isofs: let mode and dmode mount options override rock ridge mode setting
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / block / cfq-iosched.c
blob833ec18eaa63e2a20b847797c99511e41314b474
1 /*
2 * CFQ, or complete fairness queueing, disk scheduler.
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8 */
9 #include <linux/module.h>
10 #include <linux/blkdev.h>
11 #include <linux/elevator.h>
12 #include <linux/rbtree.h>
13 #include <linux/ioprio.h>
14 #include <linux/blktrace_api.h>
17 * tunables
19 /* max queue in one round of service */
20 static const int cfq_quantum = 4;
21 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
22 /* maximum backwards seek, in KiB */
23 static const int cfq_back_max = 16 * 1024;
24 /* penalty of a backwards seek */
25 static const int cfq_back_penalty = 2;
26 static const int cfq_slice_sync = HZ / 10;
27 static int cfq_slice_async = HZ / 25;
28 static const int cfq_slice_async_rq = 2;
29 static int cfq_slice_idle = HZ / 125;
32 * offset from end of service tree
34 #define CFQ_IDLE_DELAY (HZ / 5)
37 * below this threshold, we consider thinktime immediate
39 #define CFQ_MIN_TT (2)
41 #define CFQ_SLICE_SCALE (5)
42 #define CFQ_HW_QUEUE_MIN (5)
44 #define RQ_CIC(rq) \
45 ((struct cfq_io_context *) (rq)->elevator_private)
46 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
48 static struct kmem_cache *cfq_pool;
49 static struct kmem_cache *cfq_ioc_pool;
51 static DEFINE_PER_CPU(unsigned long, ioc_count);
52 static struct completion *ioc_gone;
53 static DEFINE_SPINLOCK(ioc_gone_lock);
55 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
56 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
57 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
59 #define sample_valid(samples) ((samples) > 80)
62 * Most of our rbtree usage is for sorting with min extraction, so
63 * if we cache the leftmost node we don't have to walk down the tree
64 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
65 * move this into the elevator for the rq sorting as well.
67 struct cfq_rb_root {
68 struct rb_root rb;
69 struct rb_node *left;
71 #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
74 * Per block device queue structure
76 struct cfq_data {
77 struct request_queue *queue;
80 * rr list of queues with requests and the count of them
82 struct cfq_rb_root service_tree;
85 * Each priority tree is sorted by next_request position. These
86 * trees are used when determining if two or more queues are
87 * interleaving requests (see cfq_close_cooperator).
89 struct rb_root prio_trees[CFQ_PRIO_LISTS];
91 unsigned int busy_queues;
93 * Used to track any pending rt requests so we can pre-empt current
94 * non-RT cfqq in service when this value is non-zero.
96 unsigned int busy_rt_queues;
98 int rq_in_driver;
99 int sync_flight;
102 * queue-depth detection
104 int rq_queued;
105 int hw_tag;
106 int hw_tag_samples;
107 int rq_in_driver_peak;
110 * idle window management
112 struct timer_list idle_slice_timer;
113 struct work_struct unplug_work;
115 struct cfq_queue *active_queue;
116 struct cfq_io_context *active_cic;
119 * async queue for each priority case
121 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
122 struct cfq_queue *async_idle_cfqq;
124 sector_t last_position;
127 * tunables, see top of file
129 unsigned int cfq_quantum;
130 unsigned int cfq_fifo_expire[2];
131 unsigned int cfq_back_penalty;
132 unsigned int cfq_back_max;
133 unsigned int cfq_slice[2];
134 unsigned int cfq_slice_async_rq;
135 unsigned int cfq_slice_idle;
137 struct list_head cic_list;
141 * Per process-grouping structure
143 struct cfq_queue {
144 /* reference count */
145 atomic_t ref;
146 /* various state flags, see below */
147 unsigned int flags;
148 /* parent cfq_data */
149 struct cfq_data *cfqd;
150 /* service_tree member */
151 struct rb_node rb_node;
152 /* service_tree key */
153 unsigned long rb_key;
154 /* prio tree member */
155 struct rb_node p_node;
156 /* prio tree root we belong to, if any */
157 struct rb_root *p_root;
158 /* sorted list of pending requests */
159 struct rb_root sort_list;
160 /* if fifo isn't expired, next request to serve */
161 struct request *next_rq;
162 /* requests queued in sort_list */
163 int queued[2];
164 /* currently allocated requests */
165 int allocated[2];
166 /* fifo list of requests in sort_list */
167 struct list_head fifo;
169 unsigned long slice_end;
170 long slice_resid;
171 unsigned int slice_dispatch;
173 /* pending metadata requests */
174 int meta_pending;
175 /* number of requests that are on the dispatch list or inside driver */
176 int dispatched;
178 /* io prio of this group */
179 unsigned short ioprio, org_ioprio;
180 unsigned short ioprio_class, org_ioprio_class;
182 pid_t pid;
185 enum cfqq_state_flags {
186 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
187 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
188 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
189 CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
190 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
191 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
192 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
193 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
194 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
195 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
196 CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
199 #define CFQ_CFQQ_FNS(name) \
200 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
202 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
204 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
206 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
208 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
210 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
213 CFQ_CFQQ_FNS(on_rr);
214 CFQ_CFQQ_FNS(wait_request);
215 CFQ_CFQQ_FNS(must_dispatch);
216 CFQ_CFQQ_FNS(must_alloc);
217 CFQ_CFQQ_FNS(must_alloc_slice);
218 CFQ_CFQQ_FNS(fifo_expire);
219 CFQ_CFQQ_FNS(idle_window);
220 CFQ_CFQQ_FNS(prio_changed);
221 CFQ_CFQQ_FNS(slice_new);
222 CFQ_CFQQ_FNS(sync);
223 CFQ_CFQQ_FNS(coop);
224 #undef CFQ_CFQQ_FNS
226 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
227 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
228 #define cfq_log(cfqd, fmt, args...) \
229 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
231 static void cfq_dispatch_insert(struct request_queue *, struct request *);
232 static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
233 struct io_context *, gfp_t);
234 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
235 struct io_context *);
237 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
238 int is_sync)
240 return cic->cfqq[!!is_sync];
243 static inline void cic_set_cfqq(struct cfq_io_context *cic,
244 struct cfq_queue *cfqq, int is_sync)
246 cic->cfqq[!!is_sync] = cfqq;
250 * We regard a request as SYNC, if it's either a read or has the SYNC bit
251 * set (in which case it could also be direct WRITE).
253 static inline int cfq_bio_sync(struct bio *bio)
255 if (bio_data_dir(bio) == READ || bio_sync(bio))
256 return 1;
258 return 0;
262 * scheduler run of queue, if there are requests pending and no one in the
263 * driver that will restart queueing
265 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
267 if (cfqd->busy_queues) {
268 cfq_log(cfqd, "schedule dispatch");
269 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
273 static int cfq_queue_empty(struct request_queue *q)
275 struct cfq_data *cfqd = q->elevator->elevator_data;
277 return !cfqd->busy_queues;
281 * Scale schedule slice based on io priority. Use the sync time slice only
282 * if a queue is marked sync and has sync io queued. A sync queue with async
283 * io only, should not get full sync slice length.
285 static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
286 unsigned short prio)
288 const int base_slice = cfqd->cfq_slice[sync];
290 WARN_ON(prio >= IOPRIO_BE_NR);
292 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
295 static inline int
296 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
298 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
301 static inline void
302 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
304 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
305 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
309 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
310 * isn't valid until the first request from the dispatch is activated
311 * and the slice time set.
313 static inline int cfq_slice_used(struct cfq_queue *cfqq)
315 if (cfq_cfqq_slice_new(cfqq))
316 return 0;
317 if (time_before(jiffies, cfqq->slice_end))
318 return 0;
320 return 1;
324 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
325 * We choose the request that is closest to the head right now. Distance
326 * behind the head is penalized and only allowed to a certain extent.
328 static struct request *
329 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
331 sector_t last, s1, s2, d1 = 0, d2 = 0;
332 unsigned long back_max;
333 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
334 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
335 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
337 if (rq1 == NULL || rq1 == rq2)
338 return rq2;
339 if (rq2 == NULL)
340 return rq1;
342 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
343 return rq1;
344 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
345 return rq2;
346 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
347 return rq1;
348 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
349 return rq2;
351 s1 = blk_rq_pos(rq1);
352 s2 = blk_rq_pos(rq2);
354 last = cfqd->last_position;
357 * by definition, 1KiB is 2 sectors
359 back_max = cfqd->cfq_back_max * 2;
362 * Strict one way elevator _except_ in the case where we allow
363 * short backward seeks which are biased as twice the cost of a
364 * similar forward seek.
366 if (s1 >= last)
367 d1 = s1 - last;
368 else if (s1 + back_max >= last)
369 d1 = (last - s1) * cfqd->cfq_back_penalty;
370 else
371 wrap |= CFQ_RQ1_WRAP;
373 if (s2 >= last)
374 d2 = s2 - last;
375 else if (s2 + back_max >= last)
376 d2 = (last - s2) * cfqd->cfq_back_penalty;
377 else
378 wrap |= CFQ_RQ2_WRAP;
380 /* Found required data */
383 * By doing switch() on the bit mask "wrap" we avoid having to
384 * check two variables for all permutations: --> faster!
386 switch (wrap) {
387 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
388 if (d1 < d2)
389 return rq1;
390 else if (d2 < d1)
391 return rq2;
392 else {
393 if (s1 >= s2)
394 return rq1;
395 else
396 return rq2;
399 case CFQ_RQ2_WRAP:
400 return rq1;
401 case CFQ_RQ1_WRAP:
402 return rq2;
403 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
404 default:
406 * Since both rqs are wrapped,
407 * start with the one that's further behind head
408 * (--> only *one* back seek required),
409 * since back seek takes more time than forward.
411 if (s1 <= s2)
412 return rq1;
413 else
414 return rq2;
419 * The below is leftmost cache rbtree addon
421 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
423 if (!root->left)
424 root->left = rb_first(&root->rb);
426 if (root->left)
427 return rb_entry(root->left, struct cfq_queue, rb_node);
429 return NULL;
432 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
434 rb_erase(n, root);
435 RB_CLEAR_NODE(n);
438 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
440 if (root->left == n)
441 root->left = NULL;
442 rb_erase_init(n, &root->rb);
446 * would be nice to take fifo expire time into account as well
448 static struct request *
449 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
450 struct request *last)
452 struct rb_node *rbnext = rb_next(&last->rb_node);
453 struct rb_node *rbprev = rb_prev(&last->rb_node);
454 struct request *next = NULL, *prev = NULL;
456 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
458 if (rbprev)
459 prev = rb_entry_rq(rbprev);
461 if (rbnext)
462 next = rb_entry_rq(rbnext);
463 else {
464 rbnext = rb_first(&cfqq->sort_list);
465 if (rbnext && rbnext != &last->rb_node)
466 next = rb_entry_rq(rbnext);
469 return cfq_choose_req(cfqd, next, prev);
472 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
473 struct cfq_queue *cfqq)
476 * just an approximation, should be ok.
478 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
479 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
483 * The cfqd->service_tree holds all pending cfq_queue's that have
484 * requests waiting to be processed. It is sorted in the order that
485 * we will service the queues.
487 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
488 int add_front)
490 struct rb_node **p, *parent;
491 struct cfq_queue *__cfqq;
492 unsigned long rb_key;
493 int left;
495 if (cfq_class_idle(cfqq)) {
496 rb_key = CFQ_IDLE_DELAY;
497 parent = rb_last(&cfqd->service_tree.rb);
498 if (parent && parent != &cfqq->rb_node) {
499 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
500 rb_key += __cfqq->rb_key;
501 } else
502 rb_key += jiffies;
503 } else if (!add_front) {
504 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
505 rb_key += cfqq->slice_resid;
506 cfqq->slice_resid = 0;
507 } else
508 rb_key = 0;
510 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
512 * same position, nothing more to do
514 if (rb_key == cfqq->rb_key)
515 return;
517 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
520 left = 1;
521 parent = NULL;
522 p = &cfqd->service_tree.rb.rb_node;
523 while (*p) {
524 struct rb_node **n;
526 parent = *p;
527 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
530 * sort RT queues first, we always want to give
531 * preference to them. IDLE queues goes to the back.
532 * after that, sort on the next service time.
534 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
535 n = &(*p)->rb_left;
536 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
537 n = &(*p)->rb_right;
538 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
539 n = &(*p)->rb_left;
540 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
541 n = &(*p)->rb_right;
542 else if (rb_key < __cfqq->rb_key)
543 n = &(*p)->rb_left;
544 else
545 n = &(*p)->rb_right;
547 if (n == &(*p)->rb_right)
548 left = 0;
550 p = n;
553 if (left)
554 cfqd->service_tree.left = &cfqq->rb_node;
556 cfqq->rb_key = rb_key;
557 rb_link_node(&cfqq->rb_node, parent, p);
558 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
561 static struct cfq_queue *
562 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
563 sector_t sector, struct rb_node **ret_parent,
564 struct rb_node ***rb_link)
566 struct rb_node **p, *parent;
567 struct cfq_queue *cfqq = NULL;
569 parent = NULL;
570 p = &root->rb_node;
571 while (*p) {
572 struct rb_node **n;
574 parent = *p;
575 cfqq = rb_entry(parent, struct cfq_queue, p_node);
578 * Sort strictly based on sector. Smallest to the left,
579 * largest to the right.
581 if (sector > blk_rq_pos(cfqq->next_rq))
582 n = &(*p)->rb_right;
583 else if (sector < blk_rq_pos(cfqq->next_rq))
584 n = &(*p)->rb_left;
585 else
586 break;
587 p = n;
588 cfqq = NULL;
591 *ret_parent = parent;
592 if (rb_link)
593 *rb_link = p;
594 return cfqq;
597 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
599 struct rb_node **p, *parent;
600 struct cfq_queue *__cfqq;
602 if (cfqq->p_root) {
603 rb_erase(&cfqq->p_node, cfqq->p_root);
604 cfqq->p_root = NULL;
607 if (cfq_class_idle(cfqq))
608 return;
609 if (!cfqq->next_rq)
610 return;
612 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
613 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
614 blk_rq_pos(cfqq->next_rq), &parent, &p);
615 if (!__cfqq) {
616 rb_link_node(&cfqq->p_node, parent, p);
617 rb_insert_color(&cfqq->p_node, cfqq->p_root);
618 } else
619 cfqq->p_root = NULL;
623 * Update cfqq's position in the service tree.
625 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
628 * Resorting requires the cfqq to be on the RR list already.
630 if (cfq_cfqq_on_rr(cfqq)) {
631 cfq_service_tree_add(cfqd, cfqq, 0);
632 cfq_prio_tree_add(cfqd, cfqq);
637 * add to busy list of queues for service, trying to be fair in ordering
638 * the pending list according to last request service
640 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
642 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
643 BUG_ON(cfq_cfqq_on_rr(cfqq));
644 cfq_mark_cfqq_on_rr(cfqq);
645 cfqd->busy_queues++;
646 if (cfq_class_rt(cfqq))
647 cfqd->busy_rt_queues++;
649 cfq_resort_rr_list(cfqd, cfqq);
653 * Called when the cfqq no longer has requests pending, remove it from
654 * the service tree.
656 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
658 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
659 BUG_ON(!cfq_cfqq_on_rr(cfqq));
660 cfq_clear_cfqq_on_rr(cfqq);
662 if (!RB_EMPTY_NODE(&cfqq->rb_node))
663 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
664 if (cfqq->p_root) {
665 rb_erase(&cfqq->p_node, cfqq->p_root);
666 cfqq->p_root = NULL;
669 BUG_ON(!cfqd->busy_queues);
670 cfqd->busy_queues--;
671 if (cfq_class_rt(cfqq))
672 cfqd->busy_rt_queues--;
676 * rb tree support functions
678 static void cfq_del_rq_rb(struct request *rq)
680 struct cfq_queue *cfqq = RQ_CFQQ(rq);
681 struct cfq_data *cfqd = cfqq->cfqd;
682 const int sync = rq_is_sync(rq);
684 BUG_ON(!cfqq->queued[sync]);
685 cfqq->queued[sync]--;
687 elv_rb_del(&cfqq->sort_list, rq);
689 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
690 cfq_del_cfqq_rr(cfqd, cfqq);
693 static void cfq_add_rq_rb(struct request *rq)
695 struct cfq_queue *cfqq = RQ_CFQQ(rq);
696 struct cfq_data *cfqd = cfqq->cfqd;
697 struct request *__alias, *prev;
699 cfqq->queued[rq_is_sync(rq)]++;
702 * looks a little odd, but the first insert might return an alias.
703 * if that happens, put the alias on the dispatch list
705 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
706 cfq_dispatch_insert(cfqd->queue, __alias);
708 if (!cfq_cfqq_on_rr(cfqq))
709 cfq_add_cfqq_rr(cfqd, cfqq);
712 * check if this request is a better next-serve candidate
714 prev = cfqq->next_rq;
715 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
718 * adjust priority tree position, if ->next_rq changes
720 if (prev != cfqq->next_rq)
721 cfq_prio_tree_add(cfqd, cfqq);
723 BUG_ON(!cfqq->next_rq);
726 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
728 elv_rb_del(&cfqq->sort_list, rq);
729 cfqq->queued[rq_is_sync(rq)]--;
730 cfq_add_rq_rb(rq);
733 static struct request *
734 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
736 struct task_struct *tsk = current;
737 struct cfq_io_context *cic;
738 struct cfq_queue *cfqq;
740 cic = cfq_cic_lookup(cfqd, tsk->io_context);
741 if (!cic)
742 return NULL;
744 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
745 if (cfqq) {
746 sector_t sector = bio->bi_sector + bio_sectors(bio);
748 return elv_rb_find(&cfqq->sort_list, sector);
751 return NULL;
754 static void cfq_activate_request(struct request_queue *q, struct request *rq)
756 struct cfq_data *cfqd = q->elevator->elevator_data;
758 cfqd->rq_in_driver++;
759 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
760 cfqd->rq_in_driver);
762 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
765 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
767 struct cfq_data *cfqd = q->elevator->elevator_data;
769 WARN_ON(!cfqd->rq_in_driver);
770 cfqd->rq_in_driver--;
771 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
772 cfqd->rq_in_driver);
775 static void cfq_remove_request(struct request *rq)
777 struct cfq_queue *cfqq = RQ_CFQQ(rq);
779 if (cfqq->next_rq == rq)
780 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
782 list_del_init(&rq->queuelist);
783 cfq_del_rq_rb(rq);
785 cfqq->cfqd->rq_queued--;
786 if (rq_is_meta(rq)) {
787 WARN_ON(!cfqq->meta_pending);
788 cfqq->meta_pending--;
792 static int cfq_merge(struct request_queue *q, struct request **req,
793 struct bio *bio)
795 struct cfq_data *cfqd = q->elevator->elevator_data;
796 struct request *__rq;
798 __rq = cfq_find_rq_fmerge(cfqd, bio);
799 if (__rq && elv_rq_merge_ok(__rq, bio)) {
800 *req = __rq;
801 return ELEVATOR_FRONT_MERGE;
804 return ELEVATOR_NO_MERGE;
807 static void cfq_merged_request(struct request_queue *q, struct request *req,
808 int type)
810 if (type == ELEVATOR_FRONT_MERGE) {
811 struct cfq_queue *cfqq = RQ_CFQQ(req);
813 cfq_reposition_rq_rb(cfqq, req);
817 static void
818 cfq_merged_requests(struct request_queue *q, struct request *rq,
819 struct request *next)
822 * reposition in fifo if next is older than rq
824 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
825 time_before(next->start_time, rq->start_time))
826 list_move(&rq->queuelist, &next->queuelist);
828 cfq_remove_request(next);
831 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
832 struct bio *bio)
834 struct cfq_data *cfqd = q->elevator->elevator_data;
835 struct cfq_io_context *cic;
836 struct cfq_queue *cfqq;
839 * Disallow merge of a sync bio into an async request.
841 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
842 return 0;
845 * Lookup the cfqq that this bio will be queued with. Allow
846 * merge only if rq is queued there.
848 cic = cfq_cic_lookup(cfqd, current->io_context);
849 if (!cic)
850 return 0;
852 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
853 if (cfqq == RQ_CFQQ(rq))
854 return 1;
856 return 0;
859 static void __cfq_set_active_queue(struct cfq_data *cfqd,
860 struct cfq_queue *cfqq)
862 if (cfqq) {
863 cfq_log_cfqq(cfqd, cfqq, "set_active");
864 cfqq->slice_end = 0;
865 cfqq->slice_dispatch = 0;
867 cfq_clear_cfqq_wait_request(cfqq);
868 cfq_clear_cfqq_must_dispatch(cfqq);
869 cfq_clear_cfqq_must_alloc_slice(cfqq);
870 cfq_clear_cfqq_fifo_expire(cfqq);
871 cfq_mark_cfqq_slice_new(cfqq);
873 del_timer(&cfqd->idle_slice_timer);
876 cfqd->active_queue = cfqq;
880 * current cfqq expired its slice (or was too idle), select new one
882 static void
883 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
884 int timed_out)
886 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
888 if (cfq_cfqq_wait_request(cfqq))
889 del_timer(&cfqd->idle_slice_timer);
891 cfq_clear_cfqq_wait_request(cfqq);
894 * store what was left of this slice, if the queue idled/timed out
896 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
897 cfqq->slice_resid = cfqq->slice_end - jiffies;
898 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
901 cfq_resort_rr_list(cfqd, cfqq);
903 if (cfqq == cfqd->active_queue)
904 cfqd->active_queue = NULL;
906 if (cfqd->active_cic) {
907 put_io_context(cfqd->active_cic->ioc);
908 cfqd->active_cic = NULL;
912 static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
914 struct cfq_queue *cfqq = cfqd->active_queue;
916 if (cfqq)
917 __cfq_slice_expired(cfqd, cfqq, timed_out);
921 * Get next queue for service. Unless we have a queue preemption,
922 * we'll simply select the first cfqq in the service tree.
924 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
926 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
927 return NULL;
929 return cfq_rb_first(&cfqd->service_tree);
933 * Get and set a new active queue for service.
935 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
936 struct cfq_queue *cfqq)
938 if (!cfqq) {
939 cfqq = cfq_get_next_queue(cfqd);
940 if (cfqq)
941 cfq_clear_cfqq_coop(cfqq);
944 __cfq_set_active_queue(cfqd, cfqq);
945 return cfqq;
948 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
949 struct request *rq)
951 if (blk_rq_pos(rq) >= cfqd->last_position)
952 return blk_rq_pos(rq) - cfqd->last_position;
953 else
954 return cfqd->last_position - blk_rq_pos(rq);
957 #define CIC_SEEK_THR 8 * 1024
958 #define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
960 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
962 struct cfq_io_context *cic = cfqd->active_cic;
963 sector_t sdist = cic->seek_mean;
965 if (!sample_valid(cic->seek_samples))
966 sdist = CIC_SEEK_THR;
968 return cfq_dist_from_last(cfqd, rq) <= sdist;
971 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
972 struct cfq_queue *cur_cfqq)
974 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
975 struct rb_node *parent, *node;
976 struct cfq_queue *__cfqq;
977 sector_t sector = cfqd->last_position;
979 if (RB_EMPTY_ROOT(root))
980 return NULL;
983 * First, if we find a request starting at the end of the last
984 * request, choose it.
986 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
987 if (__cfqq)
988 return __cfqq;
991 * If the exact sector wasn't found, the parent of the NULL leaf
992 * will contain the closest sector.
994 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
995 if (cfq_rq_close(cfqd, __cfqq->next_rq))
996 return __cfqq;
998 if (blk_rq_pos(__cfqq->next_rq) < sector)
999 node = rb_next(&__cfqq->p_node);
1000 else
1001 node = rb_prev(&__cfqq->p_node);
1002 if (!node)
1003 return NULL;
1005 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1006 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1007 return __cfqq;
1009 return NULL;
1013 * cfqd - obvious
1014 * cur_cfqq - passed in so that we don't decide that the current queue is
1015 * closely cooperating with itself.
1017 * So, basically we're assuming that that cur_cfqq has dispatched at least
1018 * one request, and that cfqd->last_position reflects a position on the disk
1019 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1020 * assumption.
1022 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1023 struct cfq_queue *cur_cfqq,
1024 int probe)
1026 struct cfq_queue *cfqq;
1029 * A valid cfq_io_context is necessary to compare requests against
1030 * the seek_mean of the current cfqq.
1032 if (!cfqd->active_cic)
1033 return NULL;
1036 * We should notice if some of the queues are cooperating, eg
1037 * working closely on the same area of the disk. In that case,
1038 * we can group them together and don't waste time idling.
1040 cfqq = cfqq_close(cfqd, cur_cfqq);
1041 if (!cfqq)
1042 return NULL;
1044 if (cfq_cfqq_coop(cfqq))
1045 return NULL;
1047 if (!probe)
1048 cfq_mark_cfqq_coop(cfqq);
1049 return cfqq;
1052 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1054 struct cfq_queue *cfqq = cfqd->active_queue;
1055 struct cfq_io_context *cic;
1056 unsigned long sl;
1059 * SSD device without seek penalty, disable idling. But only do so
1060 * for devices that support queuing, otherwise we still have a problem
1061 * with sync vs async workloads.
1063 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1064 return;
1066 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1067 WARN_ON(cfq_cfqq_slice_new(cfqq));
1070 * idle is disabled, either manually or by past process history
1072 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
1073 return;
1076 * still requests with the driver, don't idle
1078 if (cfqd->rq_in_driver)
1079 return;
1082 * task has exited, don't wait
1084 cic = cfqd->active_cic;
1085 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1086 return;
1088 cfq_mark_cfqq_wait_request(cfqq);
1091 * we don't want to idle for seeks, but we do want to allow
1092 * fair distribution of slice time for a process doing back-to-back
1093 * seeks. so allow a little bit of time for him to submit a new rq
1095 sl = cfqd->cfq_slice_idle;
1096 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
1097 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
1099 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1100 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1104 * Move request from internal lists to the request queue dispatch list.
1106 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1108 struct cfq_data *cfqd = q->elevator->elevator_data;
1109 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1111 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1113 cfq_remove_request(rq);
1114 cfqq->dispatched++;
1115 elv_dispatch_sort(q, rq);
1117 if (cfq_cfqq_sync(cfqq))
1118 cfqd->sync_flight++;
1122 * return expired entry, or NULL to just start from scratch in rbtree
1124 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1126 struct cfq_data *cfqd = cfqq->cfqd;
1127 struct request *rq;
1128 int fifo;
1130 if (cfq_cfqq_fifo_expire(cfqq))
1131 return NULL;
1133 cfq_mark_cfqq_fifo_expire(cfqq);
1135 if (list_empty(&cfqq->fifo))
1136 return NULL;
1138 fifo = cfq_cfqq_sync(cfqq);
1139 rq = rq_entry_fifo(cfqq->fifo.next);
1141 if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
1142 rq = NULL;
1144 cfq_log_cfqq(cfqd, cfqq, "fifo=%p", rq);
1145 return rq;
1148 static inline int
1149 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1151 const int base_rq = cfqd->cfq_slice_async_rq;
1153 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1155 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1159 * Select a queue for service. If we have a current active queue,
1160 * check whether to continue servicing it, or retrieve and set a new one.
1162 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1164 struct cfq_queue *cfqq, *new_cfqq = NULL;
1166 cfqq = cfqd->active_queue;
1167 if (!cfqq)
1168 goto new_queue;
1171 * The active queue has run out of time, expire it and select new.
1173 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
1174 goto expire;
1177 * If we have a RT cfqq waiting, then we pre-empt the current non-rt
1178 * cfqq.
1180 if (!cfq_class_rt(cfqq) && cfqd->busy_rt_queues) {
1182 * We simulate this as cfqq timed out so that it gets to bank
1183 * the remaining of its time slice.
1185 cfq_log_cfqq(cfqd, cfqq, "preempt");
1186 cfq_slice_expired(cfqd, 1);
1187 goto new_queue;
1191 * The active queue has requests and isn't expired, allow it to
1192 * dispatch.
1194 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
1195 goto keep_queue;
1198 * If another queue has a request waiting within our mean seek
1199 * distance, let it run. The expire code will check for close
1200 * cooperators and put the close queue at the front of the service
1201 * tree.
1203 new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
1204 if (new_cfqq)
1205 goto expire;
1208 * No requests pending. If the active queue still has requests in
1209 * flight or is idling for a new request, allow either of these
1210 * conditions to happen (or time out) before selecting a new queue.
1212 if (timer_pending(&cfqd->idle_slice_timer) ||
1213 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
1214 cfqq = NULL;
1215 goto keep_queue;
1218 expire:
1219 cfq_slice_expired(cfqd, 0);
1220 new_queue:
1221 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
1222 keep_queue:
1223 return cfqq;
1226 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
1228 int dispatched = 0;
1230 while (cfqq->next_rq) {
1231 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1232 dispatched++;
1235 BUG_ON(!list_empty(&cfqq->fifo));
1236 return dispatched;
1240 * Drain our current requests. Used for barriers and when switching
1241 * io schedulers on-the-fly.
1243 static int cfq_forced_dispatch(struct cfq_data *cfqd)
1245 struct cfq_queue *cfqq;
1246 int dispatched = 0;
1248 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
1249 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1251 cfq_slice_expired(cfqd, 0);
1253 BUG_ON(cfqd->busy_queues);
1255 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1256 return dispatched;
1260 * Dispatch a request from cfqq, moving them to the request queue
1261 * dispatch list.
1263 static void cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1265 struct request *rq;
1267 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1270 * follow expired path, else get first next available
1272 rq = cfq_check_fifo(cfqq);
1273 if (!rq)
1274 rq = cfqq->next_rq;
1277 * insert request into driver dispatch list
1279 cfq_dispatch_insert(cfqd->queue, rq);
1281 if (!cfqd->active_cic) {
1282 struct cfq_io_context *cic = RQ_CIC(rq);
1284 atomic_long_inc(&cic->ioc->refcount);
1285 cfqd->active_cic = cic;
1290 * Find the cfqq that we need to service and move a request from that to the
1291 * dispatch list
1293 static int cfq_dispatch_requests(struct request_queue *q, int force)
1295 struct cfq_data *cfqd = q->elevator->elevator_data;
1296 struct cfq_queue *cfqq;
1297 unsigned int max_dispatch;
1299 if (!cfqd->busy_queues)
1300 return 0;
1302 if (unlikely(force))
1303 return cfq_forced_dispatch(cfqd);
1305 cfqq = cfq_select_queue(cfqd);
1306 if (!cfqq)
1307 return 0;
1310 * If this is an async queue and we have sync IO in flight, let it wait
1312 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1313 return 0;
1315 max_dispatch = cfqd->cfq_quantum;
1316 if (cfq_class_idle(cfqq))
1317 max_dispatch = 1;
1320 * Does this cfqq already have too much IO in flight?
1322 if (cfqq->dispatched >= max_dispatch) {
1324 * idle queue must always only have a single IO in flight
1326 if (cfq_class_idle(cfqq))
1327 return 0;
1330 * We have other queues, don't allow more IO from this one
1332 if (cfqd->busy_queues > 1)
1333 return 0;
1336 * we are the only queue, allow up to 4 times of 'quantum'
1338 if (cfqq->dispatched >= 4 * max_dispatch)
1339 return 0;
1343 * Dispatch a request from this cfqq
1345 cfq_dispatch_request(cfqd, cfqq);
1346 cfqq->slice_dispatch++;
1347 cfq_clear_cfqq_must_dispatch(cfqq);
1350 * expire an async queue immediately if it has used up its slice. idle
1351 * queue always expire after 1 dispatch round.
1353 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1354 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1355 cfq_class_idle(cfqq))) {
1356 cfqq->slice_end = jiffies + 1;
1357 cfq_slice_expired(cfqd, 0);
1360 cfq_log(cfqd, "dispatched a request");
1361 return 1;
1365 * task holds one reference to the queue, dropped when task exits. each rq
1366 * in-flight on this queue also holds a reference, dropped when rq is freed.
1368 * queue lock must be held here.
1370 static void cfq_put_queue(struct cfq_queue *cfqq)
1372 struct cfq_data *cfqd = cfqq->cfqd;
1374 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1376 if (!atomic_dec_and_test(&cfqq->ref))
1377 return;
1379 cfq_log_cfqq(cfqd, cfqq, "put_queue");
1380 BUG_ON(rb_first(&cfqq->sort_list));
1381 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
1382 BUG_ON(cfq_cfqq_on_rr(cfqq));
1384 if (unlikely(cfqd->active_queue == cfqq)) {
1385 __cfq_slice_expired(cfqd, cfqq, 0);
1386 cfq_schedule_dispatch(cfqd);
1389 kmem_cache_free(cfq_pool, cfqq);
1393 * Must always be called with the rcu_read_lock() held
1395 static void
1396 __call_for_each_cic(struct io_context *ioc,
1397 void (*func)(struct io_context *, struct cfq_io_context *))
1399 struct cfq_io_context *cic;
1400 struct hlist_node *n;
1402 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
1403 func(ioc, cic);
1407 * Call func for each cic attached to this ioc.
1409 static void
1410 call_for_each_cic(struct io_context *ioc,
1411 void (*func)(struct io_context *, struct cfq_io_context *))
1413 rcu_read_lock();
1414 __call_for_each_cic(ioc, func);
1415 rcu_read_unlock();
1418 static void cfq_cic_free_rcu(struct rcu_head *head)
1420 struct cfq_io_context *cic;
1422 cic = container_of(head, struct cfq_io_context, rcu_head);
1424 kmem_cache_free(cfq_ioc_pool, cic);
1425 elv_ioc_count_dec(ioc_count);
1427 if (ioc_gone) {
1429 * CFQ scheduler is exiting, grab exit lock and check
1430 * the pending io context count. If it hits zero,
1431 * complete ioc_gone and set it back to NULL
1433 spin_lock(&ioc_gone_lock);
1434 if (ioc_gone && !elv_ioc_count_read(ioc_count)) {
1435 complete(ioc_gone);
1436 ioc_gone = NULL;
1438 spin_unlock(&ioc_gone_lock);
1442 static void cfq_cic_free(struct cfq_io_context *cic)
1444 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
1447 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1449 unsigned long flags;
1451 BUG_ON(!cic->dead_key);
1453 spin_lock_irqsave(&ioc->lock, flags);
1454 radix_tree_delete(&ioc->radix_root, cic->dead_key);
1455 hlist_del_rcu(&cic->cic_list);
1456 spin_unlock_irqrestore(&ioc->lock, flags);
1458 cfq_cic_free(cic);
1462 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1463 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1464 * and ->trim() which is called with the task lock held
1466 static void cfq_free_io_context(struct io_context *ioc)
1469 * ioc->refcount is zero here, or we are called from elv_unregister(),
1470 * so no more cic's are allowed to be linked into this ioc. So it
1471 * should be ok to iterate over the known list, we will see all cic's
1472 * since no new ones are added.
1474 __call_for_each_cic(ioc, cic_free_func);
1477 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1479 if (unlikely(cfqq == cfqd->active_queue)) {
1480 __cfq_slice_expired(cfqd, cfqq, 0);
1481 cfq_schedule_dispatch(cfqd);
1484 cfq_put_queue(cfqq);
1487 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1488 struct cfq_io_context *cic)
1490 struct io_context *ioc = cic->ioc;
1492 list_del_init(&cic->queue_list);
1495 * Make sure key == NULL is seen for dead queues
1497 smp_wmb();
1498 cic->dead_key = (unsigned long) cic->key;
1499 cic->key = NULL;
1501 if (ioc->ioc_data == cic)
1502 rcu_assign_pointer(ioc->ioc_data, NULL);
1504 if (cic->cfqq[BLK_RW_ASYNC]) {
1505 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
1506 cic->cfqq[BLK_RW_ASYNC] = NULL;
1509 if (cic->cfqq[BLK_RW_SYNC]) {
1510 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
1511 cic->cfqq[BLK_RW_SYNC] = NULL;
1515 static void cfq_exit_single_io_context(struct io_context *ioc,
1516 struct cfq_io_context *cic)
1518 struct cfq_data *cfqd = cic->key;
1520 if (cfqd) {
1521 struct request_queue *q = cfqd->queue;
1522 unsigned long flags;
1524 spin_lock_irqsave(q->queue_lock, flags);
1527 * Ensure we get a fresh copy of the ->key to prevent
1528 * race between exiting task and queue
1530 smp_read_barrier_depends();
1531 if (cic->key)
1532 __cfq_exit_single_io_context(cfqd, cic);
1534 spin_unlock_irqrestore(q->queue_lock, flags);
1539 * The process that ioc belongs to has exited, we need to clean up
1540 * and put the internal structures we have that belongs to that process.
1542 static void cfq_exit_io_context(struct io_context *ioc)
1544 call_for_each_cic(ioc, cfq_exit_single_io_context);
1547 static struct cfq_io_context *
1548 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1550 struct cfq_io_context *cic;
1552 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1553 cfqd->queue->node);
1554 if (cic) {
1555 cic->last_end_request = jiffies;
1556 INIT_LIST_HEAD(&cic->queue_list);
1557 INIT_HLIST_NODE(&cic->cic_list);
1558 cic->dtor = cfq_free_io_context;
1559 cic->exit = cfq_exit_io_context;
1560 elv_ioc_count_inc(ioc_count);
1563 return cic;
1566 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
1568 struct task_struct *tsk = current;
1569 int ioprio_class;
1571 if (!cfq_cfqq_prio_changed(cfqq))
1572 return;
1574 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
1575 switch (ioprio_class) {
1576 default:
1577 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1578 case IOPRIO_CLASS_NONE:
1580 * no prio set, inherit CPU scheduling settings
1582 cfqq->ioprio = task_nice_ioprio(tsk);
1583 cfqq->ioprio_class = task_nice_ioclass(tsk);
1584 break;
1585 case IOPRIO_CLASS_RT:
1586 cfqq->ioprio = task_ioprio(ioc);
1587 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1588 break;
1589 case IOPRIO_CLASS_BE:
1590 cfqq->ioprio = task_ioprio(ioc);
1591 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1592 break;
1593 case IOPRIO_CLASS_IDLE:
1594 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1595 cfqq->ioprio = 7;
1596 cfq_clear_cfqq_idle_window(cfqq);
1597 break;
1601 * keep track of original prio settings in case we have to temporarily
1602 * elevate the priority of this queue
1604 cfqq->org_ioprio = cfqq->ioprio;
1605 cfqq->org_ioprio_class = cfqq->ioprio_class;
1606 cfq_clear_cfqq_prio_changed(cfqq);
1609 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
1611 struct cfq_data *cfqd = cic->key;
1612 struct cfq_queue *cfqq;
1613 unsigned long flags;
1615 if (unlikely(!cfqd))
1616 return;
1618 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1620 cfqq = cic->cfqq[BLK_RW_ASYNC];
1621 if (cfqq) {
1622 struct cfq_queue *new_cfqq;
1623 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
1624 GFP_ATOMIC);
1625 if (new_cfqq) {
1626 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
1627 cfq_put_queue(cfqq);
1631 cfqq = cic->cfqq[BLK_RW_SYNC];
1632 if (cfqq)
1633 cfq_mark_cfqq_prio_changed(cfqq);
1635 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1638 static void cfq_ioc_set_ioprio(struct io_context *ioc)
1640 call_for_each_cic(ioc, changed_ioprio);
1641 ioc->ioprio_changed = 0;
1644 static struct cfq_queue *
1645 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
1646 struct io_context *ioc, gfp_t gfp_mask)
1648 struct cfq_queue *cfqq, *new_cfqq = NULL;
1649 struct cfq_io_context *cic;
1651 retry:
1652 cic = cfq_cic_lookup(cfqd, ioc);
1653 /* cic always exists here */
1654 cfqq = cic_to_cfqq(cic, is_sync);
1656 if (!cfqq) {
1657 if (new_cfqq) {
1658 cfqq = new_cfqq;
1659 new_cfqq = NULL;
1660 } else if (gfp_mask & __GFP_WAIT) {
1662 * Inform the allocator of the fact that we will
1663 * just repeat this allocation if it fails, to allow
1664 * the allocator to do whatever it needs to attempt to
1665 * free memory.
1667 spin_unlock_irq(cfqd->queue->queue_lock);
1668 new_cfqq = kmem_cache_alloc_node(cfq_pool,
1669 gfp_mask | __GFP_NOFAIL | __GFP_ZERO,
1670 cfqd->queue->node);
1671 spin_lock_irq(cfqd->queue->queue_lock);
1672 goto retry;
1673 } else {
1674 cfqq = kmem_cache_alloc_node(cfq_pool,
1675 gfp_mask | __GFP_ZERO,
1676 cfqd->queue->node);
1677 if (!cfqq)
1678 goto out;
1681 RB_CLEAR_NODE(&cfqq->rb_node);
1682 RB_CLEAR_NODE(&cfqq->p_node);
1683 INIT_LIST_HEAD(&cfqq->fifo);
1685 atomic_set(&cfqq->ref, 0);
1686 cfqq->cfqd = cfqd;
1688 cfq_mark_cfqq_prio_changed(cfqq);
1690 cfq_init_prio_data(cfqq, ioc);
1692 if (is_sync) {
1693 if (!cfq_class_idle(cfqq))
1694 cfq_mark_cfqq_idle_window(cfqq);
1695 cfq_mark_cfqq_sync(cfqq);
1697 cfqq->pid = current->pid;
1698 cfq_log_cfqq(cfqd, cfqq, "alloced");
1701 if (new_cfqq)
1702 kmem_cache_free(cfq_pool, new_cfqq);
1704 out:
1705 WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
1706 return cfqq;
1709 static struct cfq_queue **
1710 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1712 switch (ioprio_class) {
1713 case IOPRIO_CLASS_RT:
1714 return &cfqd->async_cfqq[0][ioprio];
1715 case IOPRIO_CLASS_BE:
1716 return &cfqd->async_cfqq[1][ioprio];
1717 case IOPRIO_CLASS_IDLE:
1718 return &cfqd->async_idle_cfqq;
1719 default:
1720 BUG();
1724 static struct cfq_queue *
1725 cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
1726 gfp_t gfp_mask)
1728 const int ioprio = task_ioprio(ioc);
1729 const int ioprio_class = task_ioprio_class(ioc);
1730 struct cfq_queue **async_cfqq = NULL;
1731 struct cfq_queue *cfqq = NULL;
1733 if (!is_sync) {
1734 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1735 cfqq = *async_cfqq;
1738 if (!cfqq) {
1739 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
1740 if (!cfqq)
1741 return NULL;
1745 * pin the queue now that it's allocated, scheduler exit will prune it
1747 if (!is_sync && !(*async_cfqq)) {
1748 atomic_inc(&cfqq->ref);
1749 *async_cfqq = cfqq;
1752 atomic_inc(&cfqq->ref);
1753 return cfqq;
1757 * We drop cfq io contexts lazily, so we may find a dead one.
1759 static void
1760 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1761 struct cfq_io_context *cic)
1763 unsigned long flags;
1765 WARN_ON(!list_empty(&cic->queue_list));
1767 spin_lock_irqsave(&ioc->lock, flags);
1769 BUG_ON(ioc->ioc_data == cic);
1771 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
1772 hlist_del_rcu(&cic->cic_list);
1773 spin_unlock_irqrestore(&ioc->lock, flags);
1775 cfq_cic_free(cic);
1778 static struct cfq_io_context *
1779 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
1781 struct cfq_io_context *cic;
1782 unsigned long flags;
1783 void *k;
1785 if (unlikely(!ioc))
1786 return NULL;
1788 rcu_read_lock();
1791 * we maintain a last-hit cache, to avoid browsing over the tree
1793 cic = rcu_dereference(ioc->ioc_data);
1794 if (cic && cic->key == cfqd) {
1795 rcu_read_unlock();
1796 return cic;
1799 do {
1800 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1801 rcu_read_unlock();
1802 if (!cic)
1803 break;
1804 /* ->key must be copied to avoid race with cfq_exit_queue() */
1805 k = cic->key;
1806 if (unlikely(!k)) {
1807 cfq_drop_dead_cic(cfqd, ioc, cic);
1808 rcu_read_lock();
1809 continue;
1812 spin_lock_irqsave(&ioc->lock, flags);
1813 rcu_assign_pointer(ioc->ioc_data, cic);
1814 spin_unlock_irqrestore(&ioc->lock, flags);
1815 break;
1816 } while (1);
1818 return cic;
1822 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1823 * the process specific cfq io context when entered from the block layer.
1824 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1826 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1827 struct cfq_io_context *cic, gfp_t gfp_mask)
1829 unsigned long flags;
1830 int ret;
1832 ret = radix_tree_preload(gfp_mask);
1833 if (!ret) {
1834 cic->ioc = ioc;
1835 cic->key = cfqd;
1837 spin_lock_irqsave(&ioc->lock, flags);
1838 ret = radix_tree_insert(&ioc->radix_root,
1839 (unsigned long) cfqd, cic);
1840 if (!ret)
1841 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
1842 spin_unlock_irqrestore(&ioc->lock, flags);
1844 radix_tree_preload_end();
1846 if (!ret) {
1847 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1848 list_add(&cic->queue_list, &cfqd->cic_list);
1849 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1853 if (ret)
1854 printk(KERN_ERR "cfq: cic link failed!\n");
1856 return ret;
1860 * Setup general io context and cfq io context. There can be several cfq
1861 * io contexts per general io context, if this process is doing io to more
1862 * than one device managed by cfq.
1864 static struct cfq_io_context *
1865 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1867 struct io_context *ioc = NULL;
1868 struct cfq_io_context *cic;
1870 might_sleep_if(gfp_mask & __GFP_WAIT);
1872 ioc = get_io_context(gfp_mask, cfqd->queue->node);
1873 if (!ioc)
1874 return NULL;
1876 cic = cfq_cic_lookup(cfqd, ioc);
1877 if (cic)
1878 goto out;
1880 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1881 if (cic == NULL)
1882 goto err;
1884 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1885 goto err_free;
1887 out:
1888 smp_read_barrier_depends();
1889 if (unlikely(ioc->ioprio_changed))
1890 cfq_ioc_set_ioprio(ioc);
1892 return cic;
1893 err_free:
1894 cfq_cic_free(cic);
1895 err:
1896 put_io_context(ioc);
1897 return NULL;
1900 static void
1901 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1903 unsigned long elapsed = jiffies - cic->last_end_request;
1904 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
1906 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1907 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1908 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1911 static void
1912 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1913 struct request *rq)
1915 sector_t sdist;
1916 u64 total;
1918 if (!cic->last_request_pos)
1919 sdist = 0;
1920 else if (cic->last_request_pos < blk_rq_pos(rq))
1921 sdist = blk_rq_pos(rq) - cic->last_request_pos;
1922 else
1923 sdist = cic->last_request_pos - blk_rq_pos(rq);
1926 * Don't allow the seek distance to get too large from the
1927 * odd fragment, pagein, etc
1929 if (cic->seek_samples <= 60) /* second&third seek */
1930 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1931 else
1932 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1934 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1935 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1936 total = cic->seek_total + (cic->seek_samples/2);
1937 do_div(total, cic->seek_samples);
1938 cic->seek_mean = (sector_t)total;
1942 * Disable idle window if the process thinks too long or seeks so much that
1943 * it doesn't matter
1945 static void
1946 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1947 struct cfq_io_context *cic)
1949 int old_idle, enable_idle;
1952 * Don't idle for async or idle io prio class
1954 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
1955 return;
1957 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
1959 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
1960 (cfqd->hw_tag && CIC_SEEKY(cic)))
1961 enable_idle = 0;
1962 else if (sample_valid(cic->ttime_samples)) {
1963 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1964 enable_idle = 0;
1965 else
1966 enable_idle = 1;
1969 if (old_idle != enable_idle) {
1970 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
1971 if (enable_idle)
1972 cfq_mark_cfqq_idle_window(cfqq);
1973 else
1974 cfq_clear_cfqq_idle_window(cfqq);
1979 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1980 * no or if we aren't sure, a 1 will cause a preempt.
1982 static int
1983 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
1984 struct request *rq)
1986 struct cfq_queue *cfqq;
1988 cfqq = cfqd->active_queue;
1989 if (!cfqq)
1990 return 0;
1992 if (cfq_slice_used(cfqq))
1993 return 1;
1995 if (cfq_class_idle(new_cfqq))
1996 return 0;
1998 if (cfq_class_idle(cfqq))
1999 return 1;
2002 * if the new request is sync, but the currently running queue is
2003 * not, let the sync request have priority.
2005 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
2006 return 1;
2009 * So both queues are sync. Let the new request get disk time if
2010 * it's a metadata request and the current queue is doing regular IO.
2012 if (rq_is_meta(rq) && !cfqq->meta_pending)
2013 return 1;
2016 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2018 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
2019 return 1;
2021 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
2022 return 0;
2025 * if this request is as-good as one we would expect from the
2026 * current cfqq, let it preempt
2028 if (cfq_rq_close(cfqd, rq))
2029 return 1;
2031 return 0;
2035 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2036 * let it have half of its nominal slice.
2038 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2040 cfq_log_cfqq(cfqd, cfqq, "preempt");
2041 cfq_slice_expired(cfqd, 1);
2044 * Put the new queue at the front of the of the current list,
2045 * so we know that it will be selected next.
2047 BUG_ON(!cfq_cfqq_on_rr(cfqq));
2049 cfq_service_tree_add(cfqd, cfqq, 1);
2051 cfqq->slice_end = 0;
2052 cfq_mark_cfqq_slice_new(cfqq);
2056 * Called when a new fs request (rq) is added (to cfqq). Check if there's
2057 * something we should do about it
2059 static void
2060 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2061 struct request *rq)
2063 struct cfq_io_context *cic = RQ_CIC(rq);
2065 cfqd->rq_queued++;
2066 if (rq_is_meta(rq))
2067 cfqq->meta_pending++;
2069 cfq_update_io_thinktime(cfqd, cic);
2070 cfq_update_io_seektime(cfqd, cic, rq);
2071 cfq_update_idle_window(cfqd, cfqq, cic);
2073 cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
2075 if (cfqq == cfqd->active_queue) {
2077 * Remember that we saw a request from this process, but
2078 * don't start queuing just yet. Otherwise we risk seeing lots
2079 * of tiny requests, because we disrupt the normal plugging
2080 * and merging. If the request is already larger than a single
2081 * page, let it rip immediately. For that case we assume that
2082 * merging is already done. Ditto for a busy system that
2083 * has other work pending, don't risk delaying until the
2084 * idle timer unplug to continue working.
2086 if (cfq_cfqq_wait_request(cfqq)) {
2087 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2088 cfqd->busy_queues > 1) {
2089 del_timer(&cfqd->idle_slice_timer);
2090 __blk_run_queue(cfqd->queue);
2092 cfq_mark_cfqq_must_dispatch(cfqq);
2094 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
2096 * not the active queue - expire current slice if it is
2097 * idle and has expired it's mean thinktime or this new queue
2098 * has some old slice time left and is of higher priority or
2099 * this new queue is RT and the current one is BE
2101 cfq_preempt_queue(cfqd, cfqq);
2102 __blk_run_queue(cfqd->queue);
2106 static void cfq_insert_request(struct request_queue *q, struct request *rq)
2108 struct cfq_data *cfqd = q->elevator->elevator_data;
2109 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2111 cfq_log_cfqq(cfqd, cfqq, "insert_request");
2112 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
2114 cfq_add_rq_rb(rq);
2116 list_add_tail(&rq->queuelist, &cfqq->fifo);
2118 cfq_rq_enqueued(cfqd, cfqq, rq);
2122 * Update hw_tag based on peak queue depth over 50 samples under
2123 * sufficient load.
2125 static void cfq_update_hw_tag(struct cfq_data *cfqd)
2127 if (cfqd->rq_in_driver > cfqd->rq_in_driver_peak)
2128 cfqd->rq_in_driver_peak = cfqd->rq_in_driver;
2130 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
2131 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
2132 return;
2134 if (cfqd->hw_tag_samples++ < 50)
2135 return;
2137 if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
2138 cfqd->hw_tag = 1;
2139 else
2140 cfqd->hw_tag = 0;
2142 cfqd->hw_tag_samples = 0;
2143 cfqd->rq_in_driver_peak = 0;
2146 static void cfq_completed_request(struct request_queue *q, struct request *rq)
2148 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2149 struct cfq_data *cfqd = cfqq->cfqd;
2150 const int sync = rq_is_sync(rq);
2151 unsigned long now;
2153 now = jiffies;
2154 cfq_log_cfqq(cfqd, cfqq, "complete");
2156 cfq_update_hw_tag(cfqd);
2158 WARN_ON(!cfqd->rq_in_driver);
2159 WARN_ON(!cfqq->dispatched);
2160 cfqd->rq_in_driver--;
2161 cfqq->dispatched--;
2163 if (cfq_cfqq_sync(cfqq))
2164 cfqd->sync_flight--;
2166 if (sync)
2167 RQ_CIC(rq)->last_end_request = now;
2170 * If this is the active queue, check if it needs to be expired,
2171 * or if we want to idle in case it has no pending requests.
2173 if (cfqd->active_queue == cfqq) {
2174 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2176 if (cfq_cfqq_slice_new(cfqq)) {
2177 cfq_set_prio_slice(cfqd, cfqq);
2178 cfq_clear_cfqq_slice_new(cfqq);
2181 * If there are no requests waiting in this queue, and
2182 * there are other queues ready to issue requests, AND
2183 * those other queues are issuing requests within our
2184 * mean seek distance, give them a chance to run instead
2185 * of idling.
2187 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
2188 cfq_slice_expired(cfqd, 1);
2189 else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
2190 sync && !rq_noidle(rq))
2191 cfq_arm_slice_timer(cfqd);
2194 if (!cfqd->rq_in_driver)
2195 cfq_schedule_dispatch(cfqd);
2199 * we temporarily boost lower priority queues if they are holding fs exclusive
2200 * resources. they are boosted to normal prio (CLASS_BE/4)
2202 static void cfq_prio_boost(struct cfq_queue *cfqq)
2204 if (has_fs_excl()) {
2206 * boost idle prio on transactions that would lock out other
2207 * users of the filesystem
2209 if (cfq_class_idle(cfqq))
2210 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2211 if (cfqq->ioprio > IOPRIO_NORM)
2212 cfqq->ioprio = IOPRIO_NORM;
2213 } else {
2215 * check if we need to unboost the queue
2217 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
2218 cfqq->ioprio_class = cfqq->org_ioprio_class;
2219 if (cfqq->ioprio != cfqq->org_ioprio)
2220 cfqq->ioprio = cfqq->org_ioprio;
2224 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
2226 if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
2227 !cfq_cfqq_must_alloc_slice(cfqq)) {
2228 cfq_mark_cfqq_must_alloc_slice(cfqq);
2229 return ELV_MQUEUE_MUST;
2232 return ELV_MQUEUE_MAY;
2235 static int cfq_may_queue(struct request_queue *q, int rw)
2237 struct cfq_data *cfqd = q->elevator->elevator_data;
2238 struct task_struct *tsk = current;
2239 struct cfq_io_context *cic;
2240 struct cfq_queue *cfqq;
2243 * don't force setup of a queue from here, as a call to may_queue
2244 * does not necessarily imply that a request actually will be queued.
2245 * so just lookup a possibly existing queue, or return 'may queue'
2246 * if that fails
2248 cic = cfq_cic_lookup(cfqd, tsk->io_context);
2249 if (!cic)
2250 return ELV_MQUEUE_MAY;
2252 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
2253 if (cfqq) {
2254 cfq_init_prio_data(cfqq, cic->ioc);
2255 cfq_prio_boost(cfqq);
2257 return __cfq_may_queue(cfqq);
2260 return ELV_MQUEUE_MAY;
2264 * queue lock held here
2266 static void cfq_put_request(struct request *rq)
2268 struct cfq_queue *cfqq = RQ_CFQQ(rq);
2270 if (cfqq) {
2271 const int rw = rq_data_dir(rq);
2273 BUG_ON(!cfqq->allocated[rw]);
2274 cfqq->allocated[rw]--;
2276 put_io_context(RQ_CIC(rq)->ioc);
2278 rq->elevator_private = NULL;
2279 rq->elevator_private2 = NULL;
2281 cfq_put_queue(cfqq);
2286 * Allocate cfq data structures associated with this request.
2288 static int
2289 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
2291 struct cfq_data *cfqd = q->elevator->elevator_data;
2292 struct cfq_io_context *cic;
2293 const int rw = rq_data_dir(rq);
2294 const int is_sync = rq_is_sync(rq);
2295 struct cfq_queue *cfqq;
2296 unsigned long flags;
2298 might_sleep_if(gfp_mask & __GFP_WAIT);
2300 cic = cfq_get_io_context(cfqd, gfp_mask);
2302 spin_lock_irqsave(q->queue_lock, flags);
2304 if (!cic)
2305 goto queue_fail;
2307 cfqq = cic_to_cfqq(cic, is_sync);
2308 if (!cfqq) {
2309 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
2311 if (!cfqq)
2312 goto queue_fail;
2314 cic_set_cfqq(cic, cfqq, is_sync);
2317 cfqq->allocated[rw]++;
2318 cfq_clear_cfqq_must_alloc(cfqq);
2319 atomic_inc(&cfqq->ref);
2321 spin_unlock_irqrestore(q->queue_lock, flags);
2323 rq->elevator_private = cic;
2324 rq->elevator_private2 = cfqq;
2325 return 0;
2327 queue_fail:
2328 if (cic)
2329 put_io_context(cic->ioc);
2331 cfq_schedule_dispatch(cfqd);
2332 spin_unlock_irqrestore(q->queue_lock, flags);
2333 cfq_log(cfqd, "set_request fail");
2334 return 1;
2337 static void cfq_kick_queue(struct work_struct *work)
2339 struct cfq_data *cfqd =
2340 container_of(work, struct cfq_data, unplug_work);
2341 struct request_queue *q = cfqd->queue;
2343 spin_lock_irq(q->queue_lock);
2344 __blk_run_queue(cfqd->queue);
2345 spin_unlock_irq(q->queue_lock);
2349 * Timer running if the active_queue is currently idling inside its time slice
2351 static void cfq_idle_slice_timer(unsigned long data)
2353 struct cfq_data *cfqd = (struct cfq_data *) data;
2354 struct cfq_queue *cfqq;
2355 unsigned long flags;
2356 int timed_out = 1;
2358 cfq_log(cfqd, "idle timer fired");
2360 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2362 cfqq = cfqd->active_queue;
2363 if (cfqq) {
2364 timed_out = 0;
2367 * We saw a request before the queue expired, let it through
2369 if (cfq_cfqq_must_dispatch(cfqq))
2370 goto out_kick;
2373 * expired
2375 if (cfq_slice_used(cfqq))
2376 goto expire;
2379 * only expire and reinvoke request handler, if there are
2380 * other queues with pending requests
2382 if (!cfqd->busy_queues)
2383 goto out_cont;
2386 * not expired and it has a request pending, let it dispatch
2388 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2389 goto out_kick;
2391 expire:
2392 cfq_slice_expired(cfqd, timed_out);
2393 out_kick:
2394 cfq_schedule_dispatch(cfqd);
2395 out_cont:
2396 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2399 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2401 del_timer_sync(&cfqd->idle_slice_timer);
2402 cancel_work_sync(&cfqd->unplug_work);
2405 static void cfq_put_async_queues(struct cfq_data *cfqd)
2407 int i;
2409 for (i = 0; i < IOPRIO_BE_NR; i++) {
2410 if (cfqd->async_cfqq[0][i])
2411 cfq_put_queue(cfqd->async_cfqq[0][i]);
2412 if (cfqd->async_cfqq[1][i])
2413 cfq_put_queue(cfqd->async_cfqq[1][i]);
2416 if (cfqd->async_idle_cfqq)
2417 cfq_put_queue(cfqd->async_idle_cfqq);
2420 static void cfq_exit_queue(struct elevator_queue *e)
2422 struct cfq_data *cfqd = e->elevator_data;
2423 struct request_queue *q = cfqd->queue;
2425 cfq_shutdown_timer_wq(cfqd);
2427 spin_lock_irq(q->queue_lock);
2429 if (cfqd->active_queue)
2430 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
2432 while (!list_empty(&cfqd->cic_list)) {
2433 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2434 struct cfq_io_context,
2435 queue_list);
2437 __cfq_exit_single_io_context(cfqd, cic);
2440 cfq_put_async_queues(cfqd);
2442 spin_unlock_irq(q->queue_lock);
2444 cfq_shutdown_timer_wq(cfqd);
2446 kfree(cfqd);
2449 static void *cfq_init_queue(struct request_queue *q)
2451 struct cfq_data *cfqd;
2452 int i;
2454 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
2455 if (!cfqd)
2456 return NULL;
2458 cfqd->service_tree = CFQ_RB_ROOT;
2461 * Not strictly needed (since RB_ROOT just clears the node and we
2462 * zeroed cfqd on alloc), but better be safe in case someone decides
2463 * to add magic to the rb code
2465 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2466 cfqd->prio_trees[i] = RB_ROOT;
2468 INIT_LIST_HEAD(&cfqd->cic_list);
2470 cfqd->queue = q;
2472 init_timer(&cfqd->idle_slice_timer);
2473 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2474 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2476 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
2478 cfqd->cfq_quantum = cfq_quantum;
2479 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2480 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
2481 cfqd->cfq_back_max = cfq_back_max;
2482 cfqd->cfq_back_penalty = cfq_back_penalty;
2483 cfqd->cfq_slice[0] = cfq_slice_async;
2484 cfqd->cfq_slice[1] = cfq_slice_sync;
2485 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2486 cfqd->cfq_slice_idle = cfq_slice_idle;
2487 cfqd->hw_tag = 1;
2489 return cfqd;
2492 static void cfq_slab_kill(void)
2495 * Caller already ensured that pending RCU callbacks are completed,
2496 * so we should have no busy allocations at this point.
2498 if (cfq_pool)
2499 kmem_cache_destroy(cfq_pool);
2500 if (cfq_ioc_pool)
2501 kmem_cache_destroy(cfq_ioc_pool);
2504 static int __init cfq_slab_setup(void)
2506 cfq_pool = KMEM_CACHE(cfq_queue, 0);
2507 if (!cfq_pool)
2508 goto fail;
2510 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
2511 if (!cfq_ioc_pool)
2512 goto fail;
2514 return 0;
2515 fail:
2516 cfq_slab_kill();
2517 return -ENOMEM;
2521 * sysfs parts below -->
2523 static ssize_t
2524 cfq_var_show(unsigned int var, char *page)
2526 return sprintf(page, "%d\n", var);
2529 static ssize_t
2530 cfq_var_store(unsigned int *var, const char *page, size_t count)
2532 char *p = (char *) page;
2534 *var = simple_strtoul(p, &p, 10);
2535 return count;
2538 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
2539 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
2541 struct cfq_data *cfqd = e->elevator_data; \
2542 unsigned int __data = __VAR; \
2543 if (__CONV) \
2544 __data = jiffies_to_msecs(__data); \
2545 return cfq_var_show(__data, (page)); \
2547 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
2548 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2549 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
2550 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2551 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
2552 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2553 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2554 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2555 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
2556 #undef SHOW_FUNCTION
2558 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
2559 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
2561 struct cfq_data *cfqd = e->elevator_data; \
2562 unsigned int __data; \
2563 int ret = cfq_var_store(&__data, (page), count); \
2564 if (__data < (MIN)) \
2565 __data = (MIN); \
2566 else if (__data > (MAX)) \
2567 __data = (MAX); \
2568 if (__CONV) \
2569 *(__PTR) = msecs_to_jiffies(__data); \
2570 else \
2571 *(__PTR) = __data; \
2572 return ret; \
2574 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
2575 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2576 UINT_MAX, 1);
2577 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2578 UINT_MAX, 1);
2579 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
2580 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2581 UINT_MAX, 0);
2582 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2583 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2584 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
2585 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2586 UINT_MAX, 0);
2587 #undef STORE_FUNCTION
2589 #define CFQ_ATTR(name) \
2590 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2592 static struct elv_fs_entry cfq_attrs[] = {
2593 CFQ_ATTR(quantum),
2594 CFQ_ATTR(fifo_expire_sync),
2595 CFQ_ATTR(fifo_expire_async),
2596 CFQ_ATTR(back_seek_max),
2597 CFQ_ATTR(back_seek_penalty),
2598 CFQ_ATTR(slice_sync),
2599 CFQ_ATTR(slice_async),
2600 CFQ_ATTR(slice_async_rq),
2601 CFQ_ATTR(slice_idle),
2602 __ATTR_NULL
2605 static struct elevator_type iosched_cfq = {
2606 .ops = {
2607 .elevator_merge_fn = cfq_merge,
2608 .elevator_merged_fn = cfq_merged_request,
2609 .elevator_merge_req_fn = cfq_merged_requests,
2610 .elevator_allow_merge_fn = cfq_allow_merge,
2611 .elevator_dispatch_fn = cfq_dispatch_requests,
2612 .elevator_add_req_fn = cfq_insert_request,
2613 .elevator_activate_req_fn = cfq_activate_request,
2614 .elevator_deactivate_req_fn = cfq_deactivate_request,
2615 .elevator_queue_empty_fn = cfq_queue_empty,
2616 .elevator_completed_req_fn = cfq_completed_request,
2617 .elevator_former_req_fn = elv_rb_former_request,
2618 .elevator_latter_req_fn = elv_rb_latter_request,
2619 .elevator_set_req_fn = cfq_set_request,
2620 .elevator_put_req_fn = cfq_put_request,
2621 .elevator_may_queue_fn = cfq_may_queue,
2622 .elevator_init_fn = cfq_init_queue,
2623 .elevator_exit_fn = cfq_exit_queue,
2624 .trim = cfq_free_io_context,
2626 .elevator_attrs = cfq_attrs,
2627 .elevator_name = "cfq",
2628 .elevator_owner = THIS_MODULE,
2631 static int __init cfq_init(void)
2634 * could be 0 on HZ < 1000 setups
2636 if (!cfq_slice_async)
2637 cfq_slice_async = 1;
2638 if (!cfq_slice_idle)
2639 cfq_slice_idle = 1;
2641 if (cfq_slab_setup())
2642 return -ENOMEM;
2644 elv_register(&iosched_cfq);
2646 return 0;
2649 static void __exit cfq_exit(void)
2651 DECLARE_COMPLETION_ONSTACK(all_gone);
2652 elv_unregister(&iosched_cfq);
2653 ioc_gone = &all_gone;
2654 /* ioc_gone's update must be visible before reading ioc_count */
2655 smp_wmb();
2658 * this also protects us from entering cfq_slab_kill() with
2659 * pending RCU callbacks
2661 if (elv_ioc_count_read(ioc_count))
2662 wait_for_completion(&all_gone);
2663 cfq_slab_kill();
2666 module_init(cfq_init);
2667 module_exit(cfq_exit);
2669 MODULE_AUTHOR("Jens Axboe");
2670 MODULE_LICENSE("GPL");
2671 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");