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 */ 42static 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 49struct latency_bucket { 50 unsigned long total_latency; /* ns / 1024 */ 51 int samples; 52}; 53 54struct avg_latency_bucket { 55 unsigned long latency; /* ns / 1024 */ 56 bool valid; 57}; 58 59struct 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 90static void throtl_pending_timer_fn(struct timer_list *t); 91 92static 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 */ 104static 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 */ 119static 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 */ 137static 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 147static 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 177static 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 236static 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 244static 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 */ 261static 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 */ 275static 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 */ 303static 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 */ 330static 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 338static 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 379err_exit_stat_bytes: 380 blkg_rwstat_exit(&tg->stat_bytes); 381err_free_tg: 382 kfree(tg); 383 return NULL; 384} 385 386static 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 */ 418static 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 436static 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 447static 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 468static inline void blk_throtl_update_limit_valid(struct throtl_data *td) 469{ 470} 471#endif 472 473static void throtl_upgrade_state(struct throtl_data *td); 474static 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 489static 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 499static struct throtl_grp * 500throtl_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 511static 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 518static 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 529static 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 555static 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 564static 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 */ 577static 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 */ 614static 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 633static 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 657static 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 675static 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 681static 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 */ 692static 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 700static unsigned int calculate_io_allowed(u32 iops_limit, 701 unsigned long jiffy_elapsed) 702{ 703 unsigned int io_allowed; 704 u64 tmp; 705 706 /* 707 * jiffy_elapsed should not be a big value as minimum iops can be 708 * 1 then at max jiffy elapsed should be equivalent of 1 second as we 709 * will allow dispatch after 1 second and after that slice should 710 * have been trimmed. 711 */ 712 713 tmp = (u64)iops_limit * jiffy_elapsed; 714 do_div(tmp, HZ); 715 716 if (tmp > UINT_MAX) 717 io_allowed = UINT_MAX; 718 else 719 io_allowed = tmp; 720 721 return io_allowed; 722} 723 724static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed) 725{ 726 /* 727 * Can result be wider than 64 bits? 728 * We check against 62, not 64, due to ilog2 truncation. 729 */ 730 if (ilog2(bps_limit) + ilog2(jiffy_elapsed) - ilog2(HZ) > 62) 731 return U64_MAX; 732 return mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed, (u64)HZ); 733} 734 735/* Trim the used slices and adjust slice start accordingly */ 736static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) 737{ 738 unsigned long time_elapsed; 739 long long bytes_trim; 740 int io_trim; 741 742 BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); 743 744 /* 745 * If bps are unlimited (-1), then time slice don't get 746 * renewed. Don't try to trim the slice if slice is used. A new 747 * slice will start when appropriate. 748 */ 749 if (throtl_slice_used(tg, rw)) 750 return; 751 752 /* 753 * A bio has been dispatched. Also adjust slice_end. It might happen 754 * that initially cgroup limit was very low resulting in high 755 * slice_end, but later limit was bumped up and bio was dispatched 756 * sooner, then we need to reduce slice_end. A high bogus slice_end 757 * is bad because it does not allow new slice to start. 758 */ 759 760 throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice); 761 762 time_elapsed = rounddown(jiffies - tg->slice_start[rw], 763 tg->td->throtl_slice); 764 if (!time_elapsed) 765 return; 766 767 bytes_trim = calculate_bytes_allowed(tg_bps_limit(tg, rw), 768 time_elapsed) + 769 tg->carryover_bytes[rw]; 770 io_trim = calculate_io_allowed(tg_iops_limit(tg, rw), time_elapsed) + 771 tg->carryover_ios[rw]; 772 if (bytes_trim <= 0 && io_trim <= 0) 773 return; 774 775 tg->carryover_bytes[rw] = 0; 776 if ((long long)tg->bytes_disp[rw] >= bytes_trim) 777 tg->bytes_disp[rw] -= bytes_trim; 778 else 779 tg->bytes_disp[rw] = 0; 780 781 tg->carryover_ios[rw] = 0; 782 if ((int)tg->io_disp[rw] >= io_trim) 783 tg->io_disp[rw] -= io_trim; 784 else 785 tg->io_disp[rw] = 0; 786 787 tg->slice_start[rw] += time_elapsed; 788 789 throtl_log(&tg->service_queue, 790 "[%c] trim slice nr=%lu bytes=%lld io=%d start=%lu end=%lu jiffies=%lu", 791 rw == READ ? 'R' : 'W', time_elapsed / tg->td->throtl_slice, 792 bytes_trim, io_trim, tg->slice_start[rw], tg->slice_end[rw], 793 jiffies); 794} 795 796static void __tg_update_carryover(struct throtl_grp *tg, bool rw) 797{ 798 unsigned long jiffy_elapsed = jiffies - tg->slice_start[rw]; 799 u64 bps_limit = tg_bps_limit(tg, rw); 800 u32 iops_limit = tg_iops_limit(tg, rw); 801 802 /* 803 * If config is updated while bios are still throttled, calculate and 804 * accumulate how many bytes/ios are waited across changes. And 805 * carryover_bytes/ios will be used to calculate new wait time under new 806 * configuration. 807 */ 808 if (bps_limit != U64_MAX) 809 tg->carryover_bytes[rw] += 810 calculate_bytes_allowed(bps_limit, jiffy_elapsed) - 811 tg->bytes_disp[rw]; 812 if (iops_limit != UINT_MAX) 813 tg->carryover_ios[rw] += 814 calculate_io_allowed(iops_limit, jiffy_elapsed) - 815 tg->io_disp[rw]; 816} 817 818static void tg_update_carryover(struct throtl_grp *tg) 819{ 820 if (tg->service_queue.nr_queued[READ]) 821 __tg_update_carryover(tg, READ); 822 if (tg->service_queue.nr_queued[WRITE]) 823 __tg_update_carryover(tg, WRITE); 824 825 /* see comments in struct throtl_grp for meaning of these fields. */ 826 throtl_log(&tg->service_queue, "%s: %lld %lld %d %d\n", __func__, 827 tg->carryover_bytes[READ], tg->carryover_bytes[WRITE], 828 tg->carryover_ios[READ], tg->carryover_ios[WRITE]); 829} 830 831static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio, 832 u32 iops_limit) 833{ 834 bool rw = bio_data_dir(bio); 835 int io_allowed; 836 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; 837 838 if (iops_limit == UINT_MAX) { 839 return 0; 840 } 841 842 jiffy_elapsed = jiffies - tg->slice_start[rw]; 843 844 /* Round up to the next throttle slice, wait time must be nonzero */ 845 jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice); 846 io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd) + 847 tg->carryover_ios[rw]; 848 if (io_allowed > 0 && tg->io_disp[rw] + 1 <= io_allowed) 849 return 0; 850 851 /* Calc approx time to dispatch */ 852 jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed; 853 return jiffy_wait; 854} 855 856static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, 857 u64 bps_limit) 858{ 859 bool rw = bio_data_dir(bio); 860 long long bytes_allowed; 861 u64 extra_bytes; 862 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; 863 unsigned int bio_size = throtl_bio_data_size(bio); 864 865 /* no need to throttle if this bio's bytes have been accounted */ 866 if (bps_limit == U64_MAX || bio_flagged(bio, BIO_BPS_THROTTLED)) { 867 return 0; 868 } 869 870 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; 871 872 /* Slice has just started. Consider one slice interval */ 873 if (!jiffy_elapsed) 874 jiffy_elapsed_rnd = tg->td->throtl_slice; 875 876 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); 877 bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd) + 878 tg->carryover_bytes[rw]; 879 if (bytes_allowed > 0 && tg->bytes_disp[rw] + bio_size <= bytes_allowed) 880 return 0; 881 882 /* Calc approx time to dispatch */ 883 extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed; 884 jiffy_wait = div64_u64(extra_bytes * HZ, bps_limit); 885 886 if (!jiffy_wait) 887 jiffy_wait = 1; 888 889 /* 890 * This wait time is without taking into consideration the rounding 891 * up we did. Add that time also. 892 */ 893 jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); 894 return jiffy_wait; 895} 896 897/* 898 * Returns whether one can dispatch a bio or not. Also returns approx number 899 * of jiffies to wait before this bio is with-in IO rate and can be dispatched 900 */ 901static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, 902 unsigned long *wait) 903{ 904 bool rw = bio_data_dir(bio); 905 unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; 906 u64 bps_limit = tg_bps_limit(tg, rw); 907 u32 iops_limit = tg_iops_limit(tg, rw); 908 909 /* 910 * Currently whole state machine of group depends on first bio 911 * queued in the group bio list. So one should not be calling 912 * this function with a different bio if there are other bios 913 * queued. 914 */ 915 BUG_ON(tg->service_queue.nr_queued[rw] && 916 bio != throtl_peek_queued(&tg->service_queue.queued[rw])); 917 918 /* If tg->bps = -1, then BW is unlimited */ 919 if ((bps_limit == U64_MAX && iops_limit == UINT_MAX) || 920 tg->flags & THROTL_TG_CANCELING) { 921 if (wait) 922 *wait = 0; 923 return true; 924 } 925 926 /* 927 * If previous slice expired, start a new one otherwise renew/extend 928 * existing slice to make sure it is at least throtl_slice interval 929 * long since now. New slice is started only for empty throttle group. 930 * If there is queued bio, that means there should be an active 931 * slice and it should be extended instead. 932 */ 933 if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw])) 934 throtl_start_new_slice(tg, rw, true); 935 else { 936 if (time_before(tg->slice_end[rw], 937 jiffies + tg->td->throtl_slice)) 938 throtl_extend_slice(tg, rw, 939 jiffies + tg->td->throtl_slice); 940 } 941 942 bps_wait = tg_within_bps_limit(tg, bio, bps_limit); 943 iops_wait = tg_within_iops_limit(tg, bio, iops_limit); 944 if (bps_wait + iops_wait == 0) { 945 if (wait) 946 *wait = 0; 947 return true; 948 } 949 950 max_wait = max(bps_wait, iops_wait); 951 952 if (wait) 953 *wait = max_wait; 954 955 if (time_before(tg->slice_end[rw], jiffies + max_wait)) 956 throtl_extend_slice(tg, rw, jiffies + max_wait); 957 958 return false; 959} 960 961static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) 962{ 963 bool rw = bio_data_dir(bio); 964 unsigned int bio_size = throtl_bio_data_size(bio); 965 966 /* Charge the bio to the group */ 967 if (!bio_flagged(bio, BIO_BPS_THROTTLED)) { 968 tg->bytes_disp[rw] += bio_size; 969 tg->last_bytes_disp[rw] += bio_size; 970 } 971 972 tg->io_disp[rw]++; 973 tg->last_io_disp[rw]++; 974} 975 976/** 977 * throtl_add_bio_tg - add a bio to the specified throtl_grp 978 * @bio: bio to add 979 * @qn: qnode to use 980 * @tg: the target throtl_grp 981 * 982 * Add @bio to @tg's service_queue using @qn. If @qn is not specified, 983 * tg->qnode_on_self[] is used. 984 */ 985static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn, 986 struct throtl_grp *tg) 987{ 988 struct throtl_service_queue *sq = &tg->service_queue; 989 bool rw = bio_data_dir(bio); 990 991 if (!qn) 992 qn = &tg->qnode_on_self[rw]; 993 994 /* 995 * If @tg doesn't currently have any bios queued in the same 996 * direction, queueing @bio can change when @tg should be 997 * dispatched. Mark that @tg was empty. This is automatically 998 * cleared on the next tg_update_disptime(). 999 */ 1000 if (!sq->nr_queued[rw]) 1001 tg->flags |= THROTL_TG_WAS_EMPTY; 1002 1003 throtl_qnode_add_bio(bio, qn, &sq->queued[rw]); 1004 1005 sq->nr_queued[rw]++; 1006 throtl_enqueue_tg(tg); 1007} 1008 1009static void tg_update_disptime(struct throtl_grp *tg) 1010{ 1011 struct throtl_service_queue *sq = &tg->service_queue; 1012 unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; 1013 struct bio *bio; 1014 1015 bio = throtl_peek_queued(&sq->queued[READ]); 1016 if (bio) 1017 tg_may_dispatch(tg, bio, &read_wait); 1018 1019 bio = throtl_peek_queued(&sq->queued[WRITE]); 1020 if (bio) 1021 tg_may_dispatch(tg, bio, &write_wait); 1022 1023 min_wait = min(read_wait, write_wait); 1024 disptime = jiffies + min_wait; 1025 1026 /* Update dispatch time */ 1027 throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq); 1028 tg->disptime = disptime; 1029 tg_service_queue_add(tg); 1030 1031 /* see throtl_add_bio_tg() */ 1032 tg->flags &= ~THROTL_TG_WAS_EMPTY; 1033} 1034 1035static void start_parent_slice_with_credit(struct throtl_grp *child_tg, 1036 struct throtl_grp *parent_tg, bool rw) 1037{ 1038 if (throtl_slice_used(parent_tg, rw)) { 1039 throtl_start_new_slice_with_credit(parent_tg, rw, 1040 child_tg->slice_start[rw]); 1041 } 1042 1043} 1044 1045static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) 1046{ 1047 struct throtl_service_queue *sq = &tg->service_queue; 1048 struct throtl_service_queue *parent_sq = sq->parent_sq; 1049 struct throtl_grp *parent_tg = sq_to_tg(parent_sq); 1050 struct throtl_grp *tg_to_put = NULL; 1051 struct bio *bio; 1052 1053 /* 1054 * @bio is being transferred from @tg to @parent_sq. Popping a bio 1055 * from @tg may put its reference and @parent_sq might end up 1056 * getting released prematurely. Remember the tg to put and put it 1057 * after @bio is transferred to @parent_sq. 1058 */ 1059 bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put); 1060 sq->nr_queued[rw]--; 1061 1062 throtl_charge_bio(tg, bio); 1063 1064 /* 1065 * If our parent is another tg, we just need to transfer @bio to 1066 * the parent using throtl_add_bio_tg(). If our parent is 1067 * @td->service_queue, @bio is ready to be issued. Put it on its 1068 * bio_lists[] and decrease total number queued. The caller is 1069 * responsible for issuing these bios. 1070 */ 1071 if (parent_tg) { 1072 throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); 1073 start_parent_slice_with_credit(tg, parent_tg, rw); 1074 } else { 1075 bio_set_flag(bio, BIO_BPS_THROTTLED); 1076 throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], 1077 &parent_sq->queued[rw]); 1078 BUG_ON(tg->td->nr_queued[rw] <= 0); 1079 tg->td->nr_queued[rw]--; 1080 } 1081 1082 throtl_trim_slice(tg, rw); 1083 1084 if (tg_to_put) 1085 blkg_put(tg_to_blkg(tg_to_put)); 1086} 1087 1088static int throtl_dispatch_tg(struct throtl_grp *tg) 1089{ 1090 struct throtl_service_queue *sq = &tg->service_queue; 1091 unsigned int nr_reads = 0, nr_writes = 0; 1092 unsigned int max_nr_reads = THROTL_GRP_QUANTUM * 3 / 4; 1093 unsigned int max_nr_writes = THROTL_GRP_QUANTUM - max_nr_reads; 1094 struct bio *bio; 1095 1096 /* Try to dispatch 75% READS and 25% WRITES */ 1097 1098 while ((bio = throtl_peek_queued(&sq->queued[READ])) && 1099 tg_may_dispatch(tg, bio, NULL)) { 1100 1101 tg_dispatch_one_bio(tg, READ); 1102 nr_reads++; 1103 1104 if (nr_reads >= max_nr_reads) 1105 break; 1106 } 1107 1108 while ((bio = throtl_peek_queued(&sq->queued[WRITE])) && 1109 tg_may_dispatch(tg, bio, NULL)) { 1110 1111 tg_dispatch_one_bio(tg, WRITE); 1112 nr_writes++; 1113 1114 if (nr_writes >= max_nr_writes) 1115 break; 1116 } 1117 1118 return nr_reads + nr_writes; 1119} 1120 1121static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) 1122{ 1123 unsigned int nr_disp = 0; 1124 1125 while (1) { 1126 struct throtl_grp *tg; 1127 struct throtl_service_queue *sq; 1128 1129 if (!parent_sq->nr_pending) 1130 break; 1131 1132 tg = throtl_rb_first(parent_sq); 1133 if (!tg) 1134 break; 1135 1136 if (time_before(jiffies, tg->disptime)) 1137 break; 1138 1139 nr_disp += throtl_dispatch_tg(tg); 1140 1141 sq = &tg->service_queue; 1142 if (sq->nr_queued[READ] || sq->nr_queued[WRITE]) 1143 tg_update_disptime(tg); 1144 else 1145 throtl_dequeue_tg(tg); 1146 1147 if (nr_disp >= THROTL_QUANTUM) 1148 break; 1149 } 1150 1151 return nr_disp; 1152} 1153 1154static bool throtl_can_upgrade(struct throtl_data *td, 1155 struct throtl_grp *this_tg); 1156/** 1157 * throtl_pending_timer_fn - timer function for service_queue->pending_timer 1158 * @t: the pending_timer member of the throtl_service_queue being serviced 1159 * 1160 * This timer is armed when a child throtl_grp with active bio's become 1161 * pending and queued on the service_queue's pending_tree and expires when 1162 * the first child throtl_grp should be dispatched. This function 1163 * dispatches bio's from the children throtl_grps to the parent 1164 * service_queue. 1165 * 1166 * If the parent's parent is another throtl_grp, dispatching is propagated 1167 * by either arming its pending_timer or repeating dispatch directly. If 1168 * the top-level service_tree is reached, throtl_data->dispatch_work is 1169 * kicked so that the ready bio's are issued. 1170 */ 1171static void throtl_pending_timer_fn(struct timer_list *t) 1172{ 1173 struct throtl_service_queue *sq = from_timer(sq, t, pending_timer); 1174 struct throtl_grp *tg = sq_to_tg(sq); 1175 struct throtl_data *td = sq_to_td(sq); 1176 struct throtl_service_queue *parent_sq; 1177 struct request_queue *q; 1178 bool dispatched; 1179 int ret; 1180 1181 /* throtl_data may be gone, so figure out request queue by blkg */ 1182 if (tg) 1183 q = tg->pd.blkg->q; 1184 else 1185 q = td->queue; 1186 1187 spin_lock_irq(&q->queue_lock); 1188 1189 if (!q->root_blkg) 1190 goto out_unlock; 1191 1192 if (throtl_can_upgrade(td, NULL)) 1193 throtl_upgrade_state(td); 1194 1195again: 1196 parent_sq = sq->parent_sq; 1197 dispatched = false; 1198 1199 while (true) { 1200 throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u", 1201 sq->nr_queued[READ] + sq->nr_queued[WRITE], 1202 sq->nr_queued[READ], sq->nr_queued[WRITE]); 1203 1204 ret = throtl_select_dispatch(sq); 1205 if (ret) { 1206 throtl_log(sq, "bios disp=%u", ret); 1207 dispatched = true; 1208 } 1209 1210 if (throtl_schedule_next_dispatch(sq, false)) 1211 break; 1212 1213 /* this dispatch windows is still open, relax and repeat */ 1214 spin_unlock_irq(&q->queue_lock); 1215 cpu_relax(); 1216 spin_lock_irq(&q->queue_lock); 1217 } 1218 1219 if (!dispatched) 1220 goto out_unlock; 1221 1222 if (parent_sq) { 1223 /* @parent_sq is another throl_grp, propagate dispatch */ 1224 if (tg->flags & THROTL_TG_WAS_EMPTY) { 1225 tg_update_disptime(tg); 1226 if (!throtl_schedule_next_dispatch(parent_sq, false)) { 1227 /* window is already open, repeat dispatching */ 1228 sq = parent_sq; 1229 tg = sq_to_tg(sq); 1230 goto again; 1231 } 1232 } 1233 } else { 1234 /* reached the top-level, queue issuing */ 1235 queue_work(kthrotld_workqueue, &td->dispatch_work); 1236 } 1237out_unlock: 1238 spin_unlock_irq(&q->queue_lock); 1239} 1240 1241/** 1242 * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work 1243 * @work: work item being executed 1244 * 1245 * This function is queued for execution when bios reach the bio_lists[] 1246 * of throtl_data->service_queue. Those bios are ready and issued by this 1247 * function. 1248 */ 1249static void blk_throtl_dispatch_work_fn(struct work_struct *work) 1250{ 1251 struct throtl_data *td = container_of(work, struct throtl_data, 1252 dispatch_work); 1253 struct throtl_service_queue *td_sq = &td->service_queue; 1254 struct request_queue *q = td->queue; 1255 struct bio_list bio_list_on_stack; 1256 struct bio *bio; 1257 struct blk_plug plug; 1258 int rw; 1259 1260 bio_list_init(&bio_list_on_stack); 1261 1262 spin_lock_irq(&q->queue_lock); 1263 for (rw = READ; rw <= WRITE; rw++) 1264 while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) 1265 bio_list_add(&bio_list_on_stack, bio); 1266 spin_unlock_irq(&q->queue_lock); 1267 1268 if (!bio_list_empty(&bio_list_on_stack)) { 1269 blk_start_plug(&plug); 1270 while ((bio = bio_list_pop(&bio_list_on_stack))) 1271 submit_bio_noacct_nocheck(bio); 1272 blk_finish_plug(&plug); 1273 } 1274} 1275 1276static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, 1277 int off) 1278{ 1279 struct throtl_grp *tg = pd_to_tg(pd); 1280 u64 v = *(u64 *)((void *)tg + off); 1281 1282 if (v == U64_MAX) 1283 return 0; 1284 return __blkg_prfill_u64(sf, pd, v); 1285} 1286 1287static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, 1288 int off) 1289{ 1290 struct throtl_grp *tg = pd_to_tg(pd); 1291 unsigned int v = *(unsigned int *)((void *)tg + off); 1292 1293 if (v == UINT_MAX) 1294 return 0; 1295 return __blkg_prfill_u64(sf, pd, v); 1296} 1297 1298static int tg_print_conf_u64(struct seq_file *sf, void *v) 1299{ 1300 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_u64, 1301 &blkcg_policy_throtl, seq_cft(sf)->private, false); 1302 return 0; 1303} 1304 1305static int tg_print_conf_uint(struct seq_file *sf, void *v) 1306{ 1307 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_conf_uint, 1308 &blkcg_policy_throtl, seq_cft(sf)->private, false); 1309 return 0; 1310} 1311 1312static void tg_conf_updated(struct throtl_grp *tg, bool global) 1313{ 1314 struct throtl_service_queue *sq = &tg->service_queue; 1315 struct cgroup_subsys_state *pos_css; 1316 struct blkcg_gq *blkg; 1317 1318 throtl_log(&tg->service_queue, 1319 "limit change rbps=%llu wbps=%llu riops=%u wiops=%u", 1320 tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE), 1321 tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE)); 1322 1323 rcu_read_lock(); 1324 /* 1325 * Update has_rules[] flags for the updated tg's subtree. A tg is 1326 * considered to have rules if either the tg itself or any of its 1327 * ancestors has rules. This identifies groups without any 1328 * restrictions in the whole hierarchy and allows them to bypass 1329 * blk-throttle. 1330 */ 1331 blkg_for_each_descendant_pre(blkg, pos_css, 1332 global ? tg->td->queue->root_blkg : tg_to_blkg(tg)) { 1333 struct throtl_grp *this_tg = blkg_to_tg(blkg); 1334 struct throtl_grp *parent_tg; 1335 1336 tg_update_has_rules(this_tg); 1337 /* ignore root/second level */ 1338 if (!cgroup_subsys_on_dfl(io_cgrp_subsys) || !blkg->parent || 1339 !blkg->parent->parent) 1340 continue; 1341 parent_tg = blkg_to_tg(blkg->parent); 1342 /* 1343 * make sure all children has lower idle time threshold and 1344 * higher latency target 1345 */ 1346 this_tg->idletime_threshold = min(this_tg->idletime_threshold, 1347 parent_tg->idletime_threshold); 1348 this_tg->latency_target = max(this_tg->latency_target, 1349 parent_tg->latency_target); 1350 } 1351 rcu_read_unlock(); 1352 1353 /* 1354 * We're already holding queue_lock and know @tg is valid. Let's 1355 * apply the new config directly. 1356 * 1357 * Restart the slices for both READ and WRITES. It might happen 1358 * that a group's limit are dropped suddenly and we don't want to 1359 * account recently dispatched IO with new low rate. 1360 */ 1361 throtl_start_new_slice(tg, READ, false); 1362 throtl_start_new_slice(tg, WRITE, false); 1363 1364 if (tg->flags & THROTL_TG_PENDING) { 1365 tg_update_disptime(tg); 1366 throtl_schedule_next_dispatch(sq->parent_sq, true); 1367 } 1368} 1369 1370static ssize_t tg_set_conf(struct kernfs_open_file *of, 1371 char *buf, size_t nbytes, loff_t off, bool is_u64) 1372{ 1373 struct blkcg *blkcg = css_to_blkcg(of_css(of)); 1374 struct blkg_conf_ctx ctx; 1375 struct throtl_grp *tg; 1376 int ret; 1377 u64 v; 1378 1379 blkg_conf_init(&ctx, buf); 1380 1381 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx); 1382 if (ret) 1383 goto out_finish; 1384 1385 ret = -EINVAL; 1386 if (sscanf(ctx.body, "%llu", &v) != 1) 1387 goto out_finish; 1388 if (!v) 1389 v = U64_MAX; 1390 1391 tg = blkg_to_tg(ctx.blkg); 1392 tg_update_carryover(tg); 1393 1394 if (is_u64) 1395 *(u64 *)((void *)tg + of_cft(of)->private) = v; 1396 else 1397 *(unsigned int *)((void *)tg + of_cft(of)->private) = v; 1398 1399 tg_conf_updated(tg, false); 1400 ret = 0; 1401out_finish: 1402 blkg_conf_exit(&ctx); 1403 return ret ?: nbytes; 1404} 1405 1406static ssize_t tg_set_conf_u64(struct kernfs_open_file *of, 1407 char *buf, size_t nbytes, loff_t off) 1408{ 1409 return tg_set_conf(of, buf, nbytes, off, true); 1410} 1411 1412static ssize_t tg_set_conf_uint(struct kernfs_open_file *of, 1413 char *buf, size_t nbytes, loff_t off) 1414{ 1415 return tg_set_conf(of, buf, nbytes, off, false); 1416} 1417 1418static int tg_print_rwstat(struct seq_file *sf, void *v) 1419{ 1420 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), 1421 blkg_prfill_rwstat, &blkcg_policy_throtl, 1422 seq_cft(sf)->private, true); 1423 return 0; 1424} 1425 1426static u64 tg_prfill_rwstat_recursive(struct seq_file *sf, 1427 struct blkg_policy_data *pd, int off) 1428{ 1429 struct blkg_rwstat_sample sum; 1430 1431 blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_throtl, off, 1432 &sum); 1433 return __blkg_prfill_rwstat(sf, pd, &sum); 1434} 1435 1436static int tg_print_rwstat_recursive(struct seq_file *sf, void *v) 1437{ 1438 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), 1439 tg_prfill_rwstat_recursive, &blkcg_policy_throtl, 1440 seq_cft(sf)->private, true); 1441 return 0; 1442} 1443 1444static struct cftype throtl_legacy_files[] = { 1445 { 1446 .name = "throttle.read_bps_device", 1447 .private = offsetof(struct throtl_grp, bps[READ][LIMIT_MAX]), 1448 .seq_show = tg_print_conf_u64, 1449 .write = tg_set_conf_u64, 1450 }, 1451 { 1452 .name = "throttle.write_bps_device", 1453 .private = offsetof(struct throtl_grp, bps[WRITE][LIMIT_MAX]), 1454 .seq_show = tg_print_conf_u64, 1455 .write = tg_set_conf_u64, 1456 }, 1457 { 1458 .name = "throttle.read_iops_device", 1459 .private = offsetof(struct throtl_grp, iops[READ][LIMIT_MAX]), 1460 .seq_show = tg_print_conf_uint, 1461 .write = tg_set_conf_uint, 1462 }, 1463 { 1464 .name = "throttle.write_iops_device", 1465 .private = offsetof(struct throtl_grp, iops[WRITE][LIMIT_MAX]), 1466 .seq_show = tg_print_conf_uint, 1467 .write = tg_set_conf_uint, 1468 }, 1469 { 1470 .name = "throttle.io_service_bytes", 1471 .private = offsetof(struct throtl_grp, stat_bytes), 1472 .seq_show = tg_print_rwstat, 1473 }, 1474 { 1475 .name = "throttle.io_service_bytes_recursive", 1476 .private = offsetof(struct throtl_grp, stat_bytes), 1477 .seq_show = tg_print_rwstat_recursive, 1478 }, 1479 { 1480 .name = "throttle.io_serviced", 1481 .private = offsetof(struct throtl_grp, stat_ios), 1482 .seq_show = tg_print_rwstat, 1483 }, 1484 { 1485 .name = "throttle.io_serviced_recursive", 1486 .private = offsetof(struct throtl_grp, stat_ios), 1487 .seq_show = tg_print_rwstat_recursive, 1488 }, 1489 { } /* terminate */ 1490}; 1491 1492static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd, 1493 int off) 1494{ 1495 struct throtl_grp *tg = pd_to_tg(pd); 1496 const char *dname = blkg_dev_name(pd->blkg); 1497 char bufs[4][21] = { "max", "max", "max", "max" }; 1498 u64 bps_dft; 1499 unsigned int iops_dft; 1500 char idle_time[26] = ""; 1501 char latency_time[26] = ""; 1502 1503 if (!dname) 1504 return 0; 1505 1506 if (off == LIMIT_LOW) { 1507 bps_dft = 0; 1508 iops_dft = 0; 1509 } else { 1510 bps_dft = U64_MAX; 1511 iops_dft = UINT_MAX; 1512 } 1513 1514 if (tg->bps_conf[READ][off] == bps_dft && 1515 tg->bps_conf[WRITE][off] == bps_dft && 1516 tg->iops_conf[READ][off] == iops_dft && 1517 tg->iops_conf[WRITE][off] == iops_dft && 1518 (off != LIMIT_LOW || 1519 (tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD && 1520 tg->latency_target_conf == DFL_LATENCY_TARGET))) 1521 return 0; 1522 1523 if (tg->bps_conf[READ][off] != U64_MAX) 1524 snprintf(bufs[0], sizeof(bufs[0]), "%llu", 1525 tg->bps_conf[READ][off]); 1526 if (tg->bps_conf[WRITE][off] != U64_MAX) 1527 snprintf(bufs[1], sizeof(bufs[1]), "%llu", 1528 tg->bps_conf[WRITE][off]); 1529 if (tg->iops_conf[READ][off] != UINT_MAX) 1530 snprintf(bufs[2], sizeof(bufs[2]), "%u", 1531 tg->iops_conf[READ][off]); 1532 if (tg->iops_conf[WRITE][off] != UINT_MAX) 1533 snprintf(bufs[3], sizeof(bufs[3]), "%u", 1534 tg->iops_conf[WRITE][off]); 1535 if (off == LIMIT_LOW) { 1536 if (tg->idletime_threshold_conf == ULONG_MAX) 1537 strcpy(idle_time, " idle=max"); 1538 else 1539 snprintf(idle_time, sizeof(idle_time), " idle=%lu", 1540 tg->idletime_threshold_conf); 1541 1542 if (tg->latency_target_conf == ULONG_MAX) 1543 strcpy(latency_time, " latency=max"); 1544 else 1545 snprintf(latency_time, sizeof(latency_time), 1546 " latency=%lu", tg->latency_target_conf); 1547 } 1548 1549 seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n", 1550 dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time, 1551 latency_time); 1552 return 0; 1553} 1554 1555static int tg_print_limit(struct seq_file *sf, void *v) 1556{ 1557 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_limit, 1558 &blkcg_policy_throtl, seq_cft(sf)->private, false); 1559 return 0; 1560} 1561 1562static ssize_t tg_set_limit(struct kernfs_open_file *of, 1563 char *buf, size_t nbytes, loff_t off) 1564{ 1565 struct blkcg *blkcg = css_to_blkcg(of_css(of)); 1566 struct blkg_conf_ctx ctx; 1567 struct throtl_grp *tg; 1568 u64 v[4]; 1569 unsigned long idle_time; 1570 unsigned long latency_time; 1571 int ret; 1572 int index = of_cft(of)->private; 1573 1574 blkg_conf_init(&ctx, buf); 1575 1576 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, &ctx); 1577 if (ret) 1578 goto out_finish; 1579 1580 tg = blkg_to_tg(ctx.blkg); 1581 tg_update_carryover(tg); 1582 1583 v[0] = tg->bps_conf[READ][index]; 1584 v[1] = tg->bps_conf[WRITE][index]; 1585 v[2] = tg->iops_conf[READ][index]; 1586 v[3] = tg->iops_conf[WRITE][index]; 1587 1588 idle_time = tg->idletime_threshold_conf; 1589 latency_time = tg->latency_target_conf; 1590 while (true) { 1591 char tok[27]; /* wiops=18446744073709551616 */ 1592 char *p; 1593 u64 val = U64_MAX; 1594 int len; 1595 1596 if (sscanf(ctx.body, "%26s%n", tok, &len) != 1) 1597 break; 1598 if (tok[0] == '\0') 1599 break; 1600 ctx.body += len; 1601 1602 ret = -EINVAL; 1603 p = tok; 1604 strsep(&p, "="); 1605 if (!p || (sscanf(p, "%llu", &val) != 1 && strcmp(p, "max"))) 1606 goto out_finish; 1607 1608 ret = -ERANGE; 1609 if (!val) 1610 goto out_finish; 1611 1612 ret = -EINVAL; 1613 if (!strcmp(tok, "rbps") && val > 1) 1614 v[0] = val; 1615 else if (!strcmp(tok, "wbps") && val > 1) 1616 v[1] = val; 1617 else if (!strcmp(tok, "riops") && val > 1) 1618 v[2] = min_t(u64, val, UINT_MAX); 1619 else if (!strcmp(tok, "wiops") && val > 1) 1620 v[3] = min_t(u64, val, UINT_MAX); 1621 else if (off == LIMIT_LOW && !strcmp(tok, "idle")) 1622 idle_time = val; 1623 else if (off == LIMIT_LOW && !strcmp(tok, "latency")) 1624 latency_time = val; 1625 else 1626 goto out_finish; 1627 } 1628 1629 tg->bps_conf[READ][index] = v[0]; 1630 tg->bps_conf[WRITE][index] = v[1]; 1631 tg->iops_conf[READ][index] = v[2]; 1632 tg->iops_conf[WRITE][index] = v[3]; 1633 1634 if (index == LIMIT_MAX) { 1635 tg->bps[READ][index] = v[0]; 1636 tg->bps[WRITE][index] = v[1]; 1637 tg->iops[READ][index] = v[2]; 1638 tg->iops[WRITE][index] = v[3]; 1639 } 1640 tg->bps[READ][LIMIT_LOW] = min(tg->bps_conf[READ][LIMIT_LOW], 1641 tg->bps_conf[READ][LIMIT_MAX]); 1642 tg->bps[WRITE][LIMIT_LOW] = min(tg->bps_conf[WRITE][LIMIT_LOW], 1643 tg->bps_conf[WRITE][LIMIT_MAX]); 1644 tg->iops[READ][LIMIT_LOW] = min(tg->iops_conf[READ][LIMIT_LOW], 1645 tg->iops_conf[READ][LIMIT_MAX]); 1646 tg->iops[WRITE][LIMIT_LOW] = min(tg->iops_conf[WRITE][LIMIT_LOW], 1647 tg->iops_conf[WRITE][LIMIT_MAX]); 1648 tg->idletime_threshold_conf = idle_time; 1649 tg->latency_target_conf = latency_time; 1650 1651 /* force user to configure all settings for low limit */ 1652 if (!(tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW] || 1653 tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) || 1654 tg->idletime_threshold_conf == DFL_IDLE_THRESHOLD || 1655 tg->latency_target_conf == DFL_LATENCY_TARGET) { 1656 tg->bps[READ][LIMIT_LOW] = 0; 1657 tg->bps[WRITE][LIMIT_LOW] = 0; 1658 tg->iops[READ][LIMIT_LOW] = 0; 1659 tg->iops[WRITE][LIMIT_LOW] = 0; 1660 tg->idletime_threshold = DFL_IDLE_THRESHOLD; 1661 tg->latency_target = DFL_LATENCY_TARGET; 1662 } else if (index == LIMIT_LOW) { 1663 tg->idletime_threshold = tg->idletime_threshold_conf; 1664 tg->latency_target = tg->latency_target_conf; 1665 } 1666 1667 blk_throtl_update_limit_valid(tg->td); 1668 if (tg->td->limit_valid[LIMIT_LOW]) { 1669 if (index == LIMIT_LOW) 1670 tg->td->limit_index = LIMIT_LOW; 1671 } else 1672 tg->td->limit_index = LIMIT_MAX; 1673 tg_conf_updated(tg, index == LIMIT_LOW && 1674 tg->td->limit_valid[LIMIT_LOW]); 1675 ret = 0; 1676out_finish: 1677 blkg_conf_exit(&ctx); 1678 return ret ?: nbytes; 1679} 1680 1681static struct cftype throtl_files[] = { 1682#ifdef CONFIG_BLK_DEV_THROTTLING_LOW 1683 { 1684 .name = "low", 1685 .flags = CFTYPE_NOT_ON_ROOT, 1686 .seq_show = tg_print_limit, 1687 .write = tg_set_limit, 1688 .private = LIMIT_LOW, 1689 }, 1690#endif 1691 { 1692 .name = "max", 1693 .flags = CFTYPE_NOT_ON_ROOT, 1694 .seq_show = tg_print_limit, 1695 .write = tg_set_limit, 1696 .private = LIMIT_MAX, 1697 }, 1698 { } /* terminate */ 1699}; 1700 1701static void throtl_shutdown_wq(struct request_queue *q) 1702{ 1703 struct throtl_data *td = q->td; 1704 1705 cancel_work_sync(&td->dispatch_work); 1706} 1707 1708struct blkcg_policy blkcg_policy_throtl = { 1709 .dfl_cftypes = throtl_files, 1710 .legacy_cftypes = throtl_legacy_files, 1711 1712 .pd_alloc_fn = throtl_pd_alloc, 1713 .pd_init_fn = throtl_pd_init, 1714 .pd_online_fn = throtl_pd_online, 1715 .pd_offline_fn = throtl_pd_offline, 1716 .pd_free_fn = throtl_pd_free, 1717}; 1718 1719void blk_throtl_cancel_bios(struct gendisk *disk) 1720{ 1721 struct request_queue *q = disk->queue; 1722 struct cgroup_subsys_state *pos_css; 1723 struct blkcg_gq *blkg; 1724 1725 spin_lock_irq(&q->queue_lock); 1726 /* 1727 * queue_lock is held, rcu lock is not needed here technically. 1728 * However, rcu lock is still held to emphasize that following 1729 * path need RCU protection and to prevent warning from lockdep. 1730 */ 1731 rcu_read_lock(); 1732 blkg_for_each_descendant_post(blkg, pos_css, q->root_blkg) { 1733 struct throtl_grp *tg = blkg_to_tg(blkg); 1734 struct throtl_service_queue *sq = &tg->service_queue; 1735 1736 /* 1737 * Set the flag to make sure throtl_pending_timer_fn() won't 1738 * stop until all throttled bios are dispatched. 1739 */ 1740 tg->flags |= THROTL_TG_CANCELING; 1741 1742 /* 1743 * Do not dispatch cgroup without THROTL_TG_PENDING or cgroup 1744 * will be inserted to service queue without THROTL_TG_PENDING 1745 * set in tg_update_disptime below. Then IO dispatched from 1746 * child in tg_dispatch_one_bio will trigger double insertion 1747 * and corrupt the tree. 1748 */ 1749 if (!(tg->flags & THROTL_TG_PENDING)) 1750 continue; 1751 1752 /* 1753 * Update disptime after setting the above flag to make sure 1754 * throtl_select_dispatch() won't exit without dispatching. 1755 */ 1756 tg_update_disptime(tg); 1757 1758 throtl_schedule_pending_timer(sq, jiffies + 1); 1759 } 1760 rcu_read_unlock(); 1761 spin_unlock_irq(&q->queue_lock); 1762} 1763 1764#ifdef CONFIG_BLK_DEV_THROTTLING_LOW 1765static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg) 1766{ 1767 unsigned long rtime = jiffies, wtime = jiffies; 1768 1769 if (tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW]) 1770 rtime = tg->last_low_overflow_time[READ]; 1771 if (tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW]) 1772 wtime = tg->last_low_overflow_time[WRITE]; 1773 return min(rtime, wtime); 1774} 1775 1776static unsigned long tg_last_low_overflow_time(struct throtl_grp *tg) 1777{ 1778 struct throtl_service_queue *parent_sq; 1779 struct throtl_grp *parent = tg; 1780 unsigned long ret = __tg_last_low_overflow_time(tg); 1781 1782 while (true) { 1783 parent_sq = parent->service_queue.parent_sq; 1784 parent = sq_to_tg(parent_sq); 1785 if (!parent) 1786 break; 1787 1788 /* 1789 * The parent doesn't have low limit, it always reaches low 1790 * limit. Its overflow time is useless for children 1791 */ 1792 if (!parent->bps[READ][LIMIT_LOW] && 1793 !parent->iops[READ][LIMIT_LOW] && 1794 !parent->bps[WRITE][LIMIT_LOW] && 1795 !parent->iops[WRITE][LIMIT_LOW]) 1796 continue; 1797 if (time_after(__tg_last_low_overflow_time(parent), ret)) 1798 ret = __tg_last_low_overflow_time(parent); 1799 } 1800 return ret; 1801} 1802 1803static bool throtl_tg_is_idle(struct throtl_grp *tg) 1804{ 1805 /* 1806 * cgroup is idle if: 1807 * - single idle is too long, longer than a fixed value (in case user 1808 * configure a too big threshold) or 4 times of idletime threshold 1809 * - average think time is more than threshold 1810 * - IO latency is largely below threshold 1811 */ 1812 unsigned long time; 1813 bool ret; 1814 1815 time = min_t(unsigned long, MAX_IDLE_TIME, 4 * tg->idletime_threshold); 1816 ret = tg->latency_target == DFL_LATENCY_TARGET || 1817 tg->idletime_threshold == DFL_IDLE_THRESHOLD || 1818 (blk_time_get_ns() >> 10) - tg->last_finish_time > time || 1819 tg->avg_idletime > tg->idletime_threshold || 1820 (tg->latency_target && tg->bio_cnt && 1821 tg->bad_bio_cnt * 5 < tg->bio_cnt); 1822 throtl_log(&tg->service_queue, 1823 "avg_idle=%ld, idle_threshold=%ld, bad_bio=%d, total_bio=%d, is_idle=%d, scale=%d", 1824 tg->avg_idletime, tg->idletime_threshold, tg->bad_bio_cnt, 1825 tg->bio_cnt, ret, tg->td->scale); 1826 return ret; 1827} 1828 1829static bool throtl_low_limit_reached(struct throtl_grp *tg, int rw) 1830{ 1831 struct throtl_service_queue *sq = &tg->service_queue; 1832 bool limit = tg->bps[rw][LIMIT_LOW] || tg->iops[rw][LIMIT_LOW]; 1833 1834 /* 1835 * if low limit is zero, low limit is always reached. 1836 * if low limit is non-zero, we can check if there is any request 1837 * is queued to determine if low limit is reached as we throttle 1838 * request according to limit. 1839 */ 1840 return !limit || sq->nr_queued[rw]; 1841} 1842 1843static bool throtl_tg_can_upgrade(struct throtl_grp *tg) 1844{ 1845 /* 1846 * cgroup reaches low limit when low limit of READ and WRITE are 1847 * both reached, it's ok to upgrade to next limit if cgroup reaches 1848 * low limit 1849 */ 1850 if (throtl_low_limit_reached(tg, READ) && 1851 throtl_low_limit_reached(tg, WRITE)) 1852 return true; 1853 1854 if (time_after_eq(jiffies, 1855 tg_last_low_overflow_time(tg) + tg->td->throtl_slice) && 1856 throtl_tg_is_idle(tg)) 1857 return true; 1858 return false; 1859} 1860 1861static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg) 1862{ 1863 while (true) { 1864 if (throtl_tg_can_upgrade(tg)) 1865 return true; 1866 tg = sq_to_tg(tg->service_queue.parent_sq); 1867 if (!tg || !tg_to_blkg(tg)->parent) 1868 return false; 1869 } 1870 return false; 1871} 1872 1873static bool throtl_can_upgrade(struct throtl_data *td, 1874 struct throtl_grp *this_tg) 1875{ 1876 struct cgroup_subsys_state *pos_css; 1877 struct blkcg_gq *blkg; 1878 1879 if (td->limit_index != LIMIT_LOW) 1880 return false; 1881 1882 if (time_before(jiffies, td->low_downgrade_time + td->throtl_slice)) 1883 return false; 1884 1885 rcu_read_lock(); 1886 blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { 1887 struct throtl_grp *tg = blkg_to_tg(blkg); 1888 1889 if (tg == this_tg) 1890 continue; 1891 if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) 1892 continue; 1893 if (!throtl_hierarchy_can_upgrade(tg)) { 1894 rcu_read_unlock(); 1895 return false; 1896 } 1897 } 1898 rcu_read_unlock(); 1899 return true; 1900} 1901 1902static void throtl_upgrade_check(struct throtl_grp *tg) 1903{ 1904 unsigned long now = jiffies; 1905 1906 if (tg->td->limit_index != LIMIT_LOW) 1907 return; 1908 1909 if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) 1910 return; 1911 1912 tg->last_check_time = now; 1913 1914 if (!time_after_eq(now, 1915 __tg_last_low_overflow_time(tg) + tg->td->throtl_slice)) 1916 return; 1917 1918 if (throtl_can_upgrade(tg->td, NULL)) 1919 throtl_upgrade_state(tg->td); 1920} 1921 1922static void throtl_upgrade_state(struct throtl_data *td) 1923{ 1924 struct cgroup_subsys_state *pos_css; 1925 struct blkcg_gq *blkg; 1926 1927 throtl_log(&td->service_queue, "upgrade to max"); 1928 td->limit_index = LIMIT_MAX; 1929 td->low_upgrade_time = jiffies; 1930 td->scale = 0; 1931 rcu_read_lock(); 1932 blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) { 1933 struct throtl_grp *tg = blkg_to_tg(blkg); 1934 struct throtl_service_queue *sq = &tg->service_queue; 1935 1936 tg->disptime = jiffies - 1; 1937 throtl_select_dispatch(sq); 1938 throtl_schedule_next_dispatch(sq, true); 1939 } 1940 rcu_read_unlock(); 1941 throtl_select_dispatch(&td->service_queue); 1942 throtl_schedule_next_dispatch(&td->service_queue, true); 1943 queue_work(kthrotld_workqueue, &td->dispatch_work); 1944} 1945 1946static void throtl_downgrade_state(struct throtl_data *td) 1947{ 1948 td->scale /= 2; 1949 1950 throtl_log(&td->service_queue, "downgrade, scale %d", td->scale); 1951 if (td->scale) { 1952 td->low_upgrade_time = jiffies - td->scale * td->throtl_slice; 1953 return; 1954 } 1955 1956 td->limit_index = LIMIT_LOW; 1957 td->low_downgrade_time = jiffies; 1958} 1959 1960static bool throtl_tg_can_downgrade(struct throtl_grp *tg) 1961{ 1962 struct throtl_data *td = tg->td; 1963 unsigned long now = jiffies; 1964 1965 /* 1966 * If cgroup is below low limit, consider downgrade and throttle other 1967 * cgroups 1968 */ 1969 if (time_after_eq(now, tg_last_low_overflow_time(tg) + 1970 td->throtl_slice) && 1971 (!throtl_tg_is_idle(tg) || 1972 !list_empty(&tg_to_blkg(tg)->blkcg->css.children))) 1973 return true; 1974 return false; 1975} 1976 1977static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg) 1978{ 1979 struct throtl_data *td = tg->td; 1980 1981 if (time_before(jiffies, td->low_upgrade_time + td->throtl_slice)) 1982 return false; 1983 1984 while (true) { 1985 if (!throtl_tg_can_downgrade(tg)) 1986 return false; 1987 tg = sq_to_tg(tg->service_queue.parent_sq); 1988 if (!tg || !tg_to_blkg(tg)->parent) 1989 break; 1990 } 1991 return true; 1992} 1993 1994static void throtl_downgrade_check(struct throtl_grp *tg) 1995{ 1996 uint64_t bps; 1997 unsigned int iops; 1998 unsigned long elapsed_time; 1999 unsigned long now = jiffies; 2000 2001 if (tg->td->limit_index != LIMIT_MAX || 2002 !tg->td->limit_valid[LIMIT_LOW]) 2003 return; 2004 if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children)) 2005 return; 2006 if (time_after(tg->last_check_time + tg->td->throtl_slice, now)) 2007 return; 2008 2009 elapsed_time = now - tg->last_check_time; 2010 tg->last_check_time = now; 2011 2012 if (time_before(now, tg_last_low_overflow_time(tg) + 2013 tg->td->throtl_slice)) 2014 return; 2015 2016 if (tg->bps[READ][LIMIT_LOW]) { 2017 bps = tg->last_bytes_disp[READ] * HZ; 2018 do_div(bps, elapsed_time); 2019 if (bps >= tg->bps[READ][LIMIT_LOW]) 2020 tg->last_low_overflow_time[READ] = now; 2021 } 2022 2023 if (tg->bps[WRITE][LIMIT_LOW]) { 2024 bps = tg->last_bytes_disp[WRITE] * HZ; 2025 do_div(bps, elapsed_time); 2026 if (bps >= tg->bps[WRITE][LIMIT_LOW]) 2027 tg->last_low_overflow_time[WRITE] = now; 2028 } 2029 2030 if (tg->iops[READ][LIMIT_LOW]) { 2031 iops = tg->last_io_disp[READ] * HZ / elapsed_time; 2032 if (iops >= tg->iops[READ][LIMIT_LOW]) 2033 tg->last_low_overflow_time[READ] = now; 2034 } 2035 2036 if (tg->iops[WRITE][LIMIT_LOW]) { 2037 iops = tg->last_io_disp[WRITE] * HZ / elapsed_time; 2038 if (iops >= tg->iops[WRITE][LIMIT_LOW]) 2039 tg->last_low_overflow_time[WRITE] = now; 2040 } 2041 2042 /* 2043 * If cgroup is below low limit, consider downgrade and throttle other 2044 * cgroups 2045 */ 2046 if (throtl_hierarchy_can_downgrade(tg)) 2047 throtl_downgrade_state(tg->td); 2048 2049 tg->last_bytes_disp[READ] = 0; 2050 tg->last_bytes_disp[WRITE] = 0; 2051 tg->last_io_disp[READ] = 0; 2052 tg->last_io_disp[WRITE] = 0; 2053} 2054 2055static void blk_throtl_update_idletime(struct throtl_grp *tg) 2056{ 2057 unsigned long now; 2058 unsigned long last_finish_time = tg->last_finish_time; 2059 2060 if (last_finish_time == 0) 2061 return; 2062 2063 now = blk_time_get_ns() >> 10; 2064 if (now <= last_finish_time || 2065 last_finish_time == tg->checked_last_finish_time) 2066 return; 2067 2068 tg->avg_idletime = (tg->avg_idletime * 7 + now - last_finish_time) >> 3; 2069 tg->checked_last_finish_time = last_finish_time; 2070} 2071 2072static void throtl_update_latency_buckets(struct throtl_data *td) 2073{ 2074 struct avg_latency_bucket avg_latency[2][LATENCY_BUCKET_SIZE]; 2075 int i, cpu, rw; 2076 unsigned long last_latency[2] = { 0 }; 2077 unsigned long latency[2]; 2078 2079 if (!blk_queue_nonrot(td->queue) || !td->limit_valid[LIMIT_LOW]) 2080 return; 2081 if (time_before(jiffies, td->last_calculate_time + HZ)) 2082 return; 2083 td->last_calculate_time = jiffies; 2084 2085 memset(avg_latency, 0, sizeof(avg_latency)); 2086 for (rw = READ; rw <= WRITE; rw++) { 2087 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { 2088 struct latency_bucket *tmp = &td->tmp_buckets[rw][i]; 2089 2090 for_each_possible_cpu(cpu) { 2091 struct latency_bucket *bucket; 2092 2093 /* this isn't race free, but ok in practice */ 2094 bucket = per_cpu_ptr(td->latency_buckets[rw], 2095 cpu); 2096 tmp->total_latency += bucket[i].total_latency; 2097 tmp->samples += bucket[i].samples; 2098 bucket[i].total_latency = 0; 2099 bucket[i].samples = 0; 2100 } 2101 2102 if (tmp->samples >= 32) { 2103 int samples = tmp->samples; 2104 2105 latency[rw] = tmp->total_latency; 2106 2107 tmp->total_latency = 0; 2108 tmp->samples = 0; 2109 latency[rw] /= samples; 2110 if (latency[rw] == 0) 2111 continue; 2112 avg_latency[rw][i].latency = latency[rw]; 2113 } 2114 } 2115 } 2116 2117 for (rw = READ; rw <= WRITE; rw++) { 2118 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { 2119 if (!avg_latency[rw][i].latency) { 2120 if (td->avg_buckets[rw][i].latency < last_latency[rw]) 2121 td->avg_buckets[rw][i].latency = 2122 last_latency[rw]; 2123 continue; 2124 } 2125 2126 if (!td->avg_buckets[rw][i].valid) 2127 latency[rw] = avg_latency[rw][i].latency; 2128 else 2129 latency[rw] = (td->avg_buckets[rw][i].latency * 7 + 2130 avg_latency[rw][i].latency) >> 3; 2131 2132 td->avg_buckets[rw][i].latency = max(latency[rw], 2133 last_latency[rw]); 2134 td->avg_buckets[rw][i].valid = true; 2135 last_latency[rw] = td->avg_buckets[rw][i].latency; 2136 } 2137 } 2138 2139 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) 2140 throtl_log(&td->service_queue, 2141 "Latency bucket %d: read latency=%ld, read valid=%d, " 2142 "write latency=%ld, write valid=%d", i, 2143 td->avg_buckets[READ][i].latency, 2144 td->avg_buckets[READ][i].valid, 2145 td->avg_buckets[WRITE][i].latency, 2146 td->avg_buckets[WRITE][i].valid); 2147} 2148#else 2149static inline void throtl_update_latency_buckets(struct throtl_data *td) 2150{ 2151} 2152 2153static void blk_throtl_update_idletime(struct throtl_grp *tg) 2154{ 2155} 2156 2157static void throtl_downgrade_check(struct throtl_grp *tg) 2158{ 2159} 2160 2161static void throtl_upgrade_check(struct throtl_grp *tg) 2162{ 2163} 2164 2165static bool throtl_can_upgrade(struct throtl_data *td, 2166 struct throtl_grp *this_tg) 2167{ 2168 return false; 2169} 2170 2171static void throtl_upgrade_state(struct throtl_data *td) 2172{ 2173} 2174#endif 2175 2176bool __blk_throtl_bio(struct bio *bio) 2177{ 2178 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 2179 struct blkcg_gq *blkg = bio->bi_blkg; 2180 struct throtl_qnode *qn = NULL; 2181 struct throtl_grp *tg = blkg_to_tg(blkg); 2182 struct throtl_service_queue *sq; 2183 bool rw = bio_data_dir(bio); 2184 bool throttled = false; 2185 struct throtl_data *td = tg->td; 2186 2187 rcu_read_lock(); 2188 2189 spin_lock_irq(&q->queue_lock); 2190 2191 throtl_update_latency_buckets(td); 2192 2193 blk_throtl_update_idletime(tg); 2194 2195 sq = &tg->service_queue; 2196 2197again: 2198 while (true) { 2199 if (tg->last_low_overflow_time[rw] == 0) 2200 tg->last_low_overflow_time[rw] = jiffies; 2201 throtl_downgrade_check(tg); 2202 throtl_upgrade_check(tg); 2203 /* throtl is FIFO - if bios are already queued, should queue */ 2204 if (sq->nr_queued[rw]) 2205 break; 2206 2207 /* if above limits, break to queue */ 2208 if (!tg_may_dispatch(tg, bio, NULL)) { 2209 tg->last_low_overflow_time[rw] = jiffies; 2210 if (throtl_can_upgrade(td, tg)) { 2211 throtl_upgrade_state(td); 2212 goto again; 2213 } 2214 break; 2215 } 2216 2217 /* within limits, let's charge and dispatch directly */ 2218 throtl_charge_bio(tg, bio); 2219 2220 /* 2221 * We need to trim slice even when bios are not being queued 2222 * otherwise it might happen that a bio is not queued for 2223 * a long time and slice keeps on extending and trim is not 2224 * called for a long time. Now if limits are reduced suddenly 2225 * we take into account all the IO dispatched so far at new 2226 * low rate and * newly queued IO gets a really long dispatch 2227 * time. 2228 * 2229 * So keep on trimming slice even if bio is not queued. 2230 */ 2231 throtl_trim_slice(tg, rw); 2232 2233 /* 2234 * @bio passed through this layer without being throttled. 2235 * Climb up the ladder. If we're already at the top, it 2236 * can be executed directly. 2237 */ 2238 qn = &tg->qnode_on_parent[rw]; 2239 sq = sq->parent_sq; 2240 tg = sq_to_tg(sq); 2241 if (!tg) { 2242 bio_set_flag(bio, BIO_BPS_THROTTLED); 2243 goto out_unlock; 2244 } 2245 } 2246 2247 /* out-of-limit, queue to @tg */ 2248 throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", 2249 rw == READ ? 'R' : 'W', 2250 tg->bytes_disp[rw], bio->bi_iter.bi_size, 2251 tg_bps_limit(tg, rw), 2252 tg->io_disp[rw], tg_iops_limit(tg, rw), 2253 sq->nr_queued[READ], sq->nr_queued[WRITE]); 2254 2255 tg->last_low_overflow_time[rw] = jiffies; 2256 2257 td->nr_queued[rw]++; 2258 throtl_add_bio_tg(bio, qn, tg); 2259 throttled = true; 2260 2261 /* 2262 * Update @tg's dispatch time and force schedule dispatch if @tg 2263 * was empty before @bio. The forced scheduling isn't likely to 2264 * cause undue delay as @bio is likely to be dispatched directly if 2265 * its @tg's disptime is not in the future. 2266 */ 2267 if (tg->flags & THROTL_TG_WAS_EMPTY) { 2268 tg_update_disptime(tg); 2269 throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true); 2270 } 2271 2272out_unlock: 2273#ifdef CONFIG_BLK_DEV_THROTTLING_LOW 2274 if (throttled || !td->track_bio_latency) 2275 bio->bi_issue.value |= BIO_ISSUE_THROTL_SKIP_LATENCY; 2276#endif 2277 spin_unlock_irq(&q->queue_lock); 2278 2279 rcu_read_unlock(); 2280 return throttled; 2281} 2282 2283#ifdef CONFIG_BLK_DEV_THROTTLING_LOW 2284static void throtl_track_latency(struct throtl_data *td, sector_t size, 2285 enum req_op op, unsigned long time) 2286{ 2287 const bool rw = op_is_write(op); 2288 struct latency_bucket *latency; 2289 int index; 2290 2291 if (!td || td->limit_index != LIMIT_LOW || 2292 !(op == REQ_OP_READ || op == REQ_OP_WRITE) || 2293 !blk_queue_nonrot(td->queue)) 2294 return; 2295 2296 index = request_bucket_index(size); 2297 2298 latency = get_cpu_ptr(td->latency_buckets[rw]); 2299 latency[index].total_latency += time; 2300 latency[index].samples++; 2301 put_cpu_ptr(td->latency_buckets[rw]); 2302} 2303 2304void blk_throtl_stat_add(struct request *rq, u64 time_ns) 2305{ 2306 struct request_queue *q = rq->q; 2307 struct throtl_data *td = q->td; 2308 2309 throtl_track_latency(td, blk_rq_stats_sectors(rq), req_op(rq), 2310 time_ns >> 10); 2311} 2312 2313void blk_throtl_bio_endio(struct bio *bio) 2314{ 2315 struct blkcg_gq *blkg; 2316 struct throtl_grp *tg; 2317 u64 finish_time_ns; 2318 unsigned long finish_time; 2319 unsigned long start_time; 2320 unsigned long lat; 2321 int rw = bio_data_dir(bio); 2322 2323 blkg = bio->bi_blkg; 2324 if (!blkg) 2325 return; 2326 tg = blkg_to_tg(blkg); 2327 if (!tg->td->limit_valid[LIMIT_LOW]) 2328 return; 2329 2330 finish_time_ns = blk_time_get_ns(); 2331 tg->last_finish_time = finish_time_ns >> 10; 2332 2333 start_time = bio_issue_time(&bio->bi_issue) >> 10; 2334 finish_time = __bio_issue_time(finish_time_ns) >> 10; 2335 if (!start_time || finish_time <= start_time) 2336 return; 2337 2338 lat = finish_time - start_time; 2339 /* this is only for bio based driver */ 2340 if (!(bio->bi_issue.value & BIO_ISSUE_THROTL_SKIP_LATENCY)) 2341 throtl_track_latency(tg->td, bio_issue_size(&bio->bi_issue), 2342 bio_op(bio), lat); 2343 2344 if (tg->latency_target && lat >= tg->td->filtered_latency) { 2345 int bucket; 2346 unsigned int threshold; 2347 2348 bucket = request_bucket_index(bio_issue_size(&bio->bi_issue)); 2349 threshold = tg->td->avg_buckets[rw][bucket].latency + 2350 tg->latency_target; 2351 if (lat > threshold) 2352 tg->bad_bio_cnt++; 2353 /* 2354 * Not race free, could get wrong count, which means cgroups 2355 * will be throttled 2356 */ 2357 tg->bio_cnt++; 2358 } 2359 2360 if (time_after(jiffies, tg->bio_cnt_reset_time) || tg->bio_cnt > 1024) { 2361 tg->bio_cnt_reset_time = tg->td->throtl_slice + jiffies; 2362 tg->bio_cnt /= 2; 2363 tg->bad_bio_cnt /= 2; 2364 } 2365} 2366#endif 2367 2368int blk_throtl_init(struct gendisk *disk) 2369{ 2370 struct request_queue *q = disk->queue; 2371 struct throtl_data *td; 2372 int ret; 2373 2374 td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); 2375 if (!td) 2376 return -ENOMEM; 2377 td->latency_buckets[READ] = __alloc_percpu(sizeof(struct latency_bucket) * 2378 LATENCY_BUCKET_SIZE, __alignof__(u64)); 2379 if (!td->latency_buckets[READ]) { 2380 kfree(td); 2381 return -ENOMEM; 2382 } 2383 td->latency_buckets[WRITE] = __alloc_percpu(sizeof(struct latency_bucket) * 2384 LATENCY_BUCKET_SIZE, __alignof__(u64)); 2385 if (!td->latency_buckets[WRITE]) { 2386 free_percpu(td->latency_buckets[READ]); 2387 kfree(td); 2388 return -ENOMEM; 2389 } 2390 2391 INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn); 2392 throtl_service_queue_init(&td->service_queue); 2393 2394 q->td = td; 2395 td->queue = q; 2396 2397 td->limit_valid[LIMIT_MAX] = true; 2398 td->limit_index = LIMIT_MAX; 2399 td->low_upgrade_time = jiffies; 2400 td->low_downgrade_time = jiffies; 2401 2402 /* activate policy */ 2403 ret = blkcg_activate_policy(disk, &blkcg_policy_throtl); 2404 if (ret) { 2405 free_percpu(td->latency_buckets[READ]); 2406 free_percpu(td->latency_buckets[WRITE]); 2407 kfree(td); 2408 } 2409 return ret; 2410} 2411 2412void blk_throtl_exit(struct gendisk *disk) 2413{ 2414 struct request_queue *q = disk->queue; 2415 2416 BUG_ON(!q->td); 2417 del_timer_sync(&q->td->service_queue.pending_timer); 2418 throtl_shutdown_wq(q); 2419 blkcg_deactivate_policy(disk, &blkcg_policy_throtl); 2420 free_percpu(q->td->latency_buckets[READ]); 2421 free_percpu(q->td->latency_buckets[WRITE]); 2422 kfree(q->td); 2423} 2424 2425void blk_throtl_register(struct gendisk *disk) 2426{ 2427 struct request_queue *q = disk->queue; 2428 struct throtl_data *td; 2429 int i; 2430 2431 td = q->td; 2432 BUG_ON(!td); 2433 2434 if (blk_queue_nonrot(q)) { 2435 td->throtl_slice = DFL_THROTL_SLICE_SSD; 2436 td->filtered_latency = LATENCY_FILTERED_SSD; 2437 } else { 2438 td->throtl_slice = DFL_THROTL_SLICE_HD; 2439 td->filtered_latency = LATENCY_FILTERED_HD; 2440 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) { 2441 td->avg_buckets[READ][i].latency = DFL_HD_BASELINE_LATENCY; 2442 td->avg_buckets[WRITE][i].latency = DFL_HD_BASELINE_LATENCY; 2443 } 2444 } 2445#ifndef CONFIG_BLK_DEV_THROTTLING_LOW 2446 /* if no low limit, use previous default */ 2447 td->throtl_slice = DFL_THROTL_SLICE_HD; 2448 2449#else 2450 td->track_bio_latency = !queue_is_mq(q); 2451 if (!td->track_bio_latency) 2452 blk_stat_enable_accounting(q); 2453#endif 2454} 2455 2456#ifdef CONFIG_BLK_DEV_THROTTLING_LOW 2457ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page) 2458{ 2459 if (!q->td) 2460 return -EINVAL; 2461 return sprintf(page, "%u\n", jiffies_to_msecs(q->td->throtl_slice)); 2462} 2463 2464ssize_t blk_throtl_sample_time_store(struct request_queue *q, 2465 const char *page, size_t count) 2466{ 2467 unsigned long v; 2468 unsigned long t; 2469 2470 if (!q->td) 2471 return -EINVAL; 2472 if (kstrtoul(page, 10, &v)) 2473 return -EINVAL; 2474 t = msecs_to_jiffies(v); 2475 if (t == 0 || t > MAX_THROTL_SLICE) 2476 return -EINVAL; 2477 q->td->throtl_slice = t; 2478 return count; 2479} 2480#endif 2481 2482static int __init throtl_init(void) 2483{ 2484 kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); 2485 if (!kthrotld_workqueue) 2486 panic("Failed to create kthrotld\n"); 2487 2488 return blkcg_policy_register(&blkcg_policy_throtl); 2489} 2490 2491module_init(throtl_init); 2492