1/* 2 * CDDL HEADER START 3 * 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. 7 * 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. 12 * 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] 18 * 19 * CDDL HEADER END 20 */ 21/* 22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26/* 27 * Copyright (c) 2012 by Delphix. All rights reserved. 28 */ 29 30#include <sys/zfs_context.h> 31#include <sys/vdev_impl.h> 32#include <sys/zio.h> 33#include <sys/avl.h> 34 35/* 36 * These tunables are for performance analysis. 37 */ 38 39/* The maximum number of I/Os concurrently pending to each device. */ 40int zfs_vdev_max_pending = 10; 41 42/* 43 * The initial number of I/Os pending to each device, before it starts ramping 44 * up to zfs_vdev_max_pending. 45 */ 46int zfs_vdev_min_pending = 4; 47 48/* 49 * The deadlines are grouped into buckets based on zfs_vdev_time_shift: 50 * deadline = pri + gethrtime() >> time_shift) 51 */ 52int zfs_vdev_time_shift = 29; /* each bucket is 0.537 seconds */ 53 54/* exponential I/O issue ramp-up rate */ 55int zfs_vdev_ramp_rate = 2; 56 57/* 58 * To reduce IOPs, we aggregate small adjacent I/Os into one large I/O. 59 * For read I/Os, we also aggregate across small adjacency gaps; for writes 60 * we include spans of optional I/Os to aid aggregation at the disk even when 61 * they aren't able to help us aggregate at this level. 62 */ 63int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE; 64int zfs_vdev_read_gap_limit = 32 << 10; 65int zfs_vdev_write_gap_limit = 4 << 10; 66 67SYSCTL_DECL(_vfs_zfs_vdev); 68TUNABLE_INT("vfs.zfs.vdev.max_pending", &zfs_vdev_max_pending); 69SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, max_pending, CTLFLAG_RW, 70 &zfs_vdev_max_pending, 0, "Maximum I/O requests pending on each device"); 71TUNABLE_INT("vfs.zfs.vdev.min_pending", &zfs_vdev_min_pending); 72SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, min_pending, CTLFLAG_RW, 73 &zfs_vdev_min_pending, 0, 74 "Initial number of I/O requests pending to each device"); 75TUNABLE_INT("vfs.zfs.vdev.time_shift", &zfs_vdev_time_shift); 76SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, time_shift, CTLFLAG_RW, 77 &zfs_vdev_time_shift, 0, "Used for calculating I/O request deadline"); 78TUNABLE_INT("vfs.zfs.vdev.ramp_rate", &zfs_vdev_ramp_rate); 79SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, ramp_rate, CTLFLAG_RW, 80 &zfs_vdev_ramp_rate, 0, "Exponential I/O issue ramp-up rate"); 81TUNABLE_INT("vfs.zfs.vdev.aggregation_limit", &zfs_vdev_aggregation_limit); 82SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, aggregation_limit, CTLFLAG_RW, 83 &zfs_vdev_aggregation_limit, 0, 84 "I/O requests are aggregated up to this size"); 85TUNABLE_INT("vfs.zfs.vdev.read_gap_limit", &zfs_vdev_read_gap_limit); 86SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, read_gap_limit, CTLFLAG_RW, 87 &zfs_vdev_read_gap_limit, 0, 88 "Acceptable gap between two reads being aggregated"); 89TUNABLE_INT("vfs.zfs.vdev.write_gap_limit", &zfs_vdev_write_gap_limit); 90SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, write_gap_limit, CTLFLAG_RW, 91 &zfs_vdev_write_gap_limit, 0, 92 "Acceptable gap between two writes being aggregated"); 93 94/* 95 * Virtual device vector for disk I/O scheduling. 96 */ 97int 98vdev_queue_deadline_compare(const void *x1, const void *x2) 99{ 100 const zio_t *z1 = x1; 101 const zio_t *z2 = x2; 102 103 if (z1->io_deadline < z2->io_deadline) 104 return (-1); 105 if (z1->io_deadline > z2->io_deadline) 106 return (1); 107 108 if (z1->io_offset < z2->io_offset) 109 return (-1); 110 if (z1->io_offset > z2->io_offset) 111 return (1); 112 113 if (z1 < z2) 114 return (-1); 115 if (z1 > z2) 116 return (1); 117 118 return (0); 119} 120 121int 122vdev_queue_offset_compare(const void *x1, const void *x2) 123{ 124 const zio_t *z1 = x1; 125 const zio_t *z2 = x2; 126 127 if (z1->io_offset < z2->io_offset) 128 return (-1); 129 if (z1->io_offset > z2->io_offset) 130 return (1); 131 132 if (z1 < z2) 133 return (-1); 134 if (z1 > z2) 135 return (1); 136 137 return (0); 138} 139 140void 141vdev_queue_init(vdev_t *vd) 142{ 143 vdev_queue_t *vq = &vd->vdev_queue; 144 145 mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL); 146 147 avl_create(&vq->vq_deadline_tree, vdev_queue_deadline_compare, 148 sizeof (zio_t), offsetof(struct zio, io_deadline_node)); 149 150 avl_create(&vq->vq_read_tree, vdev_queue_offset_compare, 151 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 152 153 avl_create(&vq->vq_write_tree, vdev_queue_offset_compare, 154 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 155 156 avl_create(&vq->vq_pending_tree, vdev_queue_offset_compare, 157 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 158} 159 160void 161vdev_queue_fini(vdev_t *vd) 162{ 163 vdev_queue_t *vq = &vd->vdev_queue; 164 165 avl_destroy(&vq->vq_deadline_tree); 166 avl_destroy(&vq->vq_read_tree); 167 avl_destroy(&vq->vq_write_tree); 168 avl_destroy(&vq->vq_pending_tree); 169 170 mutex_destroy(&vq->vq_lock); 171} 172 173static void 174vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio) 175{ 176 avl_add(&vq->vq_deadline_tree, zio); 177 avl_add(zio->io_vdev_tree, zio); 178} 179 180static void 181vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio) 182{ 183 avl_remove(&vq->vq_deadline_tree, zio); 184 avl_remove(zio->io_vdev_tree, zio); 185} 186 187static void 188vdev_queue_agg_io_done(zio_t *aio) 189{ 190 zio_t *pio; 191 192 while ((pio = zio_walk_parents(aio)) != NULL) 193 if (aio->io_type == ZIO_TYPE_READ) 194 bcopy((char *)aio->io_data + (pio->io_offset - 195 aio->io_offset), pio->io_data, pio->io_size); 196 197 zio_buf_free(aio->io_data, aio->io_size); 198} 199 200/* 201 * Compute the range spanned by two i/os, which is the endpoint of the last 202 * (lio->io_offset + lio->io_size) minus start of the first (fio->io_offset). 203 * Conveniently, the gap between fio and lio is given by -IO_SPAN(lio, fio); 204 * thus fio and lio are adjacent if and only if IO_SPAN(lio, fio) == 0. 205 */ 206#define IO_SPAN(fio, lio) ((lio)->io_offset + (lio)->io_size - (fio)->io_offset) 207#define IO_GAP(fio, lio) (-IO_SPAN(lio, fio)) 208 209static zio_t * 210vdev_queue_io_to_issue(vdev_queue_t *vq, uint64_t pending_limit) 211{ 212 zio_t *fio, *lio, *aio, *dio, *nio, *mio; 213 avl_tree_t *t; 214 int flags; 215 uint64_t maxspan = zfs_vdev_aggregation_limit; 216 uint64_t maxgap; 217 int stretch; 218 219again: 220 ASSERT(MUTEX_HELD(&vq->vq_lock)); 221 222 if (avl_numnodes(&vq->vq_pending_tree) >= pending_limit || 223 avl_numnodes(&vq->vq_deadline_tree) == 0) 224 return (NULL); 225 226 fio = lio = avl_first(&vq->vq_deadline_tree); 227 228 t = fio->io_vdev_tree; 229 flags = fio->io_flags & ZIO_FLAG_AGG_INHERIT; 230 maxgap = (t == &vq->vq_read_tree) ? zfs_vdev_read_gap_limit : 0; 231 232 if (!(flags & ZIO_FLAG_DONT_AGGREGATE)) { 233 /* 234 * We can aggregate I/Os that are sufficiently adjacent and of 235 * the same flavor, as expressed by the AGG_INHERIT flags. 236 * The latter requirement is necessary so that certain 237 * attributes of the I/O, such as whether it's a normal I/O 238 * or a scrub/resilver, can be preserved in the aggregate. 239 * We can include optional I/Os, but don't allow them 240 * to begin a range as they add no benefit in that situation. 241 */ 242 243 /* 244 * We keep track of the last non-optional I/O. 245 */ 246 mio = (fio->io_flags & ZIO_FLAG_OPTIONAL) ? NULL : fio; 247 248 /* 249 * Walk backwards through sufficiently contiguous I/Os 250 * recording the last non-option I/O. 251 */ 252 while ((dio = AVL_PREV(t, fio)) != NULL && 253 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && 254 IO_SPAN(dio, lio) <= maxspan && 255 IO_GAP(dio, fio) <= maxgap) { 256 fio = dio; 257 if (mio == NULL && !(fio->io_flags & ZIO_FLAG_OPTIONAL)) 258 mio = fio; 259 } 260 261 /* 262 * Skip any initial optional I/Os. 263 */ 264 while ((fio->io_flags & ZIO_FLAG_OPTIONAL) && fio != lio) { 265 fio = AVL_NEXT(t, fio); 266 ASSERT(fio != NULL); 267 } 268 269 /* 270 * Walk forward through sufficiently contiguous I/Os. 271 */ 272 while ((dio = AVL_NEXT(t, lio)) != NULL && 273 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && 274 IO_SPAN(fio, dio) <= maxspan && 275 IO_GAP(lio, dio) <= maxgap) { 276 lio = dio; 277 if (!(lio->io_flags & ZIO_FLAG_OPTIONAL)) 278 mio = lio; 279 } 280 281 /* 282 * Now that we've established the range of the I/O aggregation 283 * we must decide what to do with trailing optional I/Os. 284 * For reads, there's nothing to do. While we are unable to 285 * aggregate further, it's possible that a trailing optional 286 * I/O would allow the underlying device to aggregate with 287 * subsequent I/Os. We must therefore determine if the next 288 * non-optional I/O is close enough to make aggregation 289 * worthwhile. 290 */ 291 stretch = B_FALSE; 292 if (t != &vq->vq_read_tree && mio != NULL) { 293 nio = lio; 294 while ((dio = AVL_NEXT(t, nio)) != NULL && 295 IO_GAP(nio, dio) == 0 && 296 IO_GAP(mio, dio) <= zfs_vdev_write_gap_limit) { 297 nio = dio; 298 if (!(nio->io_flags & ZIO_FLAG_OPTIONAL)) { 299 stretch = B_TRUE; 300 break; 301 } 302 } 303 } 304 305 if (stretch) { 306 /* This may be a no-op. */ 307 VERIFY((dio = AVL_NEXT(t, lio)) != NULL); 308 dio->io_flags &= ~ZIO_FLAG_OPTIONAL; 309 } else { 310 while (lio != mio && lio != fio) { 311 ASSERT(lio->io_flags & ZIO_FLAG_OPTIONAL); 312 lio = AVL_PREV(t, lio); 313 ASSERT(lio != NULL); 314 } 315 } 316 } 317 318 if (fio != lio) { 319 uint64_t size = IO_SPAN(fio, lio); 320 ASSERT(size <= zfs_vdev_aggregation_limit); 321 322 aio = zio_vdev_delegated_io(fio->io_vd, fio->io_offset, 323 zio_buf_alloc(size), size, fio->io_type, ZIO_PRIORITY_AGG, 324 flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE, 325 vdev_queue_agg_io_done, NULL); 326 aio->io_timestamp = fio->io_timestamp; 327 328 nio = fio; 329 do { 330 dio = nio; 331 nio = AVL_NEXT(t, dio); 332 ASSERT(dio->io_type == aio->io_type); 333 ASSERT(dio->io_vdev_tree == t); 334 335 if (dio->io_flags & ZIO_FLAG_NODATA) { 336 ASSERT(dio->io_type == ZIO_TYPE_WRITE); 337 bzero((char *)aio->io_data + (dio->io_offset - 338 aio->io_offset), dio->io_size); 339 } else if (dio->io_type == ZIO_TYPE_WRITE) { 340 bcopy(dio->io_data, (char *)aio->io_data + 341 (dio->io_offset - aio->io_offset), 342 dio->io_size); 343 } 344 345 zio_add_child(dio, aio); 346 vdev_queue_io_remove(vq, dio); 347 zio_vdev_io_bypass(dio); 348 zio_execute(dio); 349 } while (dio != lio); 350 351 avl_add(&vq->vq_pending_tree, aio); 352 353 return (aio); 354 } 355 356 ASSERT(fio->io_vdev_tree == t); 357 vdev_queue_io_remove(vq, fio); 358 359 /* 360 * If the I/O is or was optional and therefore has no data, we need to 361 * simply discard it. We need to drop the vdev queue's lock to avoid a 362 * deadlock that we could encounter since this I/O will complete 363 * immediately. 364 */ 365 if (fio->io_flags & ZIO_FLAG_NODATA) { 366 mutex_exit(&vq->vq_lock); 367 zio_vdev_io_bypass(fio); 368 zio_execute(fio); 369 mutex_enter(&vq->vq_lock); 370 goto again; 371 } 372 373 avl_add(&vq->vq_pending_tree, fio); 374 375 return (fio); 376} 377 378zio_t * 379vdev_queue_io(zio_t *zio) 380{ 381 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 382 zio_t *nio; 383 384 ASSERT(zio->io_type == ZIO_TYPE_READ || zio->io_type == ZIO_TYPE_WRITE); 385 386 if (zio->io_flags & ZIO_FLAG_DONT_QUEUE) 387 return (zio); 388 389 zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE; 390 391 if (zio->io_type == ZIO_TYPE_READ) 392 zio->io_vdev_tree = &vq->vq_read_tree; 393 else 394 zio->io_vdev_tree = &vq->vq_write_tree; 395 396 mutex_enter(&vq->vq_lock); 397 398 zio->io_timestamp = gethrtime(); 399 zio->io_deadline = (zio->io_timestamp >> zfs_vdev_time_shift) + 400 zio->io_priority; 401 402 vdev_queue_io_add(vq, zio); 403 404 nio = vdev_queue_io_to_issue(vq, zfs_vdev_min_pending); 405 406 mutex_exit(&vq->vq_lock); 407 408 if (nio == NULL) 409 return (NULL); 410 411 if (nio->io_done == vdev_queue_agg_io_done) { 412 zio_nowait(nio); 413 return (NULL); 414 } 415 416 return (nio); 417} 418 419void 420vdev_queue_io_done(zio_t *zio) 421{ 422 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 423 424 if (zio_injection_enabled) 425 delay(SEC_TO_TICK(zio_handle_io_delay(zio))); 426 427 mutex_enter(&vq->vq_lock); 428 429 avl_remove(&vq->vq_pending_tree, zio); 430 431 vq->vq_io_complete_ts = gethrtime(); 432 433 for (int i = 0; i < zfs_vdev_ramp_rate; i++) { 434 zio_t *nio = vdev_queue_io_to_issue(vq, zfs_vdev_max_pending); 435 if (nio == NULL) 436 break; 437 mutex_exit(&vq->vq_lock); 438 if (nio->io_done == vdev_queue_agg_io_done) { 439 zio_nowait(nio); 440 } else { 441 zio_vdev_io_reissue(nio); 442 zio_execute(nio); 443 } 444 mutex_enter(&vq->vq_lock); 445 } 446 447 mutex_exit(&vq->vq_lock); 448} 449