* CDDL HEADER END
*/
/*
- * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
+ * 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/spa.h>
#include <sys/vdev_impl.h>
#include <sys/zio.h>
#include <sys/avl.h>
* of i/os pending to each device (before it starts ramping up to
* max_pending).
*/
-int zfs_vdev_max_pending = 35;
+int zfs_vdev_max_pending = 10;
int zfs_vdev_min_pending = 4;
-/* deadline = pri + (lbolt >> time_shift) */
+/* deadline = pri + ddi_get_lbolt64() >> time_shift) */
int zfs_vdev_time_shift = 6;
/* exponential I/O issue ramp-up rate */
int zfs_vdev_ramp_rate = 2;
/*
- * i/os will be aggregated into a single large i/o up to
- * zfs_vdev_aggregation_limit bytes long.
+ * 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 = 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.
vdev_queue_init(vdev_t *vd)
{
vdev_queue_t *vq = &vd->vdev_queue;
+ int i;
mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL);
avl_create(&vq->vq_pending_tree, vdev_queue_offset_compare,
sizeof (zio_t), offsetof(struct zio, io_offset_node));
+
+ /*
+ * A list of buffers which can be used for aggregate I/O, this
+ * avoids the need to allocate them on demand when memory is low.
+ */
+ list_create(&vq->vq_io_list, sizeof (vdev_io_t),
+ offsetof(vdev_io_t, vi_node));
+
+ for (i = 0; i < zfs_vdev_max_pending; i++)
+ list_insert_tail(&vq->vq_io_list, zio_vdev_alloc());
}
void
vdev_queue_fini(vdev_t *vd)
{
vdev_queue_t *vq = &vd->vdev_queue;
+ vdev_io_t *vi;
avl_destroy(&vq->vq_deadline_tree);
avl_destroy(&vq->vq_read_tree);
avl_destroy(&vq->vq_write_tree);
avl_destroy(&vq->vq_pending_tree);
+ while ((vi = list_head(&vq->vq_io_list)) != NULL) {
+ list_remove(&vq->vq_io_list, vi);
+ zio_vdev_free(vi);
+ }
+
+ list_destroy(&vq->vq_io_list);
+
mutex_destroy(&vq->vq_lock);
}
static void
vdev_queue_agg_io_done(zio_t *aio)
{
- zio_t *dio;
- uint64_t offset = 0;
+ vdev_queue_t *vq = &aio->io_vd->vdev_queue;
+ vdev_io_t *vi = aio->io_data;
+ zio_t *pio;
- while ((dio = aio->io_delegate_list) != NULL) {
+ while ((pio = zio_walk_parents(aio)) != NULL)
if (aio->io_type == ZIO_TYPE_READ)
- bcopy((char *)aio->io_data + offset, dio->io_data,
- dio->io_size);
- offset += dio->io_size;
- aio->io_delegate_list = dio->io_delegate_next;
- dio->io_delegate_next = NULL;
- dio->io_error = aio->io_error;
- zio_execute(dio);
- }
- ASSERT3U(offset, ==, aio->io_size);
+ 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);
+ mutex_enter(&vq->vq_lock);
+ list_insert_tail(&vq->vq_io_list, vi);
+ mutex_exit(&vq->vq_lock);
}
-#define IS_ADJACENT(io, nio) \
- ((io)->io_offset + (io)->io_size == (nio)->io_offset)
+/*
+ * 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;
- avl_tree_t *tree;
- uint64_t size;
-
+ zio_t *fio, *lio, *aio, *dio, *nio, *mio;
+ avl_tree_t *t;
+ vdev_io_t *vi;
+ int flags;
+ uint64_t maxspan = MIN(zfs_vdev_aggregation_limit, SPA_MAXBLOCKSIZE);
+ uint64_t maxgap;
+ int stretch;
+
+again:
ASSERT(MUTEX_HELD(&vq->vq_lock));
if (avl_numnodes(&vq->vq_pending_tree) >= pending_limit ||
fio = lio = avl_first(&vq->vq_deadline_tree);
- tree = fio->io_vdev_tree;
- size = fio->io_size;
+ 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;
- while ((dio = AVL_PREV(tree, fio)) != NULL && IS_ADJACENT(dio, fio) &&
- !((dio->io_flags | fio->io_flags) & ZIO_FLAG_DONT_AGGREGATE) &&
- size + dio->io_size <= zfs_vdev_aggregation_limit) {
- dio->io_delegate_next = fio;
- fio = dio;
- size += dio->io_size;
+ vi = list_head(&vq->vq_io_list);
+ if (vi == NULL) {
+ vi = zio_vdev_alloc();
+ list_insert_head(&vq->vq_io_list, vi);
}
- while ((dio = AVL_NEXT(tree, lio)) != NULL && IS_ADJACENT(lio, dio) &&
- !((lio->io_flags | dio->io_flags) & ZIO_FLAG_DONT_AGGREGATE) &&
- size + dio->io_size <= zfs_vdev_aggregation_limit) {
- lio->io_delegate_next = dio;
- lio = dio;
- size += dio->io_size;
+ 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
+ * 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.
+ */
+ 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.
+ * 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.
+ */
+ 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;
+ }
+ }
+ }
+
+ 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) {
- char *buf = zio_buf_alloc(size);
- uint64_t offset = 0;
-
- ASSERT(size <= zfs_vdev_aggregation_limit);
+ uint64_t size = IO_SPAN(fio, lio);
+ ASSERT(size <= maxspan);
+ ASSERT(vi != NULL);
aio = zio_vdev_delegated_io(fio->io_vd, fio->io_offset,
- buf, size, fio->io_type, ZIO_PRIORITY_NOW,
- ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE,
+ vi, 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;
- aio->io_delegate_list = fio;
-
- for (dio = fio; dio != NULL; dio = dio->io_delegate_next) {
+ nio = fio;
+ do {
+ dio = nio;
+ nio = AVL_NEXT(t, dio);
ASSERT(dio->io_type == aio->io_type);
- ASSERT(dio->io_vdev_tree == tree);
- if (dio->io_type == ZIO_TYPE_WRITE)
- bcopy(dio->io_data, buf + offset, dio->io_size);
- offset += dio->io_size;
+ 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),
+ dio->io_size);
+ }
+
+ zio_add_child(dio, aio);
vdev_queue_io_remove(vq, dio);
zio_vdev_io_bypass(dio);
- }
-
- ASSERT(offset == size);
+ zio_execute(dio);
+ } while (dio != lio);
avl_add(&vq->vq_pending_tree, aio);
+ list_remove(&vq->vq_io_list, vi);
return (aio);
}
- ASSERT(fio->io_vdev_tree == tree);
+ 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;
+ }
+
avl_add(&vq->vq_pending_tree, fio);
return (fio);
mutex_enter(&vq->vq_lock);
- zio->io_deadline = (lbolt64 >> zfs_vdev_time_shift) + zio->io_priority;
+ zio->io_timestamp = ddi_get_lbolt64();
+ zio->io_deadline = (zio->io_timestamp >> zfs_vdev_time_shift) +
+ zio->io_priority;
vdev_queue_io_add(vq, zio);
vdev_queue_io_done(zio_t *zio)
{
vdev_queue_t *vq = &zio->io_vd->vdev_queue;
+ int i;
+
+ if (zio_injection_enabled)
+ delay(SEC_TO_TICK(zio_handle_io_delay(zio)));
mutex_enter(&vq->vq_lock);
avl_remove(&vq->vq_pending_tree, zio);
- for (int i = 0; i < zfs_vdev_ramp_rate; i++) {
+ zio->io_delta = ddi_get_lbolt64() - zio->io_timestamp;
+ vq->vq_io_complete_ts = ddi_get_lbolt64();
+ vq->vq_io_delta_ts = vq->vq_io_complete_ts - zio->io_timestamp;
+
+ for (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 defined(_KERNEL) && defined(HAVE_SPL)
+module_param(zfs_vdev_max_pending, int, 0644);
+MODULE_PARM_DESC(zfs_vdev_max_pending, "Max pending per-vdev I/Os");
+
+module_param(zfs_vdev_min_pending, int, 0644);
+MODULE_PARM_DESC(zfs_vdev_min_pending, "Min pending per-vdev I/Os");
+
+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_time_shift, int, 0644);
+MODULE_PARM_DESC(zfs_vdev_time_shift, "Deadline time shift for vdev I/O");
+
+module_param(zfs_vdev_ramp_rate, int, 0644);
+MODULE_PARM_DESC(zfs_vdev_ramp_rate, "Exponential I/O issue ramp-up rate");
+
+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");
+#endif
git://git.camperquake.de / zfs.git / blobdiff