1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
4 * for the blk-mq scheduling framework
5 *
6 * Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
7 */
8 #include <linux/kernel.h>
9 #include <linux/fs.h>
10 #include <linux/blkdev.h>
11 #include <linux/blk-mq.h>
12 #include <linux/elevator.h>
13 #include <linux/bio.h>
14 #include <linux/module.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/compiler.h>
18 #include <linux/rbtree.h>
19 #include <linux/sbitmap.h>
20
21 #include <trace/events/block.h>
22
23 #include "blk.h"
24 #include "blk-mq.h"
25 #include "blk-mq-debugfs.h"
26 #include "blk-mq-tag.h"
27 #include "blk-mq-sched.h"
28
29 /*
30 * See Documentation/block/deadline-iosched.rst
31 */
32 static const int read_expire = HZ / 2; /* max time before a read is submitted. */
33 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
34 static const int writes_starved = 2; /* max times reads can starve a write */
35 static const int fifo_batch = 16; /* # of sequential requests treated as one
36 by the above parameters. For throughput. */
37
38 enum dd_data_dir {
39 DD_READ = READ,
40 DD_WRITE = WRITE,
41 };
42
43 enum { DD_DIR_COUNT = 2 };
44
45 enum dd_prio {
46 DD_RT_PRIO = 0,
47 DD_BE_PRIO = 1,
48 DD_IDLE_PRIO = 2,
49 DD_PRIO_MAX = 2,
50 };
51
52 enum { DD_PRIO_COUNT = 3 };
53
54 /* I/O statistics per I/O priority. */
55 struct io_stats_per_prio {
56 local_t inserted;
57 local_t merged;
58 local_t dispatched;
59 local_t completed;
60 };
61
62 /* I/O statistics for all I/O priorities (enum dd_prio). */
63 struct io_stats {
64 struct io_stats_per_prio stats[DD_PRIO_COUNT];
65 };
66
67 /*
68 * Deadline scheduler data per I/O priority (enum dd_prio). Requests are
69 * present on both sort_list[] and fifo_list[].
70 */
71 struct dd_per_prio {
72 struct list_head dispatch;
73 struct rb_root sort_list[DD_DIR_COUNT];
74 struct list_head fifo_list[DD_DIR_COUNT];
75 /* Next request in FIFO order. Read, write or both are NULL. */
76 struct request *next_rq[DD_DIR_COUNT];
77 };
78
79 struct deadline_data {
80 /*
81 * run time data
82 */
83
84 struct dd_per_prio per_prio[DD_PRIO_COUNT];
85
86 /* Data direction of latest dispatched request. */
87 enum dd_data_dir last_dir;
88 unsigned int batching; /* number of sequential requests made */
89 unsigned int starved; /* times reads have starved writes */
90
91 struct io_stats __percpu *stats;
92
93 /*
94 * settings that change how the i/o scheduler behaves
95 */
96 int fifo_expire[DD_DIR_COUNT];
97 int fifo_batch;
98 int writes_starved;
99 int front_merges;
100 u32 async_depth;
101
102 spinlock_t lock;
103 spinlock_t zone_lock;
104 };
105
106 /* Count one event of type 'event_type' and with I/O priority 'prio' */
107 #define dd_count(dd, event_type, prio) do { \
108 struct io_stats *io_stats = get_cpu_ptr((dd)->stats); \
109 \
110 BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
111 BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
112 local_inc(&io_stats->stats[(prio)].event_type); \
113 put_cpu_ptr(io_stats); \
114 } while (0)
115
116 /*
117 * Returns the total number of dd_count(dd, event_type, prio) calls across all
118 * CPUs. No locking or barriers since it is fine if the returned sum is slightly
119 * outdated.
120 */
121 #define dd_sum(dd, event_type, prio) ({ \
122 unsigned int cpu; \
123 u32 sum = 0; \
124 \
125 BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
126 BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
127 for_each_present_cpu(cpu) \
128 sum += local_read(&per_cpu_ptr((dd)->stats, cpu)-> \
129 stats[(prio)].event_type); \
130 sum; \
131 })
132
133 /* Maps an I/O priority class to a deadline scheduler priority. */
134 static const enum dd_prio ioprio_class_to_prio[] = {
135 [IOPRIO_CLASS_NONE] = DD_BE_PRIO,
136 [IOPRIO_CLASS_RT] = DD_RT_PRIO,
137 [IOPRIO_CLASS_BE] = DD_BE_PRIO,
138 [IOPRIO_CLASS_IDLE] = DD_IDLE_PRIO,
139 };
140
141 static inline struct rb_root *
deadline_rb_root(struct dd_per_prio * per_prio,struct request * rq)142 deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq)
143 {
144 return &per_prio->sort_list[rq_data_dir(rq)];
145 }
146
147 /*
148 * Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a
149 * request.
150 */
dd_rq_ioclass(struct request * rq)151 static u8 dd_rq_ioclass(struct request *rq)
152 {
153 return IOPRIO_PRIO_CLASS(req_get_ioprio(rq));
154 }
155
156 /*
157 * get the request after `rq' in sector-sorted order
158 */
159 static inline struct request *
deadline_latter_request(struct request * rq)160 deadline_latter_request(struct request *rq)
161 {
162 struct rb_node *node = rb_next(&rq->rb_node);
163
164 if (node)
165 return rb_entry_rq(node);
166
167 return NULL;
168 }
169
170 static void
deadline_add_rq_rb(struct dd_per_prio * per_prio,struct request * rq)171 deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
172 {
173 struct rb_root *root = deadline_rb_root(per_prio, rq);
174
175 elv_rb_add(root, rq);
176 }
177
178 static inline void
deadline_del_rq_rb(struct dd_per_prio * per_prio,struct request * rq)179 deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
180 {
181 const enum dd_data_dir data_dir = rq_data_dir(rq);
182
183 if (per_prio->next_rq[data_dir] == rq)
184 per_prio->next_rq[data_dir] = deadline_latter_request(rq);
185
186 elv_rb_del(deadline_rb_root(per_prio, rq), rq);
187 }
188
189 /*
190 * remove rq from rbtree and fifo.
191 */
deadline_remove_request(struct request_queue * q,struct dd_per_prio * per_prio,struct request * rq)192 static void deadline_remove_request(struct request_queue *q,
193 struct dd_per_prio *per_prio,
194 struct request *rq)
195 {
196 list_del_init(&rq->queuelist);
197
198 /*
199 * We might not be on the rbtree, if we are doing an insert merge
200 */
201 if (!RB_EMPTY_NODE(&rq->rb_node))
202 deadline_del_rq_rb(per_prio, rq);
203
204 elv_rqhash_del(q, rq);
205 if (q->last_merge == rq)
206 q->last_merge = NULL;
207 }
208
dd_request_merged(struct request_queue * q,struct request * req,enum elv_merge type)209 static void dd_request_merged(struct request_queue *q, struct request *req,
210 enum elv_merge type)
211 {
212 struct deadline_data *dd = q->elevator->elevator_data;
213 const u8 ioprio_class = dd_rq_ioclass(req);
214 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
215 struct dd_per_prio *per_prio = &dd->per_prio[prio];
216
217 /*
218 * if the merge was a front merge, we need to reposition request
219 */
220 if (type == ELEVATOR_FRONT_MERGE) {
221 elv_rb_del(deadline_rb_root(per_prio, req), req);
222 deadline_add_rq_rb(per_prio, req);
223 }
224 }
225
226 /*
227 * Callback function that is invoked after @next has been merged into @req.
228 */
dd_merged_requests(struct request_queue * q,struct request * req,struct request * next)229 static void dd_merged_requests(struct request_queue *q, struct request *req,
230 struct request *next)
231 {
232 struct deadline_data *dd = q->elevator->elevator_data;
233 const u8 ioprio_class = dd_rq_ioclass(next);
234 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
235
236 dd_count(dd, merged, prio);
237
238 /*
239 * if next expires before rq, assign its expire time to rq
240 * and move into next position (next will be deleted) in fifo
241 */
242 if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
243 if (time_before((unsigned long)next->fifo_time,
244 (unsigned long)req->fifo_time)) {
245 list_move(&req->queuelist, &next->queuelist);
246 req->fifo_time = next->fifo_time;
247 }
248 }
249
250 /*
251 * kill knowledge of next, this one is a goner
252 */
253 deadline_remove_request(q, &dd->per_prio[prio], next);
254 }
255
256 /*
257 * move an entry to dispatch queue
258 */
259 static void
deadline_move_request(struct deadline_data * dd,struct dd_per_prio * per_prio,struct request * rq)260 deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
261 struct request *rq)
262 {
263 const enum dd_data_dir data_dir = rq_data_dir(rq);
264
265 per_prio->next_rq[data_dir] = deadline_latter_request(rq);
266
267 /*
268 * take it off the sort and fifo list
269 */
270 deadline_remove_request(rq->q, per_prio, rq);
271 }
272
273 /*
274 * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
275 * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
276 */
deadline_check_fifo(struct dd_per_prio * per_prio,enum dd_data_dir data_dir)277 static inline int deadline_check_fifo(struct dd_per_prio *per_prio,
278 enum dd_data_dir data_dir)
279 {
280 struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
281
282 /*
283 * rq is expired!
284 */
285 if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
286 return 1;
287
288 return 0;
289 }
290
291 /*
292 * For the specified data direction, return the next request to
293 * dispatch using arrival ordered lists.
294 */
295 static struct request *
deadline_fifo_request(struct deadline_data * dd,struct dd_per_prio * per_prio,enum dd_data_dir data_dir)296 deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
297 enum dd_data_dir data_dir)
298 {
299 struct request *rq;
300 unsigned long flags;
301
302 if (list_empty(&per_prio->fifo_list[data_dir]))
303 return NULL;
304
305 rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
306 if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
307 return rq;
308
309 /*
310 * Look for a write request that can be dispatched, that is one with
311 * an unlocked target zone.
312 */
313 spin_lock_irqsave(&dd->zone_lock, flags);
314 list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) {
315 if (blk_req_can_dispatch_to_zone(rq))
316 goto out;
317 }
318 rq = NULL;
319 out:
320 spin_unlock_irqrestore(&dd->zone_lock, flags);
321
322 return rq;
323 }
324
325 /*
326 * For the specified data direction, return the next request to
327 * dispatch using sector position sorted lists.
328 */
329 static struct request *
deadline_next_request(struct deadline_data * dd,struct dd_per_prio * per_prio,enum dd_data_dir data_dir)330 deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
331 enum dd_data_dir data_dir)
332 {
333 struct request *rq;
334 unsigned long flags;
335
336 rq = per_prio->next_rq[data_dir];
337 if (!rq)
338 return NULL;
339
340 if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
341 return rq;
342
343 /*
344 * Look for a write request that can be dispatched, that is one with
345 * an unlocked target zone.
346 */
347 spin_lock_irqsave(&dd->zone_lock, flags);
348 while (rq) {
349 if (blk_req_can_dispatch_to_zone(rq))
350 break;
351 rq = deadline_latter_request(rq);
352 }
353 spin_unlock_irqrestore(&dd->zone_lock, flags);
354
355 return rq;
356 }
357
358 /*
359 * deadline_dispatch_requests selects the best request according to
360 * read/write expire, fifo_batch, etc
361 */
__dd_dispatch_request(struct deadline_data * dd,struct dd_per_prio * per_prio)362 static struct request *__dd_dispatch_request(struct deadline_data *dd,
363 struct dd_per_prio *per_prio)
364 {
365 struct request *rq, *next_rq;
366 enum dd_data_dir data_dir;
367 enum dd_prio prio;
368 u8 ioprio_class;
369
370 lockdep_assert_held(&dd->lock);
371
372 if (!list_empty(&per_prio->dispatch)) {
373 rq = list_first_entry(&per_prio->dispatch, struct request,
374 queuelist);
375 list_del_init(&rq->queuelist);
376 goto done;
377 }
378
379 /*
380 * batches are currently reads XOR writes
381 */
382 rq = deadline_next_request(dd, per_prio, dd->last_dir);
383 if (rq && dd->batching < dd->fifo_batch)
384 /* we have a next request are still entitled to batch */
385 goto dispatch_request;
386
387 /*
388 * at this point we are not running a batch. select the appropriate
389 * data direction (read / write)
390 */
391
392 if (!list_empty(&per_prio->fifo_list[DD_READ])) {
393 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ]));
394
395 if (deadline_fifo_request(dd, per_prio, DD_WRITE) &&
396 (dd->starved++ >= dd->writes_starved))
397 goto dispatch_writes;
398
399 data_dir = DD_READ;
400
401 goto dispatch_find_request;
402 }
403
404 /*
405 * there are either no reads or writes have been starved
406 */
407
408 if (!list_empty(&per_prio->fifo_list[DD_WRITE])) {
409 dispatch_writes:
410 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE]));
411
412 dd->starved = 0;
413
414 data_dir = DD_WRITE;
415
416 goto dispatch_find_request;
417 }
418
419 return NULL;
420
421 dispatch_find_request:
422 /*
423 * we are not running a batch, find best request for selected data_dir
424 */
425 next_rq = deadline_next_request(dd, per_prio, data_dir);
426 if (deadline_check_fifo(per_prio, data_dir) || !next_rq) {
427 /*
428 * A deadline has expired, the last request was in the other
429 * direction, or we have run out of higher-sectored requests.
430 * Start again from the request with the earliest expiry time.
431 */
432 rq = deadline_fifo_request(dd, per_prio, data_dir);
433 } else {
434 /*
435 * The last req was the same dir and we have a next request in
436 * sort order. No expired requests so continue on from here.
437 */
438 rq = next_rq;
439 }
440
441 /*
442 * For a zoned block device, if we only have writes queued and none of
443 * them can be dispatched, rq will be NULL.
444 */
445 if (!rq)
446 return NULL;
447
448 dd->last_dir = data_dir;
449 dd->batching = 0;
450
451 dispatch_request:
452 /*
453 * rq is the selected appropriate request.
454 */
455 dd->batching++;
456 deadline_move_request(dd, per_prio, rq);
457 done:
458 ioprio_class = dd_rq_ioclass(rq);
459 prio = ioprio_class_to_prio[ioprio_class];
460 dd_count(dd, dispatched, prio);
461 /*
462 * If the request needs its target zone locked, do it.
463 */
464 blk_req_zone_write_lock(rq);
465 rq->rq_flags |= RQF_STARTED;
466 return rq;
467 }
468
469 /*
470 * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
471 *
472 * One confusing aspect here is that we get called for a specific
473 * hardware queue, but we may return a request that is for a
474 * different hardware queue. This is because mq-deadline has shared
475 * state for all hardware queues, in terms of sorting, FIFOs, etc.
476 */
dd_dispatch_request(struct blk_mq_hw_ctx * hctx)477 static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
478 {
479 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
480 struct request *rq;
481 enum dd_prio prio;
482
483 spin_lock(&dd->lock);
484 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
485 rq = __dd_dispatch_request(dd, &dd->per_prio[prio]);
486 if (rq)
487 break;
488 }
489 spin_unlock(&dd->lock);
490
491 return rq;
492 }
493
494 /*
495 * Called by __blk_mq_alloc_request(). The shallow_depth value set by this
496 * function is used by __blk_mq_get_tag().
497 */
dd_limit_depth(unsigned int op,struct blk_mq_alloc_data * data)498 static void dd_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
499 {
500 struct deadline_data *dd = data->q->elevator->elevator_data;
501
502 /* Do not throttle synchronous reads. */
503 if (op_is_sync(op) && !op_is_write(op))
504 return;
505
506 /*
507 * Throttle asynchronous requests and writes such that these requests
508 * do not block the allocation of synchronous requests.
509 */
510 data->shallow_depth = dd->async_depth;
511 }
512
513 /* Called by blk_mq_update_nr_requests(). */
dd_depth_updated(struct blk_mq_hw_ctx * hctx)514 static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
515 {
516 struct request_queue *q = hctx->queue;
517 struct deadline_data *dd = q->elevator->elevator_data;
518 struct blk_mq_tags *tags = hctx->sched_tags;
519
520 dd->async_depth = max(1UL, 3 * q->nr_requests / 4);
521
522 sbitmap_queue_min_shallow_depth(tags->bitmap_tags, dd->async_depth);
523 }
524
525 /* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */
dd_init_hctx(struct blk_mq_hw_ctx * hctx,unsigned int hctx_idx)526 static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
527 {
528 dd_depth_updated(hctx);
529 return 0;
530 }
531
dd_exit_sched(struct elevator_queue * e)532 static void dd_exit_sched(struct elevator_queue *e)
533 {
534 struct deadline_data *dd = e->elevator_data;
535 enum dd_prio prio;
536
537 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
538 struct dd_per_prio *per_prio = &dd->per_prio[prio];
539
540 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
541 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
542 }
543
544 free_percpu(dd->stats);
545
546 kfree(dd);
547 }
548
549 /*
550 * initialize elevator private data (deadline_data).
551 */
dd_init_sched(struct request_queue * q,struct elevator_type * e)552 static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
553 {
554 struct deadline_data *dd;
555 struct elevator_queue *eq;
556 enum dd_prio prio;
557 int ret = -ENOMEM;
558
559 eq = elevator_alloc(q, e);
560 if (!eq)
561 return ret;
562
563 dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
564 if (!dd)
565 goto put_eq;
566
567 eq->elevator_data = dd;
568
569 dd->stats = alloc_percpu_gfp(typeof(*dd->stats),
570 GFP_KERNEL | __GFP_ZERO);
571 if (!dd->stats)
572 goto free_dd;
573
574 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
575 struct dd_per_prio *per_prio = &dd->per_prio[prio];
576
577 INIT_LIST_HEAD(&per_prio->dispatch);
578 INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]);
579 INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]);
580 per_prio->sort_list[DD_READ] = RB_ROOT;
581 per_prio->sort_list[DD_WRITE] = RB_ROOT;
582 }
583 dd->fifo_expire[DD_READ] = read_expire;
584 dd->fifo_expire[DD_WRITE] = write_expire;
585 dd->writes_starved = writes_starved;
586 dd->front_merges = 1;
587 dd->last_dir = DD_WRITE;
588 dd->fifo_batch = fifo_batch;
589 spin_lock_init(&dd->lock);
590 spin_lock_init(&dd->zone_lock);
591
592 q->elevator = eq;
593 return 0;
594
595 free_dd:
596 kfree(dd);
597
598 put_eq:
599 kobject_put(&eq->kobj);
600 return ret;
601 }
602
603 /*
604 * Try to merge @bio into an existing request. If @bio has been merged into
605 * an existing request, store the pointer to that request into *@rq.
606 */
dd_request_merge(struct request_queue * q,struct request ** rq,struct bio * bio)607 static int dd_request_merge(struct request_queue *q, struct request **rq,
608 struct bio *bio)
609 {
610 struct deadline_data *dd = q->elevator->elevator_data;
611 const u8 ioprio_class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
612 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
613 struct dd_per_prio *per_prio = &dd->per_prio[prio];
614 sector_t sector = bio_end_sector(bio);
615 struct request *__rq;
616
617 if (!dd->front_merges)
618 return ELEVATOR_NO_MERGE;
619
620 __rq = elv_rb_find(&per_prio->sort_list[bio_data_dir(bio)], sector);
621 if (__rq) {
622 BUG_ON(sector != blk_rq_pos(__rq));
623
624 if (elv_bio_merge_ok(__rq, bio)) {
625 *rq = __rq;
626 if (blk_discard_mergable(__rq))
627 return ELEVATOR_DISCARD_MERGE;
628 return ELEVATOR_FRONT_MERGE;
629 }
630 }
631
632 return ELEVATOR_NO_MERGE;
633 }
634
635 /*
636 * Attempt to merge a bio into an existing request. This function is called
637 * before @bio is associated with a request.
638 */
dd_bio_merge(struct request_queue * q,struct bio * bio,unsigned int nr_segs)639 static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
640 unsigned int nr_segs)
641 {
642 struct deadline_data *dd = q->elevator->elevator_data;
643 struct request *free = NULL;
644 bool ret;
645
646 spin_lock(&dd->lock);
647 ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
648 spin_unlock(&dd->lock);
649
650 if (free)
651 blk_mq_free_request(free);
652
653 return ret;
654 }
655
656 /*
657 * add rq to rbtree and fifo
658 */
dd_insert_request(struct blk_mq_hw_ctx * hctx,struct request * rq,bool at_head)659 static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
660 bool at_head)
661 {
662 struct request_queue *q = hctx->queue;
663 struct deadline_data *dd = q->elevator->elevator_data;
664 const enum dd_data_dir data_dir = rq_data_dir(rq);
665 u16 ioprio = req_get_ioprio(rq);
666 u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
667 struct dd_per_prio *per_prio;
668 enum dd_prio prio;
669 LIST_HEAD(free);
670
671 lockdep_assert_held(&dd->lock);
672
673 /*
674 * This may be a requeue of a write request that has locked its
675 * target zone. If it is the case, this releases the zone lock.
676 */
677 blk_req_zone_write_unlock(rq);
678
679 prio = ioprio_class_to_prio[ioprio_class];
680 dd_count(dd, inserted, prio);
681 rq->elv.priv[0] = (void *)(uintptr_t)1;
682
683 if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
684 blk_mq_free_requests(&free);
685 return;
686 }
687
688 trace_block_rq_insert(rq);
689
690 per_prio = &dd->per_prio[prio];
691 if (at_head) {
692 list_add(&rq->queuelist, &per_prio->dispatch);
693 } else {
694 deadline_add_rq_rb(per_prio, rq);
695
696 if (rq_mergeable(rq)) {
697 elv_rqhash_add(q, rq);
698 if (!q->last_merge)
699 q->last_merge = rq;
700 }
701
702 /*
703 * set expire time and add to fifo list
704 */
705 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
706 list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);
707 }
708 }
709
710 /*
711 * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests().
712 */
dd_insert_requests(struct blk_mq_hw_ctx * hctx,struct list_head * list,bool at_head)713 static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
714 struct list_head *list, bool at_head)
715 {
716 struct request_queue *q = hctx->queue;
717 struct deadline_data *dd = q->elevator->elevator_data;
718
719 spin_lock(&dd->lock);
720 while (!list_empty(list)) {
721 struct request *rq;
722
723 rq = list_first_entry(list, struct request, queuelist);
724 list_del_init(&rq->queuelist);
725 dd_insert_request(hctx, rq, at_head);
726 }
727 spin_unlock(&dd->lock);
728 }
729
730 /* Callback from inside blk_mq_rq_ctx_init(). */
dd_prepare_request(struct request * rq)731 static void dd_prepare_request(struct request *rq)
732 {
733 rq->elv.priv[0] = NULL;
734 }
735
736 /*
737 * Callback from inside blk_mq_free_request().
738 *
739 * For zoned block devices, write unlock the target zone of
740 * completed write requests. Do this while holding the zone lock
741 * spinlock so that the zone is never unlocked while deadline_fifo_request()
742 * or deadline_next_request() are executing. This function is called for
743 * all requests, whether or not these requests complete successfully.
744 *
745 * For a zoned block device, __dd_dispatch_request() may have stopped
746 * dispatching requests if all the queued requests are write requests directed
747 * at zones that are already locked due to on-going write requests. To ensure
748 * write request dispatch progress in this case, mark the queue as needing a
749 * restart to ensure that the queue is run again after completion of the
750 * request and zones being unlocked.
751 */
dd_finish_request(struct request * rq)752 static void dd_finish_request(struct request *rq)
753 {
754 struct request_queue *q = rq->q;
755 struct deadline_data *dd = q->elevator->elevator_data;
756 const u8 ioprio_class = dd_rq_ioclass(rq);
757 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
758 struct dd_per_prio *per_prio = &dd->per_prio[prio];
759
760 /*
761 * The block layer core may call dd_finish_request() without having
762 * called dd_insert_requests(). Hence only update statistics for
763 * requests for which dd_insert_requests() has been called. See also
764 * blk_mq_request_bypass_insert().
765 */
766 if (rq->elv.priv[0])
767 dd_count(dd, completed, prio);
768
769 if (blk_queue_is_zoned(q)) {
770 unsigned long flags;
771
772 spin_lock_irqsave(&dd->zone_lock, flags);
773 blk_req_zone_write_unlock(rq);
774 if (!list_empty(&per_prio->fifo_list[DD_WRITE]))
775 blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
776 spin_unlock_irqrestore(&dd->zone_lock, flags);
777 }
778 }
779
dd_has_work_for_prio(struct dd_per_prio * per_prio)780 static bool dd_has_work_for_prio(struct dd_per_prio *per_prio)
781 {
782 return !list_empty_careful(&per_prio->dispatch) ||
783 !list_empty_careful(&per_prio->fifo_list[DD_READ]) ||
784 !list_empty_careful(&per_prio->fifo_list[DD_WRITE]);
785 }
786
dd_has_work(struct blk_mq_hw_ctx * hctx)787 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
788 {
789 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
790 enum dd_prio prio;
791
792 for (prio = 0; prio <= DD_PRIO_MAX; prio++)
793 if (dd_has_work_for_prio(&dd->per_prio[prio]))
794 return true;
795
796 return false;
797 }
798
799 /*
800 * sysfs parts below
801 */
802 #define SHOW_INT(__FUNC, __VAR) \
803 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
804 { \
805 struct deadline_data *dd = e->elevator_data; \
806 \
807 return sysfs_emit(page, "%d\n", __VAR); \
808 }
809 #define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR))
810 SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]);
811 SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]);
812 SHOW_INT(deadline_writes_starved_show, dd->writes_starved);
813 SHOW_INT(deadline_front_merges_show, dd->front_merges);
814 SHOW_INT(deadline_async_depth_show, dd->front_merges);
815 SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
816 #undef SHOW_INT
817 #undef SHOW_JIFFIES
818
819 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
820 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
821 { \
822 struct deadline_data *dd = e->elevator_data; \
823 int __data, __ret; \
824 \
825 __ret = kstrtoint(page, 0, &__data); \
826 if (__ret < 0) \
827 return __ret; \
828 if (__data < (MIN)) \
829 __data = (MIN); \
830 else if (__data > (MAX)) \
831 __data = (MAX); \
832 *(__PTR) = __CONV(__data); \
833 return count; \
834 }
835 #define STORE_INT(__FUNC, __PTR, MIN, MAX) \
836 STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, )
837 #define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX) \
838 STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies)
839 STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX);
840 STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX);
841 STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX);
842 STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);
843 STORE_INT(deadline_async_depth_store, &dd->front_merges, 1, INT_MAX);
844 STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);
845 #undef STORE_FUNCTION
846 #undef STORE_INT
847 #undef STORE_JIFFIES
848
849 #define DD_ATTR(name) \
850 __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
851
852 static struct elv_fs_entry deadline_attrs[] = {
853 DD_ATTR(read_expire),
854 DD_ATTR(write_expire),
855 DD_ATTR(writes_starved),
856 DD_ATTR(front_merges),
857 DD_ATTR(async_depth),
858 DD_ATTR(fifo_batch),
859 __ATTR_NULL
860 };
861
862 #ifdef CONFIG_BLK_DEBUG_FS
863 #define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name) \
864 static void *deadline_##name##_fifo_start(struct seq_file *m, \
865 loff_t *pos) \
866 __acquires(&dd->lock) \
867 { \
868 struct request_queue *q = m->private; \
869 struct deadline_data *dd = q->elevator->elevator_data; \
870 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
871 \
872 spin_lock(&dd->lock); \
873 return seq_list_start(&per_prio->fifo_list[data_dir], *pos); \
874 } \
875 \
876 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \
877 loff_t *pos) \
878 { \
879 struct request_queue *q = m->private; \
880 struct deadline_data *dd = q->elevator->elevator_data; \
881 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
882 \
883 return seq_list_next(v, &per_prio->fifo_list[data_dir], pos); \
884 } \
885 \
886 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \
887 __releases(&dd->lock) \
888 { \
889 struct request_queue *q = m->private; \
890 struct deadline_data *dd = q->elevator->elevator_data; \
891 \
892 spin_unlock(&dd->lock); \
893 } \
894 \
895 static const struct seq_operations deadline_##name##_fifo_seq_ops = { \
896 .start = deadline_##name##_fifo_start, \
897 .next = deadline_##name##_fifo_next, \
898 .stop = deadline_##name##_fifo_stop, \
899 .show = blk_mq_debugfs_rq_show, \
900 }; \
901 \
902 static int deadline_##name##_next_rq_show(void *data, \
903 struct seq_file *m) \
904 { \
905 struct request_queue *q = data; \
906 struct deadline_data *dd = q->elevator->elevator_data; \
907 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
908 struct request *rq = per_prio->next_rq[data_dir]; \
909 \
910 if (rq) \
911 __blk_mq_debugfs_rq_show(m, rq); \
912 return 0; \
913 }
914
915 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0);
916 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0);
917 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1);
918 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1);
919 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2);
920 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2);
921 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
922
deadline_batching_show(void * data,struct seq_file * m)923 static int deadline_batching_show(void *data, struct seq_file *m)
924 {
925 struct request_queue *q = data;
926 struct deadline_data *dd = q->elevator->elevator_data;
927
928 seq_printf(m, "%u\n", dd->batching);
929 return 0;
930 }
931
deadline_starved_show(void * data,struct seq_file * m)932 static int deadline_starved_show(void *data, struct seq_file *m)
933 {
934 struct request_queue *q = data;
935 struct deadline_data *dd = q->elevator->elevator_data;
936
937 seq_printf(m, "%u\n", dd->starved);
938 return 0;
939 }
940
dd_async_depth_show(void * data,struct seq_file * m)941 static int dd_async_depth_show(void *data, struct seq_file *m)
942 {
943 struct request_queue *q = data;
944 struct deadline_data *dd = q->elevator->elevator_data;
945
946 seq_printf(m, "%u\n", dd->async_depth);
947 return 0;
948 }
949
950 /* Number of requests queued for a given priority level. */
dd_queued(struct deadline_data * dd,enum dd_prio prio)951 static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
952 {
953 return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio);
954 }
955
dd_queued_show(void * data,struct seq_file * m)956 static int dd_queued_show(void *data, struct seq_file *m)
957 {
958 struct request_queue *q = data;
959 struct deadline_data *dd = q->elevator->elevator_data;
960
961 seq_printf(m, "%u %u %u\n", dd_queued(dd, DD_RT_PRIO),
962 dd_queued(dd, DD_BE_PRIO),
963 dd_queued(dd, DD_IDLE_PRIO));
964 return 0;
965 }
966
967 /* Number of requests owned by the block driver for a given priority. */
dd_owned_by_driver(struct deadline_data * dd,enum dd_prio prio)968 static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio)
969 {
970 return dd_sum(dd, dispatched, prio) + dd_sum(dd, merged, prio)
971 - dd_sum(dd, completed, prio);
972 }
973
dd_owned_by_driver_show(void * data,struct seq_file * m)974 static int dd_owned_by_driver_show(void *data, struct seq_file *m)
975 {
976 struct request_queue *q = data;
977 struct deadline_data *dd = q->elevator->elevator_data;
978
979 seq_printf(m, "%u %u %u\n", dd_owned_by_driver(dd, DD_RT_PRIO),
980 dd_owned_by_driver(dd, DD_BE_PRIO),
981 dd_owned_by_driver(dd, DD_IDLE_PRIO));
982 return 0;
983 }
984
985 #define DEADLINE_DISPATCH_ATTR(prio) \
986 static void *deadline_dispatch##prio##_start(struct seq_file *m, \
987 loff_t *pos) \
988 __acquires(&dd->lock) \
989 { \
990 struct request_queue *q = m->private; \
991 struct deadline_data *dd = q->elevator->elevator_data; \
992 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
993 \
994 spin_lock(&dd->lock); \
995 return seq_list_start(&per_prio->dispatch, *pos); \
996 } \
997 \
998 static void *deadline_dispatch##prio##_next(struct seq_file *m, \
999 void *v, loff_t *pos) \
1000 { \
1001 struct request_queue *q = m->private; \
1002 struct deadline_data *dd = q->elevator->elevator_data; \
1003 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
1004 \
1005 return seq_list_next(v, &per_prio->dispatch, pos); \
1006 } \
1007 \
1008 static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \
1009 __releases(&dd->lock) \
1010 { \
1011 struct request_queue *q = m->private; \
1012 struct deadline_data *dd = q->elevator->elevator_data; \
1013 \
1014 spin_unlock(&dd->lock); \
1015 } \
1016 \
1017 static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \
1018 .start = deadline_dispatch##prio##_start, \
1019 .next = deadline_dispatch##prio##_next, \
1020 .stop = deadline_dispatch##prio##_stop, \
1021 .show = blk_mq_debugfs_rq_show, \
1022 }
1023
1024 DEADLINE_DISPATCH_ATTR(0);
1025 DEADLINE_DISPATCH_ATTR(1);
1026 DEADLINE_DISPATCH_ATTR(2);
1027 #undef DEADLINE_DISPATCH_ATTR
1028
1029 #define DEADLINE_QUEUE_DDIR_ATTRS(name) \
1030 {#name "_fifo_list", 0400, \
1031 .seq_ops = &deadline_##name##_fifo_seq_ops}
1032 #define DEADLINE_NEXT_RQ_ATTR(name) \
1033 {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
1034 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
1035 DEADLINE_QUEUE_DDIR_ATTRS(read0),
1036 DEADLINE_QUEUE_DDIR_ATTRS(write0),
1037 DEADLINE_QUEUE_DDIR_ATTRS(read1),
1038 DEADLINE_QUEUE_DDIR_ATTRS(write1),
1039 DEADLINE_QUEUE_DDIR_ATTRS(read2),
1040 DEADLINE_QUEUE_DDIR_ATTRS(write2),
1041 DEADLINE_NEXT_RQ_ATTR(read0),
1042 DEADLINE_NEXT_RQ_ATTR(write0),
1043 DEADLINE_NEXT_RQ_ATTR(read1),
1044 DEADLINE_NEXT_RQ_ATTR(write1),
1045 DEADLINE_NEXT_RQ_ATTR(read2),
1046 DEADLINE_NEXT_RQ_ATTR(write2),
1047 {"batching", 0400, deadline_batching_show},
1048 {"starved", 0400, deadline_starved_show},
1049 {"async_depth", 0400, dd_async_depth_show},
1050 {"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops},
1051 {"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops},
1052 {"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops},
1053 {"owned_by_driver", 0400, dd_owned_by_driver_show},
1054 {"queued", 0400, dd_queued_show},
1055 {},
1056 };
1057 #undef DEADLINE_QUEUE_DDIR_ATTRS
1058 #endif
1059
1060 static struct elevator_type mq_deadline = {
1061 .ops = {
1062 .depth_updated = dd_depth_updated,
1063 .limit_depth = dd_limit_depth,
1064 .insert_requests = dd_insert_requests,
1065 .dispatch_request = dd_dispatch_request,
1066 .prepare_request = dd_prepare_request,
1067 .finish_request = dd_finish_request,
1068 .next_request = elv_rb_latter_request,
1069 .former_request = elv_rb_former_request,
1070 .bio_merge = dd_bio_merge,
1071 .request_merge = dd_request_merge,
1072 .requests_merged = dd_merged_requests,
1073 .request_merged = dd_request_merged,
1074 .has_work = dd_has_work,
1075 .init_sched = dd_init_sched,
1076 .exit_sched = dd_exit_sched,
1077 .init_hctx = dd_init_hctx,
1078 },
1079
1080 #ifdef CONFIG_BLK_DEBUG_FS
1081 .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
1082 #endif
1083 .elevator_attrs = deadline_attrs,
1084 .elevator_name = "mq-deadline",
1085 .elevator_alias = "deadline",
1086 .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
1087 .elevator_owner = THIS_MODULE,
1088 };
1089 MODULE_ALIAS("mq-deadline-iosched");
1090
deadline_init(void)1091 static int __init deadline_init(void)
1092 {
1093 return elv_register(&mq_deadline);
1094 }
1095
deadline_exit(void)1096 static void __exit deadline_exit(void)
1097 {
1098 elv_unregister(&mq_deadline);
1099 }
1100
1101 module_init(deadline_init);
1102 module_exit(deadline_exit);
1103
1104 MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche");
1105 MODULE_LICENSE("GPL");
1106 MODULE_DESCRIPTION("MQ deadline IO scheduler");
1107
