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>
27 #include <sys/vdev_impl.h>
32 * These tunables are for performance analysis.
35 * zfs_vdev_max_pending is the maximum number of i/os concurrently
36 * pending to each device. zfs_vdev_min_pending is the initial number
37 * of i/os pending to each device (before it starts ramping up to
40 int zfs_vdev_max_pending
= 10;
41 int zfs_vdev_min_pending
= 4;
43 /* deadline = pri + ddi_get_lbolt64() >> time_shift) */
44 int zfs_vdev_time_shift
= 6;
46 /* exponential I/O issue ramp-up rate */
47 int zfs_vdev_ramp_rate
= 2;
50 * To reduce IOPs, we aggregate small adjacent I/Os into one large I/O.
51 * For read I/Os, we also aggregate across small adjacency gaps; for writes
52 * we include spans of optional I/Os to aid aggregation at the disk even when
53 * they aren't able to help us aggregate at this level.
55 int zfs_vdev_aggregation_limit
= SPA_MAXBLOCKSIZE
;
56 int zfs_vdev_read_gap_limit
= 32 << 10;
57 int zfs_vdev_write_gap_limit
= 4 << 10;
60 * Virtual device vector for disk I/O scheduling.
63 vdev_queue_deadline_compare(const void *x1
, const void *x2
)
68 if (z1
->io_deadline
< z2
->io_deadline
)
70 if (z1
->io_deadline
> z2
->io_deadline
)
73 if (z1
->io_offset
< z2
->io_offset
)
75 if (z1
->io_offset
> z2
->io_offset
)
87 vdev_queue_offset_compare(const void *x1
, const void *x2
)
92 if (z1
->io_offset
< z2
->io_offset
)
94 if (z1
->io_offset
> z2
->io_offset
)
106 vdev_queue_init(vdev_t
*vd
)
108 vdev_queue_t
*vq
= &vd
->vdev_queue
;
111 mutex_init(&vq
->vq_lock
, NULL
, MUTEX_DEFAULT
, NULL
);
113 avl_create(&vq
->vq_deadline_tree
, vdev_queue_deadline_compare
,
114 sizeof (zio_t
), offsetof(struct zio
, io_deadline_node
));
116 avl_create(&vq
->vq_read_tree
, vdev_queue_offset_compare
,
117 sizeof (zio_t
), offsetof(struct zio
, io_offset_node
));
119 avl_create(&vq
->vq_write_tree
, vdev_queue_offset_compare
,
120 sizeof (zio_t
), offsetof(struct zio
, io_offset_node
));
122 avl_create(&vq
->vq_pending_tree
, vdev_queue_offset_compare
,
123 sizeof (zio_t
), offsetof(struct zio
, io_offset_node
));
126 * A list of buffers which can be used for aggregate I/O, this
127 * avoids the need to allocate them on demand when memory is low.
129 list_create(&vq
->vq_io_list
, sizeof (vdev_io_t
),
130 offsetof(vdev_io_t
, vi_node
));
132 for (i
= 0; i
< zfs_vdev_max_pending
; i
++)
133 list_insert_tail(&vq
->vq_io_list
, zio_vdev_alloc());
137 vdev_queue_fini(vdev_t
*vd
)
139 vdev_queue_t
*vq
= &vd
->vdev_queue
;
142 avl_destroy(&vq
->vq_deadline_tree
);
143 avl_destroy(&vq
->vq_read_tree
);
144 avl_destroy(&vq
->vq_write_tree
);
145 avl_destroy(&vq
->vq_pending_tree
);
147 while ((vi
= list_head(&vq
->vq_io_list
)) != NULL
) {
148 list_remove(&vq
->vq_io_list
, vi
);
152 list_destroy(&vq
->vq_io_list
);
154 mutex_destroy(&vq
->vq_lock
);
158 vdev_queue_io_add(vdev_queue_t
*vq
, zio_t
*zio
)
160 avl_add(&vq
->vq_deadline_tree
, zio
);
161 avl_add(zio
->io_vdev_tree
, zio
);
165 vdev_queue_io_remove(vdev_queue_t
*vq
, zio_t
*zio
)
167 avl_remove(&vq
->vq_deadline_tree
, zio
);
168 avl_remove(zio
->io_vdev_tree
, zio
);
172 vdev_queue_agg_io_done(zio_t
*aio
)
174 vdev_queue_t
*vq
= &aio
->io_vd
->vdev_queue
;
175 vdev_io_t
*vi
= aio
->io_data
;
178 while ((pio
= zio_walk_parents(aio
)) != NULL
)
179 if (aio
->io_type
== ZIO_TYPE_READ
)
180 bcopy((char *)aio
->io_data
+ (pio
->io_offset
-
181 aio
->io_offset
), pio
->io_data
, pio
->io_size
);
183 mutex_enter(&vq
->vq_lock
);
184 list_insert_tail(&vq
->vq_io_list
, vi
);
185 mutex_exit(&vq
->vq_lock
);
189 * Compute the range spanned by two i/os, which is the endpoint of the last
190 * (lio->io_offset + lio->io_size) minus start of the first (fio->io_offset).
191 * Conveniently, the gap between fio and lio is given by -IO_SPAN(lio, fio);
192 * thus fio and lio are adjacent if and only if IO_SPAN(lio, fio) == 0.
194 #define IO_SPAN(fio, lio) ((lio)->io_offset + (lio)->io_size - (fio)->io_offset)
195 #define IO_GAP(fio, lio) (-IO_SPAN(lio, fio))
198 vdev_queue_io_to_issue(vdev_queue_t
*vq
, uint64_t pending_limit
)
200 zio_t
*fio
, *lio
, *aio
, *dio
, *nio
, *mio
;
204 uint64_t maxspan
= MIN(zfs_vdev_aggregation_limit
, SPA_MAXBLOCKSIZE
);
209 ASSERT(MUTEX_HELD(&vq
->vq_lock
));
211 if (avl_numnodes(&vq
->vq_pending_tree
) >= pending_limit
||
212 avl_numnodes(&vq
->vq_deadline_tree
) == 0)
215 fio
= lio
= avl_first(&vq
->vq_deadline_tree
);
217 t
= fio
->io_vdev_tree
;
218 flags
= fio
->io_flags
& ZIO_FLAG_AGG_INHERIT
;
219 maxgap
= (t
== &vq
->vq_read_tree
) ? zfs_vdev_read_gap_limit
: 0;
221 vi
= list_head(&vq
->vq_io_list
);
223 vi
= zio_vdev_alloc();
224 list_insert_head(&vq
->vq_io_list
, vi
);
227 if (!(flags
& ZIO_FLAG_DONT_AGGREGATE
)) {
229 * We can aggregate I/Os that are sufficiently adjacent and of
230 * the same flavor, as expressed by the AGG_INHERIT flags.
231 * The latter requirement is necessary so that certain
232 * attributes of the I/O, such as whether it's a normal I/O
233 * or a scrub/resilver, can be preserved in the aggregate.
234 * We can include optional I/Os, but don't allow them
235 * to begin a range as they add no benefit in that situation.
239 * We keep track of the last non-optional I/O.
241 mio
= (fio
->io_flags
& ZIO_FLAG_OPTIONAL
) ? NULL
: fio
;
244 * Walk backwards through sufficiently contiguous I/Os
245 * recording the last non-option I/O.
247 while ((dio
= AVL_PREV(t
, fio
)) != NULL
&&
248 (dio
->io_flags
& ZIO_FLAG_AGG_INHERIT
) == flags
&&
249 IO_SPAN(dio
, lio
) <= maxspan
&&
250 IO_GAP(dio
, fio
) <= maxgap
) {
252 if (mio
== NULL
&& !(fio
->io_flags
& ZIO_FLAG_OPTIONAL
))
257 * Skip any initial optional I/Os.
259 while ((fio
->io_flags
& ZIO_FLAG_OPTIONAL
) && fio
!= lio
) {
260 fio
= AVL_NEXT(t
, fio
);
265 * Walk forward through sufficiently contiguous I/Os.
267 while ((dio
= AVL_NEXT(t
, lio
)) != NULL
&&
268 (dio
->io_flags
& ZIO_FLAG_AGG_INHERIT
) == flags
&&
269 IO_SPAN(fio
, dio
) <= maxspan
&&
270 IO_GAP(lio
, dio
) <= maxgap
) {
272 if (!(lio
->io_flags
& ZIO_FLAG_OPTIONAL
))
277 * Now that we've established the range of the I/O aggregation
278 * we must decide what to do with trailing optional I/Os.
279 * For reads, there's nothing to do. While we are unable to
280 * aggregate further, it's possible that a trailing optional
281 * I/O would allow the underlying device to aggregate with
282 * subsequent I/Os. We must therefore determine if the next
283 * non-optional I/O is close enough to make aggregation
287 if (t
!= &vq
->vq_read_tree
&& mio
!= NULL
) {
289 while ((dio
= AVL_NEXT(t
, nio
)) != NULL
&&
290 IO_GAP(nio
, dio
) == 0 &&
291 IO_GAP(mio
, dio
) <= zfs_vdev_write_gap_limit
) {
293 if (!(nio
->io_flags
& ZIO_FLAG_OPTIONAL
)) {
301 /* This may be a no-op. */
302 VERIFY((dio
= AVL_NEXT(t
, lio
)) != NULL
);
303 dio
->io_flags
&= ~ZIO_FLAG_OPTIONAL
;
305 while (lio
!= mio
&& lio
!= fio
) {
306 ASSERT(lio
->io_flags
& ZIO_FLAG_OPTIONAL
);
307 lio
= AVL_PREV(t
, lio
);
314 uint64_t size
= IO_SPAN(fio
, lio
);
315 ASSERT(size
<= maxspan
);
318 aio
= zio_vdev_delegated_io(fio
->io_vd
, fio
->io_offset
,
319 vi
, size
, fio
->io_type
, ZIO_PRIORITY_AGG
,
320 flags
| ZIO_FLAG_DONT_CACHE
| ZIO_FLAG_DONT_QUEUE
,
321 vdev_queue_agg_io_done
, NULL
);
326 nio
= AVL_NEXT(t
, dio
);
327 ASSERT(dio
->io_type
== aio
->io_type
);
328 ASSERT(dio
->io_vdev_tree
== t
);
330 if (dio
->io_flags
& ZIO_FLAG_NODATA
) {
331 ASSERT(dio
->io_type
== ZIO_TYPE_WRITE
);
332 bzero((char *)aio
->io_data
+ (dio
->io_offset
-
333 aio
->io_offset
), dio
->io_size
);
334 } else if (dio
->io_type
== ZIO_TYPE_WRITE
) {
335 bcopy(dio
->io_data
, (char *)aio
->io_data
+
336 (dio
->io_offset
- aio
->io_offset
),
340 zio_add_child(dio
, aio
);
341 vdev_queue_io_remove(vq
, dio
);
342 zio_vdev_io_bypass(dio
);
344 } while (dio
!= lio
);
346 avl_add(&vq
->vq_pending_tree
, aio
);
347 list_remove(&vq
->vq_io_list
, vi
);
352 ASSERT(fio
->io_vdev_tree
== t
);
353 vdev_queue_io_remove(vq
, fio
);
356 * If the I/O is or was optional and therefore has no data, we need to
357 * simply discard it. We need to drop the vdev queue's lock to avoid a
358 * deadlock that we could encounter since this I/O will complete
361 if (fio
->io_flags
& ZIO_FLAG_NODATA
) {
362 mutex_exit(&vq
->vq_lock
);
363 zio_vdev_io_bypass(fio
);
365 mutex_enter(&vq
->vq_lock
);
369 avl_add(&vq
->vq_pending_tree
, fio
);
375 vdev_queue_io(zio_t
*zio
)
377 vdev_queue_t
*vq
= &zio
->io_vd
->vdev_queue
;
380 ASSERT(zio
->io_type
== ZIO_TYPE_READ
|| zio
->io_type
== ZIO_TYPE_WRITE
);
382 if (zio
->io_flags
& ZIO_FLAG_DONT_QUEUE
)
385 zio
->io_flags
|= ZIO_FLAG_DONT_CACHE
| ZIO_FLAG_DONT_QUEUE
;
387 if (zio
->io_type
== ZIO_TYPE_READ
)
388 zio
->io_vdev_tree
= &vq
->vq_read_tree
;
390 zio
->io_vdev_tree
= &vq
->vq_write_tree
;
392 mutex_enter(&vq
->vq_lock
);
394 zio
->io_deadline
= (ddi_get_lbolt64() >> zfs_vdev_time_shift
) +
397 vdev_queue_io_add(vq
, zio
);
399 nio
= vdev_queue_io_to_issue(vq
, zfs_vdev_min_pending
);
401 mutex_exit(&vq
->vq_lock
);
406 if (nio
->io_done
== vdev_queue_agg_io_done
) {
415 vdev_queue_io_done(zio_t
*zio
)
417 vdev_queue_t
*vq
= &zio
->io_vd
->vdev_queue
;
420 mutex_enter(&vq
->vq_lock
);
422 avl_remove(&vq
->vq_pending_tree
, zio
);
424 for (i
= 0; i
< zfs_vdev_ramp_rate
; i
++) {
425 zio_t
*nio
= vdev_queue_io_to_issue(vq
, zfs_vdev_max_pending
);
428 mutex_exit(&vq
->vq_lock
);
429 if (nio
->io_done
== vdev_queue_agg_io_done
) {
432 zio_vdev_io_reissue(nio
);
435 mutex_enter(&vq
->vq_lock
);
438 mutex_exit(&vq
->vq_lock
);
441 #if defined(_KERNEL) && defined(HAVE_SPL)
442 module_param(zfs_vdev_max_pending
, int, 0644);
443 MODULE_PARM_DESC(zfs_vdev_max_pending
, "Max pending per-vdev I/Os");
445 module_param(zfs_vdev_min_pending
, int, 0644);
446 MODULE_PARM_DESC(zfs_vdev_min_pending
, "Min pending per-vdev I/Os");
448 module_param(zfs_vdev_aggregation_limit
, int, 0644);
449 MODULE_PARM_DESC(zfs_vdev_aggregation_limit
, "Max vdev I/O aggregation size");
451 module_param(zfs_vdev_time_shift
, int, 0644);
452 MODULE_PARM_DESC(zfs_vdev_time_shift
, "Deadline time shift for vdev I/O");
454 module_param(zfs_vdev_ramp_rate
, int, 0644);
455 MODULE_PARM_DESC(zfs_vdev_ramp_rate
, "Exponential I/O issue ramp-up rate");
457 module_param(zfs_vdev_read_gap_limit
, int, 0644);
458 MODULE_PARM_DESC(zfs_vdev_read_gap_limit
, "Aggregate read I/O over gap");
460 module_param(zfs_vdev_write_gap_limit
, int, 0644);
461 MODULE_PARM_DESC(zfs_vdev_write_gap_limit
, "Aggregate write I/O over gap");