/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* * Copyright (c) 2012, 2018 by Delphix. All rights reserved. */ #include #include #include #include #include #include #include #include #include /* * 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. If the * sum of the per-queue maximums exceeds the aggregate maximum, then the * number of active i/os may reach zfs_vdev_max_active, in which case no * further i/os will be issued regardless of whether all per-queue * minimums have been met. * * 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. */ uint32_t zfs_vdev_max_active = 1000; /* * Per-queue limits on the number of i/os active to each device. If the * number of active i/os is < zfs_vdev_max_active, then the min_active comes * into play. We will send min_active from each queue round-robin, and then * send from queues in the order defined by zio_priority_t up to max_active. * Some queues have additional mechanisms to limit number of active I/Os in * addition to min_active and max_active, see below. * * 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 = 2; uint32_t zfs_vdev_async_write_max_active = 10; uint32_t zfs_vdev_scrub_min_active = 1; uint32_t zfs_vdev_scrub_max_active = 3; uint32_t zfs_vdev_removal_min_active = 1; uint32_t zfs_vdev_removal_max_active = 2; uint32_t zfs_vdev_initializing_min_active = 1; uint32_t zfs_vdev_initializing_max_active = 1; uint32_t zfs_vdev_trim_min_active = 1; uint32_t zfs_vdev_trim_max_active = 2; uint32_t zfs_vdev_rebuild_min_active = 1; uint32_t zfs_vdev_rebuild_max_active = 3; /* * 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; /* * For non-interactive I/O (scrub, resilver, removal, initialize and rebuild), * the number of concurrently-active I/O's is limited to *_min_active, unless * the vdev is "idle". When there are no interactive I/Os active (sync or * async), and zfs_vdev_nia_delay I/Os have completed since the last * interactive I/O, then the vdev is considered to be "idle", and the number * of concurrently-active non-interactive I/O's is increased to *_max_active. */ uint_t zfs_vdev_nia_delay = 5; /* * Some HDDs tend to prioritize sequential I/O so high that concurrent * random I/O latency reaches several seconds. On some HDDs it happens * even if sequential I/Os are submitted one at a time, and so setting * *_max_active to 1 does not help. To prevent non-interactive I/Os, like * scrub, from monopolizing the device no more than zfs_vdev_nia_credit * I/Os can be sent while there are outstanding incomplete interactive * I/Os. This enforced wait ensures the HDD services the interactive I/O * within a reasonable amount of time. */ uint_t zfs_vdev_nia_credit = 5; /* * 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. */ int zfs_vdev_aggregation_limit = 1 << 20; int zfs_vdev_aggregation_limit_non_rotating = SPA_OLD_MAXBLOCKSIZE; int zfs_vdev_read_gap_limit = 32 << 10; int zfs_vdev_write_gap_limit = 4 << 10; /* * Define the queue depth percentage for each top-level. This percentage is * used in conjunction with zfs_vdev_async_max_active to determine how many * allocations a specific top-level vdev should handle. Once the queue depth * reaches zfs_vdev_queue_depth_pct * zfs_vdev_async_write_max_active / 100 * then allocator will stop allocating blocks on that top-level device. * The default kernel setting is 1000% which will yield 100 allocations per * device. For userland testing, the default setting is 300% which equates * to 30 allocations per device. */ #ifdef _KERNEL int zfs_vdev_queue_depth_pct = 1000; #else int zfs_vdev_queue_depth_pct = 300; #endif /* * When performing allocations for a given metaslab, we want to make sure that * there are enough IOs to aggregate together to improve throughput. We want to * ensure that there are at least 128k worth of IOs that can be aggregated, and * we assume that the average allocation size is 4k, so we need the queue depth * to be 32 per allocator to get good aggregation of sequential writes. */ int zfs_vdev_def_queue_depth = 32; /* * Allow TRIM I/Os to be aggregated. This should normally not be needed since * TRIM I/O for extents up to zfs_trim_extent_bytes_max (128M) can be submitted * by the TRIM code in zfs_trim.c. */ int zfs_vdev_aggregate_trim = 0; static int vdev_queue_offset_compare(const void *x1, const void *x2) { const zio_t *z1 = (const zio_t *)x1; const zio_t *z2 = (const zio_t *)x2; int cmp = TREE_CMP(z1->io_offset, z2->io_offset); if (likely(cmp)) return (cmp); return (TREE_PCMP(z1, z2)); } static inline avl_tree_t * vdev_queue_class_tree(vdev_queue_t *vq, zio_priority_t p) { return (&vq->vq_class[p].vqc_queued_tree); } static inline avl_tree_t * vdev_queue_type_tree(vdev_queue_t *vq, zio_type_t t) { ASSERT(t == ZIO_TYPE_READ || t == ZIO_TYPE_WRITE || t == ZIO_TYPE_TRIM); if (t == ZIO_TYPE_READ) return (&vq->vq_read_offset_tree); else if (t == ZIO_TYPE_WRITE) return (&vq->vq_write_offset_tree); else return (&vq->vq_trim_offset_tree); } static int vdev_queue_timestamp_compare(const void *x1, const void *x2) { const zio_t *z1 = (const zio_t *)x1; const zio_t *z2 = (const zio_t *)x2; int cmp = TREE_CMP(z1->io_timestamp, z2->io_timestamp); if (likely(cmp)) return (cmp); return (TREE_PCMP(z1, z2)); } static int vdev_queue_class_min_active(vdev_queue_t *vq, 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 (vq->vq_ia_active == 0 ? zfs_vdev_scrub_min_active : MIN(vq->vq_nia_credit, zfs_vdev_scrub_min_active)); case ZIO_PRIORITY_REMOVAL: return (vq->vq_ia_active == 0 ? zfs_vdev_removal_min_active : MIN(vq->vq_nia_credit, zfs_vdev_removal_min_active)); case ZIO_PRIORITY_INITIALIZING: return (vq->vq_ia_active == 0 ?zfs_vdev_initializing_min_active: MIN(vq->vq_nia_credit, zfs_vdev_initializing_min_active)); case ZIO_PRIORITY_TRIM: return (zfs_vdev_trim_min_active); case ZIO_PRIORITY_REBUILD: return (vq->vq_ia_active == 0 ? zfs_vdev_rebuild_min_active : MIN(vq->vq_nia_credit, zfs_vdev_rebuild_min_active)); default: panic("invalid priority %u", p); return (0); } } static int vdev_queue_max_async_writes(spa_t *spa) { int writes; uint64_t dirty = 0; dsl_pool_t *dp = spa_get_dsl(spa); 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; /* * Async writes may occur before the assignment of the spa's * dsl_pool_t if a self-healing zio is issued prior to the * completion of dmu_objset_open_impl(). */ if (dp == NULL) return (zfs_vdev_async_write_max_active); /* * Sync tasks correspond to interactive user actions. To reduce the * execution time of those actions we push data out as fast as possible. */ dirty = dp->dp_dirty_total; if (dirty > max_bytes || spa_has_pending_synctask(spa)) return (zfs_vdev_async_write_max_active); if (dirty < min_bytes) return (zfs_vdev_async_write_min_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, vdev_queue_t *vq, 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)); case ZIO_PRIORITY_SCRUB: if (vq->vq_ia_active > 0) { return (MIN(vq->vq_nia_credit, zfs_vdev_scrub_min_active)); } else if (vq->vq_nia_credit < zfs_vdev_nia_delay) return (MAX(1, zfs_vdev_scrub_min_active)); return (zfs_vdev_scrub_max_active); case ZIO_PRIORITY_REMOVAL: if (vq->vq_ia_active > 0) { return (MIN(vq->vq_nia_credit, zfs_vdev_removal_min_active)); } else if (vq->vq_nia_credit < zfs_vdev_nia_delay) return (MAX(1, zfs_vdev_removal_min_active)); return (zfs_vdev_removal_max_active); case ZIO_PRIORITY_INITIALIZING: if (vq->vq_ia_active > 0) { return (MIN(vq->vq_nia_credit, zfs_vdev_initializing_min_active)); } else if (vq->vq_nia_credit < zfs_vdev_nia_delay) return (MAX(1, zfs_vdev_initializing_min_active)); return (zfs_vdev_initializing_max_active); case ZIO_PRIORITY_TRIM: return (zfs_vdev_trim_max_active); case ZIO_PRIORITY_REBUILD: if (vq->vq_ia_active > 0) { return (MIN(vq->vq_nia_credit, zfs_vdev_rebuild_min_active)); } else if (vq->vq_nia_credit < zfs_vdev_nia_delay) return (MAX(1, zfs_vdev_rebuild_min_active)); return (zfs_vdev_rebuild_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, n; 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. * Do round-robin to reduce starvation due to zfs_vdev_max_active * and vq_nia_credit limits. */ for (n = 0; n < ZIO_PRIORITY_NUM_QUEUEABLE; n++) { p = (vq->vq_last_prio + n + 1) % ZIO_PRIORITY_NUM_QUEUEABLE; if (avl_numnodes(vdev_queue_class_tree(vq, p)) > 0 && vq->vq_class[p].vqc_active < vdev_queue_class_min_active(vq, p)) { vq->vq_last_prio = 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(vdev_queue_class_tree(vq, p)) > 0 && vq->vq_class[p].vqc_active < vdev_queue_class_max_active(spa, vq, p)) { vq->vq_last_prio = p; return (p); } } /* No eligible queued i/os */ return (ZIO_PRIORITY_NUM_QUEUEABLE); } void vdev_queue_init(vdev_t *vd) { vdev_queue_t *vq = &vd->vdev_queue; zio_priority_t p; mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL); vq->vq_vdev = vd; taskq_init_ent(&vd->vdev_queue.vq_io_search.io_tqent); avl_create(&vq->vq_active_tree, vdev_queue_offset_compare, sizeof (zio_t), offsetof(struct zio, io_queue_node)); avl_create(vdev_queue_type_tree(vq, ZIO_TYPE_READ), vdev_queue_offset_compare, sizeof (zio_t), offsetof(struct zio, io_offset_node)); avl_create(vdev_queue_type_tree(vq, ZIO_TYPE_WRITE), vdev_queue_offset_compare, sizeof (zio_t), offsetof(struct zio, io_offset_node)); avl_create(vdev_queue_type_tree(vq, ZIO_TYPE_TRIM), vdev_queue_offset_compare, sizeof (zio_t), offsetof(struct zio, io_offset_node)); for (p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) { int (*compfn) (const void *, const void *); /* * The synchronous/trim i/o queues are dispatched in FIFO rather * than LBA order. This provides more consistent latency for * these i/os. */ if (p == ZIO_PRIORITY_SYNC_READ || p == ZIO_PRIORITY_SYNC_WRITE || p == ZIO_PRIORITY_TRIM) { compfn = vdev_queue_timestamp_compare; } else { compfn = vdev_queue_offset_compare; } avl_create(vdev_queue_class_tree(vq, p), compfn, sizeof (zio_t), offsetof(struct zio, io_queue_node)); } vq->vq_last_offset = 0; } 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(vdev_queue_class_tree(vq, p)); avl_destroy(&vq->vq_active_tree); avl_destroy(vdev_queue_type_tree(vq, ZIO_TYPE_READ)); avl_destroy(vdev_queue_type_tree(vq, ZIO_TYPE_WRITE)); avl_destroy(vdev_queue_type_tree(vq, ZIO_TYPE_TRIM)); mutex_destroy(&vq->vq_lock); } static void vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio) { ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); avl_add(vdev_queue_class_tree(vq, zio->io_priority), zio); avl_add(vdev_queue_type_tree(vq, zio->io_type), zio); } static void vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio) { ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); avl_remove(vdev_queue_class_tree(vq, zio->io_priority), zio); avl_remove(vdev_queue_type_tree(vq, zio->io_type), zio); } static boolean_t vdev_queue_is_interactive(zio_priority_t p) { switch (p) { case ZIO_PRIORITY_SCRUB: case ZIO_PRIORITY_REMOVAL: case ZIO_PRIORITY_INITIALIZING: case ZIO_PRIORITY_REBUILD: return (B_FALSE); default: return (B_TRUE); } } static void vdev_queue_pending_add(vdev_queue_t *vq, zio_t *zio) { ASSERT(MUTEX_HELD(&vq->vq_lock)); ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); vq->vq_class[zio->io_priority].vqc_active++; if (vdev_queue_is_interactive(zio->io_priority)) { if (++vq->vq_ia_active == 1) vq->vq_nia_credit = 1; } else if (vq->vq_ia_active > 0) { vq->vq_nia_credit--; } avl_add(&vq->vq_active_tree, zio); } static void vdev_queue_pending_remove(vdev_queue_t *vq, zio_t *zio) { ASSERT(MUTEX_HELD(&vq->vq_lock)); ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); vq->vq_class[zio->io_priority].vqc_active--; if (vdev_queue_is_interactive(zio->io_priority)) { if (--vq->vq_ia_active == 0) vq->vq_nia_credit = 0; else vq->vq_nia_credit = zfs_vdev_nia_credit; } else if (vq->vq_ia_active == 0) vq->vq_nia_credit++; avl_remove(&vq->vq_active_tree, zio); } static void vdev_queue_agg_io_done(zio_t *aio) { abd_free(aio->io_abd); } /* * 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)) /* * Sufficiently adjacent io_offset's in ZIOs will be aggregated. We do this * by creating a gang ABD from the adjacent ZIOs io_abd's. By using * a gang ABD we avoid doing memory copies to and from the parent, * child ZIOs. The gang ABD also accounts for gaps between adjacent * io_offsets by simply getting the zero ABD for writes or allocating * a new ABD for reads and placing them in the gang ABD as well. */ 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; uint64_t limit; int maxblocksize; boolean_t stretch = B_FALSE; avl_tree_t *t = vdev_queue_type_tree(vq, zio->io_type); enum zio_flag flags = zio->io_flags & ZIO_FLAG_AGG_INHERIT; uint64_t next_offset; abd_t *abd; maxblocksize = spa_maxblocksize(vq->vq_vdev->vdev_spa); if (vq->vq_vdev->vdev_nonrot) limit = zfs_vdev_aggregation_limit_non_rotating; else limit = zfs_vdev_aggregation_limit; limit = MAX(MIN(limit, maxblocksize), 0); if (zio->io_flags & ZIO_FLAG_DONT_AGGREGATE || limit == 0) return (NULL); /* * While TRIM commands could be aggregated based on offset this * behavior is disabled until it's determined to be beneficial. */ if (zio->io_type == ZIO_TYPE_TRIM && !zfs_vdev_aggregate_trim) return (NULL); /* * I/Os to distributed spares are directly dispatched to the dRAID * leaf vdevs for aggregation. See the comment at the end of the * zio_vdev_io_start() function. */ ASSERT(vq->vq_vdev->vdev_ops != &vdev_draid_spare_ops); 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 * or a scrub/resilver, can be preserved in the aggregate. * We can include optional I/Os, but don't allow them * to begin a range as they add no benefit in that situation. */ /* * 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-optional I/O. */ while ((dio = AVL_PREV(t, first)) != NULL && (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && IO_SPAN(dio, last) <= limit && IO_GAP(dio, first) <= maxgap && dio->io_type == zio->io_type) { 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. * The aggregation limit does not apply to optional i/os, so that * we can issue contiguous writes even if they are larger than the * aggregation limit. */ while ((dio = AVL_NEXT(t, last)) != NULL && (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && (IO_SPAN(first, dio) <= limit || (dio->io_flags & ZIO_FLAG_OPTIONAL)) && IO_SPAN(first, dio) <= maxblocksize && IO_GAP(last, dio) <= maxgap && dio->io_type == zio->io_type) { 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. * For reads, there's nothing to do. While we are unable to * aggregate further, it's possible that a trailing optional * 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; } } } if (stretch) { /* * We are going to include an optional io in our aggregated * span, thus closing the write gap. Only mandatory i/os can * start aggregated spans, so make sure that the next i/o * after our span is mandatory. */ dio = AVL_NEXT(t, last); dio->io_flags &= ~ZIO_FLAG_OPTIONAL; } else { /* do not include the optional i/o */ 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, <=, maxblocksize); abd = abd_alloc_gang(); if (abd == NULL) return (NULL); aio = zio_vdev_delegated_io(first->io_vd, first->io_offset, abd, 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; next_offset = first->io_offset; do { dio = nio; nio = AVL_NEXT(t, dio); zio_add_child(dio, aio); vdev_queue_io_remove(vq, dio); if (dio->io_offset != next_offset) { /* allocate a buffer for a read gap */ ASSERT3U(dio->io_type, ==, ZIO_TYPE_READ); ASSERT3U(dio->io_offset, >, next_offset); abd = abd_alloc_for_io( dio->io_offset - next_offset, B_TRUE); abd_gang_add(aio->io_abd, abd, B_TRUE); } if (dio->io_abd && (dio->io_size != abd_get_size(dio->io_abd))) { /* abd size not the same as IO size */ ASSERT3U(abd_get_size(dio->io_abd), >, dio->io_size); abd = abd_get_offset_size(dio->io_abd, 0, dio->io_size); abd_gang_add(aio->io_abd, abd, B_TRUE); } else { if (dio->io_flags & ZIO_FLAG_NODATA) { /* allocate a buffer for a write gap */ ASSERT3U(dio->io_type, ==, ZIO_TYPE_WRITE); ASSERT3P(dio->io_abd, ==, NULL); abd_gang_add(aio->io_abd, abd_get_zeros(dio->io_size), B_TRUE); } else { /* * We pass B_FALSE to abd_gang_add() * because we did not allocate a new * ABD, so it is assumed the caller * will free this ABD. */ abd_gang_add(aio->io_abd, dio->io_abd, B_FALSE); } } next_offset = dio->io_offset + dio->io_size; } while (dio != last); ASSERT3U(abd_get_size(aio->io_abd), ==, aio->io_size); /* * Callers must call zio_vdev_io_bypass() and zio_execute() for * aggregated (parent) I/Os so that we could avoid dropping the * queue's lock here to avoid a deadlock that we could encounter * due to lock order reversal between vq_lock and io_lock in * zio_change_priority(). */ 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; avl_tree_t *tree; 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 / initializing), issue the * i/o which follows the most recently issued i/o in LBA (offset) order. * * For FIFO queues (sync/trim), issue the i/o with the lowest timestamp. */ tree = vdev_queue_class_tree(vq, p); vq->vq_io_search.io_timestamp = 0; vq->vq_io_search.io_offset = vq->vq_last_offset - 1; VERIFY3P(avl_find(tree, &vq->vq_io_search, &idx), ==, NULL); zio = avl_nearest(tree, idx, AVL_AFTER); if (zio == NULL) zio = avl_first(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 + zio->io_size; return (zio); } zio_t * vdev_queue_io(zio_t *zio) { vdev_queue_t *vq = &zio->io_vd->vdev_queue; zio_t *dio, *nio; zio_link_t *zl = NULL; 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) { ASSERT(zio->io_priority != ZIO_PRIORITY_TRIM); 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_REMOVAL && zio->io_priority != ZIO_PRIORITY_INITIALIZING && zio->io_priority != ZIO_PRIORITY_REBUILD) { zio->io_priority = ZIO_PRIORITY_ASYNC_READ; } } else if (zio->io_type == ZIO_TYPE_WRITE) { ASSERT(zio->io_priority != ZIO_PRIORITY_TRIM); if (zio->io_priority != ZIO_PRIORITY_SYNC_WRITE && zio->io_priority != ZIO_PRIORITY_ASYNC_WRITE && zio->io_priority != ZIO_PRIORITY_REMOVAL && zio->io_priority != ZIO_PRIORITY_INITIALIZING && zio->io_priority != ZIO_PRIORITY_REBUILD) { zio->io_priority = ZIO_PRIORITY_ASYNC_WRITE; } } else { ASSERT(zio->io_type == ZIO_TYPE_TRIM); ASSERT(zio->io_priority == ZIO_PRIORITY_TRIM); } zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE; zio->io_timestamp = gethrtime(); mutex_enter(&vq->vq_lock); vdev_queue_io_add(vq, zio); nio = vdev_queue_io_to_issue(vq); mutex_exit(&vq->vq_lock); if (nio == NULL) return (NULL); if (nio->io_done == vdev_queue_agg_io_done) { while ((dio = zio_walk_parents(nio, &zl)) != NULL) { ASSERT3U(dio->io_type, ==, nio->io_type); zio_vdev_io_bypass(dio); zio_execute(dio); } zio_nowait(nio); return (NULL); } return (nio); } void vdev_queue_io_done(zio_t *zio) { vdev_queue_t *vq = &zio->io_vd->vdev_queue; zio_t *dio, *nio; zio_link_t *zl = NULL; hrtime_t now = gethrtime(); vq->vq_io_complete_ts = now; vq->vq_io_delta_ts = zio->io_delta = now - zio->io_timestamp; mutex_enter(&vq->vq_lock); vdev_queue_pending_remove(vq, zio); while ((nio = vdev_queue_io_to_issue(vq)) != NULL) { mutex_exit(&vq->vq_lock); if (nio->io_done == vdev_queue_agg_io_done) { while ((dio = zio_walk_parents(nio, &zl)) != NULL) { ASSERT3U(dio->io_type, ==, nio->io_type); zio_vdev_io_bypass(dio); zio_execute(dio); } zio_nowait(nio); } else { zio_vdev_io_reissue(nio); zio_execute(nio); } mutex_enter(&vq->vq_lock); } mutex_exit(&vq->vq_lock); } void vdev_queue_change_io_priority(zio_t *zio, zio_priority_t priority) { vdev_queue_t *vq = &zio->io_vd->vdev_queue; avl_tree_t *tree; /* * ZIO_PRIORITY_NOW is used by the vdev cache code and the aggregate zio * code to issue IOs without adding them to the vdev queue. In this * case, the zio is already going to be issued as quickly as possible * and so it doesn't need any reprioritization to help. */ if (zio->io_priority == ZIO_PRIORITY_NOW) return; ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); ASSERT3U(priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); if (zio->io_type == ZIO_TYPE_READ) { if (priority != ZIO_PRIORITY_SYNC_READ && priority != ZIO_PRIORITY_ASYNC_READ && priority != ZIO_PRIORITY_SCRUB) priority = ZIO_PRIORITY_ASYNC_READ; } else { ASSERT(zio->io_type == ZIO_TYPE_WRITE); if (priority != ZIO_PRIORITY_SYNC_WRITE && priority != ZIO_PRIORITY_ASYNC_WRITE) priority = ZIO_PRIORITY_ASYNC_WRITE; } mutex_enter(&vq->vq_lock); /* * If the zio is in none of the queues we can simply change * the priority. If the zio is waiting to be submitted we must * remove it from the queue and re-insert it with the new priority. * Otherwise, the zio is currently active and we cannot change its * priority. */ tree = vdev_queue_class_tree(vq, zio->io_priority); if (avl_find(tree, zio, NULL) == zio) { avl_remove(vdev_queue_class_tree(vq, zio->io_priority), zio); zio->io_priority = priority; avl_add(vdev_queue_class_tree(vq, zio->io_priority), zio); } else if (avl_find(&vq->vq_active_tree, zio, NULL) != zio) { zio->io_priority = priority; } mutex_exit(&vq->vq_lock); } /* * As these two methods are only used for load calculations we're not * concerned if we get an incorrect value on 32bit platforms due to lack of * vq_lock mutex use here, instead we prefer to keep it lock free for * performance. */ int vdev_queue_length(vdev_t *vd) { return (avl_numnodes(&vd->vdev_queue.vq_active_tree)); } uint64_t vdev_queue_last_offset(vdev_t *vd) { return (vd->vdev_queue.vq_last_offset); } /* BEGIN CSTYLED */ ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, aggregation_limit, INT, ZMOD_RW, "Max vdev I/O aggregation size"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, aggregation_limit_non_rotating, INT, ZMOD_RW, "Max vdev I/O aggregation size for non-rotating media"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, aggregate_trim, INT, ZMOD_RW, "Allow TRIM I/O to be aggregated"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, read_gap_limit, INT, ZMOD_RW, "Aggregate read I/O over gap"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, write_gap_limit, INT, ZMOD_RW, "Aggregate write I/O over gap"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, max_active, INT, ZMOD_RW, "Maximum number of active I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, async_write_active_max_dirty_percent, INT, ZMOD_RW, "Async write concurrency max threshold"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, async_write_active_min_dirty_percent, INT, ZMOD_RW, "Async write concurrency min threshold"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, async_read_max_active, INT, ZMOD_RW, "Max active async read I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, async_read_min_active, INT, ZMOD_RW, "Min active async read I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, async_write_max_active, INT, ZMOD_RW, "Max active async write I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, async_write_min_active, INT, ZMOD_RW, "Min active async write I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, initializing_max_active, INT, ZMOD_RW, "Max active initializing I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, initializing_min_active, INT, ZMOD_RW, "Min active initializing I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, removal_max_active, INT, ZMOD_RW, "Max active removal I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, removal_min_active, INT, ZMOD_RW, "Min active removal I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, scrub_max_active, INT, ZMOD_RW, "Max active scrub I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, scrub_min_active, INT, ZMOD_RW, "Min active scrub I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, sync_read_max_active, INT, ZMOD_RW, "Max active sync read I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, sync_read_min_active, INT, ZMOD_RW, "Min active sync read I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, sync_write_max_active, INT, ZMOD_RW, "Max active sync write I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, sync_write_min_active, INT, ZMOD_RW, "Min active sync write I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, trim_max_active, INT, ZMOD_RW, "Max active trim/discard I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, trim_min_active, INT, ZMOD_RW, "Min active trim/discard I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, rebuild_max_active, INT, ZMOD_RW, "Max active rebuild I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, rebuild_min_active, INT, ZMOD_RW, "Min active rebuild I/Os per vdev"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, nia_credit, INT, ZMOD_RW, "Number of non-interactive I/Os to allow in sequence"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, nia_delay, INT, ZMOD_RW, "Number of non-interactive I/Os before _max_active"); ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, queue_depth_pct, INT, ZMOD_RW, "Queue depth percentage for each top-level vdev"); /* END CSTYLED */