4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
26 #include <sys/zfs_context.h>
28 #include <sys/vdev_impl.h>
33 * These tunables are for performance analysis.
36 * zfs_vdev_max_pending is the maximum number of i/os concurrently
37 * pending to each device. zfs_vdev_min_pending is the initial number
38 * of i/os pending to each device (before it starts ramping up to
41 int zfs_vdev_max_pending = 35;
42 int zfs_vdev_min_pending = 4;
44 /* deadline = pri + (lbolt >> time_shift) */
45 int zfs_vdev_time_shift = 6;
47 /* exponential I/O issue ramp-up rate */
48 int zfs_vdev_ramp_rate = 2;
51 * i/os will be aggregated into a single large i/o up to
52 * zfs_vdev_aggregation_limit bytes long.
54 int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE;
57 * Virtual device vector for disk I/O scheduling.
60 vdev_queue_deadline_compare(const void *x1, const void *x2)
65 if (z1->io_deadline < z2->io_deadline)
67 if (z1->io_deadline > z2->io_deadline)
70 if (z1->io_offset < z2->io_offset)
72 if (z1->io_offset > z2->io_offset)
84 vdev_queue_offset_compare(const void *x1, const void *x2)
89 if (z1->io_offset < z2->io_offset)
91 if (z1->io_offset > z2->io_offset)
103 vdev_queue_init(vdev_t *vd)
105 vdev_queue_t *vq = &vd->vdev_queue;
107 mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL);
109 avl_create(&vq->vq_deadline_tree, vdev_queue_deadline_compare,
110 sizeof (zio_t), offsetof(struct zio, io_deadline_node));
112 avl_create(&vq->vq_read_tree, vdev_queue_offset_compare,
113 sizeof (zio_t), offsetof(struct zio, io_offset_node));
115 avl_create(&vq->vq_write_tree, vdev_queue_offset_compare,
116 sizeof (zio_t), offsetof(struct zio, io_offset_node));
118 avl_create(&vq->vq_pending_tree, vdev_queue_offset_compare,
119 sizeof (zio_t), offsetof(struct zio, io_offset_node));
123 vdev_queue_fini(vdev_t *vd)
125 vdev_queue_t *vq = &vd->vdev_queue;
127 avl_destroy(&vq->vq_deadline_tree);
128 avl_destroy(&vq->vq_read_tree);
129 avl_destroy(&vq->vq_write_tree);
130 avl_destroy(&vq->vq_pending_tree);
132 mutex_destroy(&vq->vq_lock);
136 vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio)
138 avl_add(&vq->vq_deadline_tree, zio);
139 avl_add(zio->io_vdev_tree, zio);
143 vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio)
145 avl_remove(&vq->vq_deadline_tree, zio);
146 avl_remove(zio->io_vdev_tree, zio);
150 vdev_queue_agg_io_done(zio_t *aio)
154 while ((pio = zio_walk_parents(aio)) != NULL)
155 if (aio->io_type == ZIO_TYPE_READ)
156 bcopy((char *)aio->io_data + (pio->io_offset -
157 aio->io_offset), pio->io_data, pio->io_size);
159 zio_buf_free(aio->io_data, aio->io_size);
162 #define IS_ADJACENT(io, nio) \
163 ((io)->io_offset + (io)->io_size == (nio)->io_offset)
166 vdev_queue_io_to_issue(vdev_queue_t *vq, uint64_t pending_limit)
168 zio_t *fio, *lio, *aio, *dio, *nio;
173 ASSERT(MUTEX_HELD(&vq->vq_lock));
175 if (avl_numnodes(&vq->vq_pending_tree) >= pending_limit ||
176 avl_numnodes(&vq->vq_deadline_tree) == 0)
179 fio = lio = avl_first(&vq->vq_deadline_tree);
181 t = fio->io_vdev_tree;
183 flags = fio->io_flags & ZIO_FLAG_AGG_INHERIT;
185 if (!(flags & ZIO_FLAG_DONT_AGGREGATE)) {
187 * We can aggregate I/Os that are adjacent and of the
188 * same flavor, as expressed by the AGG_INHERIT flags.
189 * The latter is necessary so that certain attributes
190 * of the I/O, such as whether it's a normal I/O or a
191 * scrub/resilver, can be preserved in the aggregate.
193 while ((dio = AVL_PREV(t, fio)) != NULL &&
194 IS_ADJACENT(dio, fio) &&
195 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags &&
196 size + dio->io_size <= zfs_vdev_aggregation_limit) {
198 size += dio->io_size;
200 while ((dio = AVL_NEXT(t, lio)) != NULL &&
201 IS_ADJACENT(lio, dio) &&
202 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags &&
203 size + dio->io_size <= zfs_vdev_aggregation_limit) {
205 size += dio->io_size;
210 ASSERT(size <= zfs_vdev_aggregation_limit);
212 aio = zio_vdev_delegated_io(fio->io_vd, fio->io_offset,
213 zio_buf_alloc(size), size, fio->io_type, ZIO_PRIORITY_NOW,
214 flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE,
215 vdev_queue_agg_io_done, NULL);
217 /* We want to process lio, then stop */
218 lio = AVL_NEXT(t, lio);
219 for (dio = fio; dio != lio; dio = nio) {
220 ASSERT(dio->io_type == aio->io_type);
221 ASSERT(dio->io_vdev_tree == t);
223 if (dio->io_type == ZIO_TYPE_WRITE)
224 bcopy(dio->io_data, (char *)aio->io_data +
225 (dio->io_offset - aio->io_offset),
227 nio = AVL_NEXT(t, dio);
229 zio_add_child(dio, aio);
230 vdev_queue_io_remove(vq, dio);
231 zio_vdev_io_bypass(dio);
235 avl_add(&vq->vq_pending_tree, aio);
240 ASSERT(fio->io_vdev_tree == t);
241 vdev_queue_io_remove(vq, fio);
243 avl_add(&vq->vq_pending_tree, fio);
249 vdev_queue_io(zio_t *zio)
251 vdev_queue_t *vq = &zio->io_vd->vdev_queue;
254 ASSERT(zio->io_type == ZIO_TYPE_READ || zio->io_type == ZIO_TYPE_WRITE);
256 if (zio->io_flags & ZIO_FLAG_DONT_QUEUE)
259 zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE;
261 if (zio->io_type == ZIO_TYPE_READ)
262 zio->io_vdev_tree = &vq->vq_read_tree;
264 zio->io_vdev_tree = &vq->vq_write_tree;
266 mutex_enter(&vq->vq_lock);
268 zio->io_deadline = (lbolt64 >> zfs_vdev_time_shift) + zio->io_priority;
270 vdev_queue_io_add(vq, zio);
272 nio = vdev_queue_io_to_issue(vq, zfs_vdev_min_pending);
274 mutex_exit(&vq->vq_lock);
279 if (nio->io_done == vdev_queue_agg_io_done) {
288 vdev_queue_io_done(zio_t *zio)
290 vdev_queue_t *vq = &zio->io_vd->vdev_queue;
292 mutex_enter(&vq->vq_lock);
294 avl_remove(&vq->vq_pending_tree, zio);
296 for (int i = 0; i < zfs_vdev_ramp_rate; i++) {
297 zio_t *nio = vdev_queue_io_to_issue(vq, zfs_vdev_max_pending);
300 mutex_exit(&vq->vq_lock);
301 if (nio->io_done == vdev_queue_agg_io_done) {
304 zio_vdev_io_reissue(nio);
307 mutex_enter(&vq->vq_lock);
310 mutex_exit(&vq->vq_lock);