zfs/lib/libzpool/vdev_queue.c

   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 2007 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #pragma ident   "@(#)vdev_queue.c       1.6     07/11/27 SMI"
  27
  28 #include <sys/zfs_context.h>
  29 #include <sys/spa.h>
  30 #include <sys/vdev_impl.h>
  31 #include <sys/zio.h>
  32 #include <sys/avl.h>
  33
  34 /*
  35  * These tunables are for performance analysis.
  36  */
  37 /*
  38  * zfs_vdev_max_pending is the maximum number of i/os concurrently
  39  * pending to each device.  zfs_vdev_min_pending is the initial number
  40  * of i/os pending to each device (before it starts ramping up to
  41  * max_pending).
  42  */
  43 int zfs_vdev_max_pending = 35;
  44 int zfs_vdev_min_pending = 4;
  45
  46 /* deadline = pri + (lbolt >> time_shift) */
  47 int zfs_vdev_time_shift = 6;
  48
  49 /* exponential I/O issue ramp-up rate */
  50 int zfs_vdev_ramp_rate = 2;
  51
  52 /*
  53  * i/os will be aggregated into a single large i/o up to
  54  * zfs_vdev_aggregation_limit bytes long.
  55  */
  56 int zfs_vdev_aggregation_limit = SPA_MAXBLOCKSIZE;
  57
  58 /*
  59  * Virtual device vector for disk I/O scheduling.
  60  */
  61 int
  62 vdev_queue_deadline_compare(const void *x1, const void *x2)
  63 {
  64         const zio_t *z1 = x1;
  65         const zio_t *z2 = x2;
  66
  67         if (z1->io_deadline < z2->io_deadline)
  68                 return (-1);
  69         if (z1->io_deadline > z2->io_deadline)
  70                 return (1);
  71
  72         if (z1->io_offset < z2->io_offset)
  73                 return (-1);
  74         if (z1->io_offset > z2->io_offset)
  75                 return (1);
  76
  77         if (z1 < z2)
  78                 return (-1);
  79         if (z1 > z2)
  80                 return (1);
  81
  82         return (0);
  83 }
  84
  85 int
  86 vdev_queue_offset_compare(const void *x1, const void *x2)
  87 {
  88         const zio_t *z1 = x1;
  89         const zio_t *z2 = x2;
  90
  91         if (z1->io_offset < z2->io_offset)
  92                 return (-1);
  93         if (z1->io_offset > z2->io_offset)
  94                 return (1);
  95
  96         if (z1 < z2)
  97                 return (-1);
  98         if (z1 > z2)
  99                 return (1);
 100
 101         return (0);
 102 }
 103
 104 void
 105 vdev_queue_init(vdev_t *vd)
 106 {
 107         vdev_queue_t *vq = &vd->vdev_queue;
 108
 109         mutex_init(&vq->vq_lock, NULL, MUTEX_DEFAULT, NULL);
 110
 111         avl_create(&vq->vq_deadline_tree, vdev_queue_deadline_compare,
 112             sizeof (zio_t), offsetof(struct zio, io_deadline_node));
 113
 114         avl_create(&vq->vq_read_tree, vdev_queue_offset_compare,
 115             sizeof (zio_t), offsetof(struct zio, io_offset_node));
 116
 117         avl_create(&vq->vq_write_tree, vdev_queue_offset_compare,
 118             sizeof (zio_t), offsetof(struct zio, io_offset_node));
 119
 120         avl_create(&vq->vq_pending_tree, vdev_queue_offset_compare,
 121             sizeof (zio_t), offsetof(struct zio, io_offset_node));
 122 }
 123
 124 void
 125 vdev_queue_fini(vdev_t *vd)
 126 {
 127         vdev_queue_t *vq = &vd->vdev_queue;
 128
 129         avl_destroy(&vq->vq_deadline_tree);
 130         avl_destroy(&vq->vq_read_tree);
 131         avl_destroy(&vq->vq_write_tree);
 132         avl_destroy(&vq->vq_pending_tree);
 133
 134         mutex_destroy(&vq->vq_lock);
 135 }
 136
 137 static void
 138 vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio)
 139 {
 140         avl_add(&vq->vq_deadline_tree, zio);
 141         avl_add(zio->io_vdev_tree, zio);
 142 }
 143
 144 static void
 145 vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio)
 146 {
 147         avl_remove(&vq->vq_deadline_tree, zio);
 148         avl_remove(zio->io_vdev_tree, zio);
 149 }
 150
 151 static void
 152 vdev_queue_agg_io_done(zio_t *aio)
 153 {
 154         zio_t *dio;
 155         uint64_t offset = 0;
 156
 157         while ((dio = aio->io_delegate_list) != NULL) {
 158                 if (aio->io_type == ZIO_TYPE_READ)
 159                         bcopy((char *)aio->io_data + offset, dio->io_data,
 160                             dio->io_size);
 161                 offset += dio->io_size;
 162                 aio->io_delegate_list = dio->io_delegate_next;
 163                 dio->io_delegate_next = NULL;
 164                 dio->io_error = aio->io_error;
 165                 zio_execute(dio);
 166         }
 167         ASSERT3U(offset, ==, aio->io_size);
 168
 169         zio_buf_free(aio->io_data, aio->io_size);
 170 }
 171
 172 #define IS_ADJACENT(io, nio) \
 173         ((io)->io_offset + (io)->io_size == (nio)->io_offset)
 174
 175 static zio_t *
 176 vdev_queue_io_to_issue(vdev_queue_t *vq, uint64_t pending_limit)
 177 {
 178         zio_t *fio, *lio, *aio, *dio;
 179         avl_tree_t *tree;
 180         uint64_t size;
 181
 182         ASSERT(MUTEX_HELD(&vq->vq_lock));
 183
 184         if (avl_numnodes(&vq->vq_pending_tree) >= pending_limit ||
 185             avl_numnodes(&vq->vq_deadline_tree) == 0)
 186                 return (NULL);
 187
 188         fio = lio = avl_first(&vq->vq_deadline_tree);
 189
 190         tree = fio->io_vdev_tree;
 191         size = fio->io_size;
 192
 193         while ((dio = AVL_PREV(tree, fio)) != NULL && IS_ADJACENT(dio, fio) &&
 194             size + dio->io_size <= zfs_vdev_aggregation_limit) {
 195                 dio->io_delegate_next = fio;
 196                 fio = dio;
 197                 size += dio->io_size;
 198         }
 199
 200         while ((dio = AVL_NEXT(tree, lio)) != NULL && IS_ADJACENT(lio, dio) &&
 201             size + dio->io_size <= zfs_vdev_aggregation_limit) {
 202                 lio->io_delegate_next = dio;
 203                 lio = dio;
 204                 size += dio->io_size;
 205         }
 206
 207         if (fio != lio) {
 208                 char *buf = zio_buf_alloc(size);
 209                 uint64_t offset = 0;
 210                 int nagg = 0;
 211
 212                 ASSERT(size <= zfs_vdev_aggregation_limit);
 213
 214                 aio = zio_vdev_child_io(fio, NULL, fio->io_vd,
 215                     fio->io_offset, buf, size, fio->io_type,
 216                     ZIO_PRIORITY_NOW, ZIO_FLAG_DONT_QUEUE |
 217                     ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_PROPAGATE |
 218                     ZIO_FLAG_NOBOOKMARK,
 219                     vdev_queue_agg_io_done, NULL);
 220
 221                 aio->io_delegate_list = fio;
 222
 223                 for (dio = fio; dio != NULL; dio = dio->io_delegate_next) {
 224                         ASSERT(dio->io_type == aio->io_type);
 225                         ASSERT(dio->io_vdev_tree == tree);
 226                         if (dio->io_type == ZIO_TYPE_WRITE)
 227                                 bcopy(dio->io_data, buf + offset, dio->io_size);
 228                         offset += dio->io_size;
 229                         vdev_queue_io_remove(vq, dio);
 230                         zio_vdev_io_bypass(dio);
 231                         nagg++;
 232                 }
 233
 234                 ASSERT(offset == size);
 235
 236                 dprintf("%5s  T=%llu  off=%8llx  agg=%3d  "
 237                     "old=%5llx  new=%5llx\n",
 238                     zio_type_name[fio->io_type],
 239                     fio->io_deadline, fio->io_offset, nagg, fio->io_size, size);
 240
 241                 avl_add(&vq->vq_pending_tree, aio);
 242
 243                 return (aio);
 244         }
 245
 246         ASSERT(fio->io_vdev_tree == tree);
 247         vdev_queue_io_remove(vq, fio);
 248
 249         avl_add(&vq->vq_pending_tree, fio);
 250
 251         return (fio);
 252 }
 253
 254 zio_t *
 255 vdev_queue_io(zio_t *zio)
 256 {
 257         vdev_queue_t *vq = &zio->io_vd->vdev_queue;
 258         zio_t *nio;
 259
 260         ASSERT(zio->io_type == ZIO_TYPE_READ || zio->io_type == ZIO_TYPE_WRITE);
 261
 262         if (zio->io_flags & ZIO_FLAG_DONT_QUEUE)
 263                 return (zio);
 264
 265         zio->io_flags |= ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE;
 266
 267         if (zio->io_type == ZIO_TYPE_READ)
 268                 zio->io_vdev_tree = &vq->vq_read_tree;
 269         else
 270                 zio->io_vdev_tree = &vq->vq_write_tree;
 271
 272         mutex_enter(&vq->vq_lock);
 273
 274         zio->io_deadline = (zio->io_timestamp >> zfs_vdev_time_shift) +
 275             zio->io_priority;
 276
 277         vdev_queue_io_add(vq, zio);
 278
 279         nio = vdev_queue_io_to_issue(vq, zfs_vdev_min_pending);
 280
 281         mutex_exit(&vq->vq_lock);
 282
 283         if (nio == NULL)
 284                 return (NULL);
 285
 286         if (nio->io_done == vdev_queue_agg_io_done) {
 287                 zio_nowait(nio);
 288                 return (NULL);
 289         }
 290
 291         return (nio);
 292 }
 293
 294 void
 295 vdev_queue_io_done(zio_t *zio)
 296 {
 297         vdev_queue_t *vq = &zio->io_vd->vdev_queue;
 298         zio_t *nio;
 299         int i;
 300
 301         mutex_enter(&vq->vq_lock);
 302
 303         avl_remove(&vq->vq_pending_tree, zio);
 304
 305         for (i = 0; i < zfs_vdev_ramp_rate; i++) {
 306                 nio = vdev_queue_io_to_issue(vq, zfs_vdev_max_pending);
 307                 if (nio == NULL)
 308                         break;
 309                 mutex_exit(&vq->vq_lock);
 310                 if (nio->io_done == vdev_queue_agg_io_done) {
 311                         zio_nowait(nio);
 312                 } else {
 313                         zio_vdev_io_reissue(nio);
 314                         zio_execute(nio);
 315                 }
 316                 mutex_enter(&vq->vq_lock);
 317         }
 318
 319         mutex_exit(&vq->vq_lock);
 320 }