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, 2018 by Delphix. All rights reserved. 28 * Copyright (c) 2014 Integros [integros.com] 29 */ 30 31#include <sys/zfs_context.h> 32#include <sys/vdev_impl.h> 33#include <sys/spa_impl.h> 34#include <sys/zio.h> 35#include <sys/avl.h> 36#include <sys/dsl_pool.h> 37#include <sys/metaslab_impl.h> 38#include <sys/abd.h> 39 40/* 41 * ZFS I/O Scheduler 42 * --------------- 43 * 44 * ZFS issues I/O operations to leaf vdevs to satisfy and complete zios. The 45 * I/O scheduler determines when and in what order those operations are 46 * issued. The I/O scheduler divides operations into six I/O classes 47 * prioritized in the following order: sync read, sync write, async read, 48 * async write, scrub/resilver and trim. Each queue defines the minimum and 49 * maximum number of concurrent operations that may be issued to the device. 50 * In addition, the device has an aggregate maximum. Note that the sum of the 51 * per-queue minimums must not exceed the aggregate maximum, and if the 52 * aggregate maximum is equal to or greater than the sum of the per-queue 53 * maximums, the per-queue minimum has no effect. 54 * 55 * For many physical devices, throughput increases with the number of 56 * concurrent operations, but latency typically suffers. Further, physical 57 * devices typically have a limit at which more concurrent operations have no 58 * effect on throughput or can actually cause it to decrease. 59 * 60 * The scheduler selects the next operation to issue by first looking for an 61 * I/O class whose minimum has not been satisfied. Once all are satisfied and 62 * the aggregate maximum has not been hit, the scheduler looks for classes 63 * whose maximum has not been satisfied. Iteration through the I/O classes is 64 * done in the order specified above. No further operations are issued if the 65 * aggregate maximum number of concurrent operations has been hit or if there 66 * are no operations queued for an I/O class that has not hit its maximum. 67 * Every time an I/O is queued or an operation completes, the I/O scheduler 68 * looks for new operations to issue. 69 * 70 * All I/O classes have a fixed maximum number of outstanding operations 71 * except for the async write class. Asynchronous writes represent the data 72 * that is committed to stable storage during the syncing stage for 73 * transaction groups (see txg.c). Transaction groups enter the syncing state 74 * periodically so the number of queued async writes will quickly burst up and 75 * then bleed down to zero. Rather than servicing them as quickly as possible, 76 * the I/O scheduler changes the maximum number of active async write I/Os 77 * according to the amount of dirty data in the pool (see dsl_pool.c). Since 78 * both throughput and latency typically increase with the number of 79 * concurrent operations issued to physical devices, reducing the burstiness 80 * in the number of concurrent operations also stabilizes the response time of 81 * operations from other -- and in particular synchronous -- queues. In broad 82 * strokes, the I/O scheduler will issue more concurrent operations from the 83 * async write queue as there's more dirty data in the pool. 84 * 85 * Async Writes 86 * 87 * The number of concurrent operations issued for the async write I/O class 88 * follows a piece-wise linear function defined by a few adjustable points. 89 * 90 * | o---------| <-- zfs_vdev_async_write_max_active 91 * ^ | /^ | 92 * | | / | | 93 * active | / | | 94 * I/O | / | | 95 * count | / | | 96 * | / | | 97 * |------------o | | <-- zfs_vdev_async_write_min_active 98 * 0|____________^______|_________| 99 * 0% | | 100% of zfs_dirty_data_max 100 * | | 101 * | `-- zfs_vdev_async_write_active_max_dirty_percent 102 * `--------- zfs_vdev_async_write_active_min_dirty_percent 103 * 104 * Until the amount of dirty data exceeds a minimum percentage of the dirty 105 * data allowed in the pool, the I/O scheduler will limit the number of 106 * concurrent operations to the minimum. As that threshold is crossed, the 107 * number of concurrent operations issued increases linearly to the maximum at 108 * the specified maximum percentage of the dirty data allowed in the pool. 109 * 110 * Ideally, the amount of dirty data on a busy pool will stay in the sloped 111 * part of the function between zfs_vdev_async_write_active_min_dirty_percent 112 * and zfs_vdev_async_write_active_max_dirty_percent. If it exceeds the 113 * maximum percentage, this indicates that the rate of incoming data is 114 * greater than the rate that the backend storage can handle. In this case, we 115 * must further throttle incoming writes (see dmu_tx_delay() for details). 116 */ 117 118/* 119 * The maximum number of I/Os active to each device. Ideally, this will be >= 120 * the sum of each queue's max_active. It must be at least the sum of each 121 * queue's min_active. 122 */ 123uint32_t zfs_vdev_max_active = 1000; 124 125/* 126 * Per-queue limits on the number of I/Os active to each device. If the 127 * sum of the queue's max_active is < zfs_vdev_max_active, then the 128 * min_active comes into play. We will send min_active from each queue, 129 * and then select from queues in the order defined by zio_priority_t. 130 * 131 * In general, smaller max_active's will lead to lower latency of synchronous 132 * operations. Larger max_active's may lead to higher overall throughput, 133 * depending on underlying storage. 134 * 135 * The ratio of the queues' max_actives determines the balance of performance 136 * between reads, writes, and scrubs. E.g., increasing 137 * zfs_vdev_scrub_max_active will cause the scrub or resilver to complete 138 * more quickly, but reads and writes to have higher latency and lower 139 * throughput. 140 */ 141uint32_t zfs_vdev_sync_read_min_active = 10; 142uint32_t zfs_vdev_sync_read_max_active = 10; 143uint32_t zfs_vdev_sync_write_min_active = 10; 144uint32_t zfs_vdev_sync_write_max_active = 10; 145uint32_t zfs_vdev_async_read_min_active = 1; 146uint32_t zfs_vdev_async_read_max_active = 3; 147uint32_t zfs_vdev_async_write_min_active = 1; 148uint32_t zfs_vdev_async_write_max_active = 10; 149uint32_t zfs_vdev_scrub_min_active = 1; 150uint32_t zfs_vdev_scrub_max_active = 2; 151uint32_t zfs_vdev_trim_min_active = 1; 152/* 153 * TRIM max active is large in comparison to the other values due to the fact 154 * that TRIM IOs are coalesced at the device layer. This value is set such 155 * that a typical SSD can process the queued IOs in a single request. 156 */ 157uint32_t zfs_vdev_trim_max_active = 64; 158uint32_t zfs_vdev_removal_min_active = 1; 159uint32_t zfs_vdev_removal_max_active = 2; 160uint32_t zfs_vdev_initializing_min_active = 1; 161uint32_t zfs_vdev_initializing_max_active = 1; 162 163 164/* 165 * When the pool has less than zfs_vdev_async_write_active_min_dirty_percent 166 * dirty data, use zfs_vdev_async_write_min_active. When it has more than 167 * zfs_vdev_async_write_active_max_dirty_percent, use 168 * zfs_vdev_async_write_max_active. The value is linearly interpolated 169 * between min and max. 170 */ 171int zfs_vdev_async_write_active_min_dirty_percent = 30; 172int zfs_vdev_async_write_active_max_dirty_percent = 60; 173 174/* 175 * To reduce IOPs, we aggregate small adjacent I/Os into one large I/O. 176 * For read I/Os, we also aggregate across small adjacency gaps; for writes 177 * we include spans of optional I/Os to aid aggregation at the disk even when 178 * they aren't able to help us aggregate at this level. 179 */ 180int zfs_vdev_aggregation_limit = 1 << 20; 181int zfs_vdev_aggregation_limit_non_rotating = SPA_OLD_MAXBLOCKSIZE; 182int zfs_vdev_read_gap_limit = 32 << 10; 183int zfs_vdev_write_gap_limit = 4 << 10; 184 185/* 186 * Define the queue depth percentage for each top-level. This percentage is 187 * used in conjunction with zfs_vdev_async_max_active to determine how many 188 * allocations a specific top-level vdev should handle. Once the queue depth 189 * reaches zfs_vdev_queue_depth_pct * zfs_vdev_async_write_max_active / 100 190 * then allocator will stop allocating blocks on that top-level device. 191 * The default kernel setting is 1000% which will yield 100 allocations per 192 * device. For userland testing, the default setting is 300% which equates 193 * to 30 allocations per device. 194 */ 195#ifdef _KERNEL 196int zfs_vdev_queue_depth_pct = 1000; 197#else 198int zfs_vdev_queue_depth_pct = 300; 199#endif 200 201/* 202 * When performing allocations for a given metaslab, we want to make sure that 203 * there are enough IOs to aggregate together to improve throughput. We want to 204 * ensure that there are at least 128k worth of IOs that can be aggregated, and 205 * we assume that the average allocation size is 4k, so we need the queue depth 206 * to be 32 per allocator to get good aggregation of sequential writes. 207 */ 208int zfs_vdev_def_queue_depth = 32; 209 210#ifdef __FreeBSD__ 211#ifdef _KERNEL 212SYSCTL_DECL(_vfs_zfs_vdev); 213 214static int sysctl_zfs_async_write_active_min_dirty_percent(SYSCTL_HANDLER_ARGS); 215SYSCTL_PROC(_vfs_zfs_vdev, OID_AUTO, async_write_active_min_dirty_percent, 216 CTLTYPE_UINT | CTLFLAG_MPSAFE | CTLFLAG_RWTUN, 0, sizeof(int), 217 sysctl_zfs_async_write_active_min_dirty_percent, "I", 218 "Percentage of async write dirty data below which " 219 "async_write_min_active is used."); 220 221static int sysctl_zfs_async_write_active_max_dirty_percent(SYSCTL_HANDLER_ARGS); 222SYSCTL_PROC(_vfs_zfs_vdev, OID_AUTO, async_write_active_max_dirty_percent, 223 CTLTYPE_UINT | CTLFLAG_MPSAFE | CTLFLAG_RWTUN, 0, sizeof(int), 224 sysctl_zfs_async_write_active_max_dirty_percent, "I", 225 "Percentage of async write dirty data above which " 226 "async_write_max_active is used."); 227 228SYSCTL_UINT(_vfs_zfs_vdev, OID_AUTO, max_active, CTLFLAG_RWTUN, 229 &zfs_vdev_max_active, 0, 230 "The maximum number of I/Os of all types active for each device."); 231 232#define ZFS_VDEV_QUEUE_KNOB_MIN(name) \ 233SYSCTL_UINT(_vfs_zfs_vdev, OID_AUTO, name ## _min_active, CTLFLAG_RWTUN,\ 234 &zfs_vdev_ ## name ## _min_active, 0, \ 235 "Initial number of I/O requests of type " #name \ 236 " active for each device"); 237 238#define ZFS_VDEV_QUEUE_KNOB_MAX(name) \ 239SYSCTL_UINT(_vfs_zfs_vdev, OID_AUTO, name ## _max_active, CTLFLAG_RWTUN,\ 240 &zfs_vdev_ ## name ## _max_active, 0, \ 241 "Maximum number of I/O requests of type " #name \ 242 " active for each device"); 243 244ZFS_VDEV_QUEUE_KNOB_MIN(sync_read); 245ZFS_VDEV_QUEUE_KNOB_MAX(sync_read); 246ZFS_VDEV_QUEUE_KNOB_MIN(sync_write); 247ZFS_VDEV_QUEUE_KNOB_MAX(sync_write); 248ZFS_VDEV_QUEUE_KNOB_MIN(async_read); 249ZFS_VDEV_QUEUE_KNOB_MAX(async_read); 250ZFS_VDEV_QUEUE_KNOB_MIN(async_write); 251ZFS_VDEV_QUEUE_KNOB_MAX(async_write); 252ZFS_VDEV_QUEUE_KNOB_MIN(scrub); 253ZFS_VDEV_QUEUE_KNOB_MAX(scrub); 254ZFS_VDEV_QUEUE_KNOB_MIN(trim); 255ZFS_VDEV_QUEUE_KNOB_MAX(trim); 256ZFS_VDEV_QUEUE_KNOB_MIN(removal); 257ZFS_VDEV_QUEUE_KNOB_MAX(removal); 258ZFS_VDEV_QUEUE_KNOB_MIN(initializing); 259ZFS_VDEV_QUEUE_KNOB_MAX(initializing); 260 261#undef ZFS_VDEV_QUEUE_KNOB 262 263SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, aggregation_limit, CTLFLAG_RWTUN, 264 &zfs_vdev_aggregation_limit, 0, 265 "I/O requests are aggregated up to this size"); 266SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, aggregation_limit_non_rotating, CTLFLAG_RWTUN, 267 &zfs_vdev_aggregation_limit_non_rotating, 0, 268 "I/O requests are aggregated up to this size for non-rotating media"); 269SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, read_gap_limit, CTLFLAG_RWTUN, 270 &zfs_vdev_read_gap_limit, 0, 271 "Acceptable gap between two reads being aggregated"); 272SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, write_gap_limit, CTLFLAG_RWTUN, 273 &zfs_vdev_write_gap_limit, 0, 274 "Acceptable gap between two writes being aggregated"); 275SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, queue_depth_pct, CTLFLAG_RWTUN, 276 &zfs_vdev_queue_depth_pct, 0, 277 "Queue depth percentage for each top-level"); 278SYSCTL_INT(_vfs_zfs_vdev, OID_AUTO, def_queue_depth, CTLFLAG_RWTUN, 279 &zfs_vdev_def_queue_depth, 0, 280 "Default queue depth for each allocator"); 281 282static int 283sysctl_zfs_async_write_active_min_dirty_percent(SYSCTL_HANDLER_ARGS) 284{ 285 int val, err; 286 287 val = zfs_vdev_async_write_active_min_dirty_percent; 288 err = sysctl_handle_int(oidp, &val, 0, req); 289 if (err != 0 || req->newptr == NULL) 290 return (err); 291 292 if (val < 0 || val > 100 || 293 val >= zfs_vdev_async_write_active_max_dirty_percent) 294 return (EINVAL); 295 296 zfs_vdev_async_write_active_min_dirty_percent = val; 297 298 return (0); 299} 300 301static int 302sysctl_zfs_async_write_active_max_dirty_percent(SYSCTL_HANDLER_ARGS) 303{ 304 int val, err; 305 306 val = zfs_vdev_async_write_active_max_dirty_percent; 307 err = sysctl_handle_int(oidp, &val, 0, req); 308 if (err != 0 || req->newptr == NULL) 309 return (err); 310 311 if (val < 0 || val > 100 || 312 val <= zfs_vdev_async_write_active_min_dirty_percent) 313 return (EINVAL); 314 315 zfs_vdev_async_write_active_max_dirty_percent = val; 316 317 return (0); 318} 319#endif 320#endif 321 322int 323vdev_queue_offset_compare(const void *x1, const void *x2) 324{ 325 const zio_t *z1 = (const zio_t *)x1; 326 const zio_t *z2 = (const zio_t *)x2; 327 328 int cmp = AVL_CMP(z1->io_offset, z2->io_offset); 329 330 if (likely(cmp)) 331 return (cmp); 332 333 return (AVL_PCMP(z1, z2)); 334} 335 336static inline avl_tree_t * 337vdev_queue_class_tree(vdev_queue_t *vq, zio_priority_t p) 338{ 339 return (&vq->vq_class[p].vqc_queued_tree); 340} 341 342static inline avl_tree_t * 343vdev_queue_type_tree(vdev_queue_t *vq, zio_type_t t) 344{ 345 if (t == ZIO_TYPE_READ) 346 return (&vq->vq_read_offset_tree); 347 else if (t == ZIO_TYPE_WRITE) 348 return (&vq->vq_write_offset_tree); 349 else 350 return (NULL); 351} 352 353int 354vdev_queue_timestamp_compare(const void *x1, const void *x2) 355{ 356 const zio_t *z1 = x1; 357 const zio_t *z2 = x2; 358 359 if (z1->io_timestamp < z2->io_timestamp) 360 return (-1); 361 if (z1->io_timestamp > z2->io_timestamp) 362 return (1); 363 364 if (z1->io_offset < z2->io_offset) 365 return (-1); 366 if (z1->io_offset > z2->io_offset) 367 return (1); 368 369 if (z1 < z2) 370 return (-1); 371 if (z1 > z2) 372 return (1); 373 374 return (0); 375} 376 377void 378vdev_queue_init(vdev_t *vd) 379{ 380 vdev_queue_t *vq = &vd->vdev_queue; 381 382 mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL); 383 vq->vq_vdev = vd; 384 385 avl_create(&vq->vq_active_tree, vdev_queue_offset_compare, 386 sizeof (zio_t), offsetof(struct zio, io_queue_node)); 387 avl_create(vdev_queue_type_tree(vq, ZIO_TYPE_READ), 388 vdev_queue_offset_compare, sizeof (zio_t), 389 offsetof(struct zio, io_offset_node)); 390 avl_create(vdev_queue_type_tree(vq, ZIO_TYPE_WRITE), 391 vdev_queue_offset_compare, sizeof (zio_t), 392 offsetof(struct zio, io_offset_node)); 393 394 for (zio_priority_t p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) { 395 int (*compfn) (const void *, const void *); 396 397 /* 398 * The synchronous i/o queues are dispatched in FIFO rather 399 * than LBA order. This provides more consistent latency for 400 * these i/os. 401 */ 402 if (p == ZIO_PRIORITY_SYNC_READ || p == ZIO_PRIORITY_SYNC_WRITE) 403 compfn = vdev_queue_timestamp_compare; 404 else 405 compfn = vdev_queue_offset_compare; 406 407 avl_create(vdev_queue_class_tree(vq, p), compfn, 408 sizeof (zio_t), offsetof(struct zio, io_queue_node)); 409 } 410 411 vq->vq_lastoffset = 0; 412} 413 414void 415vdev_queue_fini(vdev_t *vd) 416{ 417 vdev_queue_t *vq = &vd->vdev_queue; 418 419 for (zio_priority_t p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) 420 avl_destroy(vdev_queue_class_tree(vq, p)); 421 avl_destroy(&vq->vq_active_tree); 422 avl_destroy(vdev_queue_type_tree(vq, ZIO_TYPE_READ)); 423 avl_destroy(vdev_queue_type_tree(vq, ZIO_TYPE_WRITE)); 424 425 mutex_destroy(&vq->vq_lock); 426} 427 428static void 429vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio) 430{ 431 spa_t *spa = zio->io_spa; 432 avl_tree_t *qtt; 433 434 ASSERT(MUTEX_HELD(&vq->vq_lock)); 435 ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); 436 avl_add(vdev_queue_class_tree(vq, zio->io_priority), zio); 437 qtt = vdev_queue_type_tree(vq, zio->io_type); 438 if (qtt) 439 avl_add(qtt, zio); 440 441#ifdef illumos 442 mutex_enter(&spa->spa_iokstat_lock); 443 spa->spa_queue_stats[zio->io_priority].spa_queued++; 444 if (spa->spa_iokstat != NULL) 445 kstat_waitq_enter(spa->spa_iokstat->ks_data); 446 mutex_exit(&spa->spa_iokstat_lock); 447#endif 448} 449 450static void 451vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio) 452{ 453 spa_t *spa = zio->io_spa; 454 avl_tree_t *qtt; 455 456 ASSERT(MUTEX_HELD(&vq->vq_lock)); 457 ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); 458 avl_remove(vdev_queue_class_tree(vq, zio->io_priority), zio); 459 qtt = vdev_queue_type_tree(vq, zio->io_type); 460 if (qtt) 461 avl_remove(qtt, zio); 462 463#ifdef illumos 464 mutex_enter(&spa->spa_iokstat_lock); 465 ASSERT3U(spa->spa_queue_stats[zio->io_priority].spa_queued, >, 0); 466 spa->spa_queue_stats[zio->io_priority].spa_queued--; 467 if (spa->spa_iokstat != NULL) 468 kstat_waitq_exit(spa->spa_iokstat->ks_data); 469 mutex_exit(&spa->spa_iokstat_lock); 470#endif 471} 472 473static void 474vdev_queue_pending_add(vdev_queue_t *vq, zio_t *zio) 475{ 476 spa_t *spa = zio->io_spa; 477 ASSERT(MUTEX_HELD(&vq->vq_lock)); 478 ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); 479 vq->vq_class[zio->io_priority].vqc_active++; 480 avl_add(&vq->vq_active_tree, zio); 481 482#ifdef illumos 483 mutex_enter(&spa->spa_iokstat_lock); 484 spa->spa_queue_stats[zio->io_priority].spa_active++; 485 if (spa->spa_iokstat != NULL) 486 kstat_runq_enter(spa->spa_iokstat->ks_data); 487 mutex_exit(&spa->spa_iokstat_lock); 488#endif 489} 490 491static void 492vdev_queue_pending_remove(vdev_queue_t *vq, zio_t *zio) 493{ 494 spa_t *spa = zio->io_spa; 495 ASSERT(MUTEX_HELD(&vq->vq_lock)); 496 ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); 497 vq->vq_class[zio->io_priority].vqc_active--; 498 avl_remove(&vq->vq_active_tree, zio); 499 500#ifdef illumos 501 mutex_enter(&spa->spa_iokstat_lock); 502 ASSERT3U(spa->spa_queue_stats[zio->io_priority].spa_active, >, 0); 503 spa->spa_queue_stats[zio->io_priority].spa_active--; 504 if (spa->spa_iokstat != NULL) { 505 kstat_io_t *ksio = spa->spa_iokstat->ks_data; 506 507 kstat_runq_exit(spa->spa_iokstat->ks_data); 508 if (zio->io_type == ZIO_TYPE_READ) { 509 ksio->reads++; 510 ksio->nread += zio->io_size; 511 } else if (zio->io_type == ZIO_TYPE_WRITE) { 512 ksio->writes++; 513 ksio->nwritten += zio->io_size; 514 } 515 } 516 mutex_exit(&spa->spa_iokstat_lock); 517#endif 518} 519 520static void 521vdev_queue_agg_io_done(zio_t *aio) 522{ 523 if (aio->io_type == ZIO_TYPE_READ) { 524 zio_t *pio; 525 zio_link_t *zl = NULL; 526 while ((pio = zio_walk_parents(aio, &zl)) != NULL) { 527 abd_copy_off(pio->io_abd, aio->io_abd, 528 0, pio->io_offset - aio->io_offset, pio->io_size); 529 } 530 } 531 532 abd_free(aio->io_abd); 533} 534 535static int 536vdev_queue_class_min_active(zio_priority_t p) 537{ 538 switch (p) { 539 case ZIO_PRIORITY_SYNC_READ: 540 return (zfs_vdev_sync_read_min_active); 541 case ZIO_PRIORITY_SYNC_WRITE: 542 return (zfs_vdev_sync_write_min_active); 543 case ZIO_PRIORITY_ASYNC_READ: 544 return (zfs_vdev_async_read_min_active); 545 case ZIO_PRIORITY_ASYNC_WRITE: 546 return (zfs_vdev_async_write_min_active); 547 case ZIO_PRIORITY_SCRUB: 548 return (zfs_vdev_scrub_min_active); 549 case ZIO_PRIORITY_TRIM: 550 return (zfs_vdev_trim_min_active); 551 case ZIO_PRIORITY_REMOVAL: 552 return (zfs_vdev_removal_min_active); 553 case ZIO_PRIORITY_INITIALIZING: 554 return (zfs_vdev_initializing_min_active); 555 default: 556 panic("invalid priority %u", p); 557 return (0); 558 } 559} 560 561static __noinline int 562vdev_queue_max_async_writes(spa_t *spa) 563{ 564 int writes; 565 uint64_t dirty = spa->spa_dsl_pool->dp_dirty_total; 566 uint64_t min_bytes = zfs_dirty_data_max * 567 zfs_vdev_async_write_active_min_dirty_percent / 100; 568 uint64_t max_bytes = zfs_dirty_data_max * 569 zfs_vdev_async_write_active_max_dirty_percent / 100; 570 571 /* 572 * Sync tasks correspond to interactive user actions. To reduce the 573 * execution time of those actions we push data out as fast as possible. 574 */ 575 if (spa_has_pending_synctask(spa)) { 576 return (zfs_vdev_async_write_max_active); 577 } 578 579 if (dirty < min_bytes) 580 return (zfs_vdev_async_write_min_active); 581 if (dirty > max_bytes) 582 return (zfs_vdev_async_write_max_active); 583 584 /* 585 * linear interpolation: 586 * slope = (max_writes - min_writes) / (max_bytes - min_bytes) 587 * move right by min_bytes 588 * move up by min_writes 589 */ 590 writes = (dirty - min_bytes) * 591 (zfs_vdev_async_write_max_active - 592 zfs_vdev_async_write_min_active) / 593 (max_bytes - min_bytes) + 594 zfs_vdev_async_write_min_active; 595 ASSERT3U(writes, >=, zfs_vdev_async_write_min_active); 596 ASSERT3U(writes, <=, zfs_vdev_async_write_max_active); 597 return (writes); 598} 599 600static int 601vdev_queue_class_max_active(spa_t *spa, zio_priority_t p) 602{ 603 switch (p) { 604 case ZIO_PRIORITY_SYNC_READ: 605 return (zfs_vdev_sync_read_max_active); 606 case ZIO_PRIORITY_SYNC_WRITE: 607 return (zfs_vdev_sync_write_max_active); 608 case ZIO_PRIORITY_ASYNC_READ: 609 return (zfs_vdev_async_read_max_active); 610 case ZIO_PRIORITY_ASYNC_WRITE: 611 return (vdev_queue_max_async_writes(spa)); 612 case ZIO_PRIORITY_SCRUB: 613 return (zfs_vdev_scrub_max_active); 614 case ZIO_PRIORITY_TRIM: 615 return (zfs_vdev_trim_max_active); 616 case ZIO_PRIORITY_REMOVAL: 617 return (zfs_vdev_removal_max_active); 618 case ZIO_PRIORITY_INITIALIZING: 619 return (zfs_vdev_initializing_max_active); 620 default: 621 panic("invalid priority %u", p); 622 return (0); 623 } 624} 625 626/* 627 * Return the i/o class to issue from, or ZIO_PRIORITY_MAX_QUEUEABLE if 628 * there is no eligible class. 629 */ 630static zio_priority_t 631vdev_queue_class_to_issue(vdev_queue_t *vq) 632{ 633 spa_t *spa = vq->vq_vdev->vdev_spa; 634 zio_priority_t p; 635 636 ASSERT(MUTEX_HELD(&vq->vq_lock)); 637 638 if (avl_numnodes(&vq->vq_active_tree) >= zfs_vdev_max_active) 639 return (ZIO_PRIORITY_NUM_QUEUEABLE); 640 641 /* find a queue that has not reached its minimum # outstanding i/os */ 642 for (p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) { 643 if (avl_numnodes(vdev_queue_class_tree(vq, p)) > 0 && 644 vq->vq_class[p].vqc_active < 645 vdev_queue_class_min_active(p)) 646 return (p); 647 } 648 649 /* 650 * If we haven't found a queue, look for one that hasn't reached its 651 * maximum # outstanding i/os. 652 */ 653 for (p = 0; p < ZIO_PRIORITY_NUM_QUEUEABLE; p++) { 654 if (avl_numnodes(vdev_queue_class_tree(vq, p)) > 0 && 655 vq->vq_class[p].vqc_active < 656 vdev_queue_class_max_active(spa, p)) 657 return (p); 658 } 659 660 /* No eligible queued i/os */ 661 return (ZIO_PRIORITY_NUM_QUEUEABLE); 662} 663 664/* 665 * Compute the range spanned by two i/os, which is the endpoint of the last 666 * (lio->io_offset + lio->io_size) minus start of the first (fio->io_offset). 667 * Conveniently, the gap between fio and lio is given by -IO_SPAN(lio, fio); 668 * thus fio and lio are adjacent if and only if IO_SPAN(lio, fio) == 0. 669 */ 670#define IO_SPAN(fio, lio) ((lio)->io_offset + (lio)->io_size - (fio)->io_offset) 671#define IO_GAP(fio, lio) (-IO_SPAN(lio, fio)) 672 673static zio_t * 674vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio) 675{ 676 zio_t *first, *last, *aio, *dio, *mandatory, *nio; 677 zio_link_t *zl = NULL; 678 uint64_t maxgap = 0; 679 uint64_t size; 680 uint64_t limit; 681 int maxblocksize; 682 boolean_t stretch; 683 avl_tree_t *t; 684 enum zio_flag flags; 685 686 ASSERT(MUTEX_HELD(&vq->vq_lock)); 687 688 maxblocksize = spa_maxblocksize(vq->vq_vdev->vdev_spa); 689 if (vq->vq_vdev->vdev_nonrot) 690 limit = zfs_vdev_aggregation_limit_non_rotating; 691 else 692 limit = zfs_vdev_aggregation_limit; 693 limit = MAX(MIN(limit, maxblocksize), 0); 694 695 if (zio->io_flags & ZIO_FLAG_DONT_AGGREGATE || limit == 0) 696 return (NULL); 697 698 first = last = zio; 699 700 if (zio->io_type == ZIO_TYPE_READ) 701 maxgap = zfs_vdev_read_gap_limit; 702 703 /* 704 * We can aggregate I/Os that are sufficiently adjacent and of 705 * the same flavor, as expressed by the AGG_INHERIT flags. 706 * The latter requirement is necessary so that certain 707 * attributes of the I/O, such as whether it's a normal I/O 708 * or a scrub/resilver, can be preserved in the aggregate. 709 * We can include optional I/Os, but don't allow them 710 * to begin a range as they add no benefit in that situation. 711 */ 712 713 /* 714 * We keep track of the last non-optional I/O. 715 */ 716 mandatory = (first->io_flags & ZIO_FLAG_OPTIONAL) ? NULL : first; 717 718 /* 719 * Walk backwards through sufficiently contiguous I/Os 720 * recording the last non-optional I/O. 721 */ 722 flags = zio->io_flags & ZIO_FLAG_AGG_INHERIT; 723 t = vdev_queue_type_tree(vq, zio->io_type); 724 while (t != NULL && (dio = AVL_PREV(t, first)) != NULL && 725 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && 726 IO_SPAN(dio, last) <= limit && 727 IO_GAP(dio, first) <= maxgap && 728 dio->io_type == zio->io_type) { 729 first = dio; 730 if (mandatory == NULL && !(first->io_flags & ZIO_FLAG_OPTIONAL)) 731 mandatory = first; 732 } 733 734 /* 735 * Skip any initial optional I/Os. 736 */ 737 while ((first->io_flags & ZIO_FLAG_OPTIONAL) && first != last) { 738 first = AVL_NEXT(t, first); 739 ASSERT(first != NULL); 740 } 741 742 /* 743 * Walk forward through sufficiently contiguous I/Os. 744 * The aggregation limit does not apply to optional i/os, so that 745 * we can issue contiguous writes even if they are larger than the 746 * aggregation limit. 747 */ 748 while ((dio = AVL_NEXT(t, last)) != NULL && 749 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && 750 (IO_SPAN(first, dio) <= limit || 751 (dio->io_flags & ZIO_FLAG_OPTIONAL)) && 752 IO_SPAN(first, dio) <= maxblocksize && 753 IO_GAP(last, dio) <= maxgap && 754 dio->io_type == zio->io_type) { 755 last = dio; 756 if (!(last->io_flags & ZIO_FLAG_OPTIONAL)) 757 mandatory = last; 758 } 759 760 /* 761 * Now that we've established the range of the I/O aggregation 762 * we must decide what to do with trailing optional I/Os. 763 * For reads, there's nothing to do. While we are unable to 764 * aggregate further, it's possible that a trailing optional 765 * I/O would allow the underlying device to aggregate with 766 * subsequent I/Os. We must therefore determine if the next 767 * non-optional I/O is close enough to make aggregation 768 * worthwhile. 769 */ 770 stretch = B_FALSE; 771 if (zio->io_type == ZIO_TYPE_WRITE && mandatory != NULL) { 772 zio_t *nio = last; 773 while ((dio = AVL_NEXT(t, nio)) != NULL && 774 IO_GAP(nio, dio) == 0 && 775 IO_GAP(mandatory, dio) <= zfs_vdev_write_gap_limit) { 776 nio = dio; 777 if (!(nio->io_flags & ZIO_FLAG_OPTIONAL)) { 778 stretch = B_TRUE; 779 break; 780 } 781 } 782 } 783 784 if (stretch) { 785 /* 786 * We are going to include an optional io in our aggregated 787 * span, thus closing the write gap. Only mandatory i/os can 788 * start aggregated spans, so make sure that the next i/o 789 * after our span is mandatory. 790 */ 791 dio = AVL_NEXT(t, last); 792 dio->io_flags &= ~ZIO_FLAG_OPTIONAL; 793 } else { 794 /* do not include the optional i/o */ 795 while (last != mandatory && last != first) { 796 ASSERT(last->io_flags & ZIO_FLAG_OPTIONAL); 797 last = AVL_PREV(t, last); 798 ASSERT(last != NULL); 799 } 800 } 801 802 if (first == last) 803 return (NULL); 804 805 size = IO_SPAN(first, last); 806 ASSERT3U(size, <=, maxblocksize); 807 808 aio = zio_vdev_delegated_io(first->io_vd, first->io_offset, 809 abd_alloc_for_io(size, B_TRUE), size, first->io_type, 810 zio->io_priority, flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE, 811 vdev_queue_agg_io_done, NULL); 812 aio->io_timestamp = first->io_timestamp; 813 814 nio = first; 815 do { 816 dio = nio; 817 nio = AVL_NEXT(t, dio); 818 ASSERT3U(dio->io_type, ==, aio->io_type); 819 820 if (dio->io_flags & ZIO_FLAG_NODATA) { 821 ASSERT3U(dio->io_type, ==, ZIO_TYPE_WRITE); 822 abd_zero_off(aio->io_abd, 823 dio->io_offset - aio->io_offset, dio->io_size); 824 } else if (dio->io_type == ZIO_TYPE_WRITE) { 825 abd_copy_off(aio->io_abd, dio->io_abd, 826 dio->io_offset - aio->io_offset, 0, dio->io_size); 827 } 828 829 zio_add_child(dio, aio); 830 vdev_queue_io_remove(vq, dio); 831 } while (dio != last); 832 833 /* 834 * We need to drop the vdev queue's lock to avoid a deadlock that we 835 * could encounter since this I/O will complete immediately. 836 */ 837 mutex_exit(&vq->vq_lock); 838 while ((dio = zio_walk_parents(aio, &zl)) != NULL) { 839 zio_vdev_io_bypass(dio); 840 zio_execute(dio); 841 } 842 mutex_enter(&vq->vq_lock); 843 844 return (aio); 845} 846 847static zio_t * 848vdev_queue_io_to_issue(vdev_queue_t *vq) 849{ 850 zio_t *zio, *aio; 851 zio_priority_t p; 852 avl_index_t idx; 853 avl_tree_t *tree; 854 zio_t search; 855 856again: 857 ASSERT(MUTEX_HELD(&vq->vq_lock)); 858 859 p = vdev_queue_class_to_issue(vq); 860 861 if (p == ZIO_PRIORITY_NUM_QUEUEABLE) { 862 /* No eligible queued i/os */ 863 return (NULL); 864 } 865 866 /* 867 * For LBA-ordered queues (async / scrub / initializing), issue the 868 * i/o which follows the most recently issued i/o in LBA (offset) order. 869 * 870 * For FIFO queues (sync), issue the i/o with the lowest timestamp. 871 */ 872 tree = vdev_queue_class_tree(vq, p); 873 search.io_timestamp = 0; 874 search.io_offset = vq->vq_last_offset + 1; 875 VERIFY3P(avl_find(tree, &search, &idx), ==, NULL); 876 zio = avl_nearest(tree, idx, AVL_AFTER); 877 if (zio == NULL) 878 zio = avl_first(tree); 879 ASSERT3U(zio->io_priority, ==, p); 880 881 aio = vdev_queue_aggregate(vq, zio); 882 if (aio != NULL) 883 zio = aio; 884 else 885 vdev_queue_io_remove(vq, zio); 886 887 /* 888 * If the I/O is or was optional and therefore has no data, we need to 889 * simply discard it. We need to drop the vdev queue's lock to avoid a 890 * deadlock that we could encounter since this I/O will complete 891 * immediately. 892 */ 893 if (zio->io_flags & ZIO_FLAG_NODATA) { 894 mutex_exit(&vq->vq_lock); 895 zio_vdev_io_bypass(zio); 896 zio_execute(zio); 897 mutex_enter(&vq->vq_lock); 898 goto again; 899 } 900 901 vdev_queue_pending_add(vq, zio); 902 vq->vq_last_offset = zio->io_offset; 903 904 return (zio); 905} 906 907zio_t * 908vdev_queue_io(zio_t *zio) 909{ 910 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 911 zio_t *nio; 912 913 if (zio->io_flags & ZIO_FLAG_DONT_QUEUE) 914 return (zio); 915 916 /* 917 * Children i/os inherent their parent's priority, which might 918 * not match the child's i/o type. Fix it up here. 919 */ 920 if (zio->io_type == ZIO_TYPE_READ) { 921 if (zio->io_priority != ZIO_PRIORITY_SYNC_READ && 922 zio->io_priority != ZIO_PRIORITY_ASYNC_READ && 923 zio->io_priority != ZIO_PRIORITY_SCRUB && 924 zio->io_priority != ZIO_PRIORITY_REMOVAL && 925 zio->io_priority != ZIO_PRIORITY_INITIALIZING) 926 zio->io_priority = ZIO_PRIORITY_ASYNC_READ; 927 } else if (zio->io_type == ZIO_TYPE_WRITE) { 928 if (zio->io_priority != ZIO_PRIORITY_SYNC_WRITE && 929 zio->io_priority != ZIO_PRIORITY_ASYNC_WRITE && 930 zio->io_priority != ZIO_PRIORITY_REMOVAL && 931 zio->io_priority != ZIO_PRIORITY_INITIALIZING) 932 zio->io_priority = ZIO_PRIORITY_ASYNC_WRITE; 933 } else { 934 ASSERT(zio->io_type == ZIO_TYPE_FREE); 935 zio->io_priority = ZIO_PRIORITY_TRIM; 936 } 937 938 zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE; 939 940 mutex_enter(&vq->vq_lock); 941 zio->io_timestamp = gethrtime(); 942 vdev_queue_io_add(vq, zio); 943 nio = vdev_queue_io_to_issue(vq); 944 mutex_exit(&vq->vq_lock); 945 946 if (nio == NULL) 947 return (NULL); 948 949 if (nio->io_done == vdev_queue_agg_io_done) { 950 zio_nowait(nio); 951 return (NULL); 952 } 953 954 return (nio); 955} 956 957void 958vdev_queue_io_done(zio_t *zio) 959{ 960 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 961 zio_t *nio; 962 963 mutex_enter(&vq->vq_lock); 964 965 vdev_queue_pending_remove(vq, zio); 966 967 vq->vq_io_complete_ts = gethrtime(); 968 969 while ((nio = vdev_queue_io_to_issue(vq)) != NULL) { 970 mutex_exit(&vq->vq_lock); 971 if (nio->io_done == vdev_queue_agg_io_done) { 972 zio_nowait(nio); 973 } else { 974 zio_vdev_io_reissue(nio); 975 zio_execute(nio); 976 } 977 mutex_enter(&vq->vq_lock); 978 } 979 980 mutex_exit(&vq->vq_lock); 981} 982 983void 984vdev_queue_change_io_priority(zio_t *zio, zio_priority_t priority) 985{ 986 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 987 avl_tree_t *tree; 988 989 /* 990 * ZIO_PRIORITY_NOW is used by the vdev cache code and the aggregate zio 991 * code to issue IOs without adding them to the vdev queue. In this 992 * case, the zio is already going to be issued as quickly as possible 993 * and so it doesn't need any reprioitization to help. 994 */ 995 if (zio->io_priority == ZIO_PRIORITY_NOW) 996 return; 997 998 ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); 999 ASSERT3U(priority, <, ZIO_PRIORITY_NUM_QUEUEABLE); 1000 1001 if (zio->io_type == ZIO_TYPE_READ) { 1002 if (priority != ZIO_PRIORITY_SYNC_READ && 1003 priority != ZIO_PRIORITY_ASYNC_READ && 1004 priority != ZIO_PRIORITY_SCRUB) 1005 priority = ZIO_PRIORITY_ASYNC_READ; 1006 } else { 1007 ASSERT(zio->io_type == ZIO_TYPE_WRITE); 1008 if (priority != ZIO_PRIORITY_SYNC_WRITE && 1009 priority != ZIO_PRIORITY_ASYNC_WRITE) 1010 priority = ZIO_PRIORITY_ASYNC_WRITE; 1011 } 1012 1013 mutex_enter(&vq->vq_lock); 1014 1015 /* 1016 * If the zio is in none of the queues we can simply change 1017 * the priority. If the zio is waiting to be submitted we must 1018 * remove it from the queue and re-insert it with the new priority. 1019 * Otherwise, the zio is currently active and we cannot change its 1020 * priority. 1021 */ 1022 tree = vdev_queue_class_tree(vq, zio->io_priority); 1023 if (avl_find(tree, zio, NULL) == zio) { 1024 avl_remove(vdev_queue_class_tree(vq, zio->io_priority), zio); 1025 zio->io_priority = priority; 1026 avl_add(vdev_queue_class_tree(vq, zio->io_priority), zio); 1027 } else if (avl_find(&vq->vq_active_tree, zio, NULL) != zio) { 1028 zio->io_priority = priority; 1029 } 1030 1031 mutex_exit(&vq->vq_lock); 1032} 1033 1034/* 1035 * As these three methods are only used for load calculations we're not concerned 1036 * if we get an incorrect value on 32bit platforms due to lack of vq_lock mutex 1037 * use here, instead we prefer to keep it lock free for performance. 1038 */ 1039int 1040vdev_queue_length(vdev_t *vd) 1041{ 1042 return (avl_numnodes(&vd->vdev_queue.vq_active_tree)); 1043} 1044 1045uint64_t 1046vdev_queue_lastoffset(vdev_t *vd) 1047{ 1048 return (vd->vdev_queue.vq_lastoffset); 1049} 1050 1051void 1052vdev_queue_register_lastoffset(vdev_t *vd, zio_t *zio) 1053{ 1054 vd->vdev_queue.vq_lastoffset = zio->io_offset + zio->io_size; 1055} 1056