| 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * Interface for controlling IO bandwidth on a request queue |
| 4 | * |
| 5 | * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com> |
| 6 | */ |
| 7 | |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/slab.h> |
| 10 | #include <linux/blkdev.h> |
| 11 | #include <linux/bio.h> |
| 12 | #include <linux/blktrace_api.h> |
| 13 | #include "blk.h" |
| 14 | #include "blk-cgroup-rwstat.h" |
| 15 | #include "blk-stat.h" |
| 16 | #include "blk-throttle.h" |
| 17 | |
| 18 | /* Max dispatch from a group in 1 round */ |
| 19 | #define THROTL_GRP_QUANTUM 8 |
| 20 | |
| 21 | /* Total max dispatch from all groups in one round */ |
| 22 | #define THROTL_QUANTUM 32 |
| 23 | |
| 24 | /* Throttling is performed over a slice and after that slice is renewed */ |
| 25 | #define DFL_THROTL_SLICE_HD (HZ / 10) |
| 26 | #define DFL_THROTL_SLICE_SSD (HZ / 50) |
| 27 | #define MAX_THROTL_SLICE (HZ) |
| 28 | #define MAX_IDLE_TIME (5L * 1000 * 1000) /* 5 s */ |
| 29 | #define MIN_THROTL_BPS (320 * 1024) |
| 30 | #define MIN_THROTL_IOPS (10) |
| 31 | #define DFL_LATENCY_TARGET (-1L) |
| 32 | #define DFL_IDLE_THRESHOLD (0) |
| 33 | #define DFL_HD_BASELINE_LATENCY (4000L) /* 4ms */ |
| 34 | #define LATENCY_FILTERED_SSD (0) |
| 35 | /* |
| 36 | * For HD, very small latency comes from sequential IO. Such IO is helpless to |
| 37 | * help determine if its IO is impacted by others, hence we ignore the IO |
| 38 | */ |
| 39 | #define LATENCY_FILTERED_HD (1000L) /* 1ms */ |
| 40 | |
| 41 | /* A workqueue to queue throttle related work */ |
| 42 | static struct workqueue_struct *kthrotld_workqueue; |
| 43 | |
| 44 | #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) |
| 45 | |
| 46 | /* We measure latency for request size from <= 4k to >= 1M */ |
| 47 | #define LATENCY_BUCKET_SIZE 9 |
| 48 | |
| 49 | struct latency_bucket { |
| 50 | unsigned long total_latency; /* ns / 1024 */ |
| 51 | int samples; |
| 52 | }; |
| 53 | |
| 54 | struct avg_latency_bucket { |
| 55 | unsigned long latency; /* ns / 1024 */ |
| 56 | bool valid; |
| 57 | }; |
| 58 | |
| 59 | struct throtl_data |
| 60 | { |
| 61 | /* service tree for active throtl groups */ |
| 62 | struct throtl_service_queue service_queue; |
| 63 | |
| 64 | struct request_queue *queue; |
| 65 | |
| 66 | /* Total Number of queued bios on READ and WRITE lists */ |
| 67 | unsigned int nr_queued[2]; |
| 68 | |
| 69 | unsigned int throtl_slice; |
| 70 | |
| 71 | /* Work for dispatching throttled bios */ |
| 72 | struct work_struct dispatch_work; |
| 73 | unsigned int limit_index; |
| 74 | bool limit_valid[LIMIT_CNT]; |
| 75 | |
| 76 | unsigned long low_upgrade_time; |
| 77 | unsigned long low_downgrade_time; |
| 78 | |
| 79 | unsigned int scale; |
| 80 | |
| 81 | struct latency_bucket tmp_buckets[2][LATENCY_BUCKET_SIZE]; |
| 82 | struct avg_latency_bucket avg_buckets[2][LATENCY_BUCKET_SIZE]; |
| 83 | struct latency_bucket __percpu *latency_buckets[2]; |
| 84 | unsigned long last_calculate_time; |
| 85 | unsigned long filtered_latency; |
| 86 | |
| 87 | bool track_bio_latency; |
| 88 | }; |
| 89 | |
| 90 | static void throtl_pending_timer_fn(struct timer_list *t); |
| 91 | |
| 92 | static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg) |
| 93 | { |
| 94 | return pd_to_blkg(&tg->pd); |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * sq_to_tg - return the throl_grp the specified service queue belongs to |
| 99 | * @sq: the throtl_service_queue of interest |
| 100 | * |
| 101 | * Return the throtl_grp @sq belongs to. If @sq is the top-level one |
| 102 | * embedded in throtl_data, %NULL is returned. |
| 103 | */ |
| 104 | static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq) |
| 105 | { |
| 106 | if (sq && sq->parent_sq) |
| 107 | return container_of(sq, struct throtl_grp, service_queue); |
| 108 | else |
| 109 | return NULL; |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * sq_to_td - return throtl_data the specified service queue belongs to |
| 114 | * @sq: the throtl_service_queue of interest |
| 115 | * |
| 116 | * A service_queue can be embedded in either a throtl_grp or throtl_data. |
| 117 | * Determine the associated throtl_data accordingly and return it. |
| 118 | */ |
| 119 | static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) |
| 120 | { |
| 121 | struct throtl_grp *tg = sq_to_tg(sq); |
| 122 | |
| 123 | if (tg) |
| 124 | return tg->td; |
| 125 | else |
| 126 | return container_of(sq, struct throtl_data, service_queue); |
| 127 | } |
| 128 | |
| 129 | /* |
| 130 | * cgroup's limit in LIMIT_MAX is scaled if low limit is set. This scale is to |
| 131 | * make the IO dispatch more smooth. |
| 132 | * Scale up: linearly scale up according to elapsed time since upgrade. For |
| 133 | * every throtl_slice, the limit scales up 1/2 .low limit till the |
| 134 | * limit hits .max limit |
| 135 | * Scale down: exponentially scale down if a cgroup doesn't hit its .low limit |
| 136 | */ |
| 137 | static uint64_t throtl_adjusted_limit(uint64_t low, struct throtl_data *td) |
| 138 | { |
| 139 | /* arbitrary value to avoid too big scale */ |
| 140 | if (td->scale < 4096 && time_after_eq(jiffies, |
| 141 | td->low_upgrade_time + td->scale * td->throtl_slice)) |
| 142 | td->scale = (jiffies - td->low_upgrade_time) / td->throtl_slice; |
| 143 | |
| 144 | return low + (low >> 1) * td->scale; |
| 145 | } |
| 146 | |
| 147 | static uint64_t tg_bps_limit(struct throtl_grp *tg, int rw) |
| 148 | { |
| 149 | struct blkcg_gq *blkg = tg_to_blkg(tg); |
| 150 | struct throtl_data *td; |
| 151 | uint64_t ret; |
| 152 | |
| 153 | if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent) |
| 154 | return U64_MAX; |
| 155 | |
| 156 | td = tg->td; |
| 157 | ret = tg->bps[rw][td->limit_index]; |
| 158 | if (ret == 0 && td->limit_index == LIMIT_LOW) { |
| 159 | /* intermediate node or iops isn't 0 */ |
| 160 | if (!list_empty(&blkg->blkcg->css.children) || |
| 161 | tg->iops[rw][td->limit_index]) |
| 162 | return U64_MAX; |
| 163 | else |
| 164 | return MIN_THROTL_BPS; |
| 165 | } |
| 166 | |
| 167 | if (td->limit_index == LIMIT_MAX && tg->bps[rw][LIMIT_LOW] && |
| 168 | tg->bps[rw][LIMIT_LOW] != tg->bps[rw][LIMIT_MAX]) { |
| 169 | uint64_t adjusted; |
| 170 | |
| 171 | adjusted = throtl_adjusted_limit(tg->bps[rw][LIMIT_LOW], td); |
| 172 | ret = min(tg->bps[rw][LIMIT_MAX], adjusted); |
| 173 | } |
| 174 | return ret; |
| 175 | } |
| 176 | |
| 177 | static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw) |
| 178 | { |
| 179 | struct blkcg_gq *blkg = tg_to_blkg(tg); |
| 180 | struct throtl_data *td; |
| 181 | unsigned int ret; |
| 182 | |
| 183 | if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent) |
| 184 | return UINT_MAX; |
| 185 | |
| 186 | td = tg->td; |
| 187 | ret = tg->iops[rw][td->limit_index]; |
| 188 | if (ret == 0 && tg->td->limit_index == LIMIT_LOW) { |
| 189 | /* intermediate node or bps isn't 0 */ |
| 190 | if (!list_empty(&blkg->blkcg->css.children) || |
| 191 | tg->bps[rw][td->limit_index]) |
| 192 | return UINT_MAX; |
| 193 | else |
| 194 | return MIN_THROTL_IOPS; |
| 195 | } |
| 196 | |
| 197 | if (td->limit_index == LIMIT_MAX && tg->iops[rw][LIMIT_LOW] && |
| 198 | tg->iops[rw][LIMIT_LOW] != tg->iops[rw][LIMIT_MAX]) { |
| 199 | uint64_t adjusted; |
| 200 | |
| 201 | adjusted = throtl_adjusted_limit(tg->iops[rw][LIMIT_LOW], td); |
| 202 | if (adjusted > UINT_MAX) |
| 203 | adjusted = UINT_MAX; |
| 204 | ret = min_t(unsigned int, tg->iops[rw][LIMIT_MAX], adjusted); |
| 205 | } |
| 206 | return ret; |
| 207 | } |
| 208 | |
| 209 | #define request_bucket_index(sectors) \ |
| 210 | clamp_t(int, order_base_2(sectors) - 3, 0, LATENCY_BUCKET_SIZE - 1) |
| 211 | |
| 212 | /** |
| 213 | * throtl_log - log debug message via blktrace |
| 214 | * @sq: the service_queue being reported |
| 215 | * @fmt: printf format string |
| 216 | * @args: printf args |
| 217 | * |
| 218 | * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a |
| 219 | * throtl_grp; otherwise, just "throtl". |
| 220 | */ |
| 221 | #define throtl_log(sq, fmt, args...) do { \ |
| 222 | struct throtl_grp *__tg = sq_to_tg((sq)); \ |
| 223 | struct throtl_data *__td = sq_to_td((sq)); \ |
| 224 | \ |
| 225 | (void)__td; \ |
| 226 | if (likely(!blk_trace_note_message_enabled(__td->queue))) \ |
| 227 | break; \ |
| 228 | if ((__tg)) { \ |
| 229 | blk_add_cgroup_trace_msg(__td->queue, \ |
| 230 | &tg_to_blkg(__tg)->blkcg->css, "throtl " fmt, ##args);\ |
| 231 | } else { \ |
| 232 | blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \ |
| 233 | } \ |
| 234 | } while (0) |
| 235 | |
| 236 | static inline unsigned int throtl_bio_data_size(struct bio *bio) |
| 237 | { |
| 238 | /* assume it's one sector */ |
| 239 | if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) |
| 240 | return 512; |
| 241 | return bio->bi_iter.bi_size; |
| 242 | } |
| 243 | |
| 244 | static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg) |
| 245 | { |
| 246 | INIT_LIST_HEAD(&qn->node); |
| 247 | bio_list_init(&qn->bios); |
| 248 | qn->tg = tg; |
| 249 | } |
| 250 | |
| 251 | /** |
| 252 | * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it |
| 253 | * @bio: bio being added |
| 254 | * @qn: qnode to add bio to |
| 255 | * @queued: the service_queue->queued[] list @qn belongs to |
| 256 | * |
| 257 | * Add @bio to @qn and put @qn on @queued if it's not already on. |
| 258 | * @qn->tg's reference count is bumped when @qn is activated. See the |
| 259 | * comment on top of throtl_qnode definition for details. |
| 260 | */ |
| 261 | static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn, |
| 262 | struct list_head *queued) |
| 263 | { |
| 264 | bio_list_add(&qn->bios, bio); |
| 265 | if (list_empty(&qn->node)) { |
| 266 | list_add_tail(&qn->node, queued); |
| 267 | blkg_get(tg_to_blkg(qn->tg)); |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | /** |
| 272 | * throtl_peek_queued - peek the first bio on a qnode list |
| 273 | * @queued: the qnode list to peek |
| 274 | */ |
| 275 | static struct bio *throtl_peek_queued(struct list_head *queued) |
| 276 | { |
| 277 | struct throtl_qnode *qn; |
| 278 | struct bio *bio; |
| 279 | |
| 280 | if (list_empty(queued)) |
| 281 | return NULL; |
| 282 | |
| 283 | qn = list_first_entry(queued, struct throtl_qnode, node); |
| 284 | bio = bio_list_peek(&qn->bios); |
| 285 | WARN_ON_ONCE(!bio); |
| 286 | return bio; |
| 287 | } |
| 288 | |
| 289 | /** |
| 290 | * throtl_pop_queued - pop the first bio form a qnode list |
| 291 | * @queued: the qnode list to pop a bio from |
| 292 | * @tg_to_put: optional out argument for throtl_grp to put |
| 293 | * |
| 294 | * Pop the first bio from the qnode list @queued. After popping, the first |
| 295 | * qnode is removed from @queued if empty or moved to the end of @queued so |
| 296 | * that the popping order is round-robin. |
| 297 | * |
| 298 | * When the first qnode is removed, its associated throtl_grp should be put |
| 299 | * too. If @tg_to_put is NULL, this function automatically puts it; |
| 300 | * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is |
| 301 | * responsible for putting it. |
| 302 | */ |
| 303 | static struct bio *throtl_pop_queued(struct list_head *queued, |
| 304 | struct throtl_grp **tg_to_put) |
| 305 | { |
| 306 | struct throtl_qnode *qn; |
| 307 | struct bio *bio; |
| 308 | |
| 309 | if (list_empty(queued)) |
| 310 | return NULL; |
| 311 | |
| 312 | qn = list_first_entry(queued, struct throtl_qnode, node); |
| 313 | bio = bio_list_pop(&qn->bios); |
| 314 | WARN_ON_ONCE(!bio); |
| 315 | |
| 316 | if (bio_list_empty(&qn->bios)) { |
| 317 | list_del_init(&qn->node); |
| 318 | if (tg_to_put) |
| 319 | *tg_to_put = qn->tg; |
| 320 | else |
| 321 | blkg_put(tg_to_blkg(qn->tg)); |
| 322 | } else { |
| 323 | list_move_tail(&qn->node, queued); |
| 324 | } |
| 325 | |
| 326 | return bio; |
| 327 | } |
| 328 | |
| 329 | /* init a service_queue, assumes the caller zeroed it */ |
| 330 | static void throtl_service_queue_init(struct throtl_service_queue *sq) |
| 331 | { |
| 332 | INIT_LIST_HEAD(&sq->queued[READ]); |
| 333 | INIT_LIST_HEAD(&sq->queued[WRITE]); |
| 334 | sq->pending_tree = RB_ROOT_CACHED; |
| 335 | timer_setup(&sq->pending_timer, throtl_pending_timer_fn, 0); |
| 336 | } |
| 337 | |
| 338 | static struct blkg_policy_data *throtl_pd_alloc(struct gendisk *disk, |
| 339 | struct blkcg *blkcg, gfp_t gfp) |
| 340 | { |
| 341 | struct throtl_grp *tg; |
| 342 | int rw; |
| 343 | |
| 344 | tg = kzalloc_node(sizeof(*tg), gfp, disk->node_id); |
| 345 | if (!tg) |
| 346 | return NULL; |
| 347 | |
| 348 | if (blkg_rwstat_init(&tg->stat_bytes, gfp)) |
| 349 | goto err_free_tg; |
| 350 | |
| 351 | if (blkg_rwstat_init(&tg->stat_ios, gfp)) |
| 352 | goto err_exit_stat_bytes; |
| 353 | |
| 354 | throtl_service_queue_init(&tg->service_queue); |
| 355 | |
| 356 | for (rw = READ; rw <= WRITE; rw++) { |
| 357 | throtl_qnode_init(&tg->qnode_on_self[rw], tg); |
| 358 | throtl_qnode_init(&tg->qnode_on_parent[rw], tg); |
| 359 | } |
| 360 | |
| 361 | RB_CLEAR_NODE(&tg->rb_node); |
| 362 | tg->bps[READ][LIMIT_MAX] = U64_MAX; |
| 363 | tg->bps[WRITE][LIMIT_MAX] = U64_MAX; |
| 364 | tg->iops[READ][LIMIT_MAX] = UINT_MAX; |
| 365 | tg->iops[WRITE][LIMIT_MAX] = UINT_MAX; |
| 366 | tg->bps_conf[READ][LIMIT_MAX] = U64_MAX; |
| 367 | tg->bps_conf[WRITE][LIMIT_MAX] = U64_MAX; |
| 368 | tg->iops_conf[READ][LIMIT_MAX] = UINT_MAX; |
| 369 | tg->iops_conf[WRITE][LIMIT_MAX] = UINT_MAX; |
| 370 | /* LIMIT_LOW will have default value 0 */ |
| 371 | |
| 372 | tg->latency_target = DFL_LATENCY_TARGET; |
| 373 | tg->latency_target_conf = DFL_LATENCY_TARGET; |
| 374 | tg->idletime_threshold = DFL_IDLE_THRESHOLD; |
| 375 | tg->idletime_threshold_conf = DFL_IDLE_THRESHOLD; |
| 376 | |
| 377 | return &tg->pd; |
| 378 | |
| 379 | err_exit_stat_bytes: |
| 380 | blkg_rwstat_exit(&tg->stat_bytes); |
| 381 | err_free_tg: |
| 382 | kfree(tg); |
| 383 | return NULL; |
| 384 | } |
| 385 | |
| 386 | static void throtl_pd_init(struct blkg_policy_data *pd) |
| 387 | { |
| 388 | struct throtl_grp *tg = pd_to_tg(pd); |
| 389 | struct blkcg_gq *blkg = tg_to_blkg(tg); |
| 390 | struct throtl_data *td = blkg->q->td; |
| 391 | struct throtl_service_queue *sq = &tg->service_queue; |
| 392 | |
| 393 | /* |
| 394 | * If on the default hierarchy, we switch to properly hierarchical |
| 395 | * behavior where limits on a given throtl_grp are applied to the |
| 396 | * whole subtree rather than just the group itself. e.g. If 16M |
| 397 | * read_bps limit is set on a parent group, summary bps of |
| 398 | * parent group and its subtree groups can't exceed 16M for the |
| 399 | * device. |
| 400 | * |
| 401 | * If not on the default hierarchy, the broken flat hierarchy |
| 402 | * behavior is retained where all throtl_grps are treated as if |
| 403 | * they're all separate root groups right below throtl_data. |
| 404 | * Limits of a group don't interact with limits of other groups |
| 405 | * regardless of the position of the group in the hierarchy. |
| 406 | */ |
| 407 | sq->parent_sq = &td->service_queue; |
| 408 | if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent) |
| 409 | sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue; |
| 410 | tg->td = td; |
| 411 | } |
| 412 | |
| 413 | /* |
| 414 | * Set has_rules[] if @tg or any of its parents have limits configured. |
| 415 | * This doesn't require walking up to the top of the hierarchy as the |
| 416 | * parent's has_rules[] is guaranteed to be correct. |
| 417 | */ |
| 418 | static void tg_update_has_rules(struct throtl_grp *tg) |
| 419 | { |
| 420 | struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq); |
| 421 | struct throtl_data *td = tg->td; |
| 422 | int rw; |
| 423 | |
| 424 | for (rw = READ; rw <= WRITE; rw++) { |
| 425 | tg->has_rules_iops[rw] = |
| 426 | (parent_tg && parent_tg->has_rules_iops[rw]) || |
| 427 | (td->limit_valid[td->limit_index] && |
| 428 | tg_iops_limit(tg, rw) != UINT_MAX); |
| 429 | tg->has_rules_bps[rw] = |
| 430 | (parent_tg && parent_tg->has_rules_bps[rw]) || |
| 431 | (td->limit_valid[td->limit_index] && |
| 432 | (tg_bps_limit(tg, rw) != U64_MAX)); |
| 433 | } |
| 434 | } |
| 435 | |
| 436 | static void throtl_pd_online(struct blkg_policy_data *pd) |
| 437 | { |
| 438 | struct throtl_grp *tg = pd_to_tg(pd); |
| 439 | /* |
| 440 | * We don't want new groups to escape the limits of its ancestors. |
| 441 | * Update has_rules[] after a new group is brought online. |
| 442 | */ |
| 443 | tg_update_has_rules(tg); |
| 444 | } |
| 445 | |
| 446 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| 447 | static void blk_throtl_update_limit_valid(struct throtl_data *td) |
| 448 | { |
| 449 | struct cgroup_subsys_state *pos_css; |
| 450 | struct blkcg_gq *blkg; |
| 451 | bool low_valid = false; |
| 452 | |
| 453 | rcu_read_lock(); |
| 454 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { |
| 455 | struct throtl_grp *tg = blkg_to_tg(blkg); |
| 456 | |
| 457 | if (tg->bps[READ][LIMIT_LOW] || tg->bps[WRITE][LIMIT_LOW] || |
| 458 | tg->iops[READ][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) { |
| 459 | low_valid = true; |
| 460 | break; |
| 461 | } |
| 462 | } |
| 463 | rcu_read_unlock(); |
| 464 | |
| 465 | td->limit_valid[LIMIT_LOW] = low_valid; |
| 466 | } |
| 467 | #else |
| 468 | static inline void blk_throtl_update_limit_valid(struct throtl_data *td) |
| 469 | { |
| 470 | } |
| 471 | #endif |
| 472 | |
| 473 | static void throtl_upgrade_state(struct throtl_data *td); |
| 474 | static void throtl_pd_offline(struct blkg_policy_data *pd) |
| 475 | { |
| 476 | struct throtl_grp *tg = pd_to_tg(pd); |
| 477 | |
| 478 | tg->bps[READ][LIMIT_LOW] = 0; |
| 479 | tg->bps[WRITE][LIMIT_LOW] = 0; |
| 480 | tg->iops[READ][LIMIT_LOW] = 0; |
| 481 | tg->iops[WRITE][LIMIT_LOW] = 0; |
| 482 | |
| 483 | blk_throtl_update_limit_valid(tg->td); |
| 484 | |
| 485 | if (!tg->td->limit_valid[tg->td->limit_index]) |
| 486 | throtl_upgrade_state(tg->td); |
| 487 | } |
| 488 | |
| 489 | static void throtl_pd_free(struct blkg_policy_data *pd) |
| 490 | { |
| 491 | struct throtl_grp *tg = pd_to_tg(pd); |
| 492 | |
| 493 | del_timer_sync(&tg->service_queue.pending_timer); |
| 494 | blkg_rwstat_exit(&tg->stat_bytes); |
| 495 | blkg_rwstat_exit(&tg->stat_ios); |
| 496 | kfree(tg); |
| 497 | } |
| 498 | |
| 499 | static struct throtl_grp * |
| 500 | throtl_rb_first(struct throtl_service_queue *parent_sq) |
| 501 | { |
| 502 | struct rb_node *n; |
| 503 | |
| 504 | n = rb_first_cached(&parent_sq->pending_tree); |
| 505 | WARN_ON_ONCE(!n); |
| 506 | if (!n) |
| 507 | return NULL; |
| 508 | return rb_entry_tg(n); |
| 509 | } |
| 510 | |
| 511 | static void throtl_rb_erase(struct rb_node *n, |
| 512 | struct throtl_service_queue *parent_sq) |
| 513 | { |
| 514 | rb_erase_cached(n, &parent_sq->pending_tree); |
| 515 | RB_CLEAR_NODE(n); |
| 516 | } |
| 517 | |
| 518 | static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) |
| 519 | { |
| 520 | struct throtl_grp *tg; |
| 521 | |
| 522 | tg = throtl_rb_first(parent_sq); |
| 523 | if (!tg) |
| 524 | return; |
| 525 | |
| 526 | parent_sq->first_pending_disptime = tg->disptime; |
| 527 | } |
| 528 | |
| 529 | static void tg_service_queue_add(struct throtl_grp *tg) |
| 530 | { |
| 531 | struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq; |
| 532 | struct rb_node **node = &parent_sq->pending_tree.rb_root.rb_node; |
| 533 | struct rb_node *parent = NULL; |
| 534 | struct throtl_grp *__tg; |
| 535 | unsigned long key = tg->disptime; |
| 536 | bool leftmost = true; |
| 537 | |
| 538 | while (*node != NULL) { |
| 539 | parent = *node; |
| 540 | __tg = rb_entry_tg(parent); |
| 541 | |
| 542 | if (time_before(key, __tg->disptime)) |
| 543 | node = &parent->rb_left; |
| 544 | else { |
| 545 | node = &parent->rb_right; |
| 546 | leftmost = false; |
| 547 | } |
| 548 | } |
| 549 | |
| 550 | rb_link_node(&tg->rb_node, parent, node); |
| 551 | rb_insert_color_cached(&tg->rb_node, &parent_sq->pending_tree, |
| 552 | leftmost); |
| 553 | } |
| 554 | |
| 555 | static void throtl_enqueue_tg(struct throtl_grp *tg) |
| 556 | { |
| 557 | if (!(tg->flags & THROTL_TG_PENDING)) { |
| 558 | tg_service_queue_add(tg); |
| 559 | tg->flags |= THROTL_TG_PENDING; |
| 560 | tg->service_queue.parent_sq->nr_pending++; |
| 561 | } |
| 562 | } |
| 563 | |
| 564 | static void throtl_dequeue_tg(struct throtl_grp *tg) |
| 565 | { |
| 566 | if (tg->flags & THROTL_TG_PENDING) { |
| 567 | struct throtl_service_queue *parent_sq = |
| 568 | tg->service_queue.parent_sq; |
| 569 | |
| 570 | throtl_rb_erase(&tg->rb_node, parent_sq); |
| 571 | --parent_sq->nr_pending; |
| 572 | tg->flags &= ~THROTL_TG_PENDING; |
| 573 | } |
| 574 | } |
| 575 | |
| 576 | /* Call with queue lock held */ |
| 577 | static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, |
| 578 | unsigned long expires) |
| 579 | { |
| 580 | unsigned long max_expire = jiffies + 8 * sq_to_td(sq)->throtl_slice; |
| 581 | |
| 582 | /* |
| 583 | * Since we are adjusting the throttle limit dynamically, the sleep |
| 584 | * time calculated according to previous limit might be invalid. It's |
| 585 | * possible the cgroup sleep time is very long and no other cgroups |
| 586 | * have IO running so notify the limit changes. Make sure the cgroup |
| 587 | * doesn't sleep too long to avoid the missed notification. |
| 588 | */ |
| 589 | if (time_after(expires, max_expire)) |
| 590 | expires = max_expire; |
| 591 | mod_timer(&sq->pending_timer, expires); |
| 592 | throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu", |
| 593 | expires - jiffies, jiffies); |
| 594 | } |
| 595 | |
| 596 | /** |
| 597 | * throtl_schedule_next_dispatch - schedule the next dispatch cycle |
| 598 | * @sq: the service_queue to schedule dispatch for |
| 599 | * @force: force scheduling |
| 600 | * |
| 601 | * Arm @sq->pending_timer so that the next dispatch cycle starts on the |
| 602 | * dispatch time of the first pending child. Returns %true if either timer |
| 603 | * is armed or there's no pending child left. %false if the current |
| 604 | * dispatch window is still open and the caller should continue |
| 605 | * dispatching. |
| 606 | * |
| 607 | * If @force is %true, the dispatch timer is always scheduled and this |
| 608 | * function is guaranteed to return %true. This is to be used when the |
| 609 | * caller can't dispatch itself and needs to invoke pending_timer |
| 610 | * unconditionally. Note that forced scheduling is likely to induce short |
| 611 | * delay before dispatch starts even if @sq->first_pending_disptime is not |
| 612 | * in the future and thus shouldn't be used in hot paths. |
| 613 | */ |
| 614 | static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq, |
| 615 | bool force) |
| 616 | { |
| 617 | /* any pending children left? */ |
| 618 | if (!sq->nr_pending) |
| 619 | return true; |
| 620 | |
| 621 | update_min_dispatch_time(sq); |
| 622 | |
| 623 | /* is the next dispatch time in the future? */ |
| 624 | if (force || time_after(sq->first_pending_disptime, jiffies)) { |
| 625 | throtl_schedule_pending_timer(sq, sq->first_pending_disptime); |
| 626 | return true; |
| 627 | } |
| 628 | |
| 629 | /* tell the caller to continue dispatching */ |
| 630 | return false; |
| 631 | } |
| 632 | |
| 633 | static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg, |
| 634 | bool rw, unsigned long start) |
| 635 | { |
| 636 | tg->bytes_disp[rw] = 0; |
| 637 | tg->io_disp[rw] = 0; |
| 638 | tg->carryover_bytes[rw] = 0; |
| 639 | tg->carryover_ios[rw] = 0; |
| 640 | |
| 641 | /* |
| 642 | * Previous slice has expired. We must have trimmed it after last |
| 643 | * bio dispatch. That means since start of last slice, we never used |
| 644 | * that bandwidth. Do try to make use of that bandwidth while giving |
| 645 | * credit. |
| 646 | */ |
| 647 | if (time_after(start, tg->slice_start[rw])) |
| 648 | tg->slice_start[rw] = start; |
| 649 | |
| 650 | tg->slice_end[rw] = jiffies + tg->td->throtl_slice; |
| 651 | throtl_log(&tg->service_queue, |
| 652 | "[%c] new slice with credit start=%lu end=%lu jiffies=%lu", |
| 653 | rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| 654 | tg->slice_end[rw], jiffies); |
| 655 | } |
| 656 | |
| 657 | static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw, |
| 658 | bool clear_carryover) |
| 659 | { |
| 660 | tg->bytes_disp[rw] = 0; |
| 661 | tg->io_disp[rw] = 0; |
| 662 | tg->slice_start[rw] = jiffies; |
| 663 | tg->slice_end[rw] = jiffies + tg->td->throtl_slice; |
| 664 | if (clear_carryover) { |
| 665 | tg->carryover_bytes[rw] = 0; |
| 666 | tg->carryover_ios[rw] = 0; |
| 667 | } |
| 668 | |
| 669 | throtl_log(&tg->service_queue, |
| 670 | "[%c] new slice start=%lu end=%lu jiffies=%lu", |
| 671 | rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| 672 | tg->slice_end[rw], jiffies); |
| 673 | } |
| 674 | |
| 675 | static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw, |
| 676 | unsigned long jiffy_end) |
| 677 | { |
| 678 | tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice); |
| 679 | } |
| 680 | |
| 681 | static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw, |
| 682 | unsigned long jiffy_end) |
| 683 | { |
| 684 | throtl_set_slice_end(tg, rw, jiffy_end); |
| 685 | throtl_log(&tg->service_queue, |
| 686 | "[%c] extend slice start=%lu end=%lu jiffies=%lu", |
| 687 | rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| 688 | tg->slice_end[rw], jiffies); |
| 689 | } |
| 690 | |
| 691 | /* Determine if previously allocated or extended slice is complete or not */ |
| 692 | static bool throtl_slice_used(struct throtl_grp *tg, bool rw) |
| 693 | { |
| 694 | if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) |
| 695 | return false; |
| 696 | |
| 697 | return true; |
| 698 | } |
| 699 | |
| 700 | /* Trim the used slices and adjust slice start accordingly */ |
| 701 | static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) |
| 702 | { |
| 703 | unsigned long nr_slices, time_elapsed, io_trim; |
| 704 | u64 bytes_trim, tmp; |
| 705 | |
| 706 | BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); |
| 707 | |
| 708 | /* |
| 709 | * If bps are unlimited (-1), then time slice don't get |
| 710 | * renewed. Don't try to trim the slice if slice is used. A new |
| 711 | * slice will start when appropriate. |
| 712 | */ |
| 713 | if (throtl_slice_used(tg, rw)) |
| 714 | return; |
| 715 | |
| 716 | /* |
| 717 | * A bio has been dispatched. Also adjust slice_end. It might happen |
| 718 | * that initially cgroup limit was very low resulting in high |
| 719 | * slice_end, but later limit was bumped up and bio was dispatched |
| 720 | * sooner, then we need to reduce slice_end. A high bogus slice_end |
| 721 | * is bad because it does not allow new slice to start. |
| 722 | */ |
| 723 | |
| 724 | throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice); |
| 725 | |
| 726 | time_elapsed = jiffies - tg->slice_start[rw]; |
| 727 | |
| 728 | nr_slices = time_elapsed / tg->td->throtl_slice; |
| 729 | |
| 730 | if (!nr_slices) |
| 731 | return; |
| 732 | tmp = tg_bps_limit(tg, rw) * tg->td->throtl_slice * nr_slices; |
| 733 | do_div(tmp, HZ); |
| 734 | bytes_trim = tmp; |
| 735 | |
| 736 | io_trim = (tg_iops_limit(tg, rw) * tg->td->throtl_slice * nr_slices) / |
| 737 | HZ; |
| 738 | |
| 739 | if (!bytes_trim && !io_trim) |
| 740 | return; |
| 741 | |
| 742 | if (tg->bytes_disp[rw] >= bytes_trim) |
| 743 | tg->bytes_disp[rw] -= bytes_trim; |
| 744 | else |
| 745 | tg->bytes_disp[rw] = 0; |
| 746 | |
| 747 | if (tg->io_disp[rw] >= io_trim) |
| 748 | tg->io_disp[rw] -= io_trim; |
| 749 | else |
| 750 | tg->io_disp[rw] = 0; |
| 751 | |
| 752 | tg->slice_start[rw] += nr_slices * tg->td->throtl_slice; |
| 753 | |
| 754 | throtl_log(&tg->service_queue, |
| 755 | "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", |
| 756 | rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, |
| 757 | tg->slice_start[rw], tg->slice_end[rw], jiffies); |
| 758 | } |
| 759 | |
| 760 | static unsigned int calculate_io_allowed(u32 iops_limit, |
| 761 | unsigned long jiffy_elapsed) |
| 762 | { |
| 763 | unsigned int io_allowed; |
| 764 | u64 tmp; |
| 765 | |
| 766 | /* |
| 767 | * jiffy_elapsed should not be a big value as minimum iops can be |
| 768 | * 1 then at max jiffy elapsed should be equivalent of 1 second as we |
| 769 | * will allow dispatch after 1 second and after that slice should |
| 770 | * have been trimmed. |
| 771 | */ |
| 772 | |
| 773 | tmp = (u64)iops_limit * jiffy_elapsed; |
| 774 | do_div(tmp, HZ); |
| 775 | |
| 776 | if (tmp > UINT_MAX) |
| 777 | io_allowed = UINT_MAX; |
| 778 | else |
| 779 | io_allowed = tmp; |
| 780 | |
| 781 | return io_allowed; |
| 782 | } |
| 783 | |
| 784 | static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed) |
| 785 | { |
| 786 | return mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed, (u64)HZ); |
| 787 | } |
| 788 | |
| 789 | static void __tg_update_carryover(struct throtl_grp *tg, bool rw) |
| 790 | { |
| 791 | unsigned long jiffy_elapsed = jiffies - tg->slice_start[rw]; |
| 792 | u64 bps_limit = tg_bps_limit(tg, rw); |
| 793 | u32 iops_limit = tg_iops_limit(tg, rw); |
| 794 | |
| 795 | /* |
| 796 | * If config is updated while bios are still throttled, calculate and |
| 797 | * accumulate how many bytes/ios are waited across changes. And |
| 798 | * carryover_bytes/ios will be used to calculate new wait time under new |
| 799 | * configuration. |
| 800 | */ |
| 801 | if (bps_limit != U64_MAX) |
| 802 | tg->carryover_bytes[rw] += |
| 803 | calculate_bytes_allowed(bps_limit, jiffy_elapsed) - |
| 804 | tg->bytes_disp[rw]; |
| 805 | if (iops_limit != UINT_MAX) |
| 806 | tg->carryover_ios[rw] += |
| 807 | calculate_io_allowed(iops_limit, jiffy_elapsed) - |
| 808 | tg->io_disp[rw]; |
| 809 | } |
| 810 | |
| 811 | static void tg_update_carryover(struct throtl_grp *tg) |
| 812 | { |
| 813 | if (tg->service_queue.nr_queued[READ]) |
| 814 | __tg_update_carryover(tg, READ); |
| 815 | if (tg->service_queue.nr_queued[WRITE]) |
| 816 | __tg_update_carryover(tg, WRITE); |
| 817 | |
| 818 | /* see comments in struct throtl_grp for meaning of these fields. */ |
| 819 | throtl_log(&tg->service_queue, "%s: %llu %llu %u %u\n", __func__, |
| 820 | tg->carryover_bytes[READ], tg->carryover_bytes[WRITE], |
| 821 | tg->carryover_ios[READ], tg->carryover_ios[WRITE]); |
| 822 | } |
| 823 | |
| 824 | static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio, |
| 825 | u32 iops_limit) |
| 826 | { |
| 827 | bool rw = bio_data_dir(bio); |
| 828 | unsigned int io_allowed; |
| 829 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
| 830 | |
| 831 | if (iops_limit == UINT_MAX) { |
| 832 | return 0; |
| 833 | } |
| 834 | |
| 835 | jiffy_elapsed = jiffies - tg->slice_start[rw]; |
| 836 | |
| 837 | /* Round up to the next throttle slice, wait time must be nonzero */ |
| 838 | jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice); |
| 839 | io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd) + |
| 840 | tg->carryover_ios[rw]; |
| 841 | if (tg->io_disp[rw] + 1 <= io_allowed) { |
| 842 | return 0; |
| 843 | } |
| 844 | |
| 845 | /* Calc approx time to dispatch */ |
| 846 | jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed; |
| 847 | return jiffy_wait; |
| 848 | } |
| 849 | |
| 850 | static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, |
| 851 | u64 bps_limit) |
| 852 | { |
| 853 | bool rw = bio_data_dir(bio); |
| 854 | u64 bytes_allowed, extra_bytes; |
| 855 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
| 856 | unsigned int bio_size = throtl_bio_data_size(bio); |
| 857 | |
| 858 | /* no need to throttle if this bio's bytes have been accounted */ |
| 859 | if (bps_limit == U64_MAX || bio_flagged(bio, BIO_BPS_THROTTLED)) { |
| 860 | return 0; |
| 861 | } |
| 862 | |
| 863 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
| 864 | |
| 865 | /* Slice has just started. Consider one slice interval */ |
| 866 | if (!jiffy_elapsed) |
| 867 | jiffy_elapsed_rnd = tg->td->throtl_slice; |
| 868 | |
| 869 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); |
| 870 | bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd) + |
| 871 | tg->carryover_bytes[rw]; |
| 872 | if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) { |
| 873 | return 0; |
| 874 | } |
| 875 | |
| 876 | /* Calc approx time to dispatch */ |
| 877 | extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed; |
| 878 | jiffy_wait = div64_u64(extra_bytes * HZ, bps_limit); |
| 879 | |
| 880 | if (!jiffy_wait) |
| 881 | jiffy_wait = 1; |
| 882 | |
| 883 | /* |
| 884 | * This wait time is without taking into consideration the rounding |
| 885 | * up we did. Add that time also. |
| 886 | */ |
| 887 | jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); |
| 888 | return jiffy_wait; |
| 889 | } |
| 890 | |
| 891 | /* |
| 892 | * Returns whether one can dispatch a bio or not. Also returns approx number |
| 893 | * of jiffies to wait before this bio is with-in IO rate and can be dispatched |
| 894 | */ |
| 895 | static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, |
| 896 | unsigned long *wait) |
| 897 | { |
| 898 | bool rw = bio_data_dir(bio); |
| 899 | unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; |
| 900 | u64 bps_limit = tg_bps_limit(tg, rw); |
| 901 | u32 iops_limit = tg_iops_limit(tg, rw); |
| 902 | |
| 903 | /* |
| 904 | * Currently whole state machine of group depends on first bio |
| 905 | * queued in the group bio list. So one should not be calling |
| 906 | * this function with a different bio if there are other bios |
| 907 | * queued. |
| 908 | */ |
| 909 | BUG_ON(tg->service_queue.nr_queued[rw] && |
| 910 | bio != throtl_peek_queued(&tg->service_queue.queued[rw])); |
| 911 | |
| 912 | /* If tg->bps = -1, then BW is unlimited */ |
| 913 | if ((bps_limit == U64_MAX && iops_limit == UINT_MAX) || |
| 914 | tg->flags & THROTL_TG_CANCELING) { |
| 915 | if (wait) |
| 916 | *wait = 0; |
| 917 | return true; |
| 918 | } |
| 919 | |
| 920 | /* |
| 921 | * If previous slice expired, start a new one otherwise renew/extend |
| 922 | * existing slice to make sure it is at least throtl_slice interval |
| 923 | * long since now. New slice is started only for empty throttle group. |
| 924 | * If there is queued bio, that means there should be an active |
| 925 | * slice and it should be extended instead. |
| 926 | */ |
| 927 | if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw])) |
| 928 | throtl_start_new_slice(tg, rw, true); |
| 929 | else { |
| 930 | if (time_before(tg->slice_end[rw], |
| 931 | jiffies + tg->td->throtl_slice)) |
| 932 | throtl_extend_slice(tg, rw, |
| 933 | jiffies + tg->td->throtl_slice); |
| 934 | } |
| 935 | |
| 936 | bps_wait = tg_within_bps_limit(tg, bio, bps_limit); |
| 937 | iops_wait = tg_within_iops_limit(tg, bio, iops_limit); |
| 938 | if (bps_wait + iops_wait == 0) { |
| 939 | if (wait) |
| 940 | *wait = 0; |
| 941 | return true; |
| 942 | } |
| 943 | |
| 944 | max_wait = max(bps_wait, iops_wait); |
| 945 | |
| 946 | if (wait) |
| 947 | *wait = max_wait; |
| 948 | |
| 949 | if (time_before(tg->slice_end[rw], jiffies + max_wait)) |
| 950 | throtl_extend_slice(tg, rw, jiffies + max_wait); |
| 951 | |
| 952 | return false; |
| 953 | } |
| 954 | |
| 955 | static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) |
| 956 | { |
| 957 | bool rw = bio_data_dir(bio); |
| 958 | unsigned int bio_size = throtl_bio_data_size(bio); |
| 959 | |
| 960 | /* Charge the bio to the group */ |
| 961 | if (!bio_flagged(bio, BIO_BPS_THROTTLED)) { |
| 962 | tg->bytes_disp[rw] += bio_size; |
| 963 | tg->last_bytes_disp[rw] += bio_size; |
| 964 | } |
| 965 | |
| 966 | tg->io_disp[rw]++; |
| 967 | tg->last_io_disp[rw]++; |
| 968 | } |
| 969 | |
| 970 | /** |
| 971 | * throtl_add_bio_tg - add a bio to the specified throtl_grp |
| 972 | * @bio: bio to add |
| 973 | * @qn: qnode to use |
| 974 | * @tg: the target throtl_grp |
| 975 | * |
| 976 | * Add @bio to @tg's service_queue using @qn. If @qn is not specified, |
| 977 | * tg->qnode_on_self[] is used. |
| 978 | */ |
| 979 | static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn, |
| 980 | struct throtl_grp *tg) |
| 981 | { |
| 982 | struct throtl_service_queue *sq = &tg->service_queue; |
| 983 | bool rw = bio_data_dir(bio); |
| 984 | |
| 985 | if (!qn) |
| 986 | qn = &tg->qnode_on_self[rw]; |
| 987 | |
| 988 | /* |
| 989 | * If @tg doesn't currently have any bios queued in the same |
| 990 | * direction, queueing @bio can change when @tg should be |
| 991 | * dispatched. Mark that @tg was empty. This is automatically |
| 992 | * cleared on the next tg_update_disptime(). |
| 993 | */ |
| 994 | if (!sq->nr_queued[rw]) |
| 995 | tg->flags |= THROTL_TG_WAS_EMPTY; |
| 996 | |
| 997 | throtl_qnode_add_bio(bio, qn, &sq->queued[rw]); |
| 998 | |
| 999 | sq->nr_queued[rw]++; |
| 1000 | throtl_enqueue_tg(tg); |
| 1001 | } |
| 1002 | |
| 1003 | static void tg_update_disptime(struct throtl_grp *tg) |
| 1004 | { |
| 1005 | struct throtl_service_queue *sq = &tg->service_queue; |
| 1006 | unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; |
| 1007 | struct bio *bio; |
| 1008 | |
| 1009 | bio = throtl_peek_queued(&sq->queued[READ]); |
| 1010 | if (bio) |
| 1011 | tg_may_dispatch(tg, bio, &read_wait); |
| 1012 | |
| 1013 | bio = throtl_peek_queued(&sq->queued[WRITE]); |
| 1014 | if (bio) |
| 1015 | tg_may_dispatch(tg, bio, &write_wait); |
| 1016 | |
| 1017 | min_wait = min(read_wait, write_wait); |
| 1018 | disptime = jiffies + min_wait; |
| 1019 | |
| 1020 | /* Update dispatch time */ |
| 1021 | throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq); |
| 1022 | tg->disptime = disptime; |
| 1023 | tg_service_queue_add(tg); |
| 1024 | |
| 1025 | /* see throtl_add_bio_tg() */ |
| 1026 | tg->flags &= ~THROTL_TG_WAS_EMPTY; |
| 1027 | } |
| 1028 | |
| 1029 | static void start_parent_slice_with_credit(struct throtl_grp *child_tg, |
| 1030 | struct throtl_grp *parent_tg, bool rw) |
| 1031 | { |
| 1032 | if (throtl_slice_used(parent_tg, rw)) { |
| 1033 | throtl_start_new_slice_with_credit(parent_tg, rw, |
| 1034 | child_tg->slice_start[rw]); |
| 1035 | } |
| 1036 | |
| 1037 | } |
| 1038 | |
| 1039 | static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) |
| 1040 | { |
| 1041 | struct throtl_service_queue *sq = &tg->service_queue; |
| 1042 | struct throtl_service_queue *parent_sq = sq->parent_sq; |
| 1043 | struct throtl_grp *parent_tg = sq_to_tg(parent_sq); |
| 1044 | struct throtl_grp *tg_to_put = NULL; |
| 1045 | struct bio *bio; |
| 1046 | |
| 1047 | /* |
| 1048 | * @bio is being transferred from @tg to @parent_sq. Popping a bio |
| 1049 | * from @tg may put its reference and @parent_sq might end up |
| 1050 | * getting released prematurely. Remember the tg to put and put it |
| 1051 | * after @bio is transferred to @parent_sq. |
| 1052 | */ |
| 1053 | bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put); |
| 1054 | sq->nr_queued[rw]--; |
| 1055 | |
| 1056 | throtl_charge_bio(tg, bio); |
| 1057 | |
| 1058 | /* |
| 1059 | * If our parent is another tg, we just need to transfer @bio to |
| 1060 | * the parent using throtl_add_bio_tg(). If our parent is |
| 1061 | * @td->service_queue, @bio is ready to be issued. Put it on its |
| 1062 | * bio_lists[] and decrease total number queued. The caller is |
| 1063 | * responsible for issuing these bios. |
| 1064 | */ |
| 1065 | if (parent_tg) { |
| 1066 | throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); |
| 1067 | start_parent_slice_with_credit(tg, parent_tg, rw); |
| 1068 | } else { |
| 1069 | bio_set_flag(bio, BIO_BPS_THROTTLED); |
| 1070 | throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], |
| 1071 | &parent_sq->queued[rw]); |
| 1072 | BUG_ON(tg->td->nr_queued[rw] <= 0); |
| 1073 | tg->td->nr_queued[rw]--; |
| 1074 | } |
| 1075 | |
| 1076 | throtl_trim_slice(tg, rw); |
| 1077 | |
| 1078 | if (tg_to_put) |
| 1079 | blkg_put(tg_to_blkg(tg_to_put)); |
| 1080 | } |
| 1081 | |
| 1082 | static int throtl_dispatch_tg(struct throtl_grp *tg) |
| 1083 | { |
| 1084 | struct throtl_service_queue *sq = &tg->service_queue; |
| 1085 | unsigned int nr_reads = 0, nr_writes = 0; |
| 1086 | unsigned int max_nr_reads = THROTL_GRP_QUANTUM * 3 / 4; |
| 1087 | unsigned int max_nr_writes = THROTL_GRP_QUANTUM - max_nr_reads; |
| 1088 | struct bio *bio; |
| 1089 | |
| 1090 | /* Try to dispatch 75% READS and 25% WRITES */ |
| 1091 | |
| 1092 | while ((bio = throtl_peek_queued(&sq->queued[READ])) && |
| 1093 | tg_may_dispatch(tg, bio, NULL)) { |
| 1094 | |
| 1095 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| 1096 | nr_reads++; |
| 1097 | |
| 1098 | if (nr_reads >= max_nr_reads) |
| 1099 | break; |
| 1100 | } |
| 1101 | |
| 1102 | while ((bio = throtl_peek_queued(&sq->queued[WRITE])) && |
| 1103 | tg_may_dispatch(tg, bio, NULL)) { |
| 1104 | |
| 1105 | tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| 1106 | nr_writes++; |
| 1107 | |
| 1108 | if (nr_writes >= max_nr_writes) |
| 1109 | break; |
| 1110 | } |
| 1111 | |
| 1112 | return nr_reads + nr_writes; |
| 1113 | } |
| 1114 | |
| 1115 | static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) |
| 1116 | { |
| 1117 | unsigned int nr_disp = 0; |
| 1118 | |
| 1119 | while (1) { |
| 1120 | struct throtl_grp *tg; |
| 1121 | struct throtl_service_queue *sq; |
| 1122 | |
| 1123 | if (!parent_sq->nr_pending) |
| 1124 | break; |
| 1125 | |
| 1126 | tg = throtl_rb_first(parent_sq); |
| 1127 | if (!tg) |
| 1128 | break; |
| 1129 | |
| 1130 | if (time_before(jiffies, tg->disptime)) |
| 1131 | break; |
| 1132 | |
| 1133 | nr_disp += throtl_dispatch_tg(tg); |
| 1134 | |
| 1135 | sq = &tg->service_queue; |
| 1136 | if (sq->nr_queued[READ] || sq->nr_queued[WRITE]) |
| 1137 | tg_update_disptime(tg); |
| 1138 | else |
| 1139 | throtl_dequeue_tg(tg); |
| 1140 | |
| 1141 | if (nr_disp >= THROTL_QUANTUM) |
| 1142 | break; |
| 1143 | } |
| 1144 | |
| 1145 | return nr_disp; |
| 1146 | } |
| 1147 | |
| 1148 | static bool throtl_can_upgrade(struct throtl_data *td, |
| 1149 | struct throtl_grp *this_tg); |
| 1150 | /** |
| 1151 | * throtl_pending_timer_fn - timer function for service_queue->pending_timer |
| 1152 | * @t: the pending_timer member of the throtl_service_queue being serviced |
| 1153 | * |
| 1154 | * This timer is armed when a child throtl_grp with active bio's become |
| 1155 | * pending and queued on the service_queue's pending_tree and expires when |
| 1156 | * the first child throtl_grp should be dispatched. This function |
| 1157 | * dispatches bio's from the children throtl_grps to the parent |
| 1158 | * service_queue. |
| 1159 | * |
| 1160 | * If the parent's parent is another throtl_grp, dispatching is propagated |
| 1161 | * by either arming its pending_timer or repeating dispatch directly. If |
| 1162 | * the top-level service_tree is reached, throtl_data->dispatch_work is |
| 1163 | * kicked so that the ready bio's are issued. |
| 1164 | */ |
| 1165 | static void throtl_pending_timer_fn(struct timer_list *t) |
| 1166 | { |
| 1167 | struct throtl_service_queue *sq = from_timer(sq, t, pending_timer); |
| 1168 | struct throtl_grp *tg = sq_to_tg(sq); |
| 1169 | struct throtl_data *td = sq_to_td(sq); |
| 1170 | struct throtl_service_queue *parent_sq; |
| 1171 | struct request_queue *q; |
| 1172 | bool dispatched; |
| 1173 | int ret; |
| 1174 | |
| 1175 | /* throtl_data may be gone, so figure out request queue by blkg */ |
| 1176 | if (tg) |
| 1177 | q = tg->pd.blkg->q; |
| 1178 | else |
| 1179 | q = td->queue; |
| 1180 | |
| 1181 | spin_lock_irq(&q->queue_lock); |
| 1182 | |
| 1183 | if (!q->root_blkg) |
| 1184 | goto out_unlock; |
| 1185 | |
| 1186 | if (throtl_can_upgrade(td, NULL)) |
| 1187 | throtl_upgrade_state(td); |
| 1188 | |
| 1189 | again: |
| 1190 | parent_sq = sq->parent_sq; |
| 1191 | dispatched = false; |
| 1192 | |
| 1193 | while (true) { |
| 1194 | throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u", |
| 1195 | sq->nr_queued[READ] + sq->nr_queued[WRITE], |
| 1196 | sq->nr_queued[READ], sq->nr_queued[WRITE]); |
| 1197 | |
| 1198 | ret = throtl_select_dispatch(sq); |
| 1199 | if (ret) { |
| 1200 | throtl_log(sq, "bios disp=%u", ret); |
| 1201 | dispatched = true; |
| 1202 | } |
| 1203 | |
| 1204 | if (throtl_schedule_next_dispatch(sq, false)) |
| 1205 | break; |
| 1206 | |
| 1207 | /* this dispatch windows is still open, relax and repeat */ |
| 1208 | spin_unlock_irq(&q->queue_lock); |
| 1209 | cpu_relax(); |
| 1210 | spin_lock_irq(&q->queue_lock); |
| 1211 | } |
| 1212 | |
| 1213 | if (!dispatched) |
| 1214 | goto out_unlock; |
| 1215 | |
| 1216 | if (parent_sq) { |
| 1217 | /* @parent_sq is another throl_grp, propagate dispatch */ |
| 1218 | if (tg->flags & THROTL_TG_WAS_EMPTY) { |
| 1219 | tg_update_disptime(tg); |
| 1220 | if (!throtl_schedule_next_dispatch(parent_sq, false)) { |
| 1221 | /* window is already open, repeat dispatching */ |
| 1222 | sq = parent_sq; |
| 1223 | tg = sq_to_tg(sq); |
| 1224 | goto again; |
| 1225 | } |
| 1226 | } |
| 1227 | } else { |
| 1228 | /* reached the top-level, queue issuing */ |
| 1229 | queue_work(kthrotld_workqueue, &td->dispatch_work); |
| 1230 | } |
| 1231 | out_unlock: |
| 1232 | spin_unlock_irq(&q->queue_lock); |
| 1233 | } |
| 1234 | |
| 1235 | /** |
| 1236 | * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work |
| 1237 | * @work: work item being executed |
| 1238 | * |
| 1239 | * This function is queued for execution when bios reach the bio_lists[] |
| 1240 | * of throtl_data->service_queue. Those bios are ready and issued by this |
| 1241 | * function. |
| 1242 | */ |
| 1243 | static void blk_throtl_dispatch_work_fn(struct work_struct *work) |
| 1244 | { |
| 1245 | struct throtl_data *td = container_of(work, struct throtl_data, |
| 1246 | dispatch_work); |
| 1247 | struct throtl_service_queue *td_sq = &td->service_queue; |
| 1248 | struct request_queue *q = td->queue; |
| 1249 | struct bio_list bio_list_on_stack; |
| 1250 | struct bio *bio; |
| 1251 | struct blk_plug plug; |
| 1252 | int rw; |
| 1253 | |
| 1254 | bio_list_init(&bio_list_on_stack); |
| 1255 | |
| 1256 | spin_lock_irq(&q->queue_lock); |
| 1257 | for (rw = READ; rw <= WRITE; rw++) |
| 1258 | while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) |
| 1259 | bio_list_add(&bio_list_on_stack, bio); |
| 1260 | spin_unlock_irq(&q->queue_lock); |
| 1261 | |
| 1262 | if (!bio_list_empty(&bio_list_on_stack)) { |
| 1263 | blk_start_plug(&plug); |
| 1264 | while ((bio = bio_list_pop(&bio_list_on_stack))) |
| 1265 | submit_bio_noacct_nocheck(bio); |
| 1266 | blk_finish_plug(&plug); |
| 1267 | } |
| 1268 | } |
| 1269 | |
| 1270 | static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, |
| 1271 | int off) |
| 1272 | { |
| 1273 | struct throtl_grp *tg = pd_to_tg(pd); |
| 1274 | u64 v = *(u64 *)((void *)tg + off); |
| 1275 | |
| 1276 | if (v == U64_MAX) |
| 1277 | return 0; |
| 1278 | return __blkg_prfill_u64(sf, pd, v); |
| 1279 | } |
| 1280 | |
| 1281 | static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, |
| 1282 | int off) |
| 1283 | { |
| 1284 | struct throtl_grp *tg = pd_to_tg(pd); |
| 1285 | unsigned int v = *(unsigned int *)((void *)tg + off); |
| 1286 | |
| 1287 | if (v == UINT_MAX) |
| 1288 | return 0; |
| 1289 | return __blkg_prfill_u64(sf, pd, v); |
| 1290 | } |
| 1291 | |
| 1292 | static int tg_print_conf_u64(struct seq_file *sf, void *v) |
| 1293 | { |
| 1294 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64, |
| 1295 | &blkcg_policy_throtl, seq_cft(sf)->private, false); |
| 1296 | return 0; |
| 1297 | } |
| 1298 | |
| 1299 | static int tg_print_conf_uint(struct seq_file *sf, void *v) |
| 1300 | { |
| 1301 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint, |
| 1302 | &blkcg_policy_throtl, seq_cft(sf)->private, false); |
| 1303 | return 0; |
| 1304 | } |
| 1305 | |
| 1306 | static void tg_conf_updated(struct throtl_grp *tg, bool global) |
| 1307 | { |
| 1308 | struct throtl_service_queue *sq = &tg->service_queue; |
| 1309 | struct cgroup_subsys_state *pos_css; |
| 1310 | struct blkcg_gq *blkg; |
| 1311 | |
| 1312 | throtl_log(&tg->service_queue, |
| 1313 | "limit change rbps=%llu wbps=%llu riops=%u wiops=%u", |
| 1314 | tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE), |
| 1315 | tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE)); |
| 1316 | |
| 1317 | /* |
| 1318 | * Update has_rules[] flags for the updated tg's subtree. A tg is |
| 1319 | * considered to have rules if either the tg itself or any of its |
| 1320 | * ancestors has rules. This identifies groups without any |
| 1321 | * restrictions in the whole hierarchy and allows them to bypass |
| 1322 | * blk-throttle. |
| 1323 | */ |
| 1324 | blkg_for_each_descendant_pre(blkg, pos_css, |
| 1325 | global ? tg->td->queue->root_blkg : tg_to_blkg(tg)) { |
| 1326 | struct throtl_grp *this_tg = blkg_to_tg(blkg); |
| 1327 | struct throtl_grp *parent_tg; |
| 1328 | |
| 1329 | tg_update_has_rules(this_tg); |
| 1330 | /* ignore root/second level */ |
| 1331 | if (!cgroup_subsys_on_dfl(io_cgrp_subsys) || !blkg->parent || |
| 1332 | !blkg->parent->parent) |
| 1333 | continue; |
| 1334 | parent_tg = blkg_to_tg(blkg->parent); |
| 1335 | /* |
| 1336 | * make sure all children has lower idle time threshold and |
| 1337 | * higher latency target |
| 1338 | */ |
| 1339 | this_tg->idletime_threshold = min(this_tg->idletime_threshold, |
| 1340 | parent_tg->idletime_threshold); |
| 1341 | this_tg->latency_target = max(this_tg->latency_target, |
| 1342 | parent_tg->latency_target); |
| 1343 | } |
| 1344 | |
| 1345 | /* |
| 1346 | * We're already holding queue_lock and know @tg is valid. Let's |
| 1347 | * apply the new config directly. |
| 1348 | * |
| 1349 | * Restart the slices for both READ and WRITES. It might happen |
| 1350 | * that a group's limit are dropped suddenly and we don't want to |
| 1351 | * account recently dispatched IO with new low rate. |
| 1352 | */ |
| 1353 | throtl_start_new_slice(tg, READ, false); |
| 1354 | throtl_start_new_slice(tg, WRITE, false); |
| 1355 | |
| 1356 | if (tg->flags & THROTL_TG_PENDING) { |
| 1357 | tg_update_disptime(tg); |
| 1358 | throtl_schedule_next_dispatch(sq->parent_sq, true); |
| 1359 | } |
| 1360 | } |
| 1361 | |
| 1362 | static ssize_t tg_set_conf(struct kernfs_open_file *of, |
| 1363 | char *buf, size_t nbytes, loff_t off, bool is_u64) |
| 1364 | { |
| 1365 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); |
| 1366 | struct blkg_conf_ctx ctx; |
| 1367 | struct throtl_grp *tg; |
| 1368 | int ret; |
| 1369 | u64 v; |
| 1370 | |
| 1371 | blkg_conf_init(&ctx, buf); |
| 1372 | |
| 1373 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx); |
| 1374 | if (ret) |
| 1375 | goto out_finish; |
| 1376 | |
| 1377 | ret = -EINVAL; |
| 1378 | if (sscanf(ctx.body, "%llu", &v) != 1) |
| 1379 | goto out_finish; |
| 1380 | if (!v) |
| 1381 | v = U64_MAX; |
| 1382 | |
| 1383 | tg = blkg_to_tg(ctx.blkg); |
| 1384 | tg_update_carryover(tg); |
| 1385 | |
| 1386 | if (is_u64) |
| 1387 | *(u64 *)((void *)tg + of_cft(of)->private) = v; |
| 1388 | else |
| 1389 | *(unsigned int *)((void *)tg + of_cft(of)->private) = v; |
| 1390 | |
| 1391 | tg_conf_updated(tg, false); |
| 1392 | ret = 0; |
| 1393 | out_finish: |
| 1394 | blkg_conf_exit(&ctx); |
| 1395 | return ret ?: nbytes; |
| 1396 | } |
| 1397 | |
| 1398 | static ssize_t tg_set_conf_u64(struct kernfs_open_file *of, |
| 1399 | char *buf, size_t nbytes, loff_t off) |
| 1400 | { |
| 1401 | return tg_set_conf(of, buf, nbytes, off, true); |
| 1402 | } |
| 1403 | |
| 1404 | static ssize_t tg_set_conf_uint(struct kernfs_open_file *of, |
| 1405 | char *buf, size_t nbytes, loff_t off) |
| 1406 | { |
| 1407 | return tg_set_conf(of, buf, nbytes, off, false); |
| 1408 | } |
| 1409 | |
| 1410 | static int tg_print_rwstat(struct seq_file *sf, void *v) |
| 1411 | { |
| 1412 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), |
| 1413 | blkg_prfill_rwstat, &blkcg_policy_throtl, |
| 1414 | seq_cft(sf)->private, true); |
| 1415 | return 0; |
| 1416 | } |
| 1417 | |
| 1418 | static u64 tg_prfill_rwstat_recursive(struct seq_file *sf, |
| 1419 | struct blkg_policy_data *pd, int off) |
| 1420 | { |
| 1421 | struct blkg_rwstat_sample sum; |
| 1422 | |
| 1423 | blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_throtl, off, |
| 1424 | &sum); |
| 1425 | return __blkg_prfill_rwstat(sf, pd, &sum); |
| 1426 | } |
| 1427 | |
| 1428 | static int tg_print_rwstat_recursive(struct seq_file *sf, void *v) |
| 1429 | { |
| 1430 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), |
| 1431 | tg_prfill_rwstat_recursive, &blkcg_policy_throtl, |
| 1432 | seq_cft(sf)->private, true); |
| 1433 | return 0; |
| 1434 | } |
| 1435 | |
| 1436 | static struct cftype throtl_legacy_files[] = { |
| 1437 | { |
| 1438 | .name = "throttle.read_bps_device", |
| 1439 | .private = offsetof(struct throtl_grp, bps[READ][LIMIT_MAX]), |
| 1440 | .seq_show = tg_print_conf_u64, |
| 1441 | .write = tg_set_conf_u64, |
| 1442 | }, |
| 1443 | { |
| 1444 | .name = "throttle.write_bps_device", |
| 1445 | .private = offsetof(struct throtl_grp, bps[WRITE][LIMIT_MAX]), |
| 1446 | .seq_show = tg_print_conf_u64, |
| 1447 | .write = tg_set_conf_u64, |
| 1448 | }, |
| 1449 | { |
| 1450 | .name = "throttle.read_iops_device", |
| 1451 | .private = offsetof(struct throtl_grp, iops[READ][LIMIT_MAX]), |
| 1452 | .seq_show = tg_print_conf_uint, |
| 1453 | .write = tg_set_conf_uint, |
| 1454 | }, |
| 1455 | { |
| 1456 | .name = "throttle.write_iops_device", |
| 1457 | .private = offsetof(struct throtl_grp, iops[WRITE][LIMIT_MAX]), |
| 1458 | .seq_show = tg_print_conf_uint, |
| 1459 | .write = tg_set_conf_uint, |
| 1460 | }, |
| 1461 | { |
| 1462 | .name = "throttle.io_service_bytes", |
| 1463 | .private = offsetof(struct throtl_grp, stat_bytes), |
| 1464 | .seq_show = tg_print_rwstat, |
| 1465 | }, |
| 1466 | { |
| 1467 | .name = "throttle.io_service_bytes_recursive", |
| 1468 | .private = offsetof(struct throtl_grp, stat_bytes), |
| 1469 | .seq_show = tg_print_rwstat_recursive, |
| 1470 | }, |
| 1471 | { |
| 1472 | .name = "throttle.io_serviced", |
| 1473 | .private = offsetof(struct throtl_grp, stat_ios), |
| 1474 | .seq_show = tg_print_rwstat, |
| 1475 | }, |
| 1476 | { |
| 1477 | .name = "throttle.io_serviced_recursive", |
| 1478 | .private = offsetof(struct throtl_grp, stat_ios), |
| 1479 | .seq_show = tg_print_rwstat_recursive, |
| 1480 | }, |
| 1481 | { } /* terminate */ |
| 1482 | }; |
| 1483 | |
| 1484 | static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd, |
| 1485 | int off) |
| 1486 | { |
| 1487 | struct throtl_grp *tg = pd_to_tg(pd); |
| 1488 | const char *dname = blkg_dev_name(pd->blkg); |
| 1489 | char bufs[4][21] = { "max", "max", "max", "max" }; |
| 1490 | u64 bps_dft; |
| 1491 | unsigned int iops_dft; |
| 1492 | char idle_time[26] = ""; |
| 1493 | char latency_time[26] = ""; |
| 1494 | |
| 1495 | if (!dname) |
| 1496 | return 0; |
| 1497 | |
| 1498 | if (off == LIMIT_LOW) { |
| 1499 | bps_dft = 0; |
| 1500 | iops_dft = 0; |
| 1501 | } else { |
| 1502 | bps_dft = U64_MAX; |
| 1503 | iops_dft = UINT_MAX; |
| 1504 | } |
| 1505 | |
| 1506 | if (tg->bps_conf[READ][off] == bps_dft && |
| 1507 | tg->bps_conf[WRITE][off] == bps_dft && |
| 1508 | tg->iops_conf[READ][off] == iops_dft && |
| 1509 | tg->iops_conf[WRITE][off] == iops_dft && |
| 1510 | (off != LIMIT_LOW || |
| 1511 | (tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD && |
| 1512 | tg->latency_target_conf == DFL_LATENCY_TARGET))) |
| 1513 | return 0; |
| 1514 | |
| 1515 | if (tg->bps_conf[READ][off] != U64_MAX) |
| 1516 | snprintf(bufs[0], sizeof(bufs[0]), "%llu", |
| 1517 | tg->bps_conf[READ][off]); |
| 1518 | if (tg->bps_conf[WRITE][off] != U64_MAX) |
| 1519 | snprintf(bufs[1], sizeof(bufs[1]), "%llu", |
| 1520 | tg->bps_conf[WRITE][off]); |
| 1521 | if (tg->iops_conf[READ][off] != UINT_MAX) |
| 1522 | snprintf(bufs[2], sizeof(bufs[2]), "%u", |
| 1523 | tg->iops_conf[READ][off]); |
| 1524 | if (tg->iops_conf[WRITE][off] != UINT_MAX) |
| 1525 | snprintf(bufs[3], sizeof(bufs[3]), "%u", |
| 1526 | tg->iops_conf[WRITE][off]); |
| 1527 | if (off == LIMIT_LOW) { |
| 1528 | if (tg->idletime_threshold_conf == ULONG_MAX) |
| 1529 | strcpy(idle_time, " idle=max"); |
| 1530 | else |
| 1531 | snprintf(idle_time, sizeof(idle_time), " idle=%lu", |
| 1532 | tg->idletime_threshold_conf); |
| 1533 | |
| 1534 | if (tg->latency_target_conf == ULONG_MAX) |
| 1535 | strcpy(latency_time, " latency=max"); |
| 1536 | else |
| 1537 | snprintf(latency_time, sizeof(latency_time), |
| 1538 | " latency=%lu", tg->latency_target_conf); |
| 1539 | } |
| 1540 | |
| 1541 | seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n", |
| 1542 | dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time, |
| 1543 | latency_time); |
| 1544 | return 0; |
| 1545 | } |
| 1546 | |
| 1547 | static int tg_print_limit(struct seq_file *sf, void *v) |
| 1548 | { |
| 1549 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_limit, |
| 1550 | &blkcg_policy_throtl, seq_cft(sf)->private, false); |
| 1551 | return 0; |
| 1552 | } |
| 1553 | |
| 1554 | static ssize_t tg_set_limit(struct kernfs_open_file *of, |
| 1555 | char *buf, size_t nbytes, loff_t off) |
| 1556 | { |
| 1557 | struct blkcg *blkcg = css_to_blkcg(of_css(of)); |
| 1558 | struct blkg_conf_ctx ctx; |
| 1559 | struct throtl_grp *tg; |
| 1560 | u64 v[4]; |
| 1561 | unsigned long idle_time; |
| 1562 | unsigned long latency_time; |
| 1563 | int ret; |
| 1564 | int index = of_cft(of)->private; |
| 1565 | |
| 1566 | blkg_conf_init(&ctx, buf); |
| 1567 | |
| 1568 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx); |
| 1569 | if (ret) |
| 1570 | goto out_finish; |
| 1571 | |
| 1572 | tg = blkg_to_tg(ctx.blkg); |
| 1573 | tg_update_carryover(tg); |
| 1574 | |
| 1575 | v[0] = tg->bps_conf[READ][index]; |
| 1576 | v[1] = tg->bps_conf[WRITE][index]; |
| 1577 | v[2] = tg->iops_conf[READ][index]; |
| 1578 | v[3] = tg->iops_conf[WRITE][index]; |
| 1579 | |
| 1580 | idle_time = tg->idletime_threshold_conf; |
| 1581 | latency_time = tg->latency_target_conf; |
| 1582 | while (true) { |
| 1583 | char tok[27]; /* wiops=18446744073709551616 */ |
| 1584 | char *p; |
| 1585 | u64 val = U64_MAX; |
| 1586 | int len; |
| 1587 | |
| 1588 | if (sscanf(ctx.body, "%26s%n", tok, &len) != 1) |
| 1589 | break; |
| 1590 | if (tok[0] == '\0') |
| 1591 | break; |
| 1592 | ctx.body += len; |
| 1593 | |
| 1594 | ret = -EINVAL; |
| 1595 | p = tok; |
| 1596 | strsep(&p, "="); |
| 1597 | if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max"))) |
| 1598 | goto out_finish; |
| 1599 | |
| 1600 | ret = -ERANGE; |
| 1601 | if (!val) |
| 1602 | goto out_finish; |
| 1603 | |
| 1604 | ret = -EINVAL; |
| 1605 | if (!strcmp(tok, "rbps") && val > 1) |
| 1606 | v[0] = val; |
| 1607 | else if (!strcmp(tok, "wbps") && val > 1) |
| 1608 | v[1] = val; |
| 1609 | else if (!strcmp(tok, "riops") && val > 1) |
| 1610 | v[2] = min_t(u64, val, UINT_MAX); |
| 1611 | else if (!strcmp(tok, "wiops") && val > 1) |
| 1612 | v[3] = min_t(u64, val, UINT_MAX); |
| 1613 | else if (off == LIMIT_LOW && !strcmp(tok, "idle")) |
| 1614 | idle_time = val; |
| 1615 | else if (off == LIMIT_LOW && !strcmp(tok, "latency")) |
| 1616 | latency_time = val; |
| 1617 | else |
| 1618 | goto out_finish; |
| 1619 | } |
| 1620 | |
| 1621 | tg->bps_conf[READ][index] = v[0]; |
| 1622 | tg->bps_conf[WRITE][index] = v[1]; |
| 1623 | tg->iops_conf[READ][index] = v[2]; |
| 1624 | tg->iops_conf[WRITE][index] = v[3]; |
| 1625 | |
| 1626 | if (index == LIMIT_MAX) { |
| 1627 | tg->bps[READ][index] = v[0]; |
| 1628 | tg->bps[WRITE][index] = v[1]; |
| 1629 | tg->iops[READ][index] = v[2]; |
| 1630 | tg->iops[WRITE][index] = v[3]; |
| 1631 | } |
| 1632 | tg->bps[READ][LIMIT_LOW] = min(tg->bps_conf[READ][LIMIT_LOW], |
| 1633 | tg->bps_conf[READ][LIMIT_MAX]); |
| 1634 | tg->bps[WRITE][LIMIT_LOW] = min(tg->bps_conf[WRITE][LIMIT_LOW], |
| 1635 | tg->bps_conf[WRITE][LIMIT_MAX]); |
| 1636 | tg->iops[READ][LIMIT_LOW] = min(tg->iops_conf[READ][LIMIT_LOW], |
| 1637 | tg->iops_conf[READ][LIMIT_MAX]); |
| 1638 | tg->iops[WRITE][LIMIT_LOW] = min(tg->iops_conf[WRITE][LIMIT_LOW], |
| 1639 | tg->iops_conf[WRITE][LIMIT_MAX]); |
| 1640 | tg->idletime_threshold_conf = idle_time; |
| 1641 | tg->latency_target_conf = latency_time; |
| 1642 | |
| 1643 | /* force user to configure all settings for low limit */ |
| 1644 | if (!(tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW] || |
| 1645 | tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) || |
| 1646 | tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD || |
| 1647 | tg->latency_target_conf == DFL_LATENCY_TARGET) { |
| 1648 | tg->bps[READ][LIMIT_LOW] = 0; |
| 1649 | tg->bps[WRITE][LIMIT_LOW] = 0; |
| 1650 | tg->iops[READ][LIMIT_LOW] = 0; |
| 1651 | tg->iops[WRITE][LIMIT_LOW] = 0; |
| 1652 | tg->idletime_threshold = DFL_IDLE_THRESHOLD; |
| 1653 | tg->latency_target = DFL_LATENCY_TARGET; |
| 1654 | } else if (index == LIMIT_LOW) { |
| 1655 | tg->idletime_threshold = tg->idletime_threshold_conf; |
| 1656 | tg->latency_target = tg->latency_target_conf; |
| 1657 | } |
| 1658 | |
| 1659 | blk_throtl_update_limit_valid(tg->td); |
| 1660 | if (tg->td->limit_valid[LIMIT_LOW]) { |
| 1661 | if (index == LIMIT_LOW) |
| 1662 | tg->td->limit_index = LIMIT_LOW; |
| 1663 | } else |
| 1664 | tg->td->limit_index = LIMIT_MAX; |
| 1665 | tg_conf_updated(tg, index == LIMIT_LOW && |
| 1666 | tg->td->limit_valid[LIMIT_LOW]); |
| 1667 | ret = 0; |
| 1668 | out_finish: |
| 1669 | blkg_conf_exit(&ctx); |
| 1670 | return ret ?: nbytes; |
| 1671 | } |
| 1672 | |
| 1673 | static struct cftype throtl_files[] = { |
| 1674 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| 1675 | { |
| 1676 | .name = "low", |
| 1677 | .flags = CFTYPE_NOT_ON_ROOT, |
| 1678 | .seq_show = tg_print_limit, |
| 1679 | .write = tg_set_limit, |
| 1680 | .private = LIMIT_LOW, |
| 1681 | }, |
| 1682 | #endif |
| 1683 | { |
| 1684 | .name = "max", |
| 1685 | .flags = CFTYPE_NOT_ON_ROOT, |
| 1686 | .seq_show = tg_print_limit, |
| 1687 | .write = tg_set_limit, |
| 1688 | .private = LIMIT_MAX, |
| 1689 | }, |
| 1690 | { } /* terminate */ |
| 1691 | }; |
| 1692 | |
| 1693 | static void throtl_shutdown_wq(struct request_queue *q) |
| 1694 | { |
| 1695 | struct throtl_data *td = q->td; |
| 1696 | |
| 1697 | cancel_work_sync(&td->dispatch_work); |
| 1698 | } |
| 1699 | |
| 1700 | struct blkcg_policy blkcg_policy_throtl = { |
| 1701 | .dfl_cftypes = throtl_files, |
| 1702 | .legacy_cftypes = throtl_legacy_files, |
| 1703 | |
| 1704 | .pd_alloc_fn = throtl_pd_alloc, |
| 1705 | .pd_init_fn = throtl_pd_init, |
| 1706 | .pd_online_fn = throtl_pd_online, |
| 1707 | .pd_offline_fn = throtl_pd_offline, |
| 1708 | .pd_free_fn = throtl_pd_free, |
| 1709 | }; |
| 1710 | |
| 1711 | void blk_throtl_cancel_bios(struct gendisk *disk) |
| 1712 | { |
| 1713 | struct request_queue *q = disk->queue; |
| 1714 | struct cgroup_subsys_state *pos_css; |
| 1715 | struct blkcg_gq *blkg; |
| 1716 | |
| 1717 | spin_lock_irq(&q->queue_lock); |
| 1718 | /* |
| 1719 | * queue_lock is held, rcu lock is not needed here technically. |
| 1720 | * However, rcu lock is still held to emphasize that following |
| 1721 | * path need RCU protection and to prevent warning from lockdep. |
| 1722 | */ |
| 1723 | rcu_read_lock(); |
| 1724 | blkg_for_each_descendant_post(blkg, pos_css, q->root_blkg) { |
| 1725 | struct throtl_grp *tg = blkg_to_tg(blkg); |
| 1726 | struct throtl_service_queue *sq = &tg->service_queue; |
| 1727 | |
| 1728 | /* |
| 1729 | * Set the flag to make sure throtl_pending_timer_fn() won't |
| 1730 | * stop until all throttled bios are dispatched. |
| 1731 | */ |
| 1732 | tg->flags |= THROTL_TG_CANCELING; |
| 1733 | |
| 1734 | /* |
| 1735 | * Do not dispatch cgroup without THROTL_TG_PENDING or cgroup |
| 1736 | * will be inserted to service queue without THROTL_TG_PENDING |
| 1737 | * set in tg_update_disptime below. Then IO dispatched from |
| 1738 | * child in tg_dispatch_one_bio will trigger double insertion |
| 1739 | * and corrupt the tree. |
| 1740 | */ |
| 1741 | if (!(tg->flags & THROTL_TG_PENDING)) |
| 1742 | continue; |
| 1743 | |
| 1744 | /* |
| 1745 | * Update disptime after setting the above flag to make sure |
| 1746 | * throtl_select_dispatch() won't exit without dispatching. |
| 1747 | */ |
| 1748 | tg_update_disptime(tg); |
| 1749 | |
| 1750 | throtl_schedule_pending_timer(sq, jiffies + 1); |
| 1751 | } |
| 1752 | rcu_read_unlock(); |
| 1753 | spin_unlock_irq(&q->queue_lock); |
| 1754 | } |
| 1755 | |
| 1756 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| 1757 | static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg) |
| 1758 | { |
| 1759 | unsigned long rtime = jiffies, wtime = jiffies; |
| 1760 | |
| 1761 | if (tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW]) |
| 1762 | rtime = tg->last_low_overflow_time[READ]; |
| 1763 | if (tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) |
| 1764 | wtime = tg->last_low_overflow_time[WRITE]; |
| 1765 | return min(rtime, wtime); |
| 1766 | } |
| 1767 | |
| 1768 | static unsigned long tg_last_low_overflow_time(struct throtl_grp *tg) |
| 1769 | { |
| 1770 | struct throtl_service_queue *parent_sq; |
| 1771 | struct throtl_grp *parent = tg; |
| 1772 | unsigned long ret = __tg_last_low_overflow_time(tg); |
| 1773 | |
| 1774 | while (true) { |
| 1775 | parent_sq = parent->service_queue.parent_sq; |
| 1776 | parent = sq_to_tg(parent_sq); |
| 1777 | if (!parent) |
| 1778 | break; |
| 1779 | |
| 1780 | /* |
| 1781 | * The parent doesn't have low limit, it always reaches low |
| 1782 | * limit. Its overflow time is useless for children |
| 1783 | */ |
| 1784 | if (!parent->bps[READ][LIMIT_LOW] && |
| 1785 | !parent->iops[READ][LIMIT_LOW] && |
| 1786 | !parent->bps[WRITE][LIMIT_LOW] && |
| 1787 | !parent->iops[WRITE][LIMIT_LOW]) |
| 1788 | continue; |
| 1789 | if (time_after(__tg_last_low_overflow_time(parent), ret)) |
| 1790 | ret = __tg_last_low_overflow_time(parent); |
| 1791 | } |
| 1792 | return ret; |
| 1793 | } |
| 1794 | |
| 1795 | static bool throtl_tg_is_idle(struct throtl_grp *tg) |
| 1796 | { |
| 1797 | /* |
| 1798 | * cgroup is idle if: |
| 1799 | * - single idle is too long, longer than a fixed value (in case user |
| 1800 | * configure a too big threshold) or 4 times of idletime threshold |
| 1801 | * - average think time is more than threshold |
| 1802 | * - IO latency is largely below threshold |
| 1803 | */ |
| 1804 | unsigned long time; |
| 1805 | bool ret; |
| 1806 | |
| 1807 | time = min_t(unsigned long, MAX_IDLE_TIME, 4 * tg->idletime_threshold); |
| 1808 | ret = tg->latency_target == DFL_LATENCY_TARGET || |
| 1809 | tg->idletime_threshold == DFL_IDLE_THRESHOLD || |
| 1810 | (ktime_get_ns() >> 10) - tg->last_finish_time > time || |
| 1811 | tg->avg_idletime > tg->idletime_threshold || |
| 1812 | (tg->latency_target && tg->bio_cnt && |
| 1813 | tg->bad_bio_cnt * 5 < tg->bio_cnt); |
| 1814 | throtl_log(&tg->service_queue, |
| 1815 | "avg_idle=%ld, idle_threshold=%ld, bad_bio=%d, total_bio=%d, is_idle=%d, scale=%d", |
| 1816 | tg->avg_idletime, tg->idletime_threshold, tg->bad_bio_cnt, |
| 1817 | tg->bio_cnt, ret, tg->td->scale); |
| 1818 | return ret; |
| 1819 | } |
| 1820 | |
| 1821 | static bool throtl_low_limit_reached(struct throtl_grp *tg, int rw) |
| 1822 | { |
| 1823 | struct throtl_service_queue *sq = &tg->service_queue; |
| 1824 | bool limit = tg->bps[rw][LIMIT_LOW] || tg->iops[rw][LIMIT_LOW]; |
| 1825 | |
| 1826 | /* |
| 1827 | * if low limit is zero, low limit is always reached. |
| 1828 | * if low limit is non-zero, we can check if there is any request |
| 1829 | * is queued to determine if low limit is reached as we throttle |
| 1830 | * request according to limit. |
| 1831 | */ |
| 1832 | return !limit || sq->nr_queued[rw]; |
| 1833 | } |
| 1834 | |
| 1835 | static bool throtl_tg_can_upgrade(struct throtl_grp *tg) |
| 1836 | { |
| 1837 | /* |
| 1838 | * cgroup reaches low limit when low limit of READ and WRITE are |
| 1839 | * both reached, it's ok to upgrade to next limit if cgroup reaches |
| 1840 | * low limit |
| 1841 | */ |
| 1842 | if (throtl_low_limit_reached(tg, READ) && |
| 1843 | throtl_low_limit_reached(tg, WRITE)) |
| 1844 | return true; |
| 1845 | |
| 1846 | if (time_after_eq(jiffies, |
| 1847 | tg_last_low_overflow_time(tg) + tg->td->throtl_slice) && |
| 1848 | throtl_tg_is_idle(tg)) |
| 1849 | return true; |
| 1850 | return false; |
| 1851 | } |
| 1852 | |
| 1853 | static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg) |
| 1854 | { |
| 1855 | while (true) { |
| 1856 | if (throtl_tg_can_upgrade(tg)) |
| 1857 | return true; |
| 1858 | tg = sq_to_tg(tg->service_queue.parent_sq); |
| 1859 | if (!tg || !tg_to_blkg(tg)->parent) |
| 1860 | return false; |
| 1861 | } |
| 1862 | return false; |
| 1863 | } |
| 1864 | |
| 1865 | static bool throtl_can_upgrade(struct throtl_data *td, |
| 1866 | struct throtl_grp *this_tg) |
| 1867 | { |
| 1868 | struct cgroup_subsys_state *pos_css; |
| 1869 | struct blkcg_gq *blkg; |
| 1870 | |
| 1871 | if (td->limit_index != LIMIT_LOW) |
| 1872 | return false; |
| 1873 | |
| 1874 | if (time_before(jiffies, td->low_downgrade_time + td->throtl_slice)) |
| 1875 | return false; |
| 1876 | |
| 1877 | rcu_read_lock(); |
| 1878 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { |
| 1879 | struct throtl_grp *tg = blkg_to_tg(blkg); |
| 1880 | |
| 1881 | if (tg == this_tg) |
| 1882 | continue; |
| 1883 | if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) |
| 1884 | continue; |
| 1885 | if (!throtl_hierarchy_can_upgrade(tg)) { |
| 1886 | rcu_read_unlock(); |
| 1887 | return false; |
| 1888 | } |
| 1889 | } |
| 1890 | rcu_read_unlock(); |
| 1891 | return true; |
| 1892 | } |
| 1893 | |
| 1894 | static void throtl_upgrade_check(struct throtl_grp *tg) |
| 1895 | { |
| 1896 | unsigned long now = jiffies; |
| 1897 | |
| 1898 | if (tg->td->limit_index != LIMIT_LOW) |
| 1899 | return; |
| 1900 | |
| 1901 | if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) |
| 1902 | return; |
| 1903 | |
| 1904 | tg->last_check_time = now; |
| 1905 | |
| 1906 | if (!time_after_eq(now, |
| 1907 | __tg_last_low_overflow_time(tg) + tg->td->throtl_slice)) |
| 1908 | return; |
| 1909 | |
| 1910 | if (throtl_can_upgrade(tg->td, NULL)) |
| 1911 | throtl_upgrade_state(tg->td); |
| 1912 | } |
| 1913 | |
| 1914 | static void throtl_upgrade_state(struct throtl_data *td) |
| 1915 | { |
| 1916 | struct cgroup_subsys_state *pos_css; |
| 1917 | struct blkcg_gq *blkg; |
| 1918 | |
| 1919 | throtl_log(&td->service_queue, "upgrade to max"); |
| 1920 | td->limit_index = LIMIT_MAX; |
| 1921 | td->low_upgrade_time = jiffies; |
| 1922 | td->scale = 0; |
| 1923 | rcu_read_lock(); |
| 1924 | blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { |
| 1925 | struct throtl_grp *tg = blkg_to_tg(blkg); |
| 1926 | struct throtl_service_queue *sq = &tg->service_queue; |
| 1927 | |
| 1928 | tg->disptime = jiffies - 1; |
| 1929 | throtl_select_dispatch(sq); |
| 1930 | throtl_schedule_next_dispatch(sq, true); |
| 1931 | } |
| 1932 | rcu_read_unlock(); |
| 1933 | throtl_select_dispatch(&td->service_queue); |
| 1934 | throtl_schedule_next_dispatch(&td->service_queue, true); |
| 1935 | queue_work(kthrotld_workqueue, &td->dispatch_work); |
| 1936 | } |
| 1937 | |
| 1938 | static void throtl_downgrade_state(struct throtl_data *td) |
| 1939 | { |
| 1940 | td->scale /= 2; |
| 1941 | |
| 1942 | throtl_log(&td->service_queue, "downgrade, scale %d", td->scale); |
| 1943 | if (td->scale) { |
| 1944 | td->low_upgrade_time = jiffies - td->scale * td->throtl_slice; |
| 1945 | return; |
| 1946 | } |
| 1947 | |
| 1948 | td->limit_index = LIMIT_LOW; |
| 1949 | td->low_downgrade_time = jiffies; |
| 1950 | } |
| 1951 | |
| 1952 | static bool throtl_tg_can_downgrade(struct throtl_grp *tg) |
| 1953 | { |
| 1954 | struct throtl_data *td = tg->td; |
| 1955 | unsigned long now = jiffies; |
| 1956 | |
| 1957 | /* |
| 1958 | * If cgroup is below low limit, consider downgrade and throttle other |
| 1959 | * cgroups |
| 1960 | */ |
| 1961 | if (time_after_eq(now, tg_last_low_overflow_time(tg) + |
| 1962 | td->throtl_slice) && |
| 1963 | (!throtl_tg_is_idle(tg) || |
| 1964 | !list_empty(&tg_to_blkg(tg)->blkcg->css.children))) |
| 1965 | return true; |
| 1966 | return false; |
| 1967 | } |
| 1968 | |
| 1969 | static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg) |
| 1970 | { |
| 1971 | struct throtl_data *td = tg->td; |
| 1972 | |
| 1973 | if (time_before(jiffies, td->low_upgrade_time + td->throtl_slice)) |
| 1974 | return false; |
| 1975 | |
| 1976 | while (true) { |
| 1977 | if (!throtl_tg_can_downgrade(tg)) |
| 1978 | return false; |
| 1979 | tg = sq_to_tg(tg->service_queue.parent_sq); |
| 1980 | if (!tg || !tg_to_blkg(tg)->parent) |
| 1981 | break; |
| 1982 | } |
| 1983 | return true; |
| 1984 | } |
| 1985 | |
| 1986 | static void throtl_downgrade_check(struct throtl_grp *tg) |
| 1987 | { |
| 1988 | uint64_t bps; |
| 1989 | unsigned int iops; |
| 1990 | unsigned long elapsed_time; |
| 1991 | unsigned long now = jiffies; |
| 1992 | |
| 1993 | if (tg->td->limit_index != LIMIT_MAX || |
| 1994 | !tg->td->limit_valid[LIMIT_LOW]) |
| 1995 | return; |
| 1996 | if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) |
| 1997 | return; |
| 1998 | if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) |
| 1999 | return; |
| 2000 | |
| 2001 | elapsed_time = now - tg->last_check_time; |
| 2002 | tg->last_check_time = now; |
| 2003 | |
| 2004 | if (time_before(now, tg_last_low_overflow_time(tg) + |
| 2005 | tg->td->throtl_slice)) |
| 2006 | return; |
| 2007 | |
| 2008 | if (tg->bps[READ][LIMIT_LOW]) { |
| 2009 | bps = tg->last_bytes_disp[READ] * HZ; |
| 2010 | do_div(bps, elapsed_time); |
| 2011 | if (bps >= tg->bps[READ][LIMIT_LOW]) |
| 2012 | tg->last_low_overflow_time[READ] = now; |
| 2013 | } |
| 2014 | |
| 2015 | if (tg->bps[WRITE][LIMIT_LOW]) { |
| 2016 | bps = tg->last_bytes_disp[WRITE] * HZ; |
| 2017 | do_div(bps, elapsed_time); |
| 2018 | if (bps >= tg->bps[WRITE][LIMIT_LOW]) |
| 2019 | tg->last_low_overflow_time[WRITE] = now; |
| 2020 | } |
| 2021 | |
| 2022 | if (tg->iops[READ][LIMIT_LOW]) { |
| 2023 | iops = tg->last_io_disp[READ] * HZ / elapsed_time; |
| 2024 | if (iops >= tg->iops[READ][LIMIT_LOW]) |
| 2025 | tg->last_low_overflow_time[READ] = now; |
| 2026 | } |
| 2027 | |
| 2028 | if (tg->iops[WRITE][LIMIT_LOW]) { |
| 2029 | iops = tg->last_io_disp[WRITE] * HZ / elapsed_time; |
| 2030 | if (iops >= tg->iops[WRITE][LIMIT_LOW]) |
| 2031 | tg->last_low_overflow_time[WRITE] = now; |
| 2032 | } |
| 2033 | |
| 2034 | /* |
| 2035 | * If cgroup is below low limit, consider downgrade and throttle other |
| 2036 | * cgroups |
| 2037 | */ |
| 2038 | if (throtl_hierarchy_can_downgrade(tg)) |
| 2039 | throtl_downgrade_state(tg->td); |
| 2040 | |
| 2041 | tg->last_bytes_disp[READ] = 0; |
| 2042 | tg->last_bytes_disp[WRITE] = 0; |
| 2043 | tg->last_io_disp[READ] = 0; |
| 2044 | tg->last_io_disp[WRITE] = 0; |
| 2045 | } |
| 2046 | |
| 2047 | static void blk_throtl_update_idletime(struct throtl_grp *tg) |
| 2048 | { |
| 2049 | unsigned long now; |
| 2050 | unsigned long last_finish_time = tg->last_finish_time; |
| 2051 | |
| 2052 | if (last_finish_time == 0) |
| 2053 | return; |
| 2054 | |
| 2055 | now = ktime_get_ns() >> 10; |
| 2056 | if (now <= last_finish_time || |
| 2057 | last_finish_time == tg->checked_last_finish_time) |
| 2058 | return; |
| 2059 | |
| 2060 | tg->avg_idletime = (tg->avg_idletime * 7 + now - last_finish_time) >> 3; |
| 2061 | tg->checked_last_finish_time = last_finish_time; |
| 2062 | } |
| 2063 | |
| 2064 | static void throtl_update_latency_buckets(struct throtl_data *td) |
| 2065 | { |
| 2066 | struct avg_latency_bucket avg_latency[2][LATENCY_BUCKET_SIZE]; |
| 2067 | int i, cpu, rw; |
| 2068 | unsigned long last_latency[2] = { 0 }; |
| 2069 | unsigned long latency[2]; |
| 2070 | |
| 2071 | if (!blk_queue_nonrot(td->queue) || !td->limit_valid[LIMIT_LOW]) |
| 2072 | return; |
| 2073 | if (time_before(jiffies, td->last_calculate_time + HZ)) |
| 2074 | return; |
| 2075 | td->last_calculate_time = jiffies; |
| 2076 | |
| 2077 | memset(avg_latency, 0, sizeof(avg_latency)); |
| 2078 | for (rw = READ; rw <= WRITE; rw++) { |
| 2079 | for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { |
| 2080 | struct latency_bucket *tmp = &td->tmp_buckets[rw][i]; |
| 2081 | |
| 2082 | for_each_possible_cpu(cpu) { |
| 2083 | struct latency_bucket *bucket; |
| 2084 | |
| 2085 | /* this isn't race free, but ok in practice */ |
| 2086 | bucket = per_cpu_ptr(td->latency_buckets[rw], |
| 2087 | cpu); |
| 2088 | tmp->total_latency += bucket[i].total_latency; |
| 2089 | tmp->samples += bucket[i].samples; |
| 2090 | bucket[i].total_latency = 0; |
| 2091 | bucket[i].samples = 0; |
| 2092 | } |
| 2093 | |
| 2094 | if (tmp->samples >= 32) { |
| 2095 | int samples = tmp->samples; |
| 2096 | |
| 2097 | latency[rw] = tmp->total_latency; |
| 2098 | |
| 2099 | tmp->total_latency = 0; |
| 2100 | tmp->samples = 0; |
| 2101 | latency[rw] /= samples; |
| 2102 | if (latency[rw] == 0) |
| 2103 | continue; |
| 2104 | avg_latency[rw][i].latency = latency[rw]; |
| 2105 | } |
| 2106 | } |
| 2107 | } |
| 2108 | |
| 2109 | for (rw = READ; rw <= WRITE; rw++) { |
| 2110 | for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { |
| 2111 | if (!avg_latency[rw][i].latency) { |
| 2112 | if (td->avg_buckets[rw][i].latency < last_latency[rw]) |
| 2113 | td->avg_buckets[rw][i].latency = |
| 2114 | last_latency[rw]; |
| 2115 | continue; |
| 2116 | } |
| 2117 | |
| 2118 | if (!td->avg_buckets[rw][i].valid) |
| 2119 | latency[rw] = avg_latency[rw][i].latency; |
| 2120 | else |
| 2121 | latency[rw] = (td->avg_buckets[rw][i].latency * 7 + |
| 2122 | avg_latency[rw][i].latency) >> 3; |
| 2123 | |
| 2124 | td->avg_buckets[rw][i].latency = max(latency[rw], |
| 2125 | last_latency[rw]); |
| 2126 | td->avg_buckets[rw][i].valid = true; |
| 2127 | last_latency[rw] = td->avg_buckets[rw][i].latency; |
| 2128 | } |
| 2129 | } |
| 2130 | |
| 2131 | for (i = 0; i < LATENCY_BUCKET_SIZE; i++) |
| 2132 | throtl_log(&td->service_queue, |
| 2133 | "Latency bucket %d: read latency=%ld, read valid=%d, " |
| 2134 | "write latency=%ld, write valid=%d", i, |
| 2135 | td->avg_buckets[READ][i].latency, |
| 2136 | td->avg_buckets[READ][i].valid, |
| 2137 | td->avg_buckets[WRITE][i].latency, |
| 2138 | td->avg_buckets[WRITE][i].valid); |
| 2139 | } |
| 2140 | #else |
| 2141 | static inline void throtl_update_latency_buckets(struct throtl_data *td) |
| 2142 | { |
| 2143 | } |
| 2144 | |
| 2145 | static void blk_throtl_update_idletime(struct throtl_grp *tg) |
| 2146 | { |
| 2147 | } |
| 2148 | |
| 2149 | static void throtl_downgrade_check(struct throtl_grp *tg) |
| 2150 | { |
| 2151 | } |
| 2152 | |
| 2153 | static void throtl_upgrade_check(struct throtl_grp *tg) |
| 2154 | { |
| 2155 | } |
| 2156 | |
| 2157 | static bool throtl_can_upgrade(struct throtl_data *td, |
| 2158 | struct throtl_grp *this_tg) |
| 2159 | { |
| 2160 | return false; |
| 2161 | } |
| 2162 | |
| 2163 | static void throtl_upgrade_state(struct throtl_data *td) |
| 2164 | { |
| 2165 | } |
| 2166 | #endif |
| 2167 | |
| 2168 | bool __blk_throtl_bio(struct bio *bio) |
| 2169 | { |
| 2170 | struct request_queue *q = bdev_get_queue(bio->bi_bdev); |
| 2171 | struct blkcg_gq *blkg = bio->bi_blkg; |
| 2172 | struct throtl_qnode *qn = NULL; |
| 2173 | struct throtl_grp *tg = blkg_to_tg(blkg); |
| 2174 | struct throtl_service_queue *sq; |
| 2175 | bool rw = bio_data_dir(bio); |
| 2176 | bool throttled = false; |
| 2177 | struct throtl_data *td = tg->td; |
| 2178 | |
| 2179 | rcu_read_lock(); |
| 2180 | |
| 2181 | if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) { |
| 2182 | blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf, |
| 2183 | bio->bi_iter.bi_size); |
| 2184 | blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1); |
| 2185 | } |
| 2186 | |
| 2187 | spin_lock_irq(&q->queue_lock); |
| 2188 | |
| 2189 | throtl_update_latency_buckets(td); |
| 2190 | |
| 2191 | blk_throtl_update_idletime(tg); |
| 2192 | |
| 2193 | sq = &tg->service_queue; |
| 2194 | |
| 2195 | again: |
| 2196 | while (true) { |
| 2197 | if (tg->last_low_overflow_time[rw] == 0) |
| 2198 | tg->last_low_overflow_time[rw] = jiffies; |
| 2199 | throtl_downgrade_check(tg); |
| 2200 | throtl_upgrade_check(tg); |
| 2201 | /* throtl is FIFO - if bios are already queued, should queue */ |
| 2202 | if (sq->nr_queued[rw]) |
| 2203 | break; |
| 2204 | |
| 2205 | /* if above limits, break to queue */ |
| 2206 | if (!tg_may_dispatch(tg, bio, NULL)) { |
| 2207 | tg->last_low_overflow_time[rw] = jiffies; |
| 2208 | if (throtl_can_upgrade(td, tg)) { |
| 2209 | throtl_upgrade_state(td); |
| 2210 | goto again; |
| 2211 | } |
| 2212 | break; |
| 2213 | } |
| 2214 | |
| 2215 | /* within limits, let's charge and dispatch directly */ |
| 2216 | throtl_charge_bio(tg, bio); |
| 2217 | |
| 2218 | /* |
| 2219 | * We need to trim slice even when bios are not being queued |
| 2220 | * otherwise it might happen that a bio is not queued for |
| 2221 | * a long time and slice keeps on extending and trim is not |
| 2222 | * called for a long time. Now if limits are reduced suddenly |
| 2223 | * we take into account all the IO dispatched so far at new |
| 2224 | * low rate and * newly queued IO gets a really long dispatch |
| 2225 | * time. |
| 2226 | * |
| 2227 | * So keep on trimming slice even if bio is not queued. |
| 2228 | */ |
| 2229 | throtl_trim_slice(tg, rw); |
| 2230 | |
| 2231 | /* |
| 2232 | * @bio passed through this layer without being throttled. |
| 2233 | * Climb up the ladder. If we're already at the top, it |
| 2234 | * can be executed directly. |
| 2235 | */ |
| 2236 | qn = &tg->qnode_on_parent[rw]; |
| 2237 | sq = sq->parent_sq; |
| 2238 | tg = sq_to_tg(sq); |
| 2239 | if (!tg) { |
| 2240 | bio_set_flag(bio, BIO_BPS_THROTTLED); |
| 2241 | goto out_unlock; |
| 2242 | } |
| 2243 | } |
| 2244 | |
| 2245 | /* out-of-limit, queue to @tg */ |
| 2246 | throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", |
| 2247 | rw == READ ? 'R' : 'W', |
| 2248 | tg->bytes_disp[rw], bio->bi_iter.bi_size, |
| 2249 | tg_bps_limit(tg, rw), |
| 2250 | tg->io_disp[rw], tg_iops_limit(tg, rw), |
| 2251 | sq->nr_queued[READ], sq->nr_queued[WRITE]); |
| 2252 | |
| 2253 | tg->last_low_overflow_time[rw] = jiffies; |
| 2254 | |
| 2255 | td->nr_queued[rw]++; |
| 2256 | throtl_add_bio_tg(bio, qn, tg); |
| 2257 | throttled = true; |
| 2258 | |
| 2259 | /* |
| 2260 | * Update @tg's dispatch time and force schedule dispatch if @tg |
| 2261 | * was empty before @bio. The forced scheduling isn't likely to |
| 2262 | * cause undue delay as @bio is likely to be dispatched directly if |
| 2263 | * its @tg's disptime is not in the future. |
| 2264 | */ |
| 2265 | if (tg->flags & THROTL_TG_WAS_EMPTY) { |
| 2266 | tg_update_disptime(tg); |
| 2267 | throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true); |
| 2268 | } |
| 2269 | |
| 2270 | out_unlock: |
| 2271 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| 2272 | if (throttled || !td->track_bio_latency) |
| 2273 | bio->bi_issue.value |= BIO_ISSUE_THROTL_SKIP_LATENCY; |
| 2274 | #endif |
| 2275 | spin_unlock_irq(&q->queue_lock); |
| 2276 | |
| 2277 | rcu_read_unlock(); |
| 2278 | return throttled; |
| 2279 | } |
| 2280 | |
| 2281 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| 2282 | static void throtl_track_latency(struct throtl_data *td, sector_t size, |
| 2283 | enum req_op op, unsigned long time) |
| 2284 | { |
| 2285 | const bool rw = op_is_write(op); |
| 2286 | struct latency_bucket *latency; |
| 2287 | int index; |
| 2288 | |
| 2289 | if (!td || td->limit_index != LIMIT_LOW || |
| 2290 | !(op == REQ_OP_READ || op == REQ_OP_WRITE) || |
| 2291 | !blk_queue_nonrot(td->queue)) |
| 2292 | return; |
| 2293 | |
| 2294 | index = request_bucket_index(size); |
| 2295 | |
| 2296 | latency = get_cpu_ptr(td->latency_buckets[rw]); |
| 2297 | latency[index].total_latency += time; |
| 2298 | latency[index].samples++; |
| 2299 | put_cpu_ptr(td->latency_buckets[rw]); |
| 2300 | } |
| 2301 | |
| 2302 | void blk_throtl_stat_add(struct request *rq, u64 time_ns) |
| 2303 | { |
| 2304 | struct request_queue *q = rq->q; |
| 2305 | struct throtl_data *td = q->td; |
| 2306 | |
| 2307 | throtl_track_latency(td, blk_rq_stats_sectors(rq), req_op(rq), |
| 2308 | time_ns >> 10); |
| 2309 | } |
| 2310 | |
| 2311 | void blk_throtl_bio_endio(struct bio *bio) |
| 2312 | { |
| 2313 | struct blkcg_gq *blkg; |
| 2314 | struct throtl_grp *tg; |
| 2315 | u64 finish_time_ns; |
| 2316 | unsigned long finish_time; |
| 2317 | unsigned long start_time; |
| 2318 | unsigned long lat; |
| 2319 | int rw = bio_data_dir(bio); |
| 2320 | |
| 2321 | blkg = bio->bi_blkg; |
| 2322 | if (!blkg) |
| 2323 | return; |
| 2324 | tg = blkg_to_tg(blkg); |
| 2325 | if (!tg->td->limit_valid[LIMIT_LOW]) |
| 2326 | return; |
| 2327 | |
| 2328 | finish_time_ns = ktime_get_ns(); |
| 2329 | tg->last_finish_time = finish_time_ns >> 10; |
| 2330 | |
| 2331 | start_time = bio_issue_time(&bio->bi_issue) >> 10; |
| 2332 | finish_time = __bio_issue_time(finish_time_ns) >> 10; |
| 2333 | if (!start_time || finish_time <= start_time) |
| 2334 | return; |
| 2335 | |
| 2336 | lat = finish_time - start_time; |
| 2337 | /* this is only for bio based driver */ |
| 2338 | if (!(bio->bi_issue.value & BIO_ISSUE_THROTL_SKIP_LATENCY)) |
| 2339 | throtl_track_latency(tg->td, bio_issue_size(&bio->bi_issue), |
| 2340 | bio_op(bio), lat); |
| 2341 | |
| 2342 | if (tg->latency_target && lat >= tg->td->filtered_latency) { |
| 2343 | int bucket; |
| 2344 | unsigned int threshold; |
| 2345 | |
| 2346 | bucket = request_bucket_index(bio_issue_size(&bio->bi_issue)); |
| 2347 | threshold = tg->td->avg_buckets[rw][bucket].latency + |
| 2348 | tg->latency_target; |
| 2349 | if (lat > threshold) |
| 2350 | tg->bad_bio_cnt++; |
| 2351 | /* |
| 2352 | * Not race free, could get wrong count, which means cgroups |
| 2353 | * will be throttled |
| 2354 | */ |
| 2355 | tg->bio_cnt++; |
| 2356 | } |
| 2357 | |
| 2358 | if (time_after(jiffies, tg->bio_cnt_reset_time) || tg->bio_cnt > 1024) { |
| 2359 | tg->bio_cnt_reset_time = tg->td->throtl_slice + jiffies; |
| 2360 | tg->bio_cnt /= 2; |
| 2361 | tg->bad_bio_cnt /= 2; |
| 2362 | } |
| 2363 | } |
| 2364 | #endif |
| 2365 | |
| 2366 | int blk_throtl_init(struct gendisk *disk) |
| 2367 | { |
| 2368 | struct request_queue *q = disk->queue; |
| 2369 | struct throtl_data *td; |
| 2370 | int ret; |
| 2371 | |
| 2372 | td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); |
| 2373 | if (!td) |
| 2374 | return -ENOMEM; |
| 2375 | td->latency_buckets[READ] = __alloc_percpu(sizeof(struct latency_bucket) * |
| 2376 | LATENCY_BUCKET_SIZE, __alignof__(u64)); |
| 2377 | if (!td->latency_buckets[READ]) { |
| 2378 | kfree(td); |
| 2379 | return -ENOMEM; |
| 2380 | } |
| 2381 | td->latency_buckets[WRITE] = __alloc_percpu(sizeof(struct latency_bucket) * |
| 2382 | LATENCY_BUCKET_SIZE, __alignof__(u64)); |
| 2383 | if (!td->latency_buckets[WRITE]) { |
| 2384 | free_percpu(td->latency_buckets[READ]); |
| 2385 | kfree(td); |
| 2386 | return -ENOMEM; |
| 2387 | } |
| 2388 | |
| 2389 | INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn); |
| 2390 | throtl_service_queue_init(&td->service_queue); |
| 2391 | |
| 2392 | q->td = td; |
| 2393 | td->queue = q; |
| 2394 | |
| 2395 | td->limit_valid[LIMIT_MAX] = true; |
| 2396 | td->limit_index = LIMIT_MAX; |
| 2397 | td->low_upgrade_time = jiffies; |
| 2398 | td->low_downgrade_time = jiffies; |
| 2399 | |
| 2400 | /* activate policy */ |
| 2401 | ret = blkcg_activate_policy(disk, &blkcg_policy_throtl); |
| 2402 | if (ret) { |
| 2403 | free_percpu(td->latency_buckets[READ]); |
| 2404 | free_percpu(td->latency_buckets[WRITE]); |
| 2405 | kfree(td); |
| 2406 | } |
| 2407 | return ret; |
| 2408 | } |
| 2409 | |
| 2410 | void blk_throtl_exit(struct gendisk *disk) |
| 2411 | { |
| 2412 | struct request_queue *q = disk->queue; |
| 2413 | |
| 2414 | BUG_ON(!q->td); |
| 2415 | del_timer_sync(&q->td->service_queue.pending_timer); |
| 2416 | throtl_shutdown_wq(q); |
| 2417 | blkcg_deactivate_policy(disk, &blkcg_policy_throtl); |
| 2418 | free_percpu(q->td->latency_buckets[READ]); |
| 2419 | free_percpu(q->td->latency_buckets[WRITE]); |
| 2420 | kfree(q->td); |
| 2421 | } |
| 2422 | |
| 2423 | void blk_throtl_register(struct gendisk *disk) |
| 2424 | { |
| 2425 | struct request_queue *q = disk->queue; |
| 2426 | struct throtl_data *td; |
| 2427 | int i; |
| 2428 | |
| 2429 | td = q->td; |
| 2430 | BUG_ON(!td); |
| 2431 | |
| 2432 | if (blk_queue_nonrot(q)) { |
| 2433 | td->throtl_slice = DFL_THROTL_SLICE_SSD; |
| 2434 | td->filtered_latency = LATENCY_FILTERED_SSD; |
| 2435 | } else { |
| 2436 | td->throtl_slice = DFL_THROTL_SLICE_HD; |
| 2437 | td->filtered_latency = LATENCY_FILTERED_HD; |
| 2438 | for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { |
| 2439 | td->avg_buckets[READ][i].latency = DFL_HD_BASELINE_LATENCY; |
| 2440 | td->avg_buckets[WRITE][i].latency = DFL_HD_BASELINE_LATENCY; |
| 2441 | } |
| 2442 | } |
| 2443 | #ifndef CONFIG_BLK_DEV_THROTTLING_LOW |
| 2444 | /* if no low limit, use previous default */ |
| 2445 | td->throtl_slice = DFL_THROTL_SLICE_HD; |
| 2446 | |
| 2447 | #else |
| 2448 | td->track_bio_latency = !queue_is_mq(q); |
| 2449 | if (!td->track_bio_latency) |
| 2450 | blk_stat_enable_accounting(q); |
| 2451 | #endif |
| 2452 | } |
| 2453 | |
| 2454 | #ifdef CONFIG_BLK_DEV_THROTTLING_LOW |
| 2455 | ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page) |
| 2456 | { |
| 2457 | if (!q->td) |
| 2458 | return -EINVAL; |
| 2459 | return sprintf(page, "%u\n", jiffies_to_msecs(q->td->throtl_slice)); |
| 2460 | } |
| 2461 | |
| 2462 | ssize_t blk_throtl_sample_time_store(struct request_queue *q, |
| 2463 | const char *page, size_t count) |
| 2464 | { |
| 2465 | unsigned long v; |
| 2466 | unsigned long t; |
| 2467 | |
| 2468 | if (!q->td) |
| 2469 | return -EINVAL; |
| 2470 | if (kstrtoul(page, 10, &v)) |
| 2471 | return -EINVAL; |
| 2472 | t = msecs_to_jiffies(v); |
| 2473 | if (t == 0 || t > MAX_THROTL_SLICE) |
| 2474 | return -EINVAL; |
| 2475 | q->td->throtl_slice = t; |
| 2476 | return count; |
| 2477 | } |
| 2478 | #endif |
| 2479 | |
| 2480 | static int __init throtl_init(void) |
| 2481 | { |
| 2482 | kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); |
| 2483 | if (!kthrotld_workqueue) |
| 2484 | panic("Failed to create kthrotld\n"); |
| 2485 | |
| 2486 | return blkcg_policy_register(&blkcg_policy_throtl); |
| 2487 | } |
| 2488 | |
| 2489 | module_init(throtl_init); |