
+	}
+}
+
+/**
+ * @internal This function moves prod head value.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_do_enqueue_zc_elem_start(struct rte_ring *r, unsigned int esize,
+		uint32_t n, enum rte_ring_queue_behavior behavior,
+		struct rte_ring_zc_data *zcd, unsigned int *free_space)
+{
+	uint32_t free, head, next;
+
+	switch (r->prod.sync_type) {
+	case RTE_RING_SYNC_ST:
+		n = __rte_ring_move_prod_head(r, RTE_RING_SYNC_ST, n,
+			behavior, &head, &next, &free);
+		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd->ptr1,
+			&zcd->n1, (void **)&zcd->ptr2);
+		break;
+	case RTE_RING_SYNC_MT_HTS:
+		n = __rte_ring_hts_move_prod_head(r, n, behavior, &head, &free);
+		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd->ptr1,
+			&zcd->n1, (void **)&zcd->ptr2);
+		break;
+	case RTE_RING_SYNC_MT:
+	case RTE_RING_SYNC_MT_RTS:
+	default:
+		/* unsupported mode, shouldn't be here */
+		RTE_ASSERT(0);
+		n = 0;
+		free = 0;
+	}
+
+	if (free_space != NULL)
+		*free_space = free - n;
+	return n;
+}
+
+/**
+ * Start to enqueue several objects on the ring.
+ * Note that no actual objects are put in the queue by this function,
+ * it just reserves space for the user on the ring.
+ * User has to copy objects into the queue using the returned pointers.
+ * User should call rte_ring_enqueue_zc_elem_finish to complete the
+ * enqueue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param esize
+ *   The size of ring element, in bytes. It must be a multiple of 4.
+ * @param n
+ *   The number of objects to add in the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param free_space
+ *   If non-NULL, returns the amount of space in the ring after the
+ *   reservation operation has finished.
+ * @return
+ *   The number of objects that can be enqueued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_enqueue_zc_bulk_elem_start(struct rte_ring *r, unsigned int esize,
+	unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *free_space)
+{
+	return __rte_ring_do_enqueue_zc_elem_start(r, esize, n,
+			RTE_RING_QUEUE_FIXED, zcd, free_space);
+}
+
+/**
+ * Start to enqueue several pointers to objects on the ring.
+ * Note that no actual pointers are put in the queue by this function,
+ * it just reserves space for the user on the ring.
+ * User has to copy pointers to objects into the queue using the
+ * returned pointers.
+ * User should call rte_ring_enqueue_zc_finish to complete the
+ * enqueue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of objects to add in the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param free_space
+ *   If non-NULL, returns the amount of space in the ring after the
+ *   reservation operation has finished.
+ * @return
+ *   The number of objects that can be enqueued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_enqueue_zc_bulk_start(struct rte_ring *r, unsigned int n,
+	struct rte_ring_zc_data *zcd, unsigned int *free_space)
+{
+	return rte_ring_enqueue_zc_bulk_elem_start(r, sizeof(uintptr_t), n,
+							zcd, free_space);
+}
+/**
+ * Start to enqueue several objects on the ring.
+ * Note that no actual objects are put in the queue by this function,
+ * it just reserves space for the user on the ring.
+ * User has to copy objects into the queue using the returned pointers.
+ * User should call rte_ring_enqueue_zc_elem_finish to complete the
+ * enqueue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param esize
+ *   The size of ring element, in bytes. It must be a multiple of 4.
+ * @param n
+ *   The number of objects to add in the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param free_space
+ *   If non-NULL, returns the amount of space in the ring after the
+ *   reservation operation has finished.
+ * @return
+ *   The number of objects that can be enqueued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_enqueue_zc_burst_elem_start(struct rte_ring *r, unsigned int esize,
+	unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *free_space)
+{
+	return __rte_ring_do_enqueue_zc_elem_start(r, esize, n,
+			RTE_RING_QUEUE_VARIABLE, zcd, free_space);
+}
+
+/**
+ * Start to enqueue several pointers to objects on the ring.
+ * Note that no actual pointers are put in the queue by this function,
+ * it just reserves space for the user on the ring.
+ * User has to copy pointers to objects into the queue using the
+ * returned pointers.
+ * User should call rte_ring_enqueue_zc_finish to complete the
+ * enqueue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of objects to add in the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param free_space
+ *   If non-NULL, returns the amount of space in the ring after the
+ *   reservation operation has finished.
+ * @return
+ *   The number of objects that can be enqueued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_enqueue_zc_burst_start(struct rte_ring *r, unsigned int n,
+	struct rte_ring_zc_data *zcd, unsigned int *free_space)
+{
+	return rte_ring_enqueue_zc_burst_elem_start(r, sizeof(uintptr_t), n,
+							zcd, free_space);
+}
+
+/**
+ * Complete enqueuing several objects on the ring.
+ * Note that number of objects to enqueue should not exceed previous
+ * enqueue_start return value.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of objects to add to the ring.
+ */
+__rte_experimental
+static __rte_always_inline void
+rte_ring_enqueue_zc_elem_finish(struct rte_ring *r, unsigned int n)
+{
+	uint32_t tail;
+
+	switch (r->prod.sync_type) {
+	case RTE_RING_SYNC_ST:
+		n = __rte_ring_st_get_tail(&r->prod, &tail, n);
+		__rte_ring_st_set_head_tail(&r->prod, tail, n, 1);
+		break;
+	case RTE_RING_SYNC_MT_HTS:
+		n = __rte_ring_hts_get_tail(&r->hts_prod, &tail, n);
+		__rte_ring_hts_set_head_tail(&r->hts_prod, tail, n, 1);
+		break;
+	case RTE_RING_SYNC_MT:
+	case RTE_RING_SYNC_MT_RTS:
+	default:
+		/* unsupported mode, shouldn't be here */
+		RTE_ASSERT(0);
+	}
+}
+
+/**
+ * Complete enqueuing several pointers to objects on the ring.
+ * Note that number of objects to enqueue should not exceed previous
+ * enqueue_start return value.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of pointers to objects to add to the ring.
+ */
+__rte_experimental
+static __rte_always_inline void
+rte_ring_enqueue_zc_finish(struct rte_ring *r, unsigned int n)
+{
+	rte_ring_enqueue_zc_elem_finish(r, n);
+}
+
+/**
+ * @internal This function moves cons head value and copies up to *n*
+ * objects from the ring to the user provided obj_table.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_do_dequeue_zc_elem_start(struct rte_ring *r,
+	uint32_t esize, uint32_t n, enum rte_ring_queue_behavior behavior,
+	struct rte_ring_zc_data *zcd, unsigned int *available)
+{
+	uint32_t avail, head, next;
+
+	switch (r->cons.sync_type) {
+	case RTE_RING_SYNC_ST:
+		n = __rte_ring_move_cons_head(r, RTE_RING_SYNC_ST, n,
+			behavior, &head, &next, &avail);
+		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd->ptr1,
+			&zcd->n1, (void **)&zcd->ptr2);
+		break;
+	case RTE_RING_SYNC_MT_HTS:
+		n = __rte_ring_hts_move_cons_head(r, n, behavior,
+			&head, &avail);
+		__rte_ring_get_elem_addr(r, head, esize, n, (void **)&zcd->ptr1,
+			&zcd->n1, (void **)&zcd->ptr2);
+		break;
+	case RTE_RING_SYNC_MT:
+	case RTE_RING_SYNC_MT_RTS:
+	default:
+		/* unsupported mode, shouldn't be here */
+		RTE_ASSERT(0);
+		n = 0;
+		avail = 0;
+	}
+
+	if (available != NULL)
+		*available = avail - n;
+	return n;
+}
+
+/**
+ * Start to dequeue several objects from the ring.
+ * Note that no actual objects are copied from the queue by this function.
+ * User has to copy objects from the queue using the returned pointers.
+ * User should call rte_ring_dequeue_zc_elem_finish to complete the
+ * dequeue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param esize
+ *   The size of ring element, in bytes. It must be a multiple of 4.
+ * @param n
+ *   The number of objects to remove from the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param available
+ *   If non-NULL, returns the number of remaining ring entries after the
+ *   dequeue has finished.
+ * @return
+ *   The number of objects that can be dequeued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_dequeue_zc_bulk_elem_start(struct rte_ring *r, unsigned int esize,
+	unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *available)
+{
+	return __rte_ring_do_dequeue_zc_elem_start(r, esize, n,
+			RTE_RING_QUEUE_FIXED, zcd, available);
+}
+
+/**
+ * Start to dequeue several pointers to objects from the ring.
+ * Note that no actual pointers are removed from the queue by this function.
+ * User has to copy pointers to objects from the queue using the
+ * returned pointers.
+ * User should call rte_ring_dequeue_zc_finish to complete the
+ * dequeue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of objects to remove from the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param available
+ *   If non-NULL, returns the number of remaining ring entries after the
+ *   dequeue has finished.
+ * @return
+ *   The number of objects that can be dequeued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_dequeue_zc_bulk_start(struct rte_ring *r, unsigned int n,
+	struct rte_ring_zc_data *zcd, unsigned int *available)
+{
+	return rte_ring_dequeue_zc_bulk_elem_start(r, sizeof(uintptr_t),
+		n, zcd, available);
+}
+
+/**
+ * Start to dequeue several objects from the ring.
+ * Note that no actual objects are copied from the queue by this function.
+ * User has to copy objects from the queue using the returned pointers.
+ * User should call rte_ring_dequeue_zc_elem_finish to complete the
+ * dequeue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param esize
+ *   The size of ring element, in bytes. It must be a multiple of 4.
+ *   This must be the same value used while creating the ring. Otherwise
+ *   the results are undefined.
+ * @param n
+ *   The number of objects to dequeue from the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param available
+ *   If non-NULL, returns the number of remaining ring entries after the
+ *   dequeue has finished.
+ * @return
+ *   The number of objects that can be dequeued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_dequeue_zc_burst_elem_start(struct rte_ring *r, unsigned int esize,
+	unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *available)
+{
+	return __rte_ring_do_dequeue_zc_elem_start(r, esize, n,
+			RTE_RING_QUEUE_VARIABLE, zcd, available);
+}
+
+/**
+ * Start to dequeue several pointers to objects from the ring.
+ * Note that no actual pointers are removed from the queue by this function.
+ * User has to copy pointers to objects from the queue using the
+ * returned pointers.
+ * User should call rte_ring_dequeue_zc_finish to complete the
+ * dequeue operation.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of objects to remove from the ring.
+ * @param zcd
+ *   Structure containing the pointers and length of the space
+ *   reserved on the ring storage.
+ * @param available
+ *   If non-NULL, returns the number of remaining ring entries after the
+ *   dequeue has finished.
+ * @return
+ *   The number of objects that can be dequeued, either 0 or n
+ */
+__rte_experimental
+static __rte_always_inline unsigned int
+rte_ring_dequeue_zc_burst_start(struct rte_ring *r, unsigned int n,
+		struct rte_ring_zc_data *zcd, unsigned int *available)
+{
+	return rte_ring_dequeue_zc_burst_elem_start(r, sizeof(uintptr_t), n,
+			zcd, available);
+}
+
+/**
+ * Complete dequeuing several objects from the ring.
+ * Note that number of objects to dequeued should not exceed previous
+ * dequeue_start return value.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of objects to remove from the ring.
+ */
+__rte_experimental
+static __rte_always_inline void
+rte_ring_dequeue_zc_elem_finish(struct rte_ring *r, unsigned int n)
+{
+	uint32_t tail;
+
+	switch (r->cons.sync_type) {
+	case RTE_RING_SYNC_ST:
+		n = __rte_ring_st_get_tail(&r->cons, &tail, n);
+		__rte_ring_st_set_head_tail(&r->cons, tail, n, 0);
+		break;
+	case RTE_RING_SYNC_MT_HTS:
+		n = __rte_ring_hts_get_tail(&r->hts_cons, &tail, n);
+		__rte_ring_hts_set_head_tail(&r->hts_cons, tail, n, 0);
+		break;
+	case RTE_RING_SYNC_MT:
+	case RTE_RING_SYNC_MT_RTS:
+	default:
+		/* unsupported mode, shouldn't be here */
+		RTE_ASSERT(0);
+	}
+}
+
+/**
+ * Complete dequeuing several objects from the ring.
+ * Note that number of objects to dequeued should not exceed previous
+ * dequeue_start return value.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ * @param n
+ *   The number of objects to remove from the ring.
+ */
+__rte_experimental
+static __rte_always_inline void
+rte_ring_dequeue_zc_finish(struct rte_ring *r, unsigned int n)
+{
+	rte_ring_dequeue_elem_finish(r, n);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_RING_PEEK_ZC_H_ */