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1/*
2 * The Kyber I/O scheduler. Controls latency by throttling queue depths using
3 * scalable techniques.
4 *
5 * Copyright (C) 2017 Facebook
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public
9 * License v2 as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <https://www.gnu.org/licenses/>.
18 */
19
20#include <linux/kernel.h>
21#include <linux/blkdev.h>
22#include <linux/blk-mq.h>
23#include <linux/elevator.h>
24#include <linux/module.h>
25#include <linux/sbitmap.h>
26
27#include "blk.h"
28#include "blk-mq.h"
29#include "blk-mq-debugfs.h"
30#include "blk-mq-sched.h"
31#include "blk-mq-tag.h"
32#include "blk-stat.h"
33
34/* Scheduling domains. */
35enum {
36 KYBER_READ,
37 KYBER_SYNC_WRITE,
38 KYBER_OTHER, /* Async writes, discard, etc. */
39 KYBER_NUM_DOMAINS,
40};
41
42enum {
43 KYBER_MIN_DEPTH = 256,
44
45 /*
46 * In order to prevent starvation of synchronous requests by a flood of
47 * asynchronous requests, we reserve 25% of requests for synchronous
48 * operations.
49 */
50 KYBER_ASYNC_PERCENT = 75,
51};
52
53/*
54 * Initial device-wide depths for each scheduling domain.
55 *
56 * Even for fast devices with lots of tags like NVMe, you can saturate
57 * the device with only a fraction of the maximum possible queue depth.
58 * So, we cap these to a reasonable value.
59 */
60static const unsigned int kyber_depth[] = {
61 [KYBER_READ] = 256,
62 [KYBER_SYNC_WRITE] = 128,
63 [KYBER_OTHER] = 64,
64};
65
66/*
67 * Scheduling domain batch sizes. We favor reads.
68 */
69static const unsigned int kyber_batch_size[] = {
70 [KYBER_READ] = 16,
71 [KYBER_SYNC_WRITE] = 8,
72 [KYBER_OTHER] = 8,
73};
74
75struct kyber_queue_data {
76 struct request_queue *q;
77
78 struct blk_stat_callback *cb;
79
80 /*
81 * The device is divided into multiple scheduling domains based on the
82 * request type. Each domain has a fixed number of in-flight requests of
83 * that type device-wide, limited by these tokens.
84 */
85 struct sbitmap_queue domain_tokens[KYBER_NUM_DOMAINS];
86
87 /*
88 * Async request percentage, converted to per-word depth for
89 * sbitmap_get_shallow().
90 */
91 unsigned int async_depth;
92
93 /* Target latencies in nanoseconds. */
94 u64 read_lat_nsec, write_lat_nsec;
95};
96
97struct kyber_hctx_data {
98 spinlock_t lock;
99 struct list_head rqs[KYBER_NUM_DOMAINS];
100 unsigned int cur_domain;
101 unsigned int batching;
102 wait_queue_entry_t domain_wait[KYBER_NUM_DOMAINS];
103 struct sbq_wait_state *domain_ws[KYBER_NUM_DOMAINS];
104 atomic_t wait_index[KYBER_NUM_DOMAINS];
105};
106
107static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
108 void *key);
109
110static int rq_sched_domain(const struct request *rq)
111{
112 unsigned int op = rq->cmd_flags;
113
114 if ((op & REQ_OP_MASK) == REQ_OP_READ)
115 return KYBER_READ;
116 else if ((op & REQ_OP_MASK) == REQ_OP_WRITE && op_is_sync(op))
117 return KYBER_SYNC_WRITE;
118 else
119 return KYBER_OTHER;
120}
121
122enum {
123 NONE = 0,
124 GOOD = 1,
125 GREAT = 2,
126 BAD = -1,
127 AWFUL = -2,
128};
129
130#define IS_GOOD(status) ((status) > 0)
131#define IS_BAD(status) ((status) < 0)
132
133static int kyber_lat_status(struct blk_stat_callback *cb,
134 unsigned int sched_domain, u64 target)
135{
136 u64 latency;
137
138 if (!cb->stat[sched_domain].nr_samples)
139 return NONE;
140
141 latency = cb->stat[sched_domain].mean;
142 if (latency >= 2 * target)
143 return AWFUL;
144 else if (latency > target)
145 return BAD;
146 else if (latency <= target / 2)
147 return GREAT;
148 else /* (latency <= target) */
149 return GOOD;
150}
151
152/*
153 * Adjust the read or synchronous write depth given the status of reads and
154 * writes. The goal is that the latencies of the two domains are fair (i.e., if
155 * one is good, then the other is good).
156 */
157static void kyber_adjust_rw_depth(struct kyber_queue_data *kqd,
158 unsigned int sched_domain, int this_status,
159 int other_status)
160{
161 unsigned int orig_depth, depth;
162
163 /*
164 * If this domain had no samples, or reads and writes are both good or
165 * both bad, don't adjust the depth.
166 */
167 if (this_status == NONE ||
168 (IS_GOOD(this_status) && IS_GOOD(other_status)) ||
169 (IS_BAD(this_status) && IS_BAD(other_status)))
170 return;
171
172 orig_depth = depth = kqd->domain_tokens[sched_domain].sb.depth;
173
174 if (other_status == NONE) {
175 depth++;
176 } else {
177 switch (this_status) {
178 case GOOD:
179 if (other_status == AWFUL)
180 depth -= max(depth / 4, 1U);
181 else
182 depth -= max(depth / 8, 1U);
183 break;
184 case GREAT:
185 if (other_status == AWFUL)
186 depth /= 2;
187 else
188 depth -= max(depth / 4, 1U);
189 break;
190 case BAD:
191 depth++;
192 break;
193 case AWFUL:
194 if (other_status == GREAT)
195 depth += 2;
196 else
197 depth++;
198 break;
199 }
200 }
201
202 depth = clamp(depth, 1U, kyber_depth[sched_domain]);
203 if (depth != orig_depth)
204 sbitmap_queue_resize(&kqd->domain_tokens[sched_domain], depth);
205}
206
207/*
208 * Adjust the depth of other requests given the status of reads and synchronous
209 * writes. As long as either domain is doing fine, we don't throttle, but if
210 * both domains are doing badly, we throttle heavily.
211 */
212static void kyber_adjust_other_depth(struct kyber_queue_data *kqd,
213 int read_status, int write_status,
214 bool have_samples)
215{
216 unsigned int orig_depth, depth;
217 int status;
218
219 orig_depth = depth = kqd->domain_tokens[KYBER_OTHER].sb.depth;
220
221 if (read_status == NONE && write_status == NONE) {
222 depth += 2;
223 } else if (have_samples) {
224 if (read_status == NONE)
225 status = write_status;
226 else if (write_status == NONE)
227 status = read_status;
228 else
229 status = max(read_status, write_status);
230 switch (status) {
231 case GREAT:
232 depth += 2;
233 break;
234 case GOOD:
235 depth++;
236 break;
237 case BAD:
238 depth -= max(depth / 4, 1U);
239 break;
240 case AWFUL:
241 depth /= 2;
242 break;
243 }
244 }
245
246 depth = clamp(depth, 1U, kyber_depth[KYBER_OTHER]);
247 if (depth != orig_depth)
248 sbitmap_queue_resize(&kqd->domain_tokens[KYBER_OTHER], depth);
249}
250
251/*
252 * Apply heuristics for limiting queue depths based on gathered latency
253 * statistics.
254 */
255static void kyber_stat_timer_fn(struct blk_stat_callback *cb)
256{
257 struct kyber_queue_data *kqd = cb->data;
258 int read_status, write_status;
259
260 read_status = kyber_lat_status(cb, KYBER_READ, kqd->read_lat_nsec);
261 write_status = kyber_lat_status(cb, KYBER_SYNC_WRITE, kqd->write_lat_nsec);
262
263 kyber_adjust_rw_depth(kqd, KYBER_READ, read_status, write_status);
264 kyber_adjust_rw_depth(kqd, KYBER_SYNC_WRITE, write_status, read_status);
265 kyber_adjust_other_depth(kqd, read_status, write_status,
266 cb->stat[KYBER_OTHER].nr_samples != 0);
267
268 /*
269 * Continue monitoring latencies if we aren't hitting the targets or
270 * we're still throttling other requests.
271 */
272 if (!blk_stat_is_active(kqd->cb) &&
273 ((IS_BAD(read_status) || IS_BAD(write_status) ||
274 kqd->domain_tokens[KYBER_OTHER].sb.depth < kyber_depth[KYBER_OTHER])))
275 blk_stat_activate_msecs(kqd->cb, 100);
276}
277
278static unsigned int kyber_sched_tags_shift(struct kyber_queue_data *kqd)
279{
280 /*
281 * All of the hardware queues have the same depth, so we can just grab
282 * the shift of the first one.
283 */
284 return kqd->q->queue_hw_ctx[0]->sched_tags->bitmap_tags.sb.shift;
285}
286
287static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q)
288{
289 struct kyber_queue_data *kqd;
290 unsigned int max_tokens;
291 unsigned int shift;
292 int ret = -ENOMEM;
293 int i;
294
295 kqd = kmalloc_node(sizeof(*kqd), GFP_KERNEL, q->node);
296 if (!kqd)
297 goto err;
298 kqd->q = q;
299
300 kqd->cb = blk_stat_alloc_callback(kyber_stat_timer_fn, rq_sched_domain,
301 KYBER_NUM_DOMAINS, kqd);
302 if (!kqd->cb)
303 goto err_kqd;
304
305 /*
306 * The maximum number of tokens for any scheduling domain is at least
307 * the queue depth of a single hardware queue. If the hardware doesn't
308 * have many tags, still provide a reasonable number.
309 */
310 max_tokens = max_t(unsigned int, q->tag_set->queue_depth,
311 KYBER_MIN_DEPTH);
312 for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
313 WARN_ON(!kyber_depth[i]);
314 WARN_ON(!kyber_batch_size[i]);
315 ret = sbitmap_queue_init_node(&kqd->domain_tokens[i],
316 max_tokens, -1, false, GFP_KERNEL,
317 q->node);
318 if (ret) {
319 while (--i >= 0)
320 sbitmap_queue_free(&kqd->domain_tokens[i]);
321 goto err_cb;
322 }
323 sbitmap_queue_resize(&kqd->domain_tokens[i], kyber_depth[i]);
324 }
325
326 shift = kyber_sched_tags_shift(kqd);
327 kqd->async_depth = (1U << shift) * KYBER_ASYNC_PERCENT / 100U;
328
329 kqd->read_lat_nsec = 2000000ULL;
330 kqd->write_lat_nsec = 10000000ULL;
331
332 return kqd;
333
334err_cb:
335 blk_stat_free_callback(kqd->cb);
336err_kqd:
337 kfree(kqd);
338err:
339 return ERR_PTR(ret);
340}
341
342static int kyber_init_sched(struct request_queue *q, struct elevator_type *e)
343{
344 struct kyber_queue_data *kqd;
345 struct elevator_queue *eq;
346
347 eq = elevator_alloc(q, e);
348 if (!eq)
349 return -ENOMEM;
350
351 kqd = kyber_queue_data_alloc(q);
352 if (IS_ERR(kqd)) {
353 kobject_put(&eq->kobj);
354 return PTR_ERR(kqd);
355 }
356
357 eq->elevator_data = kqd;
358 q->elevator = eq;
359
360 blk_stat_add_callback(q, kqd->cb);
361
362 return 0;
363}
364
365static void kyber_exit_sched(struct elevator_queue *e)
366{
367 struct kyber_queue_data *kqd = e->elevator_data;
368 struct request_queue *q = kqd->q;
369 int i;
370
371 blk_stat_remove_callback(q, kqd->cb);
372
373 for (i = 0; i < KYBER_NUM_DOMAINS; i++)
374 sbitmap_queue_free(&kqd->domain_tokens[i]);
375 blk_stat_free_callback(kqd->cb);
376 kfree(kqd);
377}
378
379static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
380{
381 struct kyber_hctx_data *khd;
382 int i;
383
384 khd = kmalloc_node(sizeof(*khd), GFP_KERNEL, hctx->numa_node);
385 if (!khd)
386 return -ENOMEM;
387
388 spin_lock_init(&khd->lock);
389
390 for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
391 INIT_LIST_HEAD(&khd->rqs[i]);
392 init_waitqueue_func_entry(&khd->domain_wait[i],
393 kyber_domain_wake);
394 khd->domain_wait[i].private = hctx;
395 INIT_LIST_HEAD(&khd->domain_wait[i].entry);
396 atomic_set(&khd->wait_index[i], 0);
397 }
398
399 khd->cur_domain = 0;
400 khd->batching = 0;
401
402 hctx->sched_data = khd;
403
404 return 0;
405}
406
407static void kyber_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
408{
409 kfree(hctx->sched_data);
410}
411
412static int rq_get_domain_token(struct request *rq)
413{
414 return (long)rq->elv.priv[0];
415}
416
417static void rq_set_domain_token(struct request *rq, int token)
418{
419 rq->elv.priv[0] = (void *)(long)token;
420}
421
422static void rq_clear_domain_token(struct kyber_queue_data *kqd,
423 struct request *rq)
424{
425 unsigned int sched_domain;
426 int nr;
427
428 nr = rq_get_domain_token(rq);
429 if (nr != -1) {
430 sched_domain = rq_sched_domain(rq);
431 sbitmap_queue_clear(&kqd->domain_tokens[sched_domain], nr,
432 rq->mq_ctx->cpu);
433 }
434}
435
436static void kyber_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
437{
438 /*
439 * We use the scheduler tags as per-hardware queue queueing tokens.
440 * Async requests can be limited at this stage.
441 */
442 if (!op_is_sync(op)) {
443 struct kyber_queue_data *kqd = data->q->elevator->elevator_data;
444
445 data->shallow_depth = kqd->async_depth;
446 }
447}
448
449static void kyber_prepare_request(struct request *rq, struct bio *bio)
450{
451 rq_set_domain_token(rq, -1);
452}
453
454static void kyber_finish_request(struct request *rq)
455{
456 struct kyber_queue_data *kqd = rq->q->elevator->elevator_data;
457
458 rq_clear_domain_token(kqd, rq);
459}
460
461static void kyber_completed_request(struct request *rq)
462{
463 struct request_queue *q = rq->q;
464 struct kyber_queue_data *kqd = q->elevator->elevator_data;
465 unsigned int sched_domain;
466 u64 now, latency, target;
467
468 /*
469 * Check if this request met our latency goal. If not, quickly gather
470 * some statistics and start throttling.
471 */
472 sched_domain = rq_sched_domain(rq);
473 switch (sched_domain) {
474 case KYBER_READ:
475 target = kqd->read_lat_nsec;
476 break;
477 case KYBER_SYNC_WRITE:
478 target = kqd->write_lat_nsec;
479 break;
480 default:
481 return;
482 }
483
484 /* If we are already monitoring latencies, don't check again. */
485 if (blk_stat_is_active(kqd->cb))
486 return;
487
488 now = __blk_stat_time(ktime_to_ns(ktime_get()));
489 if (now < blk_stat_time(&rq->issue_stat))
490 return;
491
492 latency = now - blk_stat_time(&rq->issue_stat);
493
494 if (latency > target)
495 blk_stat_activate_msecs(kqd->cb, 10);
496}
497
498static void kyber_flush_busy_ctxs(struct kyber_hctx_data *khd,
499 struct blk_mq_hw_ctx *hctx)
500{
501 LIST_HEAD(rq_list);
502 struct request *rq, *next;
503
504 blk_mq_flush_busy_ctxs(hctx, &rq_list);
505 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
506 unsigned int sched_domain;
507
508 sched_domain = rq_sched_domain(rq);
509 list_move_tail(&rq->queuelist, &khd->rqs[sched_domain]);
510 }
511}
512
513static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
514 void *key)
515{
516 struct blk_mq_hw_ctx *hctx = READ_ONCE(wait->private);
517
518 list_del_init(&wait->entry);
519 blk_mq_run_hw_queue(hctx, true);
520 return 1;
521}
522
523static int kyber_get_domain_token(struct kyber_queue_data *kqd,
524 struct kyber_hctx_data *khd,
525 struct blk_mq_hw_ctx *hctx)
526{
527 unsigned int sched_domain = khd->cur_domain;
528 struct sbitmap_queue *domain_tokens = &kqd->domain_tokens[sched_domain];
529 wait_queue_entry_t *wait = &khd->domain_wait[sched_domain];
530 struct sbq_wait_state *ws;
531 int nr;
532
533 nr = __sbitmap_queue_get(domain_tokens);
534
535 /*
536 * If we failed to get a domain token, make sure the hardware queue is
537 * run when one becomes available. Note that this is serialized on
538 * khd->lock, but we still need to be careful about the waker.
539 */
540 if (nr < 0 && list_empty_careful(&wait->entry)) {
541 ws = sbq_wait_ptr(domain_tokens,
542 &khd->wait_index[sched_domain]);
543 khd->domain_ws[sched_domain] = ws;
544 add_wait_queue(&ws->wait, wait);
545
546 /*
547 * Try again in case a token was freed before we got on the wait
548 * queue.
549 */
550 nr = __sbitmap_queue_get(domain_tokens);
551 }
552
553 /*
554 * If we got a token while we were on the wait queue, remove ourselves
555 * from the wait queue to ensure that all wake ups make forward
556 * progress. It's possible that the waker already deleted the entry
557 * between the !list_empty_careful() check and us grabbing the lock, but
558 * list_del_init() is okay with that.
559 */
560 if (nr >= 0 && !list_empty_careful(&wait->entry)) {
561 ws = khd->domain_ws[sched_domain];
562 spin_lock_irq(&ws->wait.lock);
563 list_del_init(&wait->entry);
564 spin_unlock_irq(&ws->wait.lock);
565 }
566
567 return nr;
568}
569
570static struct request *
571kyber_dispatch_cur_domain(struct kyber_queue_data *kqd,
572 struct kyber_hctx_data *khd,
573 struct blk_mq_hw_ctx *hctx,
574 bool *flushed)
575{
576 struct list_head *rqs;
577 struct request *rq;
578 int nr;
579
580 rqs = &khd->rqs[khd->cur_domain];
581 rq = list_first_entry_or_null(rqs, struct request, queuelist);
582
583 /*
584 * If there wasn't already a pending request and we haven't flushed the
585 * software queues yet, flush the software queues and check again.
586 */
587 if (!rq && !*flushed) {
588 kyber_flush_busy_ctxs(khd, hctx);
589 *flushed = true;
590 rq = list_first_entry_or_null(rqs, struct request, queuelist);
591 }
592
593 if (rq) {
594 nr = kyber_get_domain_token(kqd, khd, hctx);
595 if (nr >= 0) {
596 khd->batching++;
597 rq_set_domain_token(rq, nr);
598 list_del_init(&rq->queuelist);
599 return rq;
600 }
601 }
602
603 /* There were either no pending requests or no tokens. */
604 return NULL;
605}
606
607static struct request *kyber_dispatch_request(struct blk_mq_hw_ctx *hctx)
608{
609 struct kyber_queue_data *kqd = hctx->queue->elevator->elevator_data;
610 struct kyber_hctx_data *khd = hctx->sched_data;
611 bool flushed = false;
612 struct request *rq;
613 int i;
614
615 spin_lock(&khd->lock);
616
617 /*
618 * First, if we are still entitled to batch, try to dispatch a request
619 * from the batch.
620 */
621 if (khd->batching < kyber_batch_size[khd->cur_domain]) {
622 rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
623 if (rq)
624 goto out;
625 }
626
627 /*
628 * Either,
629 * 1. We were no longer entitled to a batch.
630 * 2. The domain we were batching didn't have any requests.
631 * 3. The domain we were batching was out of tokens.
632 *
633 * Start another batch. Note that this wraps back around to the original
634 * domain if no other domains have requests or tokens.
635 */
636 khd->batching = 0;
637 for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
638 if (khd->cur_domain == KYBER_NUM_DOMAINS - 1)
639 khd->cur_domain = 0;
640 else
641 khd->cur_domain++;
642
643 rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
644 if (rq)
645 goto out;
646 }
647
648 rq = NULL;
649out:
650 spin_unlock(&khd->lock);
651 return rq;
652}
653
654static bool kyber_has_work(struct blk_mq_hw_ctx *hctx)
655{
656 struct kyber_hctx_data *khd = hctx->sched_data;
657 int i;
658
659 for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
660 if (!list_empty_careful(&khd->rqs[i]))
661 return true;
662 }
663 return sbitmap_any_bit_set(&hctx->ctx_map);
664}
665
666#define KYBER_LAT_SHOW_STORE(op) \
667static ssize_t kyber_##op##_lat_show(struct elevator_queue *e, \
668 char *page) \
669{ \
670 struct kyber_queue_data *kqd = e->elevator_data; \
671 \
672 return sprintf(page, "%llu\n", kqd->op##_lat_nsec); \
673} \
674 \
675static ssize_t kyber_##op##_lat_store(struct elevator_queue *e, \
676 const char *page, size_t count) \
677{ \
678 struct kyber_queue_data *kqd = e->elevator_data; \
679 unsigned long long nsec; \
680 int ret; \
681 \
682 ret = kstrtoull(page, 10, &nsec); \
683 if (ret) \
684 return ret; \
685 \
686 kqd->op##_lat_nsec = nsec; \
687 \
688 return count; \
689}
690KYBER_LAT_SHOW_STORE(read);
691KYBER_LAT_SHOW_STORE(write);
692#undef KYBER_LAT_SHOW_STORE
693
694#define KYBER_LAT_ATTR(op) __ATTR(op##_lat_nsec, 0644, kyber_##op##_lat_show, kyber_##op##_lat_store)
695static struct elv_fs_entry kyber_sched_attrs[] = {
696 KYBER_LAT_ATTR(read),
697 KYBER_LAT_ATTR(write),
698 __ATTR_NULL
699};
700#undef KYBER_LAT_ATTR
701
702#ifdef CONFIG_BLK_DEBUG_FS
703#define KYBER_DEBUGFS_DOMAIN_ATTRS(domain, name) \
704static int kyber_##name##_tokens_show(void *data, struct seq_file *m) \
705{ \
706 struct request_queue *q = data; \
707 struct kyber_queue_data *kqd = q->elevator->elevator_data; \
708 \
709 sbitmap_queue_show(&kqd->domain_tokens[domain], m); \
710 return 0; \
711} \
712 \
713static void *kyber_##name##_rqs_start(struct seq_file *m, loff_t *pos) \
714 __acquires(&khd->lock) \
715{ \
716 struct blk_mq_hw_ctx *hctx = m->private; \
717 struct kyber_hctx_data *khd = hctx->sched_data; \
718 \
719 spin_lock(&khd->lock); \
720 return seq_list_start(&khd->rqs[domain], *pos); \
721} \
722 \
723static void *kyber_##name##_rqs_next(struct seq_file *m, void *v, \
724 loff_t *pos) \
725{ \
726 struct blk_mq_hw_ctx *hctx = m->private; \
727 struct kyber_hctx_data *khd = hctx->sched_data; \
728 \
729 return seq_list_next(v, &khd->rqs[domain], pos); \
730} \
731 \
732static void kyber_##name##_rqs_stop(struct seq_file *m, void *v) \
733 __releases(&khd->lock) \
734{ \
735 struct blk_mq_hw_ctx *hctx = m->private; \
736 struct kyber_hctx_data *khd = hctx->sched_data; \
737 \
738 spin_unlock(&khd->lock); \
739} \
740 \
741static const struct seq_operations kyber_##name##_rqs_seq_ops = { \
742 .start = kyber_##name##_rqs_start, \
743 .next = kyber_##name##_rqs_next, \
744 .stop = kyber_##name##_rqs_stop, \
745 .show = blk_mq_debugfs_rq_show, \
746}; \
747 \
748static int kyber_##name##_waiting_show(void *data, struct seq_file *m) \
749{ \
750 struct blk_mq_hw_ctx *hctx = data; \
751 struct kyber_hctx_data *khd = hctx->sched_data; \
752 wait_queue_entry_t *wait = &khd->domain_wait[domain]; \
753 \
754 seq_printf(m, "%d\n", !list_empty_careful(&wait->entry)); \
755 return 0; \
756}
757KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_READ, read)
758KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_SYNC_WRITE, sync_write)
759KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_OTHER, other)
760#undef KYBER_DEBUGFS_DOMAIN_ATTRS
761
762static int kyber_async_depth_show(void *data, struct seq_file *m)
763{
764 struct request_queue *q = data;
765 struct kyber_queue_data *kqd = q->elevator->elevator_data;
766
767 seq_printf(m, "%u\n", kqd->async_depth);
768 return 0;
769}
770
771static int kyber_cur_domain_show(void *data, struct seq_file *m)
772{
773 struct blk_mq_hw_ctx *hctx = data;
774 struct kyber_hctx_data *khd = hctx->sched_data;
775
776 switch (khd->cur_domain) {
777 case KYBER_READ:
778 seq_puts(m, "READ\n");
779 break;
780 case KYBER_SYNC_WRITE:
781 seq_puts(m, "SYNC_WRITE\n");
782 break;
783 case KYBER_OTHER:
784 seq_puts(m, "OTHER\n");
785 break;
786 default:
787 seq_printf(m, "%u\n", khd->cur_domain);
788 break;
789 }
790 return 0;
791}
792
793static int kyber_batching_show(void *data, struct seq_file *m)
794{
795 struct blk_mq_hw_ctx *hctx = data;
796 struct kyber_hctx_data *khd = hctx->sched_data;
797
798 seq_printf(m, "%u\n", khd->batching);
799 return 0;
800}
801
802#define KYBER_QUEUE_DOMAIN_ATTRS(name) \
803 {#name "_tokens", 0400, kyber_##name##_tokens_show}
804static const struct blk_mq_debugfs_attr kyber_queue_debugfs_attrs[] = {
805 KYBER_QUEUE_DOMAIN_ATTRS(read),
806 KYBER_QUEUE_DOMAIN_ATTRS(sync_write),
807 KYBER_QUEUE_DOMAIN_ATTRS(other),
808 {"async_depth", 0400, kyber_async_depth_show},
809 {},
810};
811#undef KYBER_QUEUE_DOMAIN_ATTRS
812
813#define KYBER_HCTX_DOMAIN_ATTRS(name) \
814 {#name "_rqs", 0400, .seq_ops = &kyber_##name##_rqs_seq_ops}, \
815 {#name "_waiting", 0400, kyber_##name##_waiting_show}
816static const struct blk_mq_debugfs_attr kyber_hctx_debugfs_attrs[] = {
817 KYBER_HCTX_DOMAIN_ATTRS(read),
818 KYBER_HCTX_DOMAIN_ATTRS(sync_write),
819 KYBER_HCTX_DOMAIN_ATTRS(other),
820 {"cur_domain", 0400, kyber_cur_domain_show},
821 {"batching", 0400, kyber_batching_show},
822 {},
823};
824#undef KYBER_HCTX_DOMAIN_ATTRS
825#endif
826
827static struct elevator_type kyber_sched = {
828 .ops.mq = {
829 .init_sched = kyber_init_sched,
830 .exit_sched = kyber_exit_sched,
831 .init_hctx = kyber_init_hctx,
832 .exit_hctx = kyber_exit_hctx,
833 .limit_depth = kyber_limit_depth,
834 .prepare_request = kyber_prepare_request,
835 .finish_request = kyber_finish_request,
836 .requeue_request = kyber_finish_request,
837 .completed_request = kyber_completed_request,
838 .dispatch_request = kyber_dispatch_request,
839 .has_work = kyber_has_work,
840 },
841 .uses_mq = true,
842#ifdef CONFIG_BLK_DEBUG_FS
843 .queue_debugfs_attrs = kyber_queue_debugfs_attrs,
844 .hctx_debugfs_attrs = kyber_hctx_debugfs_attrs,
845#endif
846 .elevator_attrs = kyber_sched_attrs,
847 .elevator_name = "kyber",
848 .elevator_owner = THIS_MODULE,
849};
850
851static int __init kyber_init(void)
852{
853 return elv_register(&kyber_sched);
854}
855
856static void __exit kyber_exit(void)
857{
858 elv_unregister(&kyber_sched);
859}
860
861module_init(kyber_init);
862module_exit(kyber_exit);
863
864MODULE_AUTHOR("Omar Sandoval");
865MODULE_LICENSE("GPL");
866MODULE_DESCRIPTION("Kyber I/O scheduler");