| Message ID | 20250507-ublk_task_per_io-v6-7-a2a298783c01@purestorage.com |
|---|---|
| State | New |
| Headers | show |
| Series | ublk: decouple server threads from hctxs | expand |
On Wed, May 07, 2025 at 03:49:41PM -0600, Uday Shankar wrote: > Add support in kublk for decoupled ublk_queues and ublk server threads. > kublk now has two modes of operation: > > - (preexisting mode) threads and queues are paired 1:1, and each thread > services all the I/Os of one queue > - (new mode) thread and queue counts are independently configurable. > threads service I/Os in a way that balances load across threads even > if load is not balanced over queues. requires passing --round_robin > > The new mode of operation is exercised by the new test_generic_08, which > issues I/O against a single queue and verifies that each of the 8 ublk > server threads handles exactly 1/8 of the total I/O count. Under the old > mode of operation (i.e. without --round_robin), all I/O goes to one ublk > server thread, and the test fails. > > Signed-off-by: Uday Shankar <ushankar@purestorage.com> > --- > tools/testing/selftests/ublk/Makefile | 1 + > tools/testing/selftests/ublk/file_backed.c | 4 +- > tools/testing/selftests/ublk/kublk.c | 96 ++++++++++++++++++---- > tools/testing/selftests/ublk/kublk.h | 3 + > tools/testing/selftests/ublk/null.c | 4 +- > tools/testing/selftests/ublk/stripe.c | 4 +- > tools/testing/selftests/ublk/test_generic_08.sh | 61 ++++++++++++++ > .../selftests/ublk/trace/count_ios_per_tid.bt | 9 ++ > 8 files changed, 160 insertions(+), 22 deletions(-) > > diff --git a/tools/testing/selftests/ublk/Makefile b/tools/testing/selftests/ublk/Makefile > index e2e7b1e52a06252f626df5606221d17e3106d0d3..f8579019f0d1f9185df098440611c3b75087073b 100644 > --- a/tools/testing/selftests/ublk/Makefile > +++ b/tools/testing/selftests/ublk/Makefile > @@ -14,6 +14,7 @@ TEST_PROGS += test_generic_04.sh > TEST_PROGS += test_generic_05.sh > TEST_PROGS += test_generic_06.sh > TEST_PROGS += test_generic_07.sh > +TEST_PROGS += test_generic_08.sh > > TEST_PROGS += test_null_01.sh > TEST_PROGS += test_null_02.sh > diff --git a/tools/testing/selftests/ublk/file_backed.c b/tools/testing/selftests/ublk/file_backed.c > index 563f11a21604bbf5b9531f69f806d09cdd785960..72e22f54f7fe60d26096ace4eb4001987fbe7b15 100644 > --- a/tools/testing/selftests/ublk/file_backed.c > +++ b/tools/testing/selftests/ublk/file_backed.c > @@ -50,7 +50,7 @@ static int loop_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_de > > ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 3); > > - io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag); > + io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, ublk_get_io(q, tag)->buf_index); ->buf_index can be calculated runtime by adding helper of ublk_io_buf_idx(io), so the extra field can be avoided, CPU is fast than memory. > sqe[0]->flags |= IOSQE_CQE_SKIP_SUCCESS | IOSQE_IO_HARDLINK; > sqe[0]->user_data = build_user_data(tag, > ublk_cmd_op_nr(sqe[0]->cmd_op), 0, q->q_id, 1); > @@ -62,7 +62,7 @@ static int loop_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_de > sqe[1]->flags |= IOSQE_FIXED_FILE | IOSQE_IO_HARDLINK; > sqe[1]->user_data = build_user_data(tag, ublk_op, 0, q->q_id, 1); > > - io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, tag); > + io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, ublk_get_io(q, tag)->buf_index); > sqe[2]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[2]->cmd_op), 0, q->q_id, 1); > > return 2; > diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c > index 313689f94cd6361a9a0f4b9257085b2a62bc8b8c..27046bb6a13b99879ad164ff8eaabeba57e17387 100644 > --- a/tools/testing/selftests/ublk/kublk.c > +++ b/tools/testing/selftests/ublk/kublk.c > @@ -478,8 +478,11 @@ static int ublk_thread_init(struct ublk_thread *t) > } > > if (dev->dev_info.flags & UBLK_F_SUPPORT_ZERO_COPY) { > + unsigned nr_ios = dev->dev_info.queue_depth * dev->dev_info.nr_hw_queues; > + unsigned max_nr_ios_per_thread = nr_ios / dev->nthreads; > + max_nr_ios_per_thread += !!(nr_ios % dev->nthreads); > ret = io_uring_register_buffers_sparse( > - &t->ring, dev->dev_info.queue_depth); > + &t->ring, max_nr_ios_per_thread); > if (ret) { > ublk_err("ublk dev %d thread %d register spare buffers failed %d", > dev->dev_info.dev_id, t->idx, ret); > @@ -612,18 +615,42 @@ int ublk_queue_io_cmd(struct ublk_io *io) > > static void ublk_submit_fetch_commands(struct ublk_thread *t) > { > - /* > - * Service exclusively the queue whose q_id matches our thread > - * index. This may change in the future. > - */ > - struct ublk_queue *q = &t->dev->q[t->idx]; > + struct ublk_queue *q; > struct ublk_io *io; > - int i = 0; > + int i = 0, j = 0; > > - for (i = 0; i < q->q_depth; i++) { > - io = &q->ios[i]; > - io->t = t; > - ublk_queue_io_cmd(io); > + if (t->dev->dev_info.flags & UBLK_F_RR_TAGS) { You shouldn't depend on the generic feature of UBLK_F_RR_TAGS, which can be used for non-io-task too. Here you need one helper of ublk_use_io_task(), or sort of flags. > + /* > + * Lexicographically order all the (qid,tag) pairs, with > + * qid taking priority, and give this thread every Nth > + * entry, where N is the total number of threads. The > + * offset is controlled by the thread index. This takes > + * load which may be imbalanced across the queues and > + * balances it across the threads. > + */ > + const struct ublksrv_ctrl_dev_info *dinfo = &t->dev->dev_info; > + int nr_ios = dinfo->nr_hw_queues * dinfo->queue_depth; > + for (i = t->idx; i < nr_ios; i += t->dev->nthreads, j++) { > + int q_id = i / dinfo->queue_depth; > + int tag = i % dinfo->queue_depth; I understand UBLK_F_RR_TAGS means that IO with adjacent tag should be handled locally, but the above actually does the opposite, only IOs with non-adjacent tags are handled in same pthread, can you explain a bit why UBLK_F_RR_TAGS helps for this way? > + q = &t->dev->q[q_id]; > + io = &q->ios[tag]; > + io->t = t; > + io->buf_index = j; > + ublk_queue_io_cmd(io); > + } > + } else { > + /* > + * Service exclusively the queue whose q_id matches our > + * thread index. > + */ > + struct ublk_queue *q = &t->dev->q[t->idx]; > + for (i = 0; i < q->q_depth; i++) { > + io = &q->ios[i]; > + io->t = t; > + io->buf_index = i; > + ublk_queue_io_cmd(io); > + } > } > } > > @@ -778,7 +805,8 @@ static void *ublk_io_handler_fn(void *data) > return NULL; > } > /* IO perf is sensitive with queue pthread affinity on NUMA machine*/ > - ublk_thread_set_sched_affinity(t, info->affinity); > + if (info->affinity) > + ublk_thread_set_sched_affinity(t, info->affinity); > sem_post(info->ready); > > ublk_dbg(UBLK_DBG_THREAD, "tid %d: ublk dev %d thread %u started\n", > @@ -844,7 +872,7 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev) > > ublk_dbg(UBLK_DBG_DEV, "%s enter\n", __func__); > > - tinfo = calloc(sizeof(struct ublk_thread_info), dinfo->nr_hw_queues); > + tinfo = calloc(sizeof(struct ublk_thread_info), dev->nthreads); > if (!tinfo) > return -ENOMEM; > > @@ -867,17 +895,24 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev) > dinfo->dev_id, i); > goto fail; > } > + } > > + for (i = 0; i < dev->nthreads; i++) { > tinfo[i].dev = dev; > tinfo[i].idx = i; > tinfo[i].ready = &ready; > - tinfo[i].affinity = &affinity_buf[i]; > + /* > + * If threads are not tied to queues, setting thread > + * affinity based on queue affinity makes no sense. > + */ > + if (!(dinfo->flags & UBLK_F_RR_TAGS)) > + tinfo[i].affinity = &affinity_buf[i]; > pthread_create(&dev->threads[i].thread, NULL, > ublk_io_handler_fn, > &tinfo[i]); > } > > - for (i = 0; i < dinfo->nr_hw_queues; i++) > + for (i = 0; i < dev->nthreads; i++) > sem_wait(&ready); > free(tinfo); > free(affinity_buf); > @@ -901,7 +936,7 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev) > ublk_send_dev_event(ctx, dev, dev->dev_info.dev_id); > > /* wait until we are terminated */ > - for (i = 0; i < dinfo->nr_hw_queues; i++) > + for (i = 0; i < dev->nthreads; i++) > pthread_join(dev->threads[i].thread, &thread_ret); > fail: > for (i = 0; i < dinfo->nr_hw_queues; i++) > @@ -1011,6 +1046,7 @@ static int ublk_stop_io_daemon(const struct ublk_dev *dev) > > static int __cmd_dev_add(const struct dev_ctx *ctx) > { > + unsigned nthreads = ctx->nthreads; > unsigned nr_queues = ctx->nr_hw_queues; > const char *tgt_type = ctx->tgt_type; > unsigned depth = ctx->queue_depth; > @@ -1034,6 +1070,23 @@ static int __cmd_dev_add(const struct dev_ctx *ctx) > return -EINVAL; > } > > + /* default to 1:1 threads:queues if nthreads is unspecified */ > + if (nthreads == -1) > + nthreads = nr_queues; Maybe we can start 1:1 for nrthreads == 0, which looks more readable, and you needn't to set -1 default. > + > + if (nthreads > UBLK_MAX_THREADS) { > + ublk_err("%s: %u is too many threads (max %u)\n", > + __func__, nthreads, UBLK_MAX_THREADS); > + return -EINVAL; > + } > + > + if (nthreads != nr_queues && !(ctx->flags & UBLK_F_RR_TAGS)) { > + ublk_err("%s: threads %u must be same as queues %u if " > + "not using round robin\n", > + __func__, nthreads, nr_queues); > + return -EINVAL; > + } > + > dev = ublk_ctrl_init(); > if (!dev) { > ublk_err("%s: can't alloc dev id %d, type %s\n", > @@ -1054,6 +1107,7 @@ static int __cmd_dev_add(const struct dev_ctx *ctx) > info->nr_hw_queues = nr_queues; > info->queue_depth = depth; > info->flags = ctx->flags; > + dev->nthreads = nthreads; > dev->tgt.ops = ops; > dev->tgt.sq_depth = depth; > dev->tgt.cq_depth = depth; > @@ -1249,6 +1303,7 @@ static int cmd_dev_get_features(void) > [const_ilog2(UBLK_F_USER_COPY)] = "USER_COPY", > [const_ilog2(UBLK_F_ZONED)] = "ZONED", > [const_ilog2(UBLK_F_USER_RECOVERY_FAIL_IO)] = "RECOVERY_FAIL_IO", > + [const_ilog2(UBLK_F_RR_TAGS)] = "RR_TAGS", > }; > struct ublk_dev *dev; > __u64 features = 0; > @@ -1290,8 +1345,10 @@ static void __cmd_create_help(char *exe, bool recovery) > exe, recovery ? "recover" : "add"); > printf("\t[--foreground] [--quiet] [-z] [--debug_mask mask] [-r 0|1 ] [-g]\n"); > printf("\t[-e 0|1 ] [-i 0|1]\n"); > + printf("\t[--nthreads threads] [--round_robin]\n"); > printf("\t[target options] [backfile1] [backfile2] ...\n"); > printf("\tdefault: nr_queues=2(max 32), depth=128(max 1024), dev_id=-1(auto allocation)\n"); > + printf("\tdefault: nthreads=nr_queues"); > > for (i = 0; i < sizeof(tgt_ops_list) / sizeof(tgt_ops_list[0]); i++) { > const struct ublk_tgt_ops *ops = tgt_ops_list[i]; > @@ -1343,6 +1400,8 @@ int main(int argc, char *argv[]) > { "recovery_fail_io", 1, NULL, 'e'}, > { "recovery_reissue", 1, NULL, 'i'}, > { "get_data", 1, NULL, 'g'}, > + { "nthreads", 1, NULL, 0 }, > + { "round_robin", 0, NULL, 0 }, > { 0, 0, 0, 0 } > }; > const struct ublk_tgt_ops *ops = NULL; > @@ -1351,6 +1410,7 @@ int main(int argc, char *argv[]) > struct dev_ctx ctx = { > .queue_depth = 128, > .nr_hw_queues = 2, > + .nthreads = -1, > .dev_id = -1, > .tgt_type = "unknown", > }; > @@ -1411,6 +1471,10 @@ int main(int argc, char *argv[]) > ublk_dbg_mask = 0; > if (!strcmp(longopts[option_idx].name, "foreground")) > ctx.fg = 1; > + if (!strcmp(longopts[option_idx].name, "nthreads")) > + ctx.nthreads = strtol(optarg, NULL, 10); > + if (!strcmp(longopts[option_idx].name, "round_robin")) > + ctx.flags |= UBLK_F_RR_TAGS; maybe `--io_task` is more readable, and you can always enable UBLK_F_RR_TAGS for this '--io_task' ublk server feature. Thanks, Ming
diff --git a/tools/testing/selftests/ublk/Makefile b/tools/testing/selftests/ublk/Makefile index e2e7b1e52a06252f626df5606221d17e3106d0d3..f8579019f0d1f9185df098440611c3b75087073b 100644 --- a/tools/testing/selftests/ublk/Makefile +++ b/tools/testing/selftests/ublk/Makefile @@ -14,6 +14,7 @@ TEST_PROGS += test_generic_04.sh TEST_PROGS += test_generic_05.sh TEST_PROGS += test_generic_06.sh TEST_PROGS += test_generic_07.sh +TEST_PROGS += test_generic_08.sh TEST_PROGS += test_null_01.sh TEST_PROGS += test_null_02.sh diff --git a/tools/testing/selftests/ublk/file_backed.c b/tools/testing/selftests/ublk/file_backed.c index 563f11a21604bbf5b9531f69f806d09cdd785960..72e22f54f7fe60d26096ace4eb4001987fbe7b15 100644 --- a/tools/testing/selftests/ublk/file_backed.c +++ b/tools/testing/selftests/ublk/file_backed.c @@ -50,7 +50,7 @@ static int loop_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_de ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 3); - io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag); + io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, ublk_get_io(q, tag)->buf_index); sqe[0]->flags |= IOSQE_CQE_SKIP_SUCCESS | IOSQE_IO_HARDLINK; sqe[0]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[0]->cmd_op), 0, q->q_id, 1); @@ -62,7 +62,7 @@ static int loop_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_de sqe[1]->flags |= IOSQE_FIXED_FILE | IOSQE_IO_HARDLINK; sqe[1]->user_data = build_user_data(tag, ublk_op, 0, q->q_id, 1); - io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, tag); + io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, ublk_get_io(q, tag)->buf_index); sqe[2]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[2]->cmd_op), 0, q->q_id, 1); return 2; diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c index 313689f94cd6361a9a0f4b9257085b2a62bc8b8c..27046bb6a13b99879ad164ff8eaabeba57e17387 100644 --- a/tools/testing/selftests/ublk/kublk.c +++ b/tools/testing/selftests/ublk/kublk.c @@ -478,8 +478,11 @@ static int ublk_thread_init(struct ublk_thread *t) } if (dev->dev_info.flags & UBLK_F_SUPPORT_ZERO_COPY) { + unsigned nr_ios = dev->dev_info.queue_depth * dev->dev_info.nr_hw_queues; + unsigned max_nr_ios_per_thread = nr_ios / dev->nthreads; + max_nr_ios_per_thread += !!(nr_ios % dev->nthreads); ret = io_uring_register_buffers_sparse( - &t->ring, dev->dev_info.queue_depth); + &t->ring, max_nr_ios_per_thread); if (ret) { ublk_err("ublk dev %d thread %d register spare buffers failed %d", dev->dev_info.dev_id, t->idx, ret); @@ -612,18 +615,42 @@ int ublk_queue_io_cmd(struct ublk_io *io) static void ublk_submit_fetch_commands(struct ublk_thread *t) { - /* - * Service exclusively the queue whose q_id matches our thread - * index. This may change in the future. - */ - struct ublk_queue *q = &t->dev->q[t->idx]; + struct ublk_queue *q; struct ublk_io *io; - int i = 0; + int i = 0, j = 0; - for (i = 0; i < q->q_depth; i++) { - io = &q->ios[i]; - io->t = t; - ublk_queue_io_cmd(io); + if (t->dev->dev_info.flags & UBLK_F_RR_TAGS) { + /* + * Lexicographically order all the (qid,tag) pairs, with + * qid taking priority, and give this thread every Nth + * entry, where N is the total number of threads. The + * offset is controlled by the thread index. This takes + * load which may be imbalanced across the queues and + * balances it across the threads. + */ + const struct ublksrv_ctrl_dev_info *dinfo = &t->dev->dev_info; + int nr_ios = dinfo->nr_hw_queues * dinfo->queue_depth; + for (i = t->idx; i < nr_ios; i += t->dev->nthreads, j++) { + int q_id = i / dinfo->queue_depth; + int tag = i % dinfo->queue_depth; + q = &t->dev->q[q_id]; + io = &q->ios[tag]; + io->t = t; + io->buf_index = j; + ublk_queue_io_cmd(io); + } + } else { + /* + * Service exclusively the queue whose q_id matches our + * thread index. + */ + struct ublk_queue *q = &t->dev->q[t->idx]; + for (i = 0; i < q->q_depth; i++) { + io = &q->ios[i]; + io->t = t; + io->buf_index = i; + ublk_queue_io_cmd(io); + } } } @@ -778,7 +805,8 @@ static void *ublk_io_handler_fn(void *data) return NULL; } /* IO perf is sensitive with queue pthread affinity on NUMA machine*/ - ublk_thread_set_sched_affinity(t, info->affinity); + if (info->affinity) + ublk_thread_set_sched_affinity(t, info->affinity); sem_post(info->ready); ublk_dbg(UBLK_DBG_THREAD, "tid %d: ublk dev %d thread %u started\n", @@ -844,7 +872,7 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev) ublk_dbg(UBLK_DBG_DEV, "%s enter\n", __func__); - tinfo = calloc(sizeof(struct ublk_thread_info), dinfo->nr_hw_queues); + tinfo = calloc(sizeof(struct ublk_thread_info), dev->nthreads); if (!tinfo) return -ENOMEM; @@ -867,17 +895,24 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev) dinfo->dev_id, i); goto fail; } + } + for (i = 0; i < dev->nthreads; i++) { tinfo[i].dev = dev; tinfo[i].idx = i; tinfo[i].ready = &ready; - tinfo[i].affinity = &affinity_buf[i]; + /* + * If threads are not tied to queues, setting thread + * affinity based on queue affinity makes no sense. + */ + if (!(dinfo->flags & UBLK_F_RR_TAGS)) + tinfo[i].affinity = &affinity_buf[i]; pthread_create(&dev->threads[i].thread, NULL, ublk_io_handler_fn, &tinfo[i]); } - for (i = 0; i < dinfo->nr_hw_queues; i++) + for (i = 0; i < dev->nthreads; i++) sem_wait(&ready); free(tinfo); free(affinity_buf); @@ -901,7 +936,7 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev) ublk_send_dev_event(ctx, dev, dev->dev_info.dev_id); /* wait until we are terminated */ - for (i = 0; i < dinfo->nr_hw_queues; i++) + for (i = 0; i < dev->nthreads; i++) pthread_join(dev->threads[i].thread, &thread_ret); fail: for (i = 0; i < dinfo->nr_hw_queues; i++) @@ -1011,6 +1046,7 @@ static int ublk_stop_io_daemon(const struct ublk_dev *dev) static int __cmd_dev_add(const struct dev_ctx *ctx) { + unsigned nthreads = ctx->nthreads; unsigned nr_queues = ctx->nr_hw_queues; const char *tgt_type = ctx->tgt_type; unsigned depth = ctx->queue_depth; @@ -1034,6 +1070,23 @@ static int __cmd_dev_add(const struct dev_ctx *ctx) return -EINVAL; } + /* default to 1:1 threads:queues if nthreads is unspecified */ + if (nthreads == -1) + nthreads = nr_queues; + + if (nthreads > UBLK_MAX_THREADS) { + ublk_err("%s: %u is too many threads (max %u)\n", + __func__, nthreads, UBLK_MAX_THREADS); + return -EINVAL; + } + + if (nthreads != nr_queues && !(ctx->flags & UBLK_F_RR_TAGS)) { + ublk_err("%s: threads %u must be same as queues %u if " + "not using round robin\n", + __func__, nthreads, nr_queues); + return -EINVAL; + } + dev = ublk_ctrl_init(); if (!dev) { ublk_err("%s: can't alloc dev id %d, type %s\n", @@ -1054,6 +1107,7 @@ static int __cmd_dev_add(const struct dev_ctx *ctx) info->nr_hw_queues = nr_queues; info->queue_depth = depth; info->flags = ctx->flags; + dev->nthreads = nthreads; dev->tgt.ops = ops; dev->tgt.sq_depth = depth; dev->tgt.cq_depth = depth; @@ -1249,6 +1303,7 @@ static int cmd_dev_get_features(void) [const_ilog2(UBLK_F_USER_COPY)] = "USER_COPY", [const_ilog2(UBLK_F_ZONED)] = "ZONED", [const_ilog2(UBLK_F_USER_RECOVERY_FAIL_IO)] = "RECOVERY_FAIL_IO", + [const_ilog2(UBLK_F_RR_TAGS)] = "RR_TAGS", }; struct ublk_dev *dev; __u64 features = 0; @@ -1290,8 +1345,10 @@ static void __cmd_create_help(char *exe, bool recovery) exe, recovery ? "recover" : "add"); printf("\t[--foreground] [--quiet] [-z] [--debug_mask mask] [-r 0|1 ] [-g]\n"); printf("\t[-e 0|1 ] [-i 0|1]\n"); + printf("\t[--nthreads threads] [--round_robin]\n"); printf("\t[target options] [backfile1] [backfile2] ...\n"); printf("\tdefault: nr_queues=2(max 32), depth=128(max 1024), dev_id=-1(auto allocation)\n"); + printf("\tdefault: nthreads=nr_queues"); for (i = 0; i < sizeof(tgt_ops_list) / sizeof(tgt_ops_list[0]); i++) { const struct ublk_tgt_ops *ops = tgt_ops_list[i]; @@ -1343,6 +1400,8 @@ int main(int argc, char *argv[]) { "recovery_fail_io", 1, NULL, 'e'}, { "recovery_reissue", 1, NULL, 'i'}, { "get_data", 1, NULL, 'g'}, + { "nthreads", 1, NULL, 0 }, + { "round_robin", 0, NULL, 0 }, { 0, 0, 0, 0 } }; const struct ublk_tgt_ops *ops = NULL; @@ -1351,6 +1410,7 @@ int main(int argc, char *argv[]) struct dev_ctx ctx = { .queue_depth = 128, .nr_hw_queues = 2, + .nthreads = -1, .dev_id = -1, .tgt_type = "unknown", }; @@ -1411,6 +1471,10 @@ int main(int argc, char *argv[]) ublk_dbg_mask = 0; if (!strcmp(longopts[option_idx].name, "foreground")) ctx.fg = 1; + if (!strcmp(longopts[option_idx].name, "nthreads")) + ctx.nthreads = strtol(optarg, NULL, 10); + if (!strcmp(longopts[option_idx].name, "round_robin")) + ctx.flags |= UBLK_F_RR_TAGS; break; case '?': /* diff --git a/tools/testing/selftests/ublk/kublk.h b/tools/testing/selftests/ublk/kublk.h index 9eb2207fcebe96d34488d057c881db262b9767b3..c51c01d8be43293fc0760f3b5ebac927afbc1fe3 100644 --- a/tools/testing/selftests/ublk/kublk.h +++ b/tools/testing/selftests/ublk/kublk.h @@ -80,6 +80,7 @@ struct dev_ctx { char tgt_type[16]; unsigned long flags; unsigned nr_hw_queues; + unsigned nthreads; unsigned queue_depth; int dev_id; int nr_files; @@ -125,6 +126,7 @@ struct ublk_io { struct ublk_queue *q; struct ublk_thread *t; int tag; + int buf_index; int result; @@ -194,6 +196,7 @@ struct ublk_dev { struct ublksrv_ctrl_dev_info dev_info; struct ublk_queue q[UBLK_MAX_QUEUES]; struct ublk_thread threads[UBLK_MAX_THREADS]; + unsigned nthreads; int fds[MAX_BACK_FILES + 1]; /* fds[0] points to /dev/ublkcN */ int nr_fds; diff --git a/tools/testing/selftests/ublk/null.c b/tools/testing/selftests/ublk/null.c index 7323fe61212f6041ef5a04758d30e62376ac9c6b..776da92306d8449b5b1ab89375ea4078a7948390 100644 --- a/tools/testing/selftests/ublk/null.c +++ b/tools/testing/selftests/ublk/null.c @@ -50,7 +50,7 @@ static int null_queue_zc_io(struct ublk_queue *q, int tag) ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, 3); - io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag); + io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, ublk_get_io(q, tag)->buf_index); sqe[0]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[0]->cmd_op), 0, q->q_id, 1); sqe[0]->flags |= IOSQE_CQE_SKIP_SUCCESS | IOSQE_IO_HARDLINK; @@ -62,7 +62,7 @@ static int null_queue_zc_io(struct ublk_queue *q, int tag) sqe[1]->len = iod->nr_sectors << 9; /* injected result */ sqe[1]->user_data = build_user_data(tag, ublk_op, 0, q->q_id, 1); - io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, tag); + io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, ublk_get_io(q, tag)->buf_index); sqe[2]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[2]->cmd_op), 0, q->q_id, 1); // buf register is marked as IOSQE_CQE_SKIP_SUCCESS diff --git a/tools/testing/selftests/ublk/stripe.c b/tools/testing/selftests/ublk/stripe.c index d569f62c9b7b5a6b9d82506c4aaab74b77a10305..4c87dc76712f18acd73834c87081a44fb87b7956 100644 --- a/tools/testing/selftests/ublk/stripe.c +++ b/tools/testing/selftests/ublk/stripe.c @@ -139,7 +139,7 @@ static int stripe_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_ ublk_io_alloc_sqes(ublk_get_io(q, tag), sqe, s->nr + extra); if (zc) { - io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag); + io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, io->buf_index); sqe[0]->flags |= IOSQE_CQE_SKIP_SUCCESS | IOSQE_IO_HARDLINK; sqe[0]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[0]->cmd_op), 0, q->q_id, 1); @@ -166,7 +166,7 @@ static int stripe_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_ if (zc) { struct io_uring_sqe *unreg = sqe[s->nr + 1]; - io_uring_prep_buf_unregister(unreg, 0, tag, q->q_id, tag); + io_uring_prep_buf_unregister(unreg, 0, tag, q->q_id, io->buf_index); unreg->user_data = build_user_data( tag, ublk_cmd_op_nr(unreg->cmd_op), 0, q->q_id, 1); } diff --git a/tools/testing/selftests/ublk/test_generic_08.sh b/tools/testing/selftests/ublk/test_generic_08.sh new file mode 100755 index 0000000000000000000000000000000000000000..8dfb11606610b263810f28ce501aedbed0d87a86 --- /dev/null +++ b/tools/testing/selftests/ublk/test_generic_08.sh @@ -0,0 +1,61 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh + +TID="generic_08" +ERR_CODE=0 + +if ! _have_program bpftrace; then + exit "$UBLK_SKIP_CODE" +fi + +_prep_test "null" "do imbalanced load, it should be balanced over I/O threads" + +NTHREADS=8 +dev_id=$(_add_ublk_dev -t null -q 4 -d 16 --nthreads $NTHREADS --round_robin) +_check_add_dev $TID $? + +dev_t=$(_get_disk_dev_t "$dev_id") +bpftrace trace/count_ios_per_tid.bt "$dev_t" > "$UBLK_TMP" 2>&1 & +btrace_pid=$! +sleep 2 + +if ! kill -0 "$btrace_pid" > /dev/null 2>&1; then + _cleanup_test "null" + exit "$UBLK_SKIP_CODE" +fi + +# do imbalanced I/O on the ublk device +# single-threaded because while tags are assigned round-robin, I/O +# completions can come in any order, and this can cause imperfect +# balance (in practice, balance is close to perfect, with less than 0.1% +# error, but prefer perfection/determinism for automated tests) +# pin to cpu 0 to prevent migration/only target one queue +IOS_PER_THREAD=1024 +TOTAL_IOS=$(($IOS_PER_THREAD * $NTHREADS)) +taskset -c 0 dd if=/dev/urandom of=/dev/ublkb"${dev_id}" \ + oflag=direct bs=4k count=${TOTAL_IOS} > /dev/null 2>&1 +ERR_CODE=$? +kill "$btrace_pid" +wait + +# check for perfectly balanced I/O +# note that this depends on few things: +# - $NTHREADS should divide the queue depth +# - the queue depth should divide $IOS_PER_THREAD +# - no I/O on the device should happen while the bpftrace script is +# running, besides the dd in this script +# the check below could be made more sophisticated to relax the first +# two constraints above +grep '@' < ${UBLK_TMP} | cut -d ' ' -f2 | while read ios; do + if [ "${ios}" -ne "${IOS_PER_THREAD}" ]; then + echo "imbalanced i/o detected!" + cat "$UBLK_TMP" + exit 255 + fi +done +ERR_CODE=$? + +_cleanup_test "null" +_show_result $TID $ERR_CODE diff --git a/tools/testing/selftests/ublk/trace/count_ios_per_tid.bt b/tools/testing/selftests/ublk/trace/count_ios_per_tid.bt new file mode 100644 index 0000000000000000000000000000000000000000..a62ef428a3dff1db33b128868baa62533d4066aa --- /dev/null +++ b/tools/testing/selftests/ublk/trace/count_ios_per_tid.bt @@ -0,0 +1,9 @@ +/* + $1: dev_t +*/ +tracepoint:block:block_rq_complete +{ + if ((int64)args.dev == $1 && !strncmp(args.rwbs, "W", 1)) { + @[tid] = count(); + } +}
Add support in kublk for decoupled ublk_queues and ublk server threads. kublk now has two modes of operation: - (preexisting mode) threads and queues are paired 1:1, and each thread services all the I/Os of one queue - (new mode) thread and queue counts are independently configurable. threads service I/Os in a way that balances load across threads even if load is not balanced over queues. requires passing --round_robin The new mode of operation is exercised by the new test_generic_08, which issues I/O against a single queue and verifies that each of the 8 ublk server threads handles exactly 1/8 of the total I/O count. Under the old mode of operation (i.e. without --round_robin), all I/O goes to one ublk server thread, and the test fails. Signed-off-by: Uday Shankar <ushankar@purestorage.com> --- tools/testing/selftests/ublk/Makefile | 1 + tools/testing/selftests/ublk/file_backed.c | 4 +- tools/testing/selftests/ublk/kublk.c | 96 ++++++++++++++++++---- tools/testing/selftests/ublk/kublk.h | 3 + tools/testing/selftests/ublk/null.c | 4 +- tools/testing/selftests/ublk/stripe.c | 4 +- tools/testing/selftests/ublk/test_generic_08.sh | 61 ++++++++++++++ .../selftests/ublk/trace/count_ios_per_tid.bt | 9 ++ 8 files changed, 160 insertions(+), 22 deletions(-)