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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 | // SPDX-License-Identifier: GPL-2.0 #include "blk-rq-qos.h" /* * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded, * false if 'v' + 1 would be bigger than 'below'. */ static bool atomic_inc_below(atomic_t *v, unsigned int below) { unsigned int cur = atomic_read(v); do { if (cur >= below) return false; } while (!atomic_try_cmpxchg(v, &cur, cur + 1)); return true; } bool rq_wait_inc_below(struct rq_wait *rq_wait, unsigned int limit) { return atomic_inc_below(&rq_wait->inflight, limit); } void __rq_qos_cleanup(struct rq_qos *rqos, struct bio *bio) { do { if (rqos->ops->cleanup) rqos->ops->cleanup(rqos, bio); rqos = rqos->next; } while (rqos); } void __rq_qos_done(struct rq_qos *rqos, struct request *rq) { do { if (rqos->ops->done) rqos->ops->done(rqos, rq); rqos = rqos->next; } while (rqos); } void __rq_qos_issue(struct rq_qos *rqos, struct request *rq) { do { if (rqos->ops->issue) rqos->ops->issue(rqos, rq); rqos = rqos->next; } while (rqos); } void __rq_qos_requeue(struct rq_qos *rqos, struct request *rq) { do { if (rqos->ops->requeue) rqos->ops->requeue(rqos, rq); rqos = rqos->next; } while (rqos); } void __rq_qos_throttle(struct rq_qos *rqos, struct bio *bio) { do { if (rqos->ops->throttle) rqos->ops->throttle(rqos, bio); rqos = rqos->next; } while (rqos); } void __rq_qos_track(struct rq_qos *rqos, struct request *rq, struct bio *bio) { do { if (rqos->ops->track) rqos->ops->track(rqos, rq, bio); rqos = rqos->next; } while (rqos); } void __rq_qos_merge(struct rq_qos *rqos, struct request *rq, struct bio *bio) { do { if (rqos->ops->merge) rqos->ops->merge(rqos, rq, bio); rqos = rqos->next; } while (rqos); } void __rq_qos_done_bio(struct rq_qos *rqos, struct bio *bio) { do { if (rqos->ops->done_bio) rqos->ops->done_bio(rqos, bio); rqos = rqos->next; } while (rqos); } void __rq_qos_queue_depth_changed(struct rq_qos *rqos) { do { if (rqos->ops->queue_depth_changed) rqos->ops->queue_depth_changed(rqos); rqos = rqos->next; } while (rqos); } /* * Return true, if we can't increase the depth further by scaling */ bool rq_depth_calc_max_depth(struct rq_depth *rqd) { unsigned int depth; bool ret = false; /* * For QD=1 devices, this is a special case. It's important for those * to have one request ready when one completes, so force a depth of * 2 for those devices. On the backend, it'll be a depth of 1 anyway, * since the device can't have more than that in flight. If we're * scaling down, then keep a setting of 1/1/1. */ if (rqd->queue_depth == 1) { if (rqd->scale_step > 0) rqd->max_depth = 1; else { rqd->max_depth = 2; ret = true; } } else { /* * scale_step == 0 is our default state. If we have suffered * latency spikes, step will be > 0, and we shrink the * allowed write depths. If step is < 0, we're only doing * writes, and we allow a temporarily higher depth to * increase performance. */ depth = min_t(unsigned int, rqd->default_depth, rqd->queue_depth); if (rqd->scale_step > 0) depth = 1 + ((depth - 1) >> min(31, rqd->scale_step)); else if (rqd->scale_step < 0) { unsigned int maxd = 3 * rqd->queue_depth / 4; depth = 1 + ((depth - 1) << -rqd->scale_step); if (depth > maxd) { depth = maxd; ret = true; } } rqd->max_depth = depth; } return ret; } /* Returns true on success and false if scaling up wasn't possible */ bool rq_depth_scale_up(struct rq_depth *rqd) { /* * Hit max in previous round, stop here */ if (rqd->scaled_max) return false; rqd->scale_step--; rqd->scaled_max = rq_depth_calc_max_depth(rqd); return true; } /* * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we * had a latency violation. Returns true on success and returns false if * scaling down wasn't possible. */ bool rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle) { /* * Stop scaling down when we've hit the limit. This also prevents * ->scale_step from going to crazy values, if the device can't * keep up. */ if (rqd->max_depth == 1) return false; if (rqd->scale_step < 0 && hard_throttle) rqd->scale_step = 0; else rqd->scale_step++; rqd->scaled_max = false; rq_depth_calc_max_depth(rqd); return true; } struct rq_qos_wait_data { struct wait_queue_entry wq; struct task_struct *task; struct rq_wait *rqw; acquire_inflight_cb_t *cb; void *private_data; bool got_token; }; static int rq_qos_wake_function(struct wait_queue_entry *curr, unsigned int mode, int wake_flags, void *key) { struct rq_qos_wait_data *data = container_of(curr, struct rq_qos_wait_data, wq); /* * If we fail to get a budget, return -1 to interrupt the wake up loop * in __wake_up_common. */ if (!data->cb(data->rqw, data->private_data)) return -1; data->got_token = true; smp_wmb(); list_del_init(&curr->entry); wake_up_process(data->task); return 1; } /** * rq_qos_wait - throttle on a rqw if we need to * @rqw: rqw to throttle on * @private_data: caller provided specific data * @acquire_inflight_cb: inc the rqw->inflight counter if we can * @cleanup_cb: the callback to cleanup in case we race with a waker * * This provides a uniform place for the rq_qos users to do their throttling. * Since you can end up with a lot of things sleeping at once, this manages the * waking up based on the resources available. The acquire_inflight_cb should * inc the rqw->inflight if we have the ability to do so, or return false if not * and then we will sleep until the room becomes available. * * cleanup_cb is in case that we race with a waker and need to cleanup the * inflight count accordingly. */ void rq_qos_wait(struct rq_wait *rqw, void *private_data, acquire_inflight_cb_t *acquire_inflight_cb, cleanup_cb_t *cleanup_cb) { struct rq_qos_wait_data data = { .wq = { .func = rq_qos_wake_function, .entry = LIST_HEAD_INIT(data.wq.entry), }, .task = current, .rqw = rqw, .cb = acquire_inflight_cb, .private_data = private_data, }; bool has_sleeper; has_sleeper = wq_has_sleeper(&rqw->wait); if (!has_sleeper && acquire_inflight_cb(rqw, private_data)) return; has_sleeper = !prepare_to_wait_exclusive(&rqw->wait, &data.wq, TASK_UNINTERRUPTIBLE); do { /* The memory barrier in set_task_state saves us here. */ if (data.got_token) break; if (!has_sleeper && acquire_inflight_cb(rqw, private_data)) { finish_wait(&rqw->wait, &data.wq); /* * We raced with wbt_wake_function() getting a token, * which means we now have two. Put our local token * and wake anyone else potentially waiting for one. */ smp_rmb(); if (data.got_token) cleanup_cb(rqw, private_data); break; } io_schedule(); has_sleeper = true; set_current_state(TASK_UNINTERRUPTIBLE); } while (1); finish_wait(&rqw->wait, &data.wq); } void rq_qos_exit(struct request_queue *q) { while (q->rq_qos) { struct rq_qos *rqos = q->rq_qos; q->rq_qos = rqos->next; rqos->ops->exit(rqos); } } int rq_qos_add(struct rq_qos *rqos, struct gendisk *disk, enum rq_qos_id id, const struct rq_qos_ops *ops) { struct request_queue *q = disk->queue; rqos->disk = disk; rqos->id = id; rqos->ops = ops; /* * No IO can be in-flight when adding rqos, so freeze queue, which * is fine since we only support rq_qos for blk-mq queue. * * Reuse ->queue_lock for protecting against other concurrent * rq_qos adding/deleting */ blk_mq_freeze_queue(q); spin_lock_irq(&q->queue_lock); if (rq_qos_id(q, rqos->id)) goto ebusy; rqos->next = q->rq_qos; q->rq_qos = rqos; spin_unlock_irq(&q->queue_lock); blk_mq_unfreeze_queue(q); if (rqos->ops->debugfs_attrs) { mutex_lock(&q->debugfs_mutex); blk_mq_debugfs_register_rqos(rqos); mutex_unlock(&q->debugfs_mutex); } return 0; ebusy: spin_unlock_irq(&q->queue_lock); blk_mq_unfreeze_queue(q); return -EBUSY; } void rq_qos_del(struct rq_qos *rqos) { struct request_queue *q = rqos->disk->queue; struct rq_qos **cur; /* * See comment in rq_qos_add() about freezing queue & using * ->queue_lock. */ blk_mq_freeze_queue(q); spin_lock_irq(&q->queue_lock); for (cur = &q->rq_qos; *cur; cur = &(*cur)->next) { if (*cur == rqos) { *cur = rqos->next; break; } } spin_unlock_irq(&q->queue_lock); blk_mq_unfreeze_queue(q); mutex_lock(&q->debugfs_mutex); blk_mq_debugfs_unregister_rqos(rqos); mutex_unlock(&q->debugfs_mutex); } |