diff --git a/man/man4/zfs.4 b/man/man4/zfs.4 index a98ec519a..bab40dd91 100644 --- a/man/man4/zfs.4 +++ b/man/man4/zfs.4 @@ -2370,6 +2370,13 @@ The number of requests which can be handled concurrently is controlled by is ignored when running on a kernel that supports block multiqueue .Pq Li blk-mq . . +.It Sy zvol_num_taskqs Ns = Ns Sy 0 Pq uint +Number of zvol taskqs. +If +.Sy 0 +(the default) then scaling is done internally to prefer 6 threads per taskq. +This only applies on Linux. +. .It Sy zvol_threads Ns = Ns Sy 0 Pq uint The number of system wide threads to use for processing zvol block IOs. If diff --git a/module/os/linux/zfs/zvol_os.c b/module/os/linux/zfs/zvol_os.c index 8562e9897..f9c64a8a8 100644 --- a/module/os/linux/zfs/zvol_os.c +++ b/module/os/linux/zfs/zvol_os.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include @@ -53,6 +54,12 @@ static unsigned int zvol_request_sync = 0; static unsigned int zvol_prefetch_bytes = (128 * 1024); static unsigned long zvol_max_discard_blocks = 16384; +/* + * Switch taskq at multiple of 512 MB offset. This can be set to a lower value + * to utilize more threads for small files but may affect prefetch hits. + */ +#define ZVOL_TASKQ_OFFSET_SHIFT 29 + #ifndef HAVE_BLKDEV_GET_ERESTARTSYS static unsigned int zvol_open_timeout_ms = 1000; #endif @@ -74,6 +81,7 @@ static boolean_t zvol_use_blk_mq = B_FALSE; * read and write tests to a zvol in an NVMe pool (with 16 CPUs). */ static unsigned int zvol_blk_mq_blocks_per_thread = 8; +static unsigned int zvol_num_taskqs = 0; #endif #ifndef BLKDEV_DEFAULT_RQ @@ -114,7 +122,11 @@ struct zvol_state_os { boolean_t use_blk_mq; }; -static taskq_t *zvol_taskq; +typedef struct zv_taskq { + uint_t tqs_cnt; + taskq_t **tqs_taskq; +} zv_taskq_t; +static zv_taskq_t zvol_taskqs; static struct ida zvol_ida; typedef struct zv_request_stack { @@ -532,6 +544,17 @@ zvol_request_impl(zvol_state_t *zv, struct bio *bio, struct request *rq, } zv_request_task_t *task; + zv_taskq_t *ztqs = &zvol_taskqs; + uint_t blk_mq_hw_queue = 0; + uint_t tq_idx; + uint_t taskq_hash; +#ifdef HAVE_BLK_MQ + if (rq) + blk_mq_hw_queue = rq->mq_hctx->queue_num; +#endif + taskq_hash = cityhash4((uintptr_t)zv, offset >> ZVOL_TASKQ_OFFSET_SHIFT, + blk_mq_hw_queue, 0); + tq_idx = taskq_hash % ztqs->tqs_cnt; if (rw == WRITE) { if (unlikely(zv->zv_flags & ZVOL_RDONLY)) { @@ -601,7 +624,7 @@ zvol_request_impl(zvol_state_t *zv, struct bio *bio, struct request *rq, zvol_discard(&zvr); } else { task = zv_request_task_create(zvr); - taskq_dispatch_ent(zvol_taskq, + taskq_dispatch_ent(ztqs->tqs_taskq[tq_idx], zvol_discard_task, task, 0, &task->ent); } } else { @@ -609,7 +632,7 @@ zvol_request_impl(zvol_state_t *zv, struct bio *bio, struct request *rq, zvol_write(&zvr); } else { task = zv_request_task_create(zvr); - taskq_dispatch_ent(zvol_taskq, + taskq_dispatch_ent(ztqs->tqs_taskq[tq_idx], zvol_write_task, task, 0, &task->ent); } } @@ -631,7 +654,7 @@ zvol_request_impl(zvol_state_t *zv, struct bio *bio, struct request *rq, zvol_read(&zvr); } else { task = zv_request_task_create(zvr); - taskq_dispatch_ent(zvol_taskq, + taskq_dispatch_ent(ztqs->tqs_taskq[tq_idx], zvol_read_task, task, 0, &task->ent); } } @@ -1563,8 +1586,40 @@ zvol_init(void) zvol_actual_threads = MIN(MAX(zvol_threads, 1), 1024); } + /* + * Use atleast 32 zvol_threads but for many core system, + * prefer 6 threads per taskq, but no more taskqs + * than threads in them on large systems. + * + * taskq total + * cpus taskqs threads threads + * ------- ------- ------- ------- + * 1 1 32 32 + * 2 1 32 32 + * 4 1 32 32 + * 8 2 16 32 + * 16 3 11 33 + * 32 5 7 35 + * 64 8 8 64 + * 128 11 12 132 + * 256 16 16 256 + */ + zv_taskq_t *ztqs = &zvol_taskqs; + uint_t num_tqs = MIN(num_online_cpus(), zvol_num_taskqs); + if (num_tqs == 0) { + num_tqs = 1 + num_online_cpus() / 6; + while (num_tqs * num_tqs > zvol_actual_threads) + num_tqs--; + } + uint_t per_tq_thread = zvol_actual_threads / num_tqs; + if (per_tq_thread * num_tqs < zvol_actual_threads) + per_tq_thread++; + ztqs->tqs_cnt = num_tqs; + ztqs->tqs_taskq = kmem_alloc(num_tqs * sizeof (taskq_t *), KM_SLEEP); error = register_blkdev(zvol_major, ZVOL_DRIVER); if (error) { + kmem_free(ztqs->tqs_taskq, ztqs->tqs_cnt * sizeof (taskq_t *)); + ztqs->tqs_taskq = NULL; printk(KERN_INFO "ZFS: register_blkdev() failed %d\n", error); return (error); } @@ -1584,11 +1639,22 @@ zvol_init(void) 1024); } #endif - zvol_taskq = taskq_create(ZVOL_DRIVER, zvol_actual_threads, maxclsyspri, - zvol_actual_threads, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC); - if (zvol_taskq == NULL) { - unregister_blkdev(zvol_major, ZVOL_DRIVER); - return (-ENOMEM); + for (uint_t i = 0; i < num_tqs; i++) { + char name[32]; + (void) snprintf(name, sizeof (name), "%s_tq-%u", + ZVOL_DRIVER, i); + ztqs->tqs_taskq[i] = taskq_create(name, per_tq_thread, + maxclsyspri, per_tq_thread, INT_MAX, + TASKQ_PREPOPULATE | TASKQ_DYNAMIC); + if (ztqs->tqs_taskq[i] == NULL) { + for (int j = i - 1; j >= 0; j--) + taskq_destroy(ztqs->tqs_taskq[j]); + unregister_blkdev(zvol_major, ZVOL_DRIVER); + kmem_free(ztqs->tqs_taskq, ztqs->tqs_cnt * + sizeof (taskq_t *)); + ztqs->tqs_taskq = NULL; + return (-ENOMEM); + } } zvol_init_impl(); @@ -1599,9 +1665,22 @@ zvol_init(void) void zvol_fini(void) { + zv_taskq_t *ztqs = &zvol_taskqs; zvol_fini_impl(); unregister_blkdev(zvol_major, ZVOL_DRIVER); - taskq_destroy(zvol_taskq); + + if (ztqs->tqs_taskq == NULL) { + ASSERT3U(ztqs->tqs_cnt, ==, 0); + } else { + for (uint_t i = 0; i < ztqs->tqs_cnt; i++) { + ASSERT3P(ztqs->tqs_taskq[i], !=, NULL); + taskq_destroy(ztqs->tqs_taskq[i]); + } + kmem_free(ztqs->tqs_taskq, ztqs->tqs_cnt * + sizeof (taskq_t *)); + ztqs->tqs_taskq = NULL; + } + ida_destroy(&zvol_ida); } @@ -1622,6 +1701,9 @@ MODULE_PARM_DESC(zvol_request_sync, "Synchronously handle bio requests"); module_param(zvol_max_discard_blocks, ulong, 0444); MODULE_PARM_DESC(zvol_max_discard_blocks, "Max number of blocks to discard"); +module_param(zvol_num_taskqs, uint, 0444); +MODULE_PARM_DESC(zvol_num_taskqs, "Number of zvol taskqs"); + module_param(zvol_prefetch_bytes, uint, 0644); MODULE_PARM_DESC(zvol_prefetch_bytes, "Prefetch N bytes at zvol start+end");