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 #include <sys/zfs_context.h> 27 #include <sys/spa.h> 28 #include <sys/vdev_impl.h> 29 #include <sys/zio.h> 30 #include <sys/avl.h> 31 32 /* 33 * These tunables are for performance analysis. 34 */ 35 /* 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 39 * max_pending). 40 */ 41 int zfs_vdev_max_pending = 35; 42 int zfs_vdev_min_pending = 4; 43 44 /* deadline = pri + (lbolt >> time_shift) */ 45 int zfs_vdev_time_shift = 6; 46 47 /* exponential I/O issue ramp-up rate */ 48 int zfs_vdev_ramp_rate = 2; 49 50 /* 51 * i/os will be aggregated into a single large i/o up to 52 * zfs_vdev_aggregation_limit bytes long. 53 */ 54 int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE; 55 56 /* 57 * Virtual device vector for disk I/O scheduling. 58 */ 59 int 60 vdev_queue_deadline_compare(const void *x1, const void *x2) 61 { 62 const zio_t *z1 = x1; 63 const zio_t *z2 = x2; 64 65 if (z1->io_deadline < z2->io_deadline) 66 return (-1); 67 if (z1->io_deadline > z2->io_deadline) 68 return (1); 69 70 if (z1->io_offset < z2->io_offset) 71 return (-1); 72 if (z1->io_offset > z2->io_offset) 73 return (1); 74 75 if (z1 < z2) 76 return (-1); 77 if (z1 > z2) 78 return (1); 79 80 return (0); 81 } 82 83 int 84 vdev_queue_offset_compare(const void *x1, const void *x2) 85 { 86 const zio_t *z1 = x1; 87 const zio_t *z2 = x2; 88 89 if (z1->io_offset < z2->io_offset) 90 return (-1); 91 if (z1->io_offset > z2->io_offset) 92 return (1); 93 94 if (z1 < z2) 95 return (-1); 96 if (z1 > z2) 97 return (1); 98 99 return (0); 100 } 101 102 void 103 vdev_queue_init(vdev_t *vd) 104 { 105 vdev_queue_t *vq = &vd->vdev_queue; 106 107 mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL); 108 109 avl_create(&vq->vq_deadline_tree, vdev_queue_deadline_compare, 110 sizeof (zio_t), offsetof(struct zio, io_deadline_node)); 111 112 avl_create(&vq->vq_read_tree, vdev_queue_offset_compare, 113 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 114 115 avl_create(&vq->vq_write_tree, vdev_queue_offset_compare, 116 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 117 118 avl_create(&vq->vq_pending_tree, vdev_queue_offset_compare, 119 sizeof (zio_t), offsetof(struct zio, io_offset_node)); 120 } 121 122 void 123 vdev_queue_fini(vdev_t *vd) 124 { 125 vdev_queue_t *vq = &vd->vdev_queue; 126 127 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); 131 132 mutex_destroy(&vq->vq_lock); 133 } 134 135 static void 136 vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio) 137 { 138 avl_add(&vq->vq_deadline_tree, zio); 139 avl_add(zio->io_vdev_tree, zio); 140 } 141 142 static void 143 vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio) 144 { 145 avl_remove(&vq->vq_deadline_tree, zio); 146 avl_remove(zio->io_vdev_tree, zio); 147 } 148 149 static void 150 vdev_queue_agg_io_done(zio_t *aio) 151 { 152 zio_t *pio; 153 154 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); 158 159 zio_buf_free(aio->io_data, aio->io_size); 160 } 161 162 #define IS_ADJACENT(io, nio) \ 163 ((io)->io_offset + (io)->io_size == (nio)->io_offset) 164 165 static zio_t * 166 vdev_queue_io_to_issue(vdev_queue_t *vq, uint64_t pending_limit) 167 { 168 zio_t *fio, *lio, *aio, *dio, *nio; 169 avl_tree_t *t; 170 uint64_t size; 171 int flags; 172 173 ASSERT(MUTEX_HELD(&vq->vq_lock)); 174 175 if (avl_numnodes(&vq->vq_pending_tree) >= pending_limit || 176 avl_numnodes(&vq->vq_deadline_tree) == 0) 177 return (NULL); 178 179 fio = lio = avl_first(&vq->vq_deadline_tree); 180 181 t = fio->io_vdev_tree; 182 size = fio->io_size; 183 flags = fio->io_flags & ZIO_FLAG_AGG_INHERIT; 184 185 if (!(flags & ZIO_FLAG_DONT_AGGREGATE)) { 186 /* 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. 192 */ 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) { 197 fio = dio; 198 size += dio->io_size; 199 } 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) { 204 lio = dio; 205 size += dio->io_size; 206 } 207 } 208 209 if (fio != lio) { 210 ASSERT(size <= zfs_vdev_aggregation_limit); 211 212 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); 216 217 /* 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); 222 223 if (dio->io_type == ZIO_TYPE_WRITE) 224 bcopy(dio->io_data, (char *)aio->io_data + 225 (dio->io_offset - aio->io_offset), 226 dio->io_size); 227 nio = AVL_NEXT(t, dio); 228 229 zio_add_child(dio, aio); 230 vdev_queue_io_remove(vq, dio); 231 zio_vdev_io_bypass(dio); 232 zio_execute(dio); 233 } 234 235 avl_add(&vq->vq_pending_tree, aio); 236 237 return (aio); 238 } 239 240 ASSERT(fio->io_vdev_tree == t); 241 vdev_queue_io_remove(vq, fio); 242 243 avl_add(&vq->vq_pending_tree, fio); 244 245 return (fio); 246 } 247 248 zio_t * 249 vdev_queue_io(zio_t *zio) 250 { 251 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 252 zio_t *nio; 253 254 ASSERT(zio->io_type == ZIO_TYPE_READ || zio->io_type == ZIO_TYPE_WRITE); 255 256 if (zio->io_flags & ZIO_FLAG_DONT_QUEUE) 257 return (zio); 258 259 zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE; 260 261 if (zio->io_type == ZIO_TYPE_READ) 262 zio->io_vdev_tree = &vq->vq_read_tree; 263 else 264 zio->io_vdev_tree = &vq->vq_write_tree; 265 266 mutex_enter(&vq->vq_lock); 267 268 zio->io_deadline = (lbolt64 >> zfs_vdev_time_shift) + zio->io_priority; 269 270 vdev_queue_io_add(vq, zio); 271 272 nio = vdev_queue_io_to_issue(vq, zfs_vdev_min_pending); 273 274 mutex_exit(&vq->vq_lock); 275 276 if (nio == NULL) 277 return (NULL); 278 279 if (nio->io_done == vdev_queue_agg_io_done) { 280 zio_nowait(nio); 281 return (NULL); 282 } 283 284 return (nio); 285 } 286 287 void 288 vdev_queue_io_done(zio_t *zio) 289 { 290 vdev_queue_t *vq = &zio->io_vd->vdev_queue; 291 292 mutex_enter(&vq->vq_lock); 293 294 avl_remove(&vq->vq_pending_tree, zio); 295 296 for (int i = 0; i < zfs_vdev_ramp_rate; i++) { 297 zio_t *nio = vdev_queue_io_to_issue(vq, zfs_vdev_max_pending); 298 if (nio == NULL) 299 break; 300 mutex_exit(&vq->vq_lock); 301 if (nio->io_done == vdev_queue_agg_io_done) { 302 zio_nowait(nio); 303 } else { 304 zio_vdev_io_reissue(nio); 305 zio_execute(nio); 306 } 307 mutex_enter(&vq->vq_lock); 308 } 309 310 mutex_exit(&vq->vq_lock); 311 } 312