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4045 zfs write throttle & i/o scheduler performance work
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>

*** 22,62 **** * Copyright 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* ! * Copyright (c) 2012 by Delphix. All rights reserved. */ #include <sys/zfs_context.h> #include <sys/vdev_impl.h> #include <sys/spa_impl.h> #include <sys/zio.h> #include <sys/avl.h> /* ! * These tunables are for performance analysis. */ ! /* The maximum number of I/Os concurrently pending to each device. */ ! int zfs_vdev_max_pending = 10; /* ! * The initial number of I/Os pending to each device, before it starts ramping ! * up to zfs_vdev_max_pending. */ ! int zfs_vdev_min_pending = 4; /* ! * The deadlines are grouped into buckets based on zfs_vdev_time_shift: ! * deadline = pri + gethrtime() >> time_shift) */ ! int zfs_vdev_time_shift = 29; /* each bucket is 0.537 seconds */ - /* exponential I/O issue ramp-up rate */ - int zfs_vdev_ramp_rate = 2; - /* * To reduce IOPs, we aggregate small adjacent I/Os into one large I/O. * For read I/Os, we also aggregate across small adjacency gaps; for writes * we include spans of optional I/Os to aid aggregation at the disk even when * they aren't able to help us aggregate at this level. --- 22,163 ---- * Copyright 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* ! * Copyright (c) 2013 by Delphix. All rights reserved. */ #include <sys/zfs_context.h> #include <sys/vdev_impl.h> #include <sys/spa_impl.h> #include <sys/zio.h> #include <sys/avl.h> + #include <sys/dsl_pool.h> /* ! * ZFS I/O Scheduler ! * --------------- ! * ! * ZFS issues I/O operations to leaf vdevs to satisfy and complete zios. The ! * I/O scheduler determines when and in what order those operations are ! * issued. The I/O scheduler divides operations into five I/O classes ! * prioritized in the following order: sync read, sync write, async read, ! * async write, and scrub/resilver. Each queue defines the minimum and ! * maximum number of concurrent operations that may be issued to the device. ! * In addition, the device has an aggregate maximum. Note that the sum of the ! * per-queue minimums must not exceed the aggregate maximum, and if the ! * aggregate maximum is equal to or greater than the sum of the per-queue ! * maximums, the per-queue minimum has no effect. ! * ! * For many physical devices, throughput increases with the number of ! * concurrent operations, but latency typically suffers. Further, physical ! * devices typically have a limit at which more concurrent operations have no ! * effect on throughput or can actually cause it to decrease. ! * ! * The scheduler selects the next operation to issue by first looking for an ! * I/O class whose minimum has not been satisfied. Once all are satisfied and ! * the aggregate maximum has not been hit, the scheduler looks for classes ! * whose maximum has not been satisfied. Iteration through the I/O classes is ! * done in the order specified above. No further operations are issued if the ! * aggregate maximum number of concurrent operations has been hit or if there ! * are no operations queued for an I/O class that has not hit its maximum. ! * Every time an i/o is queued or an operation completes, the I/O scheduler ! * looks for new operations to issue. ! * ! * All I/O classes have a fixed maximum number of outstanding operations ! * except for the async write class. Asynchronous writes represent the data ! * that is committed to stable storage during the syncing stage for ! * transaction groups (see txg.c). Transaction groups enter the syncing state ! * periodically so the number of queued async writes will quickly burst up and ! * then bleed down to zero. Rather than servicing them as quickly as possible, ! * the I/O scheduler changes the maximum number of active async write i/os ! * according to the amount of dirty data in the pool (see dsl_pool.c). Since ! * both throughput and latency typically increase with the number of ! * concurrent operations issued to physical devices, reducing the burstiness ! * in the number of concurrent operations also stabilizes the response time of ! * operations from other -- and in particular synchronous -- queues. In broad ! * strokes, the I/O scheduler will issue more concurrent operations from the ! * async write queue as there's more dirty data in the pool. ! * ! * Async Writes ! * ! * The number of concurrent operations issued for the async write I/O class ! * follows a piece-wise linear function defined by a few adjustable points. ! * ! * | o---------| <-- zfs_vdev_async_write_max_active ! * ^ | /^ | ! * | | / | | ! * active | / | | ! * I/O | / | | ! * count | / | | ! * | / | | ! * |------------o | | <-- zfs_vdev_async_write_min_active ! * 0|____________^______|_________| ! * 0% | | 100% of zfs_dirty_data_max ! * | | ! * | `-- zfs_vdev_async_write_active_max_dirty_percent ! * `--------- zfs_vdev_async_write_active_min_dirty_percent ! * ! * Until the amount of dirty data exceeds a minimum percentage of the dirty ! * data allowed in the pool, the I/O scheduler will limit the number of ! * concurrent operations to the minimum. As that threshold is crossed, the ! * number of concurrent operations issued increases linearly to the maximum at ! * the specified maximum percentage of the dirty data allowed in the pool. ! * ! * Ideally, the amount of dirty data on a busy pool will stay in the sloped ! * part of the function between zfs_vdev_async_write_active_min_dirty_percent ! * and zfs_vdev_async_write_active_max_dirty_percent. If it exceeds the ! * maximum percentage, this indicates that the rate of incoming data is ! * greater than the rate that the backend storage can handle. In this case, we ! * must further throttle incoming writes (see dmu_tx_delay() for details). */ ! /* ! * The maximum number of i/os active to each device. Ideally, this will be >= ! * the sum of each queue's max_active. It must be at least the sum of each ! * queue's min_active. ! */ ! uint32_t zfs_vdev_max_active = 1000; /* ! * Per-queue limits on the number of i/os active to each device. If the ! * sum of the queue's max_active is < zfs_vdev_max_active, then the ! * min_active comes into play. We will send min_active from each queue, ! * and then select from queues in the order defined by zio_priority_t. ! * ! * In general, smaller max_active's will lead to lower latency of synchronous ! * operations. Larger max_active's may lead to higher overall throughput, ! * depending on underlying storage. ! * ! * The ratio of the queues' max_actives determines the balance of performance ! * between reads, writes, and scrubs. E.g., increasing ! * zfs_vdev_scrub_max_active will cause the scrub or resilver to complete ! * more quickly, but reads and writes to have higher latency and lower ! * throughput. */ ! uint32_t zfs_vdev_sync_read_min_active = 10; ! uint32_t zfs_vdev_sync_read_max_active = 10; ! uint32_t zfs_vdev_sync_write_min_active = 10; ! uint32_t zfs_vdev_sync_write_max_active = 10; ! uint32_t zfs_vdev_async_read_min_active = 1; ! uint32_t zfs_vdev_async_read_max_active = 3; ! uint32_t zfs_vdev_async_write_min_active = 1; ! uint32_t zfs_vdev_async_write_max_active = 10; ! uint32_t zfs_vdev_scrub_min_active = 1; ! uint32_t zfs_vdev_scrub_max_active = 2; /* ! * When the pool has less than zfs_vdev_async_write_active_min_dirty_percent ! * dirty data, use zfs_vdev_async_write_min_active. When it has more than ! * zfs_vdev_async_write_active_max_dirty_percent, use ! * zfs_vdev_async_write_max_active. The value is linearly interpolated ! * between min and max. */ ! int zfs_vdev_async_write_active_min_dirty_percent = 30; ! int zfs_vdev_async_write_active_max_dirty_percent = 60; /* * To reduce IOPs, we aggregate small adjacent I/Os into one large I/O. * For read I/Os, we also aggregate across small adjacency gaps; for writes * we include spans of optional I/Os to aid aggregation at the disk even when * they aren't able to help us aggregate at this level.
*** 63,86 **** */ int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE; int zfs_vdev_read_gap_limit = 32 << 10; int zfs_vdev_write_gap_limit = 4 << 10; - /* - * Virtual device vector for disk I/O scheduling. - */ int ! vdev_queue_deadline_compare(const void *x1, const void *x2) { const zio_t *z1 = x1; const zio_t *z2 = x2; - if (z1->io_deadline < z2->io_deadline) - return (-1); - if (z1->io_deadline > z2->io_deadline) - return (1); - if (z1->io_offset < z2->io_offset) return (-1); if (z1->io_offset > z2->io_offset) return (1); --- 164,179 ---- */ int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE; int zfs_vdev_read_gap_limit = 32 << 10; int zfs_vdev_write_gap_limit = 4 << 10; int ! vdev_queue_offset_compare(const void *x1, const void *x2) { const zio_t *z1 = x1; const zio_t *z2 = x2; if (z1->io_offset < z2->io_offset) return (-1); if (z1->io_offset > z2->io_offset) return (1);
*** 91,108 **** return (0); } int ! vdev_queue_offset_compare(const void *x1, const void *x2) { const zio_t *z1 = x1; const zio_t *z2 = x2; ! if (z1->io_offset < z2->io_offset) return (-1); ! if (z1->io_offset > z2->io_offset) return (1); if (z1 < z2) return (-1); if (z1 > z2) --- 184,201 ---- return (0); } int ! vdev_queue_timestamp_compare(const void *x1, const void *x2) { const zio_t *z1 = x1; const zio_t *z2 = x2; ! if (z1->io_timestamp < z2->io_timestamp) return (-1); ! if (z1->io_timestamp > z2->io_timestamp) return (1); if (z1 < z2) return (-1); if (z1 > z2)
*** 115,258 **** vdev_queue_init(vdev_t *vd) { vdev_queue_t *vq = &vd->vdev_queue; mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL); ! avl_create(&vq->vq_deadline_tree, vdev_queue_deadline_compare, ! sizeof (zio_t), offsetof(struct zio, io_deadline_node)); ! avl_create(&vq->vq_read_tree, vdev_queue_offset_compare, ! sizeof (zio_t), offsetof(struct zio, io_offset_node)); ! ! avl_create(&vq->vq_write_tree, vdev_queue_offset_compare, ! sizeof (zio_t), offsetof(struct zio, io_offset_node)); ! ! avl_create(&vq->vq_pending_tree, vdev_queue_offset_compare, ! sizeof (zio_t), offsetof(struct zio, io_offset_node)); } void vdev_queue_fini(vdev_t *vd) { vdev_queue_t *vq = &vd->vdev_queue; ! avl_destroy(&vq->vq_deadline_tree); ! avl_destroy(&vq->vq_read_tree); ! avl_destroy(&vq->vq_write_tree); ! avl_destroy(&vq->vq_pending_tree); mutex_destroy(&vq->vq_lock); } static void vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! avl_add(&vq->vq_deadline_tree, zio); ! avl_add(zio->io_vdev_tree, zio); - if (spa->spa_iokstat != NULL) { mutex_enter(&spa->spa_iokstat_lock); kstat_waitq_enter(spa->spa_iokstat->ks_data); mutex_exit(&spa->spa_iokstat_lock); - } } static void vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! avl_remove(&vq->vq_deadline_tree, zio); ! avl_remove(zio->io_vdev_tree, zio); - if (spa->spa_iokstat != NULL) { mutex_enter(&spa->spa_iokstat_lock); kstat_waitq_exit(spa->spa_iokstat->ks_data); mutex_exit(&spa->spa_iokstat_lock); - } } static void vdev_queue_pending_add(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! avl_add(&vq->vq_pending_tree, zio); ! if (spa->spa_iokstat != NULL) { mutex_enter(&spa->spa_iokstat_lock); kstat_runq_enter(spa->spa_iokstat->ks_data); mutex_exit(&spa->spa_iokstat_lock); - } } static void vdev_queue_pending_remove(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! avl_remove(&vq->vq_pending_tree, zio); if (spa->spa_iokstat != NULL) { kstat_io_t *ksio = spa->spa_iokstat->ks_data; - mutex_enter(&spa->spa_iokstat_lock); kstat_runq_exit(spa->spa_iokstat->ks_data); if (zio->io_type == ZIO_TYPE_READ) { ksio->reads++; ksio->nread += zio->io_size; } else if (zio->io_type == ZIO_TYPE_WRITE) { ksio->writes++; ksio->nwritten += zio->io_size; } - mutex_exit(&spa->spa_iokstat_lock); } } static void vdev_queue_agg_io_done(zio_t *aio) { zio_t *pio; ! ! while ((pio = zio_walk_parents(aio)) != NULL) ! if (aio->io_type == ZIO_TYPE_READ) bcopy((char *)aio->io_data + (pio->io_offset - aio->io_offset), pio->io_data, pio->io_size); zio_buf_free(aio->io_data, aio->io_size); } /* * Compute the range spanned by two i/os, which is the endpoint of the last * (lio->io_offset + lio->io_size) minus start of the first (fio->io_offset). * Conveniently, the gap between fio and lio is given by -IO_SPAN(lio, fio); * thus fio and lio are adjacent if and only if IO_SPAN(lio, fio) == 0. */ #define IO_SPAN(fio, lio) ((lio)->io_offset + (lio)->io_size - (fio)->io_offset) #define IO_GAP(fio, lio) (-IO_SPAN(lio, fio)) static zio_t * ! vdev_queue_io_to_issue(vdev_queue_t *vq, uint64_t pending_limit) { ! zio_t *fio, *lio, *aio, *dio, *nio, *mio; ! avl_tree_t *t; ! int flags; ! uint64_t maxspan = zfs_vdev_aggregation_limit; ! uint64_t maxgap; ! int stretch; ! again: ! ASSERT(MUTEX_HELD(&vq->vq_lock)); ! if (avl_numnodes(&vq->vq_pending_tree) >= pending_limit || ! avl_numnodes(&vq->vq_deadline_tree) == 0) return (NULL); ! fio = lio = avl_first(&vq->vq_deadline_tree); ! t = fio->io_vdev_tree; ! flags = fio->io_flags & ZIO_FLAG_AGG_INHERIT; ! maxgap = (t == &vq->vq_read_tree) ? zfs_vdev_read_gap_limit : 0; - if (!(flags & ZIO_FLAG_DONT_AGGREGATE)) { /* * We can aggregate I/Os that are sufficiently adjacent and of * the same flavor, as expressed by the AGG_INHERIT flags. * The latter requirement is necessary so that certain * attributes of the I/O, such as whether it's a normal I/O --- 208,480 ---- vdev_queue_init(vdev_t *vd) { vdev_queue_t *vq = &vd->vdev_queue; mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL); + vq->vq_vdev = vd; ! avl_create(&vq->vq_active_tree, vdev_queue_offset_compare, ! sizeof (zio_t), offsetof(struct zio, io_queue_node)); ! for (zio_priority_t p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) { ! /* ! * The synchronous i/o queues are FIFO rather than LBA ordered. ! * This provides more consistent latency for these i/os, and ! * they tend to not be tightly clustered anyway so there is ! * little to no throughput loss. ! */ ! boolean_t fifo = (p == ZIO_PRIORITY_SYNC_READ || ! p == ZIO_PRIORITY_SYNC_WRITE); ! avl_create(&vq->vq_class[p].vqc_queued_tree, ! fifo ? vdev_queue_timestamp_compare : ! vdev_queue_offset_compare, ! sizeof (zio_t), offsetof(struct zio, io_queue_node)); ! } } void vdev_queue_fini(vdev_t *vd) { vdev_queue_t *vq = &vd->vdev_queue; ! for (zio_priority_t p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) ! avl_destroy(&vq->vq_class[p].vqc_queued_tree); ! avl_destroy(&vq->vq_active_tree); mutex_destroy(&vq->vq_lock); } static void vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); ! avl_add(&vq->vq_class[zio->io_priority].vqc_queued_tree, zio); mutex_enter(&spa->spa_iokstat_lock); + spa->spa_queue_stats[zio->io_priority].spa_queued++; + if (spa->spa_iokstat != NULL) kstat_waitq_enter(spa->spa_iokstat->ks_data); mutex_exit(&spa->spa_iokstat_lock); } static void vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); ! avl_remove(&vq->vq_class[zio->io_priority].vqc_queued_tree, zio); mutex_enter(&spa->spa_iokstat_lock); + ASSERT3U(spa->spa_queue_stats[zio->io_priority].spa_queued, >, 0); + spa->spa_queue_stats[zio->io_priority].spa_queued--; + if (spa->spa_iokstat != NULL) kstat_waitq_exit(spa->spa_iokstat->ks_data); mutex_exit(&spa->spa_iokstat_lock); } static void vdev_queue_pending_add(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! ASSERT(MUTEX_HELD(&vq->vq_lock)); ! ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); ! vq->vq_class[zio->io_priority].vqc_active++; ! avl_add(&vq->vq_active_tree, zio); ! mutex_enter(&spa->spa_iokstat_lock); + spa->spa_queue_stats[zio->io_priority].spa_active++; + if (spa->spa_iokstat != NULL) kstat_runq_enter(spa->spa_iokstat->ks_data); mutex_exit(&spa->spa_iokstat_lock); } static void vdev_queue_pending_remove(vdev_queue_t *vq, zio_t *zio) { spa_t *spa = zio->io_spa; ! ASSERT(MUTEX_HELD(&vq->vq_lock)); ! ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); ! vq->vq_class[zio->io_priority].vqc_active--; ! avl_remove(&vq->vq_active_tree, zio); ! ! mutex_enter(&spa->spa_iokstat_lock); ! ASSERT3U(spa->spa_queue_stats[zio->io_priority].spa_active, >, 0); ! spa->spa_queue_stats[zio->io_priority].spa_active--; if (spa->spa_iokstat != NULL) { kstat_io_t *ksio = spa->spa_iokstat->ks_data; kstat_runq_exit(spa->spa_iokstat->ks_data); if (zio->io_type == ZIO_TYPE_READ) { ksio->reads++; ksio->nread += zio->io_size; } else if (zio->io_type == ZIO_TYPE_WRITE) { ksio->writes++; ksio->nwritten += zio->io_size; } } + mutex_exit(&spa->spa_iokstat_lock); } static void vdev_queue_agg_io_done(zio_t *aio) { + if (aio->io_type == ZIO_TYPE_READ) { zio_t *pio; ! while ((pio = zio_walk_parents(aio)) != NULL) { bcopy((char *)aio->io_data + (pio->io_offset - aio->io_offset), pio->io_data, pio->io_size); + } + } zio_buf_free(aio->io_data, aio->io_size); } + static int + vdev_queue_class_min_active(zio_priority_t p) + { + switch (p) { + case ZIO_PRIORITY_SYNC_READ: + return (zfs_vdev_sync_read_min_active); + case ZIO_PRIORITY_SYNC_WRITE: + return (zfs_vdev_sync_write_min_active); + case ZIO_PRIORITY_ASYNC_READ: + return (zfs_vdev_async_read_min_active); + case ZIO_PRIORITY_ASYNC_WRITE: + return (zfs_vdev_async_write_min_active); + case ZIO_PRIORITY_SCRUB: + return (zfs_vdev_scrub_min_active); + default: + panic("invalid priority %u", p); + return (0); + } + } + + static int + vdev_queue_max_async_writes(uint64_t dirty) + { + int writes; + uint64_t min_bytes = zfs_dirty_data_max * + zfs_vdev_async_write_active_min_dirty_percent / 100; + uint64_t max_bytes = zfs_dirty_data_max * + zfs_vdev_async_write_active_max_dirty_percent / 100; + + if (dirty < min_bytes) + return (zfs_vdev_async_write_min_active); + if (dirty > max_bytes) + return (zfs_vdev_async_write_max_active); + + /* + * linear interpolation: + * slope = (max_writes - min_writes) / (max_bytes - min_bytes) + * move right by min_bytes + * move up by min_writes + */ + writes = (dirty - min_bytes) * + (zfs_vdev_async_write_max_active - + zfs_vdev_async_write_min_active) / + (max_bytes - min_bytes) + + zfs_vdev_async_write_min_active; + ASSERT3U(writes, >=, zfs_vdev_async_write_min_active); + ASSERT3U(writes, <=, zfs_vdev_async_write_max_active); + return (writes); + } + + static int + vdev_queue_class_max_active(spa_t *spa, zio_priority_t p) + { + switch (p) { + case ZIO_PRIORITY_SYNC_READ: + return (zfs_vdev_sync_read_max_active); + case ZIO_PRIORITY_SYNC_WRITE: + return (zfs_vdev_sync_write_max_active); + case ZIO_PRIORITY_ASYNC_READ: + return (zfs_vdev_async_read_max_active); + case ZIO_PRIORITY_ASYNC_WRITE: + return (vdev_queue_max_async_writes( + spa->spa_dsl_pool->dp_dirty_total)); + case ZIO_PRIORITY_SCRUB: + return (zfs_vdev_scrub_max_active); + default: + panic("invalid priority %u", p); + return (0); + } + } + /* + * Return the i/o class to issue from, or ZIO_PRIORITY_MAX_QUEUEABLE if + * there is no eligible class. + */ + static zio_priority_t + vdev_queue_class_to_issue(vdev_queue_t *vq) + { + spa_t *spa = vq->vq_vdev->vdev_spa; + zio_priority_t p; + + if (avl_numnodes(&vq->vq_active_tree) >= zfs_vdev_max_active) + return (ZIO_PRIORITY_NUM_QUEUEABLE); + + /* find a queue that has not reached its minimum # outstanding i/os */ + for (p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) { + if (avl_numnodes(&vq->vq_class[p].vqc_queued_tree) > 0 && + vq->vq_class[p].vqc_active < + vdev_queue_class_min_active(p)) + return (p); + } + + /* + * If we haven't found a queue, look for one that hasn't reached its + * maximum # outstanding i/os. + */ + for (p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) { + if (avl_numnodes(&vq->vq_class[p].vqc_queued_tree) > 0 && + vq->vq_class[p].vqc_active < + vdev_queue_class_max_active(spa, p)) + return (p); + } + + /* No eligible queued i/os */ + return (ZIO_PRIORITY_NUM_QUEUEABLE); + } + + /* * Compute the range spanned by two i/os, which is the endpoint of the last * (lio->io_offset + lio->io_size) minus start of the first (fio->io_offset). * Conveniently, the gap between fio and lio is given by -IO_SPAN(lio, fio); * thus fio and lio are adjacent if and only if IO_SPAN(lio, fio) == 0. */ #define IO_SPAN(fio, lio) ((lio)->io_offset + (lio)->io_size - (fio)->io_offset) #define IO_GAP(fio, lio) (-IO_SPAN(lio, fio)) static zio_t * ! vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio) { ! zio_t *first, *last, *aio, *dio, *mandatory, *nio; ! uint64_t maxgap = 0; ! uint64_t size; ! boolean_t stretch = B_FALSE; ! vdev_queue_class_t *vqc = &vq->vq_class[zio->io_priority]; ! avl_tree_t *t = &vqc->vqc_queued_tree; ! enum zio_flag flags = zio->io_flags & ZIO_FLAG_AGG_INHERIT; ! if (zio->io_flags & ZIO_FLAG_DONT_AGGREGATE) ! return (NULL); ! /* ! * The synchronous i/o queues are not sorted by LBA, so we can't ! * find adjacent i/os. These i/os tend to not be tightly clustered, ! * or too large to aggregate, so this has little impact on performance. ! */ ! if (zio->io_priority == ZIO_PRIORITY_SYNC_READ || ! zio->io_priority == ZIO_PRIORITY_SYNC_WRITE) return (NULL); ! first = last = zio; ! if (zio->io_type == ZIO_TYPE_READ) ! maxgap = zfs_vdev_read_gap_limit; /* * We can aggregate I/Os that are sufficiently adjacent and of * the same flavor, as expressed by the AGG_INHERIT flags. * The latter requirement is necessary so that certain * attributes of the I/O, such as whether it's a normal I/O
*** 262,304 **** */ /* * We keep track of the last non-optional I/O. */ ! mio = (fio->io_flags & ZIO_FLAG_OPTIONAL) ? NULL : fio; /* * Walk backwards through sufficiently contiguous I/Os * recording the last non-option I/O. */ ! while ((dio = AVL_PREV(t, fio)) != NULL && (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && ! IO_SPAN(dio, lio) <= maxspan && ! IO_GAP(dio, fio) <= maxgap) { ! fio = dio; ! if (mio == NULL && !(fio->io_flags & ZIO_FLAG_OPTIONAL)) ! mio = fio; } /* * Skip any initial optional I/Os. */ ! while ((fio->io_flags & ZIO_FLAG_OPTIONAL) && fio != lio) { ! fio = AVL_NEXT(t, fio); ! ASSERT(fio != NULL); } /* * Walk forward through sufficiently contiguous I/Os. */ ! while ((dio = AVL_NEXT(t, lio)) != NULL && (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && ! IO_SPAN(fio, dio) <= maxspan && ! IO_GAP(lio, dio) <= maxgap) { ! lio = dio; ! if (!(lio->io_flags & ZIO_FLAG_OPTIONAL)) ! mio = lio; } /* * Now that we've established the range of the I/O aggregation * we must decide what to do with trailing optional I/Os. --- 484,526 ---- */ /* * We keep track of the last non-optional I/O. */ ! mandatory = (first->io_flags & ZIO_FLAG_OPTIONAL) ? NULL : first; /* * Walk backwards through sufficiently contiguous I/Os * recording the last non-option I/O. */ ! while ((dio = AVL_PREV(t, first)) != NULL && (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && ! IO_SPAN(dio, last) <= zfs_vdev_aggregation_limit && ! IO_GAP(dio, first) <= maxgap) { ! first = dio; ! if (mandatory == NULL && !(first->io_flags & ZIO_FLAG_OPTIONAL)) ! mandatory = first; } /* * Skip any initial optional I/Os. */ ! while ((first->io_flags & ZIO_FLAG_OPTIONAL) && first != last) { ! first = AVL_NEXT(t, first); ! ASSERT(first != NULL); } /* * Walk forward through sufficiently contiguous I/Os. */ ! while ((dio = AVL_NEXT(t, last)) != NULL && (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && ! IO_SPAN(first, dio) <= zfs_vdev_aggregation_limit && ! IO_GAP(last, dio) <= maxgap) { ! last = dio; ! if (!(last->io_flags & ZIO_FLAG_OPTIONAL)) ! mandatory = last; } /* * Now that we've established the range of the I/O aggregation * we must decide what to do with trailing optional I/Os.
*** 307,322 **** * I/O would allow the underlying device to aggregate with * subsequent I/Os. We must therefore determine if the next * non-optional I/O is close enough to make aggregation * worthwhile. */ ! stretch = B_FALSE; ! if (t != &vq->vq_read_tree && mio != NULL) { ! nio = lio; while ((dio = AVL_NEXT(t, nio)) != NULL && IO_GAP(nio, dio) == 0 && ! IO_GAP(mio, dio) <= zfs_vdev_write_gap_limit) { nio = dio; if (!(nio->io_flags & ZIO_FLAG_OPTIONAL)) { stretch = B_TRUE; break; } --- 529,543 ---- * I/O would allow the underlying device to aggregate with * subsequent I/Os. We must therefore determine if the next * non-optional I/O is close enough to make aggregation * worthwhile. */ ! if (zio->io_type == ZIO_TYPE_WRITE && mandatory != NULL) { ! zio_t *nio = last; while ((dio = AVL_NEXT(t, nio)) != NULL && IO_GAP(nio, dio) == 0 && ! IO_GAP(mandatory, dio) <= zfs_vdev_write_gap_limit) { nio = dio; if (!(nio->io_flags & ZIO_FLAG_OPTIONAL)) { stretch = B_TRUE; break; }
*** 323,362 **** } } if (stretch) { /* This may be a no-op. */ ! VERIFY((dio = AVL_NEXT(t, lio)) != NULL); dio->io_flags &= ~ZIO_FLAG_OPTIONAL; } else { ! while (lio != mio && lio != fio) { ! ASSERT(lio->io_flags & ZIO_FLAG_OPTIONAL); ! lio = AVL_PREV(t, lio); ! ASSERT(lio != NULL); } } - } ! if (fio != lio) { ! uint64_t size = IO_SPAN(fio, lio); ! ASSERT(size <= zfs_vdev_aggregation_limit); ! aio = zio_vdev_delegated_io(fio->io_vd, fio->io_offset, ! zio_buf_alloc(size), size, fio->io_type, ZIO_PRIORITY_AGG, flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE, vdev_queue_agg_io_done, NULL); ! aio->io_timestamp = fio->io_timestamp; ! nio = fio; do { dio = nio; nio = AVL_NEXT(t, dio); ! ASSERT(dio->io_type == aio->io_type); ! ASSERT(dio->io_vdev_tree == t); if (dio->io_flags & ZIO_FLAG_NODATA) { ! ASSERT(dio->io_type == ZIO_TYPE_WRITE); bzero((char *)aio->io_data + (dio->io_offset - aio->io_offset), dio->io_size); } else if (dio->io_type == ZIO_TYPE_WRITE) { bcopy(dio->io_data, (char *)aio->io_data + (dio->io_offset - aio->io_offset), --- 544,583 ---- } } if (stretch) { /* This may be a no-op. */ ! dio = AVL_NEXT(t, last); dio->io_flags &= ~ZIO_FLAG_OPTIONAL; } else { ! while (last != mandatory && last != first) { ! ASSERT(last->io_flags & ZIO_FLAG_OPTIONAL); ! last = AVL_PREV(t, last); ! ASSERT(last != NULL); } } ! if (first == last) ! return (NULL); ! size = IO_SPAN(first, last); ! ASSERT3U(size, <=, zfs_vdev_aggregation_limit); ! ! aio = zio_vdev_delegated_io(first->io_vd, first->io_offset, ! zio_buf_alloc(size), size, first->io_type, zio->io_priority, flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE, vdev_queue_agg_io_done, NULL); ! aio->io_timestamp = first->io_timestamp; ! nio = first; do { dio = nio; nio = AVL_NEXT(t, dio); ! ASSERT3U(dio->io_type, ==, aio->io_type); if (dio->io_flags & ZIO_FLAG_NODATA) { ! ASSERT3U(dio->io_type, ==, ZIO_TYPE_WRITE); bzero((char *)aio->io_data + (dio->io_offset - aio->io_offset), dio->io_size); } else if (dio->io_type == ZIO_TYPE_WRITE) { bcopy(dio->io_data, (char *)aio->io_data + (dio->io_offset - aio->io_offset),
*** 365,431 **** zio_add_child(dio, aio); vdev_queue_io_remove(vq, dio); zio_vdev_io_bypass(dio); zio_execute(dio); ! } while (dio != lio); - vdev_queue_pending_add(vq, aio); - return (aio); } ! ASSERT(fio->io_vdev_tree == t); ! vdev_queue_io_remove(vq, fio); /* * If the I/O is or was optional and therefore has no data, we need to * simply discard it. We need to drop the vdev queue's lock to avoid a * deadlock that we could encounter since this I/O will complete * immediately. */ ! if (fio->io_flags & ZIO_FLAG_NODATA) { mutex_exit(&vq->vq_lock); ! zio_vdev_io_bypass(fio); ! zio_execute(fio); mutex_enter(&vq->vq_lock); goto again; } ! vdev_queue_pending_add(vq, fio); ! return (fio); } zio_t * vdev_queue_io(zio_t *zio) { vdev_queue_t *vq = &zio->io_vd->vdev_queue; zio_t *nio; - ASSERT(zio->io_type == ZIO_TYPE_READ || zio->io_type == ZIO_TYPE_WRITE); - if (zio->io_flags & ZIO_FLAG_DONT_QUEUE) return (zio); zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE; - if (zio->io_type == ZIO_TYPE_READ) - zio->io_vdev_tree = &vq->vq_read_tree; - else - zio->io_vdev_tree = &vq->vq_write_tree; - mutex_enter(&vq->vq_lock); - zio->io_timestamp = gethrtime(); - zio->io_deadline = (zio->io_timestamp >> zfs_vdev_time_shift) + - zio->io_priority; - vdev_queue_io_add(vq, zio); ! ! nio = vdev_queue_io_to_issue(vq, zfs_vdev_min_pending); ! mutex_exit(&vq->vq_lock); if (nio == NULL) return (NULL); --- 586,691 ---- zio_add_child(dio, aio); vdev_queue_io_remove(vq, dio); zio_vdev_io_bypass(dio); zio_execute(dio); ! } while (dio != last); return (aio); + } + + static zio_t * + vdev_queue_io_to_issue(vdev_queue_t *vq) + { + zio_t *zio, *aio; + zio_priority_t p; + avl_index_t idx; + vdev_queue_class_t *vqc; + zio_t search; + + again: + ASSERT(MUTEX_HELD(&vq->vq_lock)); + + p = vdev_queue_class_to_issue(vq); + + if (p == ZIO_PRIORITY_NUM_QUEUEABLE) { + /* No eligible queued i/os */ + return (NULL); } ! /* ! * For LBA-ordered queues (async / scrub), issue the i/o which follows ! * the most recently issued i/o in LBA (offset) order. ! * ! * For FIFO queues (sync), issue the i/o with the lowest timestamp. ! */ ! vqc = &vq->vq_class[p]; ! search.io_timestamp = 0; ! search.io_offset = vq->vq_last_offset + 1; ! VERIFY3P(avl_find(&vqc->vqc_queued_tree, &search, &idx), ==, NULL); ! zio = avl_nearest(&vqc->vqc_queued_tree, idx, AVL_AFTER); ! if (zio == NULL) ! zio = avl_first(&vqc->vqc_queued_tree); ! ASSERT3U(zio->io_priority, ==, p); + aio = vdev_queue_aggregate(vq, zio); + if (aio != NULL) + zio = aio; + else + vdev_queue_io_remove(vq, zio); + /* * If the I/O is or was optional and therefore has no data, we need to * simply discard it. We need to drop the vdev queue's lock to avoid a * deadlock that we could encounter since this I/O will complete * immediately. */ ! if (zio->io_flags & ZIO_FLAG_NODATA) { mutex_exit(&vq->vq_lock); ! zio_vdev_io_bypass(zio); ! zio_execute(zio); mutex_enter(&vq->vq_lock); goto again; } ! vdev_queue_pending_add(vq, zio); ! vq->vq_last_offset = zio->io_offset; ! return (zio); } zio_t * vdev_queue_io(zio_t *zio) { vdev_queue_t *vq = &zio->io_vd->vdev_queue; zio_t *nio; if (zio->io_flags & ZIO_FLAG_DONT_QUEUE) return (zio); + /* + * Children i/os inherent their parent's priority, which might + * not match the child's i/o type. Fix it up here. + */ + if (zio->io_type == ZIO_TYPE_READ) { + if (zio->io_priority != ZIO_PRIORITY_SYNC_READ && + zio->io_priority != ZIO_PRIORITY_ASYNC_READ && + zio->io_priority != ZIO_PRIORITY_SCRUB) + zio->io_priority = ZIO_PRIORITY_ASYNC_READ; + } else { + ASSERT(zio->io_type == ZIO_TYPE_WRITE); + if (zio->io_priority != ZIO_PRIORITY_SYNC_WRITE && + zio->io_priority != ZIO_PRIORITY_ASYNC_WRITE) + zio->io_priority = ZIO_PRIORITY_ASYNC_WRITE; + } + zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE; mutex_enter(&vq->vq_lock); zio->io_timestamp = gethrtime(); vdev_queue_io_add(vq, zio); ! nio = vdev_queue_io_to_issue(vq); mutex_exit(&vq->vq_lock); if (nio == NULL) return (NULL);
*** 439,448 **** --- 699,709 ---- void vdev_queue_io_done(zio_t *zio) { vdev_queue_t *vq = &zio->io_vd->vdev_queue; + zio_t *nio; if (zio_injection_enabled) delay(SEC_TO_TICK(zio_handle_io_delay(zio))); mutex_enter(&vq->vq_lock);
*** 449,462 **** vdev_queue_pending_remove(vq, zio); vq->vq_io_complete_ts = gethrtime(); ! for (int i = 0; i < zfs_vdev_ramp_rate; i++) { ! zio_t *nio = vdev_queue_io_to_issue(vq, zfs_vdev_max_pending); ! if (nio == NULL) ! break; mutex_exit(&vq->vq_lock); if (nio->io_done == vdev_queue_agg_io_done) { zio_nowait(nio); } else { zio_vdev_io_reissue(nio); --- 710,720 ---- vdev_queue_pending_remove(vq, zio); vq->vq_io_complete_ts = gethrtime(); ! while ((nio = vdev_queue_io_to_issue(vq)) != NULL) { mutex_exit(&vq->vq_lock); if (nio->io_done == vdev_queue_agg_io_done) { zio_nowait(nio); } else { zio_vdev_io_reissue(nio);