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 * zfs_vdev_max_pending is the maximum number of i/os concurrently 40 * pending to each device. zfs_vdev_min_pending is the initial number 41 * of i/os pending to each device (before it starts ramping up to 42 * max_pending). 43 */ 44 int zfs_vdev_max_pending = 10; 45 int zfs_vdev_min_pending = 4; 46 47 /* deadline = pri + ddi_get_lbolt64() >> time_shift) */ 48 int zfs_vdev_time_shift = 6; 49 50 /* exponential I/O issue ramp-up rate */ 51 int zfs_vdev_ramp_rate = 2; 52 53 /* 54 * To reduce IOPs, we aggregate small adjacent I/Os into one large I/O. 55 * For read I/Os, we also aggregate across small adjacency gaps; for writes 56 * we include spans of optional I/Os to aid aggregation at the disk even when 57 * they aren't able to help us aggregate at this level. 58 */ 59 int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE; 60 int zfs_vdev_read_gap_limit = 32 << 10; 61 int zfs_vdev_write_gap_limit = 4 << 10; 62 63 /* 64 * Virtual device vector for disk I/O scheduling. 65 */ 66 int 67 vdev_queue_deadline_compare(const void *x1, const void *x2) 68 { 69 const zio_t *z1 = x1; 70 const zio_t *z2 = x2; 71 72 if (z1->io_deadline < z2->io_deadline) 73 return (-1); 74 if (z1->io_deadline > z2->io_deadline) 75 return (1); 76 77 if (z1->io_offset < z2->io_offset) 78 return (-1); 79 if (z1->io_offset > z2->io_offset) 80 return (1); 81 82 if (z1 < z2) 83 return (-1); 84 if (z1 > z2) 85 return (1); 86 87 return (0); 88 } 89 90 int 91 vdev_queue_offset_compare(const void *x1, const void *x2) 92 { 93 const zio_t *z1 = x1; 94 const zio_t *z2 = x2; 95 96 if (z1->io_offset < z2->io_offset) 97 return (-1); 98 if (z1->io_offset > z2->io_offset) 99 return (1); 100 101 if (z1 < z2) 102 return (-1); 103 if (z1 > z2) 104 return (1); 105 106 return (0); 107 } 108 109 void 110 vdev_queue_init(vdev_t *vd) 111 { 112 vdev_queue_t *vq = &vd->vdev_queue; 113 114 mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL); 115 116 avl_create(&vq->vq_deadline_tree, vdev_queue_deadline_compare, 117 sizeof (zio_t), offsetof(struct zio, io_deadline_node)); 118 119 avl_create(&vq->vq_read_tree, vdev_queue_offset_compare, 120 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 121 122 avl_create(&vq->vq_write_tree, vdev_queue_offset_compare, 123 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 124 125 avl_create(&vq->vq_pending_tree, vdev_queue_offset_compare, 126 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 127 } 128 129 void 130 vdev_queue_fini(vdev_t *vd) 131 { 132 vdev_queue_t *vq = &vd->vdev_queue; 133 134 avl_destroy(&vq->vq_deadline_tree); 135 avl_destroy(&vq->vq_read_tree); 136 avl_destroy(&vq->vq_write_tree); 137 avl_destroy(&vq->vq_pending_tree); 138 139 mutex_destroy(&vq->vq_lock); 140 } 141 142 static void 143 vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio) 144 { 145 avl_add(&vq->vq_deadline_tree, zio); 146 avl_add(zio->io_vdev_tree, zio); 147 } 148 149 static void 150 vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio) 151 { 152 avl_remove(&vq->vq_deadline_tree, zio); 153 avl_remove(zio->io_vdev_tree, zio); 154 } 155 156 static void 157 vdev_queue_agg_io_done(zio_t *aio) 158 { 159 zio_t *pio; 160 161 while ((pio = zio_walk_parents(aio)) != NULL) 162 if (aio->io_type == ZIO_TYPE_READ) 163 bcopy((char *)aio->io_data + (pio->io_offset - 164 aio->io_offset), pio->io_data, pio->io_size); 165 166 zio_buf_free(aio->io_data, aio->io_size); 167 } 168 169 /* 170 * Compute the range spanned by two i/os, which is the endpoint of the last 171 * (lio->io_offset + lio->io_size) minus start of the first (fio->io_offset). 172 * Conveniently, the gap between fio and lio is given by -IO_SPAN(lio, fio); 173 * thus fio and lio are adjacent if and only if IO_SPAN(lio, fio) == 0. 174 */ 175 #define IO_SPAN(fio, lio) ((lio)->io_offset + (lio)->io_size - (fio)->io_offset) 176 #define IO_GAP(fio, lio) (-IO_SPAN(lio, fio)) 177 178 static zio_t * 179 vdev_queue_io_to_issue(vdev_queue_t *vq, uint64_t pending_limit) 180 { 181 zio_t *fio, *lio, *aio, *dio, *nio, *mio; 182 avl_tree_t *t; 183 int flags; 184 uint64_t maxspan = zfs_vdev_aggregation_limit; 185 uint64_t maxgap; 186 int stretch; 187 188 again: 189 ASSERT(MUTEX_HELD(&vq->vq_lock)); 190 191 if (avl_numnodes(&vq->vq_pending_tree) >= pending_limit || 192 avl_numnodes(&vq->vq_deadline_tree) == 0) 193 return (NULL); 194 195 fio = lio = avl_first(&vq->vq_deadline_tree); 196 197 t = fio->io_vdev_tree; 198 flags = fio->io_flags & ZIO_FLAG_AGG_INHERIT; 199 maxgap = (t == &vq->vq_read_tree) ? zfs_vdev_read_gap_limit : 0; 200 201 if (!(flags & ZIO_FLAG_DONT_AGGREGATE)) { 202 /* 203 * We can aggregate I/Os that are sufficiently adjacent and of 204 * the same flavor, as expressed by the AGG_INHERIT flags. 205 * The latter requirement is necessary so that certain 206 * attributes of the I/O, such as whether it's a normal I/O 207 * or a scrub/resilver, can be preserved in the aggregate. 208 * We can include optional I/Os, but don't allow them 209 * to begin a range as they add no benefit in that situation. 210 */ 211 212 /* 213 * We keep track of the last non-optional I/O. 214 */ 215 mio = (fio->io_flags & ZIO_FLAG_OPTIONAL) ? NULL : fio; 216 217 /* 218 * Walk backwards through sufficiently contiguous I/Os 219 * recording the last non-option I/O. 220 */ 221 while ((dio = AVL_PREV(t, fio)) != NULL && 222 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && 223 IO_SPAN(dio, lio) <= maxspan && 224 IO_GAP(dio, fio) <= maxgap) { 225 fio = dio; 226 if (mio == NULL && !(fio->io_flags & ZIO_FLAG_OPTIONAL)) 227 mio = fio; 228 } 229 230 /* 231 * Skip any initial optional I/Os. 232 */ 233 while ((fio->io_flags & ZIO_FLAG_OPTIONAL) && fio != lio) { 234 fio = AVL_NEXT(t, fio); 235 ASSERT(fio != NULL); 236 } 237 238 /* 239 * Walk forward through sufficiently contiguous I/Os. 240 */ 241 while ((dio = AVL_NEXT(t, lio)) != NULL && 242 (dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags && 243 IO_SPAN(fio, dio) <= maxspan && 244 IO_GAP(lio, dio) <= maxgap) { 245 lio = dio; 246 if (!(lio->io_flags & ZIO_FLAG_OPTIONAL)) 247 mio = lio; 248 } 249 250 /* 251 * Now that we've established the range of the I/O aggregation 252 * we must decide what to do with trailing optional I/Os. 253 * For reads, there's nothing to do. While we are unable to 254 * aggregate further, it's possible that a trailing optional 255 * I/O would allow the underlying device to aggregate with 256 * subsequent I/Os. We must therefore determine if the next 257 * non-optional I/O is close enough to make aggregation 258 * worthwhile. 259 */ 260 stretch = B_FALSE; 261 if (t != &vq->vq_read_tree && mio != NULL) { 262 nio = lio; 263 while ((dio = AVL_NEXT(t, nio)) != NULL && 264 IO_GAP(nio, dio) == 0 && 265 IO_GAP(mio, dio) <= zfs_vdev_write_gap_limit) { 266 nio = dio; 267 if (!(nio->io_flags & ZIO_FLAG_OPTIONAL)) { 268 stretch = B_TRUE; 269 break; 270 } 271 } 272 } 273 274 if (stretch) { 275 /* This may be a no-op. */ 276 VERIFY((dio = AVL_NEXT(t, lio)) != NULL); 277 dio->io_flags &= ~ZIO_FLAG_OPTIONAL; 278 } else { 279 while (lio != mio && lio != fio) { 280 ASSERT(lio->io_flags & ZIO_FLAG_OPTIONAL); 281 lio = AVL_PREV(t, lio); 282 ASSERT(lio != NULL); 283 } 284 } 285 } 286 287 if (fio != lio) { 288 uint64_t size = IO_SPAN(fio, lio); 289 ASSERT(size <= zfs_vdev_aggregation_limit); 290 291 aio = zio_vdev_delegated_io(fio->io_vd, fio->io_offset, 292 zio_buf_alloc(size), size, fio->io_type, ZIO_PRIORITY_AGG, 293 flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE, 294 vdev_queue_agg_io_done, NULL); 295 aio->io_timestamp = fio->io_timestamp; 296 297 nio = fio; 298 do { 299 dio = nio; 300 nio = AVL_NEXT(t, dio); 301 ASSERT(dio->io_type == aio->io_type); 302 ASSERT(dio->io_vdev_tree == t); 303 304 if (dio->io_flags & ZIO_FLAG_NODATA) { 305 ASSERT(dio->io_type == ZIO_TYPE_WRITE); 306 bzero((char *)aio->io_data + (dio->io_offset - 307 aio->io_offset), dio->io_size); 308 } else if (dio->io_type == ZIO_TYPE_WRITE) { 309 bcopy(dio->io_data, (char *)aio->io_data + 310 (dio->io_offset - aio->io_offset), 311 dio->io_size); 312 } 313 314 zio_add_child(dio, aio); 315 vdev_queue_io_remove(vq, dio); 316 zio_vdev_io_bypass(dio); 317 zio_execute(dio); 318 } while (dio != lio); 319 320 avl_add(&vq->vq_pending_tree, aio); 321 322 return (aio); 323 } 324 325 ASSERT(fio->io_vdev_tree == t); 326 vdev_queue_io_remove(vq, fio); 327 328 /* 329 * If the I/O is or was optional and therefore has no data, we need to 330 * simply discard it. We need to drop the vdev queue's lock to avoid a 331 * deadlock that we could encounter since this I/O will complete 332 * immediately. 333 */ 334 if (fio->io_flags & ZIO_FLAG_NODATA) { 335 mutex_exit(&vq->vq_lock); 336 zio_vdev_io_bypass(fio); 337 zio_execute(fio); 338 mutex_enter(&vq->vq_lock); 339 goto again; 340 } 341 342 avl_add(&vq->vq_pending_tree, fio); 343 344 return (fio); 345 } 346 347 zio_t * 348 vdev_queue_io(zio_t *zio) 349 { 350 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 351 zio_t *nio; 352 353 ASSERT(zio->io_type == ZIO_TYPE_READ || zio->io_type == ZIO_TYPE_WRITE); 354 355 if (zio->io_flags & ZIO_FLAG_DONT_QUEUE) 356 return (zio); 357 358 zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE; 359 360 if (zio->io_type == ZIO_TYPE_READ) 361 zio->io_vdev_tree = &vq->vq_read_tree; 362 else 363 zio->io_vdev_tree = &vq->vq_write_tree; 364 365 mutex_enter(&vq->vq_lock); 366 367 zio->io_timestamp = ddi_get_lbolt64(); 368 zio->io_deadline = (zio->io_timestamp >> zfs_vdev_time_shift) + 369 zio->io_priority; 370 371 vdev_queue_io_add(vq, zio); 372 373 nio = vdev_queue_io_to_issue(vq, zfs_vdev_min_pending); 374 375 mutex_exit(&vq->vq_lock); 376 377 if (nio == NULL) 378 return (NULL); 379 380 if (nio->io_done == vdev_queue_agg_io_done) { 381 zio_nowait(nio); 382 return (NULL); 383 } 384 385 return (nio); 386 } 387 388 void 389 vdev_queue_io_done(zio_t *zio) 390 { 391 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 392 393 if (zio_injection_enabled) 394 delay(SEC_TO_TICK(zio_handle_io_delay(zio))); 395 396 mutex_enter(&vq->vq_lock); 397 398 avl_remove(&vq->vq_pending_tree, zio); 399 400 vq->vq_io_complete_ts = ddi_get_lbolt64(); 401 vq->vq_io_delta_ts = vq->vq_io_complete_ts - zio->io_timestamp; 402 403 for (int i = 0; i < zfs_vdev_ramp_rate; i++) { 404 zio_t *nio = vdev_queue_io_to_issue(vq, zfs_vdev_max_pending); 405 if (nio == NULL) 406 break; 407 mutex_exit(&vq->vq_lock); 408 if (nio->io_done == vdev_queue_agg_io_done) { 409 zio_nowait(nio); 410 } else { 411 zio_vdev_io_reissue(nio); 412 zio_execute(nio); 413 } 414 mutex_enter(&vq->vq_lock); 415 } 416 417 mutex_exit(&vq->vq_lock); 418 } 419