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zfs-builds-mm/zfs-0.8.2/module/zfs/vdev_queue.c
root 88bc8283fc zfs-0.8.2
2019-10-24 23:13:56 +02:00

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/*
* 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 <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>
#include <sys/metaslab_impl.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/kstat.h>
#include <sys/abd.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. 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. 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
* 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, 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 = 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 = 2;
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;
/*
* 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.
*/
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;
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 = AVL_CMP(z1->io_offset, z2->io_offset);
if (likely(cmp))
return (cmp);
return (AVL_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);
}
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 = AVL_CMP(z1->io_timestamp, z2->io_timestamp);
if (likely(cmp))
return (cmp);
return (AVL_PCMP(z1, z2));
}
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);
case ZIO_PRIORITY_REMOVAL:
return (zfs_vdev_removal_min_active);
case ZIO_PRIORITY_INITIALIZING:
return (zfs_vdev_initializing_min_active);
case ZIO_PRIORITY_TRIM:
return (zfs_vdev_trim_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.
*/
if (spa_has_pending_synctask(spa))
return (zfs_vdev_async_write_max_active);
dirty = dp->dp_dirty_total;
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));
case ZIO_PRIORITY_SCRUB:
return (zfs_vdev_scrub_max_active);
case ZIO_PRIORITY_REMOVAL:
return (zfs_vdev_removal_max_active);
case ZIO_PRIORITY_INITIALIZING:
return (zfs_vdev_initializing_max_active);
case ZIO_PRIORITY_TRIM:
return (zfs_vdev_trim_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(vdev_queue_class_tree(vq, p)) > 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(vdev_queue_class_tree(vq, p)) > 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);
}
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)
{
spa_t *spa = zio->io_spa;
spa_history_kstat_t *shk = &spa->spa_stats.io_history;
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);
if (shk->kstat != NULL) {
mutex_enter(&shk->lock);
kstat_waitq_enter(shk->kstat->ks_data);
mutex_exit(&shk->lock);
}
}
static void
vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio)
{
spa_t *spa = zio->io_spa;
spa_history_kstat_t *shk = &spa->spa_stats.io_history;
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);
if (shk->kstat != NULL) {
mutex_enter(&shk->lock);
kstat_waitq_exit(shk->kstat->ks_data);
mutex_exit(&shk->lock);
}
}
static void
vdev_queue_pending_add(vdev_queue_t *vq, zio_t *zio)
{
spa_t *spa = zio->io_spa;
spa_history_kstat_t *shk = &spa->spa_stats.io_history;
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);
if (shk->kstat != NULL) {
mutex_enter(&shk->lock);
kstat_runq_enter(shk->kstat->ks_data);
mutex_exit(&shk->lock);
}
}
static void
vdev_queue_pending_remove(vdev_queue_t *vq, zio_t *zio)
{
spa_t *spa = zio->io_spa;
spa_history_kstat_t *shk = &spa->spa_stats.io_history;
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);
if (shk->kstat != NULL) {
kstat_io_t *ksio = shk->kstat->ks_data;
mutex_enter(&shk->lock);
kstat_runq_exit(ksio);
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(&shk->lock);
}
}
static void
vdev_queue_agg_io_done(zio_t *aio)
{
if (aio->io_type == ZIO_TYPE_READ) {
zio_t *pio;
zio_link_t *zl = NULL;
while ((pio = zio_walk_parents(aio, &zl)) != NULL) {
abd_copy_off(pio->io_abd, aio->io_abd,
0, pio->io_offset - aio->io_offset, pio->io_size);
}
}
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))
static zio_t *
vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
{
zio_t *first, *last, *aio, *dio, *mandatory, *nio;
zio_link_t *zl = NULL;
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;
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);
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_for_io(size, B_TRUE);
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;
do {
dio = nio;
nio = AVL_NEXT(t, dio);
zio_add_child(dio, aio);
vdev_queue_io_remove(vq, dio);
} while (dio != last);
/*
* We need to drop the vdev queue's lock during zio_execute() to
* avoid a deadlock that we could encounter due to lock order
* reversal between vq_lock and io_lock in zio_change_priority().
* Use the dropped lock to do memory copy without congestion.
*/
mutex_exit(&vq->vq_lock);
while ((dio = zio_walk_parents(aio, &zl)) != NULL) {
ASSERT3U(dio->io_type, ==, aio->io_type);
if (dio->io_flags & ZIO_FLAG_NODATA) {
ASSERT3U(dio->io_type, ==, ZIO_TYPE_WRITE);
abd_zero_off(aio->io_abd,
dio->io_offset - aio->io_offset, dio->io_size);
} else if (dio->io_type == ZIO_TYPE_WRITE) {
abd_copy_off(aio->io_abd, dio->io_abd,
dio->io_offset - aio->io_offset, 0, dio->io_size);
}
zio_vdev_io_bypass(dio);
zio_execute(dio);
}
mutex_enter(&vq->vq_lock);
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 *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) {
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_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_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;
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);
if (nio->io_done == vdev_queue_agg_io_done) {
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 *nio;
mutex_enter(&vq->vq_lock);
vdev_queue_pending_remove(vq, zio);
zio->io_delta = gethrtime() - zio->io_timestamp;
vq->vq_io_complete_ts = gethrtime();
vq->vq_io_delta_ts = vq->vq_io_complete_ts - zio->io_timestamp;
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);
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 reprioitization 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);
}
#if defined(_KERNEL)
module_param(zfs_vdev_aggregation_limit, int, 0644);
MODULE_PARM_DESC(zfs_vdev_aggregation_limit, "Max vdev I/O aggregation size");
module_param(zfs_vdev_aggregation_limit_non_rotating, int, 0644);
MODULE_PARM_DESC(zfs_vdev_aggregation_limit_non_rotating,
"Max vdev I/O aggregation size for non-rotating media");
module_param(zfs_vdev_aggregate_trim, int, 0644);
MODULE_PARM_DESC(zfs_vdev_aggregate_trim, "Allow TRIM I/O to be aggregated");
module_param(zfs_vdev_read_gap_limit, int, 0644);
MODULE_PARM_DESC(zfs_vdev_read_gap_limit, "Aggregate read I/O over gap");
module_param(zfs_vdev_write_gap_limit, int, 0644);
MODULE_PARM_DESC(zfs_vdev_write_gap_limit, "Aggregate write I/O over gap");
module_param(zfs_vdev_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_max_active, "Maximum number of active I/Os per vdev");
module_param(zfs_vdev_async_write_active_max_dirty_percent, int, 0644);
MODULE_PARM_DESC(zfs_vdev_async_write_active_max_dirty_percent,
"Async write concurrency max threshold");
module_param(zfs_vdev_async_write_active_min_dirty_percent, int, 0644);
MODULE_PARM_DESC(zfs_vdev_async_write_active_min_dirty_percent,
"Async write concurrency min threshold");
module_param(zfs_vdev_async_read_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_async_read_max_active,
"Max active async read I/Os per vdev");
module_param(zfs_vdev_async_read_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_async_read_min_active,
"Min active async read I/Os per vdev");
module_param(zfs_vdev_async_write_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_async_write_max_active,
"Max active async write I/Os per vdev");
module_param(zfs_vdev_async_write_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_async_write_min_active,
"Min active async write I/Os per vdev");
module_param(zfs_vdev_initializing_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_initializing_max_active,
"Max active initializing I/Os per vdev");
module_param(zfs_vdev_initializing_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_initializing_min_active,
"Min active initializing I/Os per vdev");
module_param(zfs_vdev_removal_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_removal_max_active,
"Max active removal I/Os per vdev");
module_param(zfs_vdev_removal_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_removal_min_active,
"Min active removal I/Os per vdev");
module_param(zfs_vdev_scrub_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_scrub_max_active,
"Max active scrub I/Os per vdev");
module_param(zfs_vdev_scrub_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_scrub_min_active,
"Min active scrub I/Os per vdev");
module_param(zfs_vdev_sync_read_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_sync_read_max_active,
"Max active sync read I/Os per vdev");
module_param(zfs_vdev_sync_read_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_sync_read_min_active,
"Min active sync read I/Os per vdev");
module_param(zfs_vdev_sync_write_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_sync_write_max_active,
"Max active sync write I/Os per vdev");
module_param(zfs_vdev_sync_write_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_sync_write_min_active,
"Min active sync write I/Os per vdev");
module_param(zfs_vdev_trim_max_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_trim_max_active,
"Max active trim/discard I/Os per vdev");
module_param(zfs_vdev_trim_min_active, int, 0644);
MODULE_PARM_DESC(zfs_vdev_trim_min_active,
"Min active trim/discard I/Os per vdev");
module_param(zfs_vdev_queue_depth_pct, int, 0644);
MODULE_PARM_DESC(zfs_vdev_queue_depth_pct,
"Queue depth percentage for each top-level vdev");
#endif
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