freebsd-nq/zfs/lib/libzpool/vdev_queue.c

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2008-11-20 20:01:55 +00:00
/*
* 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 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "@(#)vdev_queue.c 1.6 07/11/27 SMI"
#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/vdev_impl.h>
#include <sys/zio.h>
#include <sys/avl.h>
/*
* These tunables are for performance analysis.
*/
/*
* zfs_vdev_max_pending is the maximum number of i/os concurrently
* pending to each device. zfs_vdev_min_pending is the initial number
* of i/os pending to each device (before it starts ramping up to
* max_pending).
*/
int zfs_vdev_max_pending = 35;
int zfs_vdev_min_pending = 4;
/* deadline = pri + (lbolt >> 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.
*/
int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE;
/*
* 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);
if (z1 < z2)
return (-1);
if (z1 > z2)
return (1);
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)
return (1);
return (0);
}
void
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)
{
avl_add(&vq->vq_deadline_tree, zio);
avl_add(zio->io_vdev_tree, zio);
}
static void
vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio)
{
avl_remove(&vq->vq_deadline_tree, zio);
avl_remove(zio->io_vdev_tree, zio);
}
static void
vdev_queue_agg_io_done(zio_t *aio)
{
zio_t *dio;
uint64_t offset = 0;
while ((dio = aio->io_delegate_list) != 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);
zio_buf_free(aio->io_data, aio->io_size);
}
#define IS_ADJACENT(io, nio) \
((io)->io_offset + (io)->io_size == (nio)->io_offset)
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;
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);
tree = fio->io_vdev_tree;
size = fio->io_size;
while ((dio = AVL_PREV(tree, fio)) != NULL && IS_ADJACENT(dio, fio) &&
size + dio->io_size <= zfs_vdev_aggregation_limit) {
dio->io_delegate_next = fio;
fio = dio;
size += dio->io_size;
}
while ((dio = AVL_NEXT(tree, lio)) != NULL && IS_ADJACENT(lio, dio) &&
size + dio->io_size <= zfs_vdev_aggregation_limit) {
lio->io_delegate_next = dio;
lio = dio;
size += dio->io_size;
}
if (fio != lio) {
char *buf = zio_buf_alloc(size);
uint64_t offset = 0;
int nagg = 0;
ASSERT(size <= zfs_vdev_aggregation_limit);
aio = zio_vdev_child_io(fio, NULL, fio->io_vd,
fio->io_offset, buf, size, fio->io_type,
ZIO_PRIORITY_NOW, ZIO_FLAG_DONT_QUEUE |
ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_PROPAGATE |
ZIO_FLAG_NOBOOKMARK,
vdev_queue_agg_io_done, NULL);
aio->io_delegate_list = fio;
for (dio = fio; dio != NULL; dio = dio->io_delegate_next) {
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;
vdev_queue_io_remove(vq, dio);
zio_vdev_io_bypass(dio);
nagg++;
}
ASSERT(offset == size);
dprintf("%5s T=%llu off=%8llx agg=%3d "
"old=%5llx new=%5llx\n",
zio_type_name[fio->io_type],
fio->io_deadline, fio->io_offset, nagg, fio->io_size, size);
avl_add(&vq->vq_pending_tree, aio);
return (aio);
}
ASSERT(fio->io_vdev_tree == tree);
vdev_queue_io_remove(vq, fio);
avl_add(&vq->vq_pending_tree, 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_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);
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;
int i;
mutex_enter(&vq->vq_lock);
avl_remove(&vq->vq_pending_tree, zio);
for (i = 0; i < zfs_vdev_ramp_rate; i++) {
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);
zio_execute(nio);
}
mutex_enter(&vq->vq_lock);
}
mutex_exit(&vq->vq_lock);
}