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>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
22 /* max queue in one round of service */
23 static const int cfq_quantum
= 8;
24 static const int cfq_fifo_expire
[2] = { HZ
/ 4, HZ
/ 8 };
25 /* maximum backwards seek, in KiB */
26 static const int cfq_back_max
= 16 * 1024;
27 /* penalty of a backwards seek */
28 static const int cfq_back_penalty
= 2;
29 static const int cfq_slice_sync
= HZ
/ 10;
30 static int cfq_slice_async
= HZ
/ 25;
31 static const int cfq_slice_async_rq
= 2;
32 static int cfq_slice_idle
= HZ
/ 125;
33 static int cfq_group_idle
= HZ
/ 125;
34 static const int cfq_target_latency
= HZ
* 3/10; /* 300 ms */
35 static const int cfq_hist_divisor
= 4;
38 * offset from end of service tree
40 #define CFQ_IDLE_DELAY (HZ / 5)
43 * below this threshold, we consider thinktime immediate
45 #define CFQ_MIN_TT (2)
47 #define CFQ_SLICE_SCALE (5)
48 #define CFQ_HW_QUEUE_MIN (5)
49 #define CFQ_SERVICE_SHIFT 12
51 #define CFQQ_SEEK_THR (sector_t)(8 * 100)
52 #define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
53 #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
54 #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
57 ((struct cfq_io_context *) (rq)->elevator_private[0])
58 #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
59 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
61 static struct kmem_cache
*cfq_pool
;
62 static struct kmem_cache
*cfq_ioc_pool
;
64 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count
);
65 static struct completion
*ioc_gone
;
66 static DEFINE_SPINLOCK(ioc_gone_lock
);
68 static DEFINE_SPINLOCK(cic_index_lock
);
69 static DEFINE_IDA(cic_index_ida
);
71 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
72 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
73 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
75 #define sample_valid(samples) ((samples) > 80)
76 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
79 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
88 unsigned total_weight
;
91 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
92 .count = 0, .min_vdisktime = 0, }
95 * Per process-grouping structure
100 /* various state flags, see below */
102 /* parent cfq_data */
103 struct cfq_data
*cfqd
;
104 /* service_tree member */
105 struct rb_node rb_node
;
106 /* service_tree key */
107 unsigned long rb_key
;
108 /* prio tree member */
109 struct rb_node p_node
;
110 /* prio tree root we belong to, if any */
111 struct rb_root
*p_root
;
112 /* sorted list of pending requests */
113 struct rb_root sort_list
;
114 /* if fifo isn't expired, next request to serve */
115 struct request
*next_rq
;
116 /* requests queued in sort_list */
118 /* currently allocated requests */
120 /* fifo list of requests in sort_list */
121 struct list_head fifo
;
123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start
;
125 unsigned int allocated_slice
;
126 unsigned int slice_dispatch
;
127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start
;
129 unsigned long slice_end
;
132 /* pending metadata requests */
134 /* number of requests that are on the dispatch list or inside driver */
137 /* io prio of this group */
138 unsigned short ioprio
, org_ioprio
;
139 unsigned short ioprio_class
, org_ioprio_class
;
144 sector_t last_request_pos
;
146 struct cfq_rb_root
*service_tree
;
147 struct cfq_queue
*new_cfqq
;
148 struct cfq_group
*cfqg
;
149 /* Number of sectors dispatched from queue in single dispatch round */
150 unsigned long nr_sectors
;
154 * First index in the service_trees.
155 * IDLE is handled separately, so it has negative index
165 * Second index in the service_trees.
169 SYNC_NOIDLE_WORKLOAD
= 1,
173 /* This is per cgroup per device grouping structure */
175 /* group service_tree member */
176 struct rb_node rb_node
;
178 /* group service_tree key */
182 /* number of cfqq currently on this group */
186 * Per group busy queus average. Useful for workload slice calc. We
187 * create the array for each prio class but at run time it is used
188 * only for RT and BE class and slot for IDLE class remains unused.
189 * This is primarily done to avoid confusion and a gcc warning.
191 unsigned int busy_queues_avg
[CFQ_PRIO_NR
];
193 * rr lists of queues with requests. We maintain service trees for
194 * RT and BE classes. These trees are subdivided in subclasses
195 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
196 * class there is no subclassification and all the cfq queues go on
197 * a single tree service_tree_idle.
198 * Counts are embedded in the cfq_rb_root
200 struct cfq_rb_root service_trees
[2][3];
201 struct cfq_rb_root service_tree_idle
;
203 unsigned long saved_workload_slice
;
204 enum wl_type_t saved_workload
;
205 enum wl_prio_t saved_serving_prio
;
206 struct blkio_group blkg
;
207 #ifdef CONFIG_CFQ_GROUP_IOSCHED
208 struct hlist_node cfqd_node
;
211 /* number of requests that are on the dispatch list or inside driver */
216 * Per block device queue structure
219 struct request_queue
*queue
;
220 /* Root service tree for cfq_groups */
221 struct cfq_rb_root grp_service_tree
;
222 struct cfq_group root_group
;
225 * The priority currently being served
227 enum wl_prio_t serving_prio
;
228 enum wl_type_t serving_type
;
229 unsigned long workload_expires
;
230 struct cfq_group
*serving_group
;
233 * Each priority tree is sorted by next_request position. These
234 * trees are used when determining if two or more queues are
235 * interleaving requests (see cfq_close_cooperator).
237 struct rb_root prio_trees
[CFQ_PRIO_LISTS
];
239 unsigned int busy_queues
;
245 * queue-depth detection
251 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
252 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
255 int hw_tag_est_depth
;
256 unsigned int hw_tag_samples
;
259 * idle window management
261 struct timer_list idle_slice_timer
;
262 struct work_struct unplug_work
;
264 struct cfq_queue
*active_queue
;
265 struct cfq_io_context
*active_cic
;
268 * async queue for each priority case
270 struct cfq_queue
*async_cfqq
[2][IOPRIO_BE_NR
];
271 struct cfq_queue
*async_idle_cfqq
;
273 sector_t last_position
;
276 * tunables, see top of file
278 unsigned int cfq_quantum
;
279 unsigned int cfq_fifo_expire
[2];
280 unsigned int cfq_back_penalty
;
281 unsigned int cfq_back_max
;
282 unsigned int cfq_slice
[2];
283 unsigned int cfq_slice_async_rq
;
284 unsigned int cfq_slice_idle
;
285 unsigned int cfq_group_idle
;
286 unsigned int cfq_latency
;
288 unsigned int cic_index
;
289 struct list_head cic_list
;
292 * Fallback dummy cfqq for extreme OOM conditions
294 struct cfq_queue oom_cfqq
;
296 unsigned long last_delayed_sync
;
298 /* List of cfq groups being managed on this device*/
299 struct hlist_head cfqg_list
;
303 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
);
305 static struct cfq_rb_root
*service_tree_for(struct cfq_group
*cfqg
,
312 if (prio
== IDLE_WORKLOAD
)
313 return &cfqg
->service_tree_idle
;
315 return &cfqg
->service_trees
[prio
][type
];
318 enum cfqq_state_flags
{
319 CFQ_CFQQ_FLAG_on_rr
= 0, /* on round-robin busy list */
320 CFQ_CFQQ_FLAG_wait_request
, /* waiting for a request */
321 CFQ_CFQQ_FLAG_must_dispatch
, /* must be allowed a dispatch */
322 CFQ_CFQQ_FLAG_must_alloc_slice
, /* per-slice must_alloc flag */
323 CFQ_CFQQ_FLAG_fifo_expire
, /* FIFO checked in this slice */
324 CFQ_CFQQ_FLAG_idle_window
, /* slice idling enabled */
325 CFQ_CFQQ_FLAG_prio_changed
, /* task priority has changed */
326 CFQ_CFQQ_FLAG_slice_new
, /* no requests dispatched in slice */
327 CFQ_CFQQ_FLAG_sync
, /* synchronous queue */
328 CFQ_CFQQ_FLAG_coop
, /* cfqq is shared */
329 CFQ_CFQQ_FLAG_split_coop
, /* shared cfqq will be splitted */
330 CFQ_CFQQ_FLAG_deep
, /* sync cfqq experienced large depth */
331 CFQ_CFQQ_FLAG_wait_busy
, /* Waiting for next request */
334 #define CFQ_CFQQ_FNS(name) \
335 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
337 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
339 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
341 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
343 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
345 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
349 CFQ_CFQQ_FNS(wait_request
);
350 CFQ_CFQQ_FNS(must_dispatch
);
351 CFQ_CFQQ_FNS(must_alloc_slice
);
352 CFQ_CFQQ_FNS(fifo_expire
);
353 CFQ_CFQQ_FNS(idle_window
);
354 CFQ_CFQQ_FNS(prio_changed
);
355 CFQ_CFQQ_FNS(slice_new
);
358 CFQ_CFQQ_FNS(split_coop
);
360 CFQ_CFQQ_FNS(wait_busy
);
363 #ifdef CONFIG_CFQ_GROUP_IOSCHED
364 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
365 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
366 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
367 blkg_path(&(cfqq)->cfqg->blkg), ##args);
369 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
370 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
371 blkg_path(&(cfqg)->blkg), ##args); \
374 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
375 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
376 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
378 #define cfq_log(cfqd, fmt, args...) \
379 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
381 /* Traverses through cfq group service trees */
382 #define for_each_cfqg_st(cfqg, i, j, st) \
383 for (i = 0; i <= IDLE_WORKLOAD; i++) \
384 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
385 : &cfqg->service_tree_idle; \
386 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
387 (i == IDLE_WORKLOAD && j == 0); \
388 j++, st = i < IDLE_WORKLOAD ? \
389 &cfqg->service_trees[i][j]: NULL) \
392 static inline bool iops_mode(struct cfq_data *cfqd)
395 * If we are not idling on queues and it is a NCQ drive, parallel
396 * execution of requests is on and measuring time is not possible
397 * in most of the cases until and unless we drive shallower queue
398 * depths and that becomes a performance bottleneck. In such cases
399 * switch to start providing fairness in terms of number of IOs.
401 if (!cfqd
->cfq_slice_idle
&& cfqd
->hw_tag
)
407 static inline enum wl_prio_t
cfqq_prio(struct cfq_queue
*cfqq
)
409 if (cfq_class_idle(cfqq
))
410 return IDLE_WORKLOAD
;
411 if (cfq_class_rt(cfqq
))
417 static enum wl_type_t
cfqq_type(struct cfq_queue
*cfqq
)
419 if (!cfq_cfqq_sync(cfqq
))
420 return ASYNC_WORKLOAD
;
421 if (!cfq_cfqq_idle_window(cfqq
))
422 return SYNC_NOIDLE_WORKLOAD
;
423 return SYNC_WORKLOAD
;
426 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl
,
427 struct cfq_data
*cfqd
,
428 struct cfq_group
*cfqg
)
430 if (wl
== IDLE_WORKLOAD
)
431 return cfqg
->service_tree_idle
.count
;
433 return cfqg
->service_trees
[wl
][ASYNC_WORKLOAD
].count
434 + cfqg
->service_trees
[wl
][SYNC_NOIDLE_WORKLOAD
].count
435 + cfqg
->service_trees
[wl
][SYNC_WORKLOAD
].count
;
438 static inline int cfqg_busy_async_queues(struct cfq_data
*cfqd
,
439 struct cfq_group
*cfqg
)
441 return cfqg
->service_trees
[RT_WORKLOAD
][ASYNC_WORKLOAD
].count
442 + cfqg
->service_trees
[BE_WORKLOAD
][ASYNC_WORKLOAD
].count
;
445 static void cfq_dispatch_insert(struct request_queue
*, struct request
*);
446 static struct cfq_queue
*cfq_get_queue(struct cfq_data
*, bool,
447 struct io_context
*, gfp_t
);
448 static struct cfq_io_context
*cfq_cic_lookup(struct cfq_data
*,
449 struct io_context
*);
451 static inline struct cfq_queue
*cic_to_cfqq(struct cfq_io_context
*cic
,
454 return cic
->cfqq
[is_sync
];
457 static inline void cic_set_cfqq(struct cfq_io_context
*cic
,
458 struct cfq_queue
*cfqq
, bool is_sync
)
460 cic
->cfqq
[is_sync
] = cfqq
;
463 #define CIC_DEAD_KEY 1ul
464 #define CIC_DEAD_INDEX_SHIFT 1
466 static inline void *cfqd_dead_key(struct cfq_data
*cfqd
)
468 return (void *)(cfqd
->cic_index
<< CIC_DEAD_INDEX_SHIFT
| CIC_DEAD_KEY
);
471 static inline struct cfq_data
*cic_to_cfqd(struct cfq_io_context
*cic
)
473 struct cfq_data
*cfqd
= cic
->key
;
475 if (unlikely((unsigned long) cfqd
& CIC_DEAD_KEY
))
482 * We regard a request as SYNC, if it's either a read or has the SYNC bit
483 * set (in which case it could also be direct WRITE).
485 static inline bool cfq_bio_sync(struct bio
*bio
)
487 return bio_data_dir(bio
) == READ
|| (bio
->bi_rw
& REQ_SYNC
);
491 * scheduler run of queue, if there are requests pending and no one in the
492 * driver that will restart queueing
494 static inline void cfq_schedule_dispatch(struct cfq_data
*cfqd
)
496 if (cfqd
->busy_queues
) {
497 cfq_log(cfqd
, "schedule dispatch");
498 kblockd_schedule_work(cfqd
->queue
, &cfqd
->unplug_work
);
502 static int cfq_queue_empty(struct request_queue
*q
)
504 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
506 return !cfqd
->rq_queued
;
510 * Scale schedule slice based on io priority. Use the sync time slice only
511 * if a queue is marked sync and has sync io queued. A sync queue with async
512 * io only, should not get full sync slice length.
514 static inline int cfq_prio_slice(struct cfq_data
*cfqd
, bool sync
,
517 const int base_slice
= cfqd
->cfq_slice
[sync
];
519 WARN_ON(prio
>= IOPRIO_BE_NR
);
521 return base_slice
+ (base_slice
/CFQ_SLICE_SCALE
* (4 - prio
));
525 cfq_prio_to_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
527 return cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
);
530 static inline u64
cfq_scale_slice(unsigned long delta
, struct cfq_group
*cfqg
)
532 u64 d
= delta
<< CFQ_SERVICE_SHIFT
;
534 d
= d
* BLKIO_WEIGHT_DEFAULT
;
535 do_div(d
, cfqg
->weight
);
539 static inline u64
max_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
541 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
543 min_vdisktime
= vdisktime
;
545 return min_vdisktime
;
548 static inline u64
min_vdisktime(u64 min_vdisktime
, u64 vdisktime
)
550 s64 delta
= (s64
)(vdisktime
- min_vdisktime
);
552 min_vdisktime
= vdisktime
;
554 return min_vdisktime
;
557 static void update_min_vdisktime(struct cfq_rb_root
*st
)
559 u64 vdisktime
= st
->min_vdisktime
;
560 struct cfq_group
*cfqg
;
563 cfqg
= rb_entry_cfqg(st
->left
);
564 vdisktime
= min_vdisktime(vdisktime
, cfqg
->vdisktime
);
567 st
->min_vdisktime
= max_vdisktime(st
->min_vdisktime
, vdisktime
);
571 * get averaged number of queues of RT/BE priority.
572 * average is updated, with a formula that gives more weight to higher numbers,
573 * to quickly follows sudden increases and decrease slowly
576 static inline unsigned cfq_group_get_avg_queues(struct cfq_data
*cfqd
,
577 struct cfq_group
*cfqg
, bool rt
)
579 unsigned min_q
, max_q
;
580 unsigned mult
= cfq_hist_divisor
- 1;
581 unsigned round
= cfq_hist_divisor
/ 2;
582 unsigned busy
= cfq_group_busy_queues_wl(rt
, cfqd
, cfqg
);
584 min_q
= min(cfqg
->busy_queues_avg
[rt
], busy
);
585 max_q
= max(cfqg
->busy_queues_avg
[rt
], busy
);
586 cfqg
->busy_queues_avg
[rt
] = (mult
* max_q
+ min_q
+ round
) /
588 return cfqg
->busy_queues_avg
[rt
];
591 static inline unsigned
592 cfq_group_slice(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
594 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
596 return cfq_target_latency
* cfqg
->weight
/ st
->total_weight
;
599 static inline unsigned
600 cfq_scaled_cfqq_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
602 unsigned slice
= cfq_prio_to_slice(cfqd
, cfqq
);
603 if (cfqd
->cfq_latency
) {
605 * interested queues (we consider only the ones with the same
606 * priority class in the cfq group)
608 unsigned iq
= cfq_group_get_avg_queues(cfqd
, cfqq
->cfqg
,
610 unsigned sync_slice
= cfqd
->cfq_slice
[1];
611 unsigned expect_latency
= sync_slice
* iq
;
612 unsigned group_slice
= cfq_group_slice(cfqd
, cfqq
->cfqg
);
614 if (expect_latency
> group_slice
) {
615 unsigned base_low_slice
= 2 * cfqd
->cfq_slice_idle
;
616 /* scale low_slice according to IO priority
617 * and sync vs async */
619 min(slice
, base_low_slice
* slice
/ sync_slice
);
620 /* the adapted slice value is scaled to fit all iqs
621 * into the target latency */
622 slice
= max(slice
* group_slice
/ expect_latency
,
630 cfq_set_prio_slice(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
632 unsigned slice
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
634 cfqq
->slice_start
= jiffies
;
635 cfqq
->slice_end
= jiffies
+ slice
;
636 cfqq
->allocated_slice
= slice
;
637 cfq_log_cfqq(cfqd
, cfqq
, "set_slice=%lu", cfqq
->slice_end
- jiffies
);
641 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
642 * isn't valid until the first request from the dispatch is activated
643 * and the slice time set.
645 static inline bool cfq_slice_used(struct cfq_queue
*cfqq
)
647 if (cfq_cfqq_slice_new(cfqq
))
649 if (time_before(jiffies
, cfqq
->slice_end
))
656 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
657 * We choose the request that is closest to the head right now. Distance
658 * behind the head is penalized and only allowed to a certain extent.
660 static struct request
*
661 cfq_choose_req(struct cfq_data
*cfqd
, struct request
*rq1
, struct request
*rq2
, sector_t last
)
663 sector_t s1
, s2
, d1
= 0, d2
= 0;
664 unsigned long back_max
;
665 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
666 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
667 unsigned wrap
= 0; /* bit mask: requests behind the disk head? */
669 if (rq1
== NULL
|| rq1
== rq2
)
674 if (rq_is_sync(rq1
) && !rq_is_sync(rq2
))
676 else if (rq_is_sync(rq2
) && !rq_is_sync(rq1
))
678 if ((rq1
->cmd_flags
& REQ_META
) && !(rq2
->cmd_flags
& REQ_META
))
680 else if ((rq2
->cmd_flags
& REQ_META
) &&
681 !(rq1
->cmd_flags
& REQ_META
))
684 s1
= blk_rq_pos(rq1
);
685 s2
= blk_rq_pos(rq2
);
688 * by definition, 1KiB is 2 sectors
690 back_max
= cfqd
->cfq_back_max
* 2;
693 * Strict one way elevator _except_ in the case where we allow
694 * short backward seeks which are biased as twice the cost of a
695 * similar forward seek.
699 else if (s1
+ back_max
>= last
)
700 d1
= (last
- s1
) * cfqd
->cfq_back_penalty
;
702 wrap
|= CFQ_RQ1_WRAP
;
706 else if (s2
+ back_max
>= last
)
707 d2
= (last
- s2
) * cfqd
->cfq_back_penalty
;
709 wrap
|= CFQ_RQ2_WRAP
;
711 /* Found required data */
714 * By doing switch() on the bit mask "wrap" we avoid having to
715 * check two variables for all permutations: --> faster!
718 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
734 case (CFQ_RQ1_WRAP
|CFQ_RQ2_WRAP
): /* both rqs wrapped */
737 * Since both rqs are wrapped,
738 * start with the one that's further behind head
739 * (--> only *one* back seek required),
740 * since back seek takes more time than forward.
750 * The below is leftmost cache rbtree addon
752 static struct cfq_queue
*cfq_rb_first(struct cfq_rb_root
*root
)
754 /* Service tree is empty */
759 root
->left
= rb_first(&root
->rb
);
762 return rb_entry(root
->left
, struct cfq_queue
, rb_node
);
767 static struct cfq_group
*cfq_rb_first_group(struct cfq_rb_root
*root
)
770 root
->left
= rb_first(&root
->rb
);
773 return rb_entry_cfqg(root
->left
);
778 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
784 static void cfq_rb_erase(struct rb_node
*n
, struct cfq_rb_root
*root
)
788 rb_erase_init(n
, &root
->rb
);
793 * would be nice to take fifo expire time into account as well
795 static struct request
*
796 cfq_find_next_rq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
797 struct request
*last
)
799 struct rb_node
*rbnext
= rb_next(&last
->rb_node
);
800 struct rb_node
*rbprev
= rb_prev(&last
->rb_node
);
801 struct request
*next
= NULL
, *prev
= NULL
;
803 BUG_ON(RB_EMPTY_NODE(&last
->rb_node
));
806 prev
= rb_entry_rq(rbprev
);
809 next
= rb_entry_rq(rbnext
);
811 rbnext
= rb_first(&cfqq
->sort_list
);
812 if (rbnext
&& rbnext
!= &last
->rb_node
)
813 next
= rb_entry_rq(rbnext
);
816 return cfq_choose_req(cfqd
, next
, prev
, blk_rq_pos(last
));
819 static unsigned long cfq_slice_offset(struct cfq_data
*cfqd
,
820 struct cfq_queue
*cfqq
)
823 * just an approximation, should be ok.
825 return (cfqq
->cfqg
->nr_cfqq
- 1) * (cfq_prio_slice(cfqd
, 1, 0) -
826 cfq_prio_slice(cfqd
, cfq_cfqq_sync(cfqq
), cfqq
->ioprio
));
830 cfqg_key(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
832 return cfqg
->vdisktime
- st
->min_vdisktime
;
836 __cfq_group_service_tree_add(struct cfq_rb_root
*st
, struct cfq_group
*cfqg
)
838 struct rb_node
**node
= &st
->rb
.rb_node
;
839 struct rb_node
*parent
= NULL
;
840 struct cfq_group
*__cfqg
;
841 s64 key
= cfqg_key(st
, cfqg
);
844 while (*node
!= NULL
) {
846 __cfqg
= rb_entry_cfqg(parent
);
848 if (key
< cfqg_key(st
, __cfqg
))
849 node
= &parent
->rb_left
;
851 node
= &parent
->rb_right
;
857 st
->left
= &cfqg
->rb_node
;
859 rb_link_node(&cfqg
->rb_node
, parent
, node
);
860 rb_insert_color(&cfqg
->rb_node
, &st
->rb
);
864 cfq_group_service_tree_add(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
866 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
867 struct cfq_group
*__cfqg
;
871 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
875 * Currently put the group at the end. Later implement something
876 * so that groups get lesser vtime based on their weights, so that
877 * if group does not loose all if it was not continously backlogged.
879 n
= rb_last(&st
->rb
);
881 __cfqg
= rb_entry_cfqg(n
);
882 cfqg
->vdisktime
= __cfqg
->vdisktime
+ CFQ_IDLE_DELAY
;
884 cfqg
->vdisktime
= st
->min_vdisktime
;
886 __cfq_group_service_tree_add(st
, cfqg
);
887 st
->total_weight
+= cfqg
->weight
;
891 cfq_group_service_tree_del(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
893 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
895 BUG_ON(cfqg
->nr_cfqq
< 1);
898 /* If there are other cfq queues under this group, don't delete it */
902 cfq_log_cfqg(cfqd
, cfqg
, "del_from_rr group");
903 st
->total_weight
-= cfqg
->weight
;
904 if (!RB_EMPTY_NODE(&cfqg
->rb_node
))
905 cfq_rb_erase(&cfqg
->rb_node
, st
);
906 cfqg
->saved_workload_slice
= 0;
907 cfq_blkiocg_update_dequeue_stats(&cfqg
->blkg
, 1);
910 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue
*cfqq
)
912 unsigned int slice_used
;
915 * Queue got expired before even a single request completed or
916 * got expired immediately after first request completion.
918 if (!cfqq
->slice_start
|| cfqq
->slice_start
== jiffies
) {
920 * Also charge the seek time incurred to the group, otherwise
921 * if there are mutiple queues in the group, each can dispatch
922 * a single request on seeky media and cause lots of seek time
923 * and group will never know it.
925 slice_used
= max_t(unsigned, (jiffies
- cfqq
->dispatch_start
),
928 slice_used
= jiffies
- cfqq
->slice_start
;
929 if (slice_used
> cfqq
->allocated_slice
)
930 slice_used
= cfqq
->allocated_slice
;
936 static void cfq_group_served(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
,
937 struct cfq_queue
*cfqq
)
939 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
940 unsigned int used_sl
, charge
;
941 int nr_sync
= cfqg
->nr_cfqq
- cfqg_busy_async_queues(cfqd
, cfqg
)
942 - cfqg
->service_tree_idle
.count
;
945 used_sl
= charge
= cfq_cfqq_slice_usage(cfqq
);
948 charge
= cfqq
->slice_dispatch
;
949 else if (!cfq_cfqq_sync(cfqq
) && !nr_sync
)
950 charge
= cfqq
->allocated_slice
;
952 /* Can't update vdisktime while group is on service tree */
953 cfq_rb_erase(&cfqg
->rb_node
, st
);
954 cfqg
->vdisktime
+= cfq_scale_slice(charge
, cfqg
);
955 __cfq_group_service_tree_add(st
, cfqg
);
957 /* This group is being expired. Save the context */
958 if (time_after(cfqd
->workload_expires
, jiffies
)) {
959 cfqg
->saved_workload_slice
= cfqd
->workload_expires
961 cfqg
->saved_workload
= cfqd
->serving_type
;
962 cfqg
->saved_serving_prio
= cfqd
->serving_prio
;
964 cfqg
->saved_workload_slice
= 0;
966 cfq_log_cfqg(cfqd
, cfqg
, "served: vt=%llu min_vt=%llu", cfqg
->vdisktime
,
968 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "sl_used=%u disp=%u charge=%u iops=%u"
969 " sect=%u", used_sl
, cfqq
->slice_dispatch
, charge
,
970 iops_mode(cfqd
), cfqq
->nr_sectors
);
971 cfq_blkiocg_update_timeslice_used(&cfqg
->blkg
, used_sl
);
972 cfq_blkiocg_set_start_empty_time(&cfqg
->blkg
);
975 #ifdef CONFIG_CFQ_GROUP_IOSCHED
976 static inline struct cfq_group
*cfqg_of_blkg(struct blkio_group
*blkg
)
979 return container_of(blkg
, struct cfq_group
, blkg
);
983 void cfq_update_blkio_group_weight(void *key
, struct blkio_group
*blkg
,
986 cfqg_of_blkg(blkg
)->weight
= weight
;
989 static struct cfq_group
*
990 cfq_find_alloc_cfqg(struct cfq_data
*cfqd
, struct cgroup
*cgroup
, int create
)
992 struct blkio_cgroup
*blkcg
= cgroup_to_blkio_cgroup(cgroup
);
993 struct cfq_group
*cfqg
= NULL
;
996 struct cfq_rb_root
*st
;
997 struct backing_dev_info
*bdi
= &cfqd
->queue
->backing_dev_info
;
998 unsigned int major
, minor
;
1000 cfqg
= cfqg_of_blkg(blkiocg_lookup_group(blkcg
, key
));
1001 if (cfqg
&& !cfqg
->blkg
.dev
&& bdi
->dev
&& dev_name(bdi
->dev
)) {
1002 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1003 cfqg
->blkg
.dev
= MKDEV(major
, minor
);
1006 if (cfqg
|| !create
)
1009 cfqg
= kzalloc_node(sizeof(*cfqg
), GFP_ATOMIC
, cfqd
->queue
->node
);
1013 for_each_cfqg_st(cfqg
, i
, j
, st
)
1015 RB_CLEAR_NODE(&cfqg
->rb_node
);
1018 * Take the initial reference that will be released on destroy
1019 * This can be thought of a joint reference by cgroup and
1020 * elevator which will be dropped by either elevator exit
1021 * or cgroup deletion path depending on who is exiting first.
1026 * Add group onto cgroup list. It might happen that bdi->dev is
1027 * not initialized yet. Initialize this new group without major
1028 * and minor info and this info will be filled in once a new thread
1029 * comes for IO. See code above.
1032 sscanf(dev_name(bdi
->dev
), "%u:%u", &major
, &minor
);
1033 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
, (void *)cfqd
,
1034 MKDEV(major
, minor
));
1036 cfq_blkiocg_add_blkio_group(blkcg
, &cfqg
->blkg
, (void *)cfqd
,
1039 cfqg
->weight
= blkcg_get_weight(blkcg
, cfqg
->blkg
.dev
);
1041 /* Add group on cfqd list */
1042 hlist_add_head(&cfqg
->cfqd_node
, &cfqd
->cfqg_list
);
1049 * Search for the cfq group current task belongs to. If create = 1, then also
1050 * create the cfq group if it does not exist. request_queue lock must be held.
1052 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1054 struct cgroup
*cgroup
;
1055 struct cfq_group
*cfqg
= NULL
;
1058 cgroup
= task_cgroup(current
, blkio_subsys_id
);
1059 cfqg
= cfq_find_alloc_cfqg(cfqd
, cgroup
, create
);
1060 if (!cfqg
&& create
)
1061 cfqg
= &cfqd
->root_group
;
1066 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1072 static void cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
)
1074 /* Currently, all async queues are mapped to root group */
1075 if (!cfq_cfqq_sync(cfqq
))
1076 cfqg
= &cfqq
->cfqd
->root_group
;
1079 /* cfqq reference on cfqg */
1083 static void cfq_put_cfqg(struct cfq_group
*cfqg
)
1085 struct cfq_rb_root
*st
;
1088 BUG_ON(cfqg
->ref
<= 0);
1092 for_each_cfqg_st(cfqg
, i
, j
, st
)
1093 BUG_ON(!RB_EMPTY_ROOT(&st
->rb
));
1097 static void cfq_destroy_cfqg(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
1099 /* Something wrong if we are trying to remove same group twice */
1100 BUG_ON(hlist_unhashed(&cfqg
->cfqd_node
));
1102 hlist_del_init(&cfqg
->cfqd_node
);
1105 * Put the reference taken at the time of creation so that when all
1106 * queues are gone, group can be destroyed.
1111 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
)
1113 struct hlist_node
*pos
, *n
;
1114 struct cfq_group
*cfqg
;
1116 hlist_for_each_entry_safe(cfqg
, pos
, n
, &cfqd
->cfqg_list
, cfqd_node
) {
1118 * If cgroup removal path got to blk_group first and removed
1119 * it from cgroup list, then it will take care of destroying
1122 if (!cfq_blkiocg_del_blkio_group(&cfqg
->blkg
))
1123 cfq_destroy_cfqg(cfqd
, cfqg
);
1128 * Blk cgroup controller notification saying that blkio_group object is being
1129 * delinked as associated cgroup object is going away. That also means that
1130 * no new IO will come in this group. So get rid of this group as soon as
1131 * any pending IO in the group is finished.
1133 * This function is called under rcu_read_lock(). key is the rcu protected
1134 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1137 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1138 * it should not be NULL as even if elevator was exiting, cgroup deltion
1139 * path got to it first.
1141 void cfq_unlink_blkio_group(void *key
, struct blkio_group
*blkg
)
1143 unsigned long flags
;
1144 struct cfq_data
*cfqd
= key
;
1146 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
1147 cfq_destroy_cfqg(cfqd
, cfqg_of_blkg(blkg
));
1148 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
1151 #else /* GROUP_IOSCHED */
1152 static struct cfq_group
*cfq_get_cfqg(struct cfq_data
*cfqd
, int create
)
1154 return &cfqd
->root_group
;
1157 static inline struct cfq_group
*cfq_ref_get_cfqg(struct cfq_group
*cfqg
)
1163 cfq_link_cfqq_cfqg(struct cfq_queue
*cfqq
, struct cfq_group
*cfqg
) {
1167 static void cfq_release_cfq_groups(struct cfq_data
*cfqd
) {}
1168 static inline void cfq_put_cfqg(struct cfq_group
*cfqg
) {}
1170 #endif /* GROUP_IOSCHED */
1173 * The cfqd->service_trees holds all pending cfq_queue's that have
1174 * requests waiting to be processed. It is sorted in the order that
1175 * we will service the queues.
1177 static void cfq_service_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1180 struct rb_node
**p
, *parent
;
1181 struct cfq_queue
*__cfqq
;
1182 unsigned long rb_key
;
1183 struct cfq_rb_root
*service_tree
;
1186 int group_changed
= 0;
1188 service_tree
= service_tree_for(cfqq
->cfqg
, cfqq_prio(cfqq
),
1190 if (cfq_class_idle(cfqq
)) {
1191 rb_key
= CFQ_IDLE_DELAY
;
1192 parent
= rb_last(&service_tree
->rb
);
1193 if (parent
&& parent
!= &cfqq
->rb_node
) {
1194 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1195 rb_key
+= __cfqq
->rb_key
;
1198 } else if (!add_front
) {
1200 * Get our rb key offset. Subtract any residual slice
1201 * value carried from last service. A negative resid
1202 * count indicates slice overrun, and this should position
1203 * the next service time further away in the tree.
1205 rb_key
= cfq_slice_offset(cfqd
, cfqq
) + jiffies
;
1206 rb_key
-= cfqq
->slice_resid
;
1207 cfqq
->slice_resid
= 0;
1210 __cfqq
= cfq_rb_first(service_tree
);
1211 rb_key
+= __cfqq
? __cfqq
->rb_key
: jiffies
;
1214 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1217 * same position, nothing more to do
1219 if (rb_key
== cfqq
->rb_key
&&
1220 cfqq
->service_tree
== service_tree
)
1223 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1224 cfqq
->service_tree
= NULL
;
1229 cfqq
->service_tree
= service_tree
;
1230 p
= &service_tree
->rb
.rb_node
;
1235 __cfqq
= rb_entry(parent
, struct cfq_queue
, rb_node
);
1238 * sort by key, that represents service time.
1240 if (time_before(rb_key
, __cfqq
->rb_key
))
1243 n
= &(*p
)->rb_right
;
1251 service_tree
->left
= &cfqq
->rb_node
;
1253 cfqq
->rb_key
= rb_key
;
1254 rb_link_node(&cfqq
->rb_node
, parent
, p
);
1255 rb_insert_color(&cfqq
->rb_node
, &service_tree
->rb
);
1256 service_tree
->count
++;
1257 if ((add_front
|| !new_cfqq
) && !group_changed
)
1259 cfq_group_service_tree_add(cfqd
, cfqq
->cfqg
);
1262 static struct cfq_queue
*
1263 cfq_prio_tree_lookup(struct cfq_data
*cfqd
, struct rb_root
*root
,
1264 sector_t sector
, struct rb_node
**ret_parent
,
1265 struct rb_node
***rb_link
)
1267 struct rb_node
**p
, *parent
;
1268 struct cfq_queue
*cfqq
= NULL
;
1276 cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1279 * Sort strictly based on sector. Smallest to the left,
1280 * largest to the right.
1282 if (sector
> blk_rq_pos(cfqq
->next_rq
))
1283 n
= &(*p
)->rb_right
;
1284 else if (sector
< blk_rq_pos(cfqq
->next_rq
))
1292 *ret_parent
= parent
;
1298 static void cfq_prio_tree_add(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1300 struct rb_node
**p
, *parent
;
1301 struct cfq_queue
*__cfqq
;
1304 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1305 cfqq
->p_root
= NULL
;
1308 if (cfq_class_idle(cfqq
))
1313 cfqq
->p_root
= &cfqd
->prio_trees
[cfqq
->org_ioprio
];
1314 __cfqq
= cfq_prio_tree_lookup(cfqd
, cfqq
->p_root
,
1315 blk_rq_pos(cfqq
->next_rq
), &parent
, &p
);
1317 rb_link_node(&cfqq
->p_node
, parent
, p
);
1318 rb_insert_color(&cfqq
->p_node
, cfqq
->p_root
);
1320 cfqq
->p_root
= NULL
;
1324 * Update cfqq's position in the service tree.
1326 static void cfq_resort_rr_list(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1329 * Resorting requires the cfqq to be on the RR list already.
1331 if (cfq_cfqq_on_rr(cfqq
)) {
1332 cfq_service_tree_add(cfqd
, cfqq
, 0);
1333 cfq_prio_tree_add(cfqd
, cfqq
);
1338 * add to busy list of queues for service, trying to be fair in ordering
1339 * the pending list according to last request service
1341 static void cfq_add_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1343 cfq_log_cfqq(cfqd
, cfqq
, "add_to_rr");
1344 BUG_ON(cfq_cfqq_on_rr(cfqq
));
1345 cfq_mark_cfqq_on_rr(cfqq
);
1346 cfqd
->busy_queues
++;
1348 cfq_resort_rr_list(cfqd
, cfqq
);
1352 * Called when the cfqq no longer has requests pending, remove it from
1355 static void cfq_del_cfqq_rr(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1357 cfq_log_cfqq(cfqd
, cfqq
, "del_from_rr");
1358 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
1359 cfq_clear_cfqq_on_rr(cfqq
);
1361 if (!RB_EMPTY_NODE(&cfqq
->rb_node
)) {
1362 cfq_rb_erase(&cfqq
->rb_node
, cfqq
->service_tree
);
1363 cfqq
->service_tree
= NULL
;
1366 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1367 cfqq
->p_root
= NULL
;
1370 cfq_group_service_tree_del(cfqd
, cfqq
->cfqg
);
1371 BUG_ON(!cfqd
->busy_queues
);
1372 cfqd
->busy_queues
--;
1376 * rb tree support functions
1378 static void cfq_del_rq_rb(struct request
*rq
)
1380 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1381 const int sync
= rq_is_sync(rq
);
1383 BUG_ON(!cfqq
->queued
[sync
]);
1384 cfqq
->queued
[sync
]--;
1386 elv_rb_del(&cfqq
->sort_list
, rq
);
1388 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
)) {
1390 * Queue will be deleted from service tree when we actually
1391 * expire it later. Right now just remove it from prio tree
1395 rb_erase(&cfqq
->p_node
, cfqq
->p_root
);
1396 cfqq
->p_root
= NULL
;
1401 static void cfq_add_rq_rb(struct request
*rq
)
1403 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1404 struct cfq_data
*cfqd
= cfqq
->cfqd
;
1405 struct request
*__alias
, *prev
;
1407 cfqq
->queued
[rq_is_sync(rq
)]++;
1410 * looks a little odd, but the first insert might return an alias.
1411 * if that happens, put the alias on the dispatch list
1413 while ((__alias
= elv_rb_add(&cfqq
->sort_list
, rq
)) != NULL
)
1414 cfq_dispatch_insert(cfqd
->queue
, __alias
);
1416 if (!cfq_cfqq_on_rr(cfqq
))
1417 cfq_add_cfqq_rr(cfqd
, cfqq
);
1420 * check if this request is a better next-serve candidate
1422 prev
= cfqq
->next_rq
;
1423 cfqq
->next_rq
= cfq_choose_req(cfqd
, cfqq
->next_rq
, rq
, cfqd
->last_position
);
1426 * adjust priority tree position, if ->next_rq changes
1428 if (prev
!= cfqq
->next_rq
)
1429 cfq_prio_tree_add(cfqd
, cfqq
);
1431 BUG_ON(!cfqq
->next_rq
);
1434 static void cfq_reposition_rq_rb(struct cfq_queue
*cfqq
, struct request
*rq
)
1436 elv_rb_del(&cfqq
->sort_list
, rq
);
1437 cfqq
->queued
[rq_is_sync(rq
)]--;
1438 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1439 rq_data_dir(rq
), rq_is_sync(rq
));
1441 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
1442 &cfqq
->cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
1446 static struct request
*
1447 cfq_find_rq_fmerge(struct cfq_data
*cfqd
, struct bio
*bio
)
1449 struct task_struct
*tsk
= current
;
1450 struct cfq_io_context
*cic
;
1451 struct cfq_queue
*cfqq
;
1453 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
1457 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1459 sector_t sector
= bio
->bi_sector
+ bio_sectors(bio
);
1461 return elv_rb_find(&cfqq
->sort_list
, sector
);
1467 static void cfq_activate_request(struct request_queue
*q
, struct request
*rq
)
1469 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1471 cfqd
->rq_in_driver
++;
1472 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "activate rq, drv=%d",
1473 cfqd
->rq_in_driver
);
1475 cfqd
->last_position
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
1478 static void cfq_deactivate_request(struct request_queue
*q
, struct request
*rq
)
1480 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1482 WARN_ON(!cfqd
->rq_in_driver
);
1483 cfqd
->rq_in_driver
--;
1484 cfq_log_cfqq(cfqd
, RQ_CFQQ(rq
), "deactivate rq, drv=%d",
1485 cfqd
->rq_in_driver
);
1488 static void cfq_remove_request(struct request
*rq
)
1490 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1492 if (cfqq
->next_rq
== rq
)
1493 cfqq
->next_rq
= cfq_find_next_rq(cfqq
->cfqd
, cfqq
, rq
);
1495 list_del_init(&rq
->queuelist
);
1498 cfqq
->cfqd
->rq_queued
--;
1499 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq
))->blkg
,
1500 rq_data_dir(rq
), rq_is_sync(rq
));
1501 if (rq
->cmd_flags
& REQ_META
) {
1502 WARN_ON(!cfqq
->meta_pending
);
1503 cfqq
->meta_pending
--;
1507 static int cfq_merge(struct request_queue
*q
, struct request
**req
,
1510 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1511 struct request
*__rq
;
1513 __rq
= cfq_find_rq_fmerge(cfqd
, bio
);
1514 if (__rq
&& elv_rq_merge_ok(__rq
, bio
)) {
1516 return ELEVATOR_FRONT_MERGE
;
1519 return ELEVATOR_NO_MERGE
;
1522 static void cfq_merged_request(struct request_queue
*q
, struct request
*req
,
1525 if (type
== ELEVATOR_FRONT_MERGE
) {
1526 struct cfq_queue
*cfqq
= RQ_CFQQ(req
);
1528 cfq_reposition_rq_rb(cfqq
, req
);
1532 static void cfq_bio_merged(struct request_queue
*q
, struct request
*req
,
1535 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req
))->blkg
,
1536 bio_data_dir(bio
), cfq_bio_sync(bio
));
1540 cfq_merged_requests(struct request_queue
*q
, struct request
*rq
,
1541 struct request
*next
)
1543 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1545 * reposition in fifo if next is older than rq
1547 if (!list_empty(&rq
->queuelist
) && !list_empty(&next
->queuelist
) &&
1548 time_before(rq_fifo_time(next
), rq_fifo_time(rq
))) {
1549 list_move(&rq
->queuelist
, &next
->queuelist
);
1550 rq_set_fifo_time(rq
, rq_fifo_time(next
));
1553 if (cfqq
->next_rq
== next
)
1555 cfq_remove_request(next
);
1556 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq
))->blkg
,
1557 rq_data_dir(next
), rq_is_sync(next
));
1560 static int cfq_allow_merge(struct request_queue
*q
, struct request
*rq
,
1563 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1564 struct cfq_io_context
*cic
;
1565 struct cfq_queue
*cfqq
;
1568 * Disallow merge of a sync bio into an async request.
1570 if (cfq_bio_sync(bio
) && !rq_is_sync(rq
))
1574 * Lookup the cfqq that this bio will be queued with. Allow
1575 * merge only if rq is queued there.
1577 cic
= cfq_cic_lookup(cfqd
, current
->io_context
);
1581 cfqq
= cic_to_cfqq(cic
, cfq_bio_sync(bio
));
1582 return cfqq
== RQ_CFQQ(rq
);
1585 static inline void cfq_del_timer(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1587 del_timer(&cfqd
->idle_slice_timer
);
1588 cfq_blkiocg_update_idle_time_stats(&cfqq
->cfqg
->blkg
);
1591 static void __cfq_set_active_queue(struct cfq_data
*cfqd
,
1592 struct cfq_queue
*cfqq
)
1595 cfq_log_cfqq(cfqd
, cfqq
, "set_active wl_prio:%d wl_type:%d",
1596 cfqd
->serving_prio
, cfqd
->serving_type
);
1597 cfq_blkiocg_update_avg_queue_size_stats(&cfqq
->cfqg
->blkg
);
1598 cfqq
->slice_start
= 0;
1599 cfqq
->dispatch_start
= jiffies
;
1600 cfqq
->allocated_slice
= 0;
1601 cfqq
->slice_end
= 0;
1602 cfqq
->slice_dispatch
= 0;
1603 cfqq
->nr_sectors
= 0;
1605 cfq_clear_cfqq_wait_request(cfqq
);
1606 cfq_clear_cfqq_must_dispatch(cfqq
);
1607 cfq_clear_cfqq_must_alloc_slice(cfqq
);
1608 cfq_clear_cfqq_fifo_expire(cfqq
);
1609 cfq_mark_cfqq_slice_new(cfqq
);
1611 cfq_del_timer(cfqd
, cfqq
);
1614 cfqd
->active_queue
= cfqq
;
1618 * current cfqq expired its slice (or was too idle), select new one
1621 __cfq_slice_expired(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1624 cfq_log_cfqq(cfqd
, cfqq
, "slice expired t=%d", timed_out
);
1626 if (cfq_cfqq_wait_request(cfqq
))
1627 cfq_del_timer(cfqd
, cfqq
);
1629 cfq_clear_cfqq_wait_request(cfqq
);
1630 cfq_clear_cfqq_wait_busy(cfqq
);
1633 * If this cfqq is shared between multiple processes, check to
1634 * make sure that those processes are still issuing I/Os within
1635 * the mean seek distance. If not, it may be time to break the
1636 * queues apart again.
1638 if (cfq_cfqq_coop(cfqq
) && CFQQ_SEEKY(cfqq
))
1639 cfq_mark_cfqq_split_coop(cfqq
);
1642 * store what was left of this slice, if the queue idled/timed out
1645 if (cfq_cfqq_slice_new(cfqq
))
1646 cfqq
->slice_resid
= cfq_scaled_cfqq_slice(cfqd
, cfqq
);
1648 cfqq
->slice_resid
= cfqq
->slice_end
- jiffies
;
1649 cfq_log_cfqq(cfqd
, cfqq
, "resid=%ld", cfqq
->slice_resid
);
1652 cfq_group_served(cfqd
, cfqq
->cfqg
, cfqq
);
1654 if (cfq_cfqq_on_rr(cfqq
) && RB_EMPTY_ROOT(&cfqq
->sort_list
))
1655 cfq_del_cfqq_rr(cfqd
, cfqq
);
1657 cfq_resort_rr_list(cfqd
, cfqq
);
1659 if (cfqq
== cfqd
->active_queue
)
1660 cfqd
->active_queue
= NULL
;
1662 if (cfqd
->active_cic
) {
1663 put_io_context(cfqd
->active_cic
->ioc
);
1664 cfqd
->active_cic
= NULL
;
1668 static inline void cfq_slice_expired(struct cfq_data
*cfqd
, bool timed_out
)
1670 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1673 __cfq_slice_expired(cfqd
, cfqq
, timed_out
);
1677 * Get next queue for service. Unless we have a queue preemption,
1678 * we'll simply select the first cfqq in the service tree.
1680 static struct cfq_queue
*cfq_get_next_queue(struct cfq_data
*cfqd
)
1682 struct cfq_rb_root
*service_tree
=
1683 service_tree_for(cfqd
->serving_group
, cfqd
->serving_prio
,
1684 cfqd
->serving_type
);
1686 if (!cfqd
->rq_queued
)
1689 /* There is nothing to dispatch */
1692 if (RB_EMPTY_ROOT(&service_tree
->rb
))
1694 return cfq_rb_first(service_tree
);
1697 static struct cfq_queue
*cfq_get_next_queue_forced(struct cfq_data
*cfqd
)
1699 struct cfq_group
*cfqg
;
1700 struct cfq_queue
*cfqq
;
1702 struct cfq_rb_root
*st
;
1704 if (!cfqd
->rq_queued
)
1707 cfqg
= cfq_get_next_cfqg(cfqd
);
1711 for_each_cfqg_st(cfqg
, i
, j
, st
)
1712 if ((cfqq
= cfq_rb_first(st
)) != NULL
)
1718 * Get and set a new active queue for service.
1720 static struct cfq_queue
*cfq_set_active_queue(struct cfq_data
*cfqd
,
1721 struct cfq_queue
*cfqq
)
1724 cfqq
= cfq_get_next_queue(cfqd
);
1726 __cfq_set_active_queue(cfqd
, cfqq
);
1730 static inline sector_t
cfq_dist_from_last(struct cfq_data
*cfqd
,
1733 if (blk_rq_pos(rq
) >= cfqd
->last_position
)
1734 return blk_rq_pos(rq
) - cfqd
->last_position
;
1736 return cfqd
->last_position
- blk_rq_pos(rq
);
1739 static inline int cfq_rq_close(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
1742 return cfq_dist_from_last(cfqd
, rq
) <= CFQQ_CLOSE_THR
;
1745 static struct cfq_queue
*cfqq_close(struct cfq_data
*cfqd
,
1746 struct cfq_queue
*cur_cfqq
)
1748 struct rb_root
*root
= &cfqd
->prio_trees
[cur_cfqq
->org_ioprio
];
1749 struct rb_node
*parent
, *node
;
1750 struct cfq_queue
*__cfqq
;
1751 sector_t sector
= cfqd
->last_position
;
1753 if (RB_EMPTY_ROOT(root
))
1757 * First, if we find a request starting at the end of the last
1758 * request, choose it.
1760 __cfqq
= cfq_prio_tree_lookup(cfqd
, root
, sector
, &parent
, NULL
);
1765 * If the exact sector wasn't found, the parent of the NULL leaf
1766 * will contain the closest sector.
1768 __cfqq
= rb_entry(parent
, struct cfq_queue
, p_node
);
1769 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1772 if (blk_rq_pos(__cfqq
->next_rq
) < sector
)
1773 node
= rb_next(&__cfqq
->p_node
);
1775 node
= rb_prev(&__cfqq
->p_node
);
1779 __cfqq
= rb_entry(node
, struct cfq_queue
, p_node
);
1780 if (cfq_rq_close(cfqd
, cur_cfqq
, __cfqq
->next_rq
))
1788 * cur_cfqq - passed in so that we don't decide that the current queue is
1789 * closely cooperating with itself.
1791 * So, basically we're assuming that that cur_cfqq has dispatched at least
1792 * one request, and that cfqd->last_position reflects a position on the disk
1793 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1796 static struct cfq_queue
*cfq_close_cooperator(struct cfq_data
*cfqd
,
1797 struct cfq_queue
*cur_cfqq
)
1799 struct cfq_queue
*cfqq
;
1801 if (cfq_class_idle(cur_cfqq
))
1803 if (!cfq_cfqq_sync(cur_cfqq
))
1805 if (CFQQ_SEEKY(cur_cfqq
))
1809 * Don't search priority tree if it's the only queue in the group.
1811 if (cur_cfqq
->cfqg
->nr_cfqq
== 1)
1815 * We should notice if some of the queues are cooperating, eg
1816 * working closely on the same area of the disk. In that case,
1817 * we can group them together and don't waste time idling.
1819 cfqq
= cfqq_close(cfqd
, cur_cfqq
);
1823 /* If new queue belongs to different cfq_group, don't choose it */
1824 if (cur_cfqq
->cfqg
!= cfqq
->cfqg
)
1828 * It only makes sense to merge sync queues.
1830 if (!cfq_cfqq_sync(cfqq
))
1832 if (CFQQ_SEEKY(cfqq
))
1836 * Do not merge queues of different priority classes
1838 if (cfq_class_rt(cfqq
) != cfq_class_rt(cur_cfqq
))
1845 * Determine whether we should enforce idle window for this queue.
1848 static bool cfq_should_idle(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1850 enum wl_prio_t prio
= cfqq_prio(cfqq
);
1851 struct cfq_rb_root
*service_tree
= cfqq
->service_tree
;
1853 BUG_ON(!service_tree
);
1854 BUG_ON(!service_tree
->count
);
1856 if (!cfqd
->cfq_slice_idle
)
1859 /* We never do for idle class queues. */
1860 if (prio
== IDLE_WORKLOAD
)
1863 /* We do for queues that were marked with idle window flag. */
1864 if (cfq_cfqq_idle_window(cfqq
) &&
1865 !(blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
))
1869 * Otherwise, we do only if they are the last ones
1870 * in their service tree.
1872 if (service_tree
->count
== 1 && cfq_cfqq_sync(cfqq
))
1874 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. st->count:%d",
1875 service_tree
->count
);
1879 static void cfq_arm_slice_timer(struct cfq_data
*cfqd
)
1881 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
1882 struct cfq_io_context
*cic
;
1883 unsigned long sl
, group_idle
= 0;
1886 * SSD device without seek penalty, disable idling. But only do so
1887 * for devices that support queuing, otherwise we still have a problem
1888 * with sync vs async workloads.
1890 if (blk_queue_nonrot(cfqd
->queue
) && cfqd
->hw_tag
)
1893 WARN_ON(!RB_EMPTY_ROOT(&cfqq
->sort_list
));
1894 WARN_ON(cfq_cfqq_slice_new(cfqq
));
1897 * idle is disabled, either manually or by past process history
1899 if (!cfq_should_idle(cfqd
, cfqq
)) {
1900 /* no queue idling. Check for group idling */
1901 if (cfqd
->cfq_group_idle
)
1902 group_idle
= cfqd
->cfq_group_idle
;
1908 * still active requests from this queue, don't idle
1910 if (cfqq
->dispatched
)
1914 * task has exited, don't wait
1916 cic
= cfqd
->active_cic
;
1917 if (!cic
|| !atomic_read(&cic
->ioc
->nr_tasks
))
1921 * If our average think time is larger than the remaining time
1922 * slice, then don't idle. This avoids overrunning the allotted
1925 if (sample_valid(cic
->ttime_samples
) &&
1926 (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
)) {
1927 cfq_log_cfqq(cfqd
, cfqq
, "Not idling. think_time:%d",
1932 /* There are other queues in the group, don't do group idle */
1933 if (group_idle
&& cfqq
->cfqg
->nr_cfqq
> 1)
1936 cfq_mark_cfqq_wait_request(cfqq
);
1939 sl
= cfqd
->cfq_group_idle
;
1941 sl
= cfqd
->cfq_slice_idle
;
1943 mod_timer(&cfqd
->idle_slice_timer
, jiffies
+ sl
);
1944 cfq_blkiocg_update_set_idle_time_stats(&cfqq
->cfqg
->blkg
);
1945 cfq_log_cfqq(cfqd
, cfqq
, "arm_idle: %lu group_idle: %d", sl
,
1946 group_idle
? 1 : 0);
1950 * Move request from internal lists to the request queue dispatch list.
1952 static void cfq_dispatch_insert(struct request_queue
*q
, struct request
*rq
)
1954 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
1955 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
1957 cfq_log_cfqq(cfqd
, cfqq
, "dispatch_insert");
1959 cfqq
->next_rq
= cfq_find_next_rq(cfqd
, cfqq
, rq
);
1960 cfq_remove_request(rq
);
1962 (RQ_CFQG(rq
))->dispatched
++;
1963 elv_dispatch_sort(q
, rq
);
1965 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]++;
1966 cfqq
->nr_sectors
+= blk_rq_sectors(rq
);
1967 cfq_blkiocg_update_dispatch_stats(&cfqq
->cfqg
->blkg
, blk_rq_bytes(rq
),
1968 rq_data_dir(rq
), rq_is_sync(rq
));
1972 * return expired entry, or NULL to just start from scratch in rbtree
1974 static struct request
*cfq_check_fifo(struct cfq_queue
*cfqq
)
1976 struct request
*rq
= NULL
;
1978 if (cfq_cfqq_fifo_expire(cfqq
))
1981 cfq_mark_cfqq_fifo_expire(cfqq
);
1983 if (list_empty(&cfqq
->fifo
))
1986 rq
= rq_entry_fifo(cfqq
->fifo
.next
);
1987 if (time_before(jiffies
, rq_fifo_time(rq
)))
1990 cfq_log_cfqq(cfqq
->cfqd
, cfqq
, "fifo=%p", rq
);
1995 cfq_prio_to_maxrq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
1997 const int base_rq
= cfqd
->cfq_slice_async_rq
;
1999 WARN_ON(cfqq
->ioprio
>= IOPRIO_BE_NR
);
2001 return 2 * (base_rq
+ base_rq
* (CFQ_PRIO_LISTS
- 1 - cfqq
->ioprio
));
2005 * Must be called with the queue_lock held.
2007 static int cfqq_process_refs(struct cfq_queue
*cfqq
)
2009 int process_refs
, io_refs
;
2011 io_refs
= cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
];
2012 process_refs
= cfqq
->ref
- io_refs
;
2013 BUG_ON(process_refs
< 0);
2014 return process_refs
;
2017 static void cfq_setup_merge(struct cfq_queue
*cfqq
, struct cfq_queue
*new_cfqq
)
2019 int process_refs
, new_process_refs
;
2020 struct cfq_queue
*__cfqq
;
2023 * If there are no process references on the new_cfqq, then it is
2024 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2025 * chain may have dropped their last reference (not just their
2026 * last process reference).
2028 if (!cfqq_process_refs(new_cfqq
))
2031 /* Avoid a circular list and skip interim queue merges */
2032 while ((__cfqq
= new_cfqq
->new_cfqq
)) {
2038 process_refs
= cfqq_process_refs(cfqq
);
2039 new_process_refs
= cfqq_process_refs(new_cfqq
);
2041 * If the process for the cfqq has gone away, there is no
2042 * sense in merging the queues.
2044 if (process_refs
== 0 || new_process_refs
== 0)
2048 * Merge in the direction of the lesser amount of work.
2050 if (new_process_refs
>= process_refs
) {
2051 cfqq
->new_cfqq
= new_cfqq
;
2052 new_cfqq
->ref
+= process_refs
;
2054 new_cfqq
->new_cfqq
= cfqq
;
2055 cfqq
->ref
+= new_process_refs
;
2059 static enum wl_type_t
cfq_choose_wl(struct cfq_data
*cfqd
,
2060 struct cfq_group
*cfqg
, enum wl_prio_t prio
)
2062 struct cfq_queue
*queue
;
2064 bool key_valid
= false;
2065 unsigned long lowest_key
= 0;
2066 enum wl_type_t cur_best
= SYNC_NOIDLE_WORKLOAD
;
2068 for (i
= 0; i
<= SYNC_WORKLOAD
; ++i
) {
2069 /* select the one with lowest rb_key */
2070 queue
= cfq_rb_first(service_tree_for(cfqg
, prio
, i
));
2072 (!key_valid
|| time_before(queue
->rb_key
, lowest_key
))) {
2073 lowest_key
= queue
->rb_key
;
2082 static void choose_service_tree(struct cfq_data
*cfqd
, struct cfq_group
*cfqg
)
2086 struct cfq_rb_root
*st
;
2087 unsigned group_slice
;
2088 enum wl_prio_t original_prio
= cfqd
->serving_prio
;
2090 /* Choose next priority. RT > BE > IDLE */
2091 if (cfq_group_busy_queues_wl(RT_WORKLOAD
, cfqd
, cfqg
))
2092 cfqd
->serving_prio
= RT_WORKLOAD
;
2093 else if (cfq_group_busy_queues_wl(BE_WORKLOAD
, cfqd
, cfqg
))
2094 cfqd
->serving_prio
= BE_WORKLOAD
;
2096 cfqd
->serving_prio
= IDLE_WORKLOAD
;
2097 cfqd
->workload_expires
= jiffies
+ 1;
2101 if (original_prio
!= cfqd
->serving_prio
)
2105 * For RT and BE, we have to choose also the type
2106 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2109 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2113 * check workload expiration, and that we still have other queues ready
2115 if (count
&& !time_after(jiffies
, cfqd
->workload_expires
))
2119 /* otherwise select new workload type */
2120 cfqd
->serving_type
=
2121 cfq_choose_wl(cfqd
, cfqg
, cfqd
->serving_prio
);
2122 st
= service_tree_for(cfqg
, cfqd
->serving_prio
, cfqd
->serving_type
);
2126 * the workload slice is computed as a fraction of target latency
2127 * proportional to the number of queues in that workload, over
2128 * all the queues in the same priority class
2130 group_slice
= cfq_group_slice(cfqd
, cfqg
);
2132 slice
= group_slice
* count
/
2133 max_t(unsigned, cfqg
->busy_queues_avg
[cfqd
->serving_prio
],
2134 cfq_group_busy_queues_wl(cfqd
->serving_prio
, cfqd
, cfqg
));
2136 if (cfqd
->serving_type
== ASYNC_WORKLOAD
) {
2140 * Async queues are currently system wide. Just taking
2141 * proportion of queues with-in same group will lead to higher
2142 * async ratio system wide as generally root group is going
2143 * to have higher weight. A more accurate thing would be to
2144 * calculate system wide asnc/sync ratio.
2146 tmp
= cfq_target_latency
* cfqg_busy_async_queues(cfqd
, cfqg
);
2147 tmp
= tmp
/cfqd
->busy_queues
;
2148 slice
= min_t(unsigned, slice
, tmp
);
2150 /* async workload slice is scaled down according to
2151 * the sync/async slice ratio. */
2152 slice
= slice
* cfqd
->cfq_slice
[0] / cfqd
->cfq_slice
[1];
2154 /* sync workload slice is at least 2 * cfq_slice_idle */
2155 slice
= max(slice
, 2 * cfqd
->cfq_slice_idle
);
2157 slice
= max_t(unsigned, slice
, CFQ_MIN_TT
);
2158 cfq_log(cfqd
, "workload slice:%d", slice
);
2159 cfqd
->workload_expires
= jiffies
+ slice
;
2162 static struct cfq_group
*cfq_get_next_cfqg(struct cfq_data
*cfqd
)
2164 struct cfq_rb_root
*st
= &cfqd
->grp_service_tree
;
2165 struct cfq_group
*cfqg
;
2167 if (RB_EMPTY_ROOT(&st
->rb
))
2169 cfqg
= cfq_rb_first_group(st
);
2170 update_min_vdisktime(st
);
2174 static void cfq_choose_cfqg(struct cfq_data
*cfqd
)
2176 struct cfq_group
*cfqg
= cfq_get_next_cfqg(cfqd
);
2178 cfqd
->serving_group
= cfqg
;
2180 /* Restore the workload type data */
2181 if (cfqg
->saved_workload_slice
) {
2182 cfqd
->workload_expires
= jiffies
+ cfqg
->saved_workload_slice
;
2183 cfqd
->serving_type
= cfqg
->saved_workload
;
2184 cfqd
->serving_prio
= cfqg
->saved_serving_prio
;
2186 cfqd
->workload_expires
= jiffies
- 1;
2188 choose_service_tree(cfqd
, cfqg
);
2192 * Select a queue for service. If we have a current active queue,
2193 * check whether to continue servicing it, or retrieve and set a new one.
2195 static struct cfq_queue
*cfq_select_queue(struct cfq_data
*cfqd
)
2197 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2199 cfqq
= cfqd
->active_queue
;
2203 if (!cfqd
->rq_queued
)
2207 * We were waiting for group to get backlogged. Expire the queue
2209 if (cfq_cfqq_wait_busy(cfqq
) && !RB_EMPTY_ROOT(&cfqq
->sort_list
))
2213 * The active queue has run out of time, expire it and select new.
2215 if (cfq_slice_used(cfqq
) && !cfq_cfqq_must_dispatch(cfqq
)) {
2217 * If slice had not expired at the completion of last request
2218 * we might not have turned on wait_busy flag. Don't expire
2219 * the queue yet. Allow the group to get backlogged.
2221 * The very fact that we have used the slice, that means we
2222 * have been idling all along on this queue and it should be
2223 * ok to wait for this request to complete.
2225 if (cfqq
->cfqg
->nr_cfqq
== 1 && RB_EMPTY_ROOT(&cfqq
->sort_list
)
2226 && cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2230 goto check_group_idle
;
2234 * The active queue has requests and isn't expired, allow it to
2237 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
2241 * If another queue has a request waiting within our mean seek
2242 * distance, let it run. The expire code will check for close
2243 * cooperators and put the close queue at the front of the service
2244 * tree. If possible, merge the expiring queue with the new cfqq.
2246 new_cfqq
= cfq_close_cooperator(cfqd
, cfqq
);
2248 if (!cfqq
->new_cfqq
)
2249 cfq_setup_merge(cfqq
, new_cfqq
);
2254 * No requests pending. If the active queue still has requests in
2255 * flight or is idling for a new request, allow either of these
2256 * conditions to happen (or time out) before selecting a new queue.
2258 if (timer_pending(&cfqd
->idle_slice_timer
)) {
2264 * This is a deep seek queue, but the device is much faster than
2265 * the queue can deliver, don't idle
2267 if (CFQQ_SEEKY(cfqq
) && cfq_cfqq_idle_window(cfqq
) &&
2268 (cfq_cfqq_slice_new(cfqq
) ||
2269 (cfqq
->slice_end
- jiffies
> jiffies
- cfqq
->slice_start
))) {
2270 cfq_clear_cfqq_deep(cfqq
);
2271 cfq_clear_cfqq_idle_window(cfqq
);
2274 if (cfqq
->dispatched
&& cfq_should_idle(cfqd
, cfqq
)) {
2280 * If group idle is enabled and there are requests dispatched from
2281 * this group, wait for requests to complete.
2284 if (cfqd
->cfq_group_idle
&& cfqq
->cfqg
->nr_cfqq
== 1
2285 && cfqq
->cfqg
->dispatched
) {
2291 cfq_slice_expired(cfqd
, 0);
2294 * Current queue expired. Check if we have to switch to a new
2298 cfq_choose_cfqg(cfqd
);
2300 cfqq
= cfq_set_active_queue(cfqd
, new_cfqq
);
2305 static int __cfq_forced_dispatch_cfqq(struct cfq_queue
*cfqq
)
2309 while (cfqq
->next_rq
) {
2310 cfq_dispatch_insert(cfqq
->cfqd
->queue
, cfqq
->next_rq
);
2314 BUG_ON(!list_empty(&cfqq
->fifo
));
2316 /* By default cfqq is not expired if it is empty. Do it explicitly */
2317 __cfq_slice_expired(cfqq
->cfqd
, cfqq
, 0);
2322 * Drain our current requests. Used for barriers and when switching
2323 * io schedulers on-the-fly.
2325 static int cfq_forced_dispatch(struct cfq_data
*cfqd
)
2327 struct cfq_queue
*cfqq
;
2330 /* Expire the timeslice of the current active queue first */
2331 cfq_slice_expired(cfqd
, 0);
2332 while ((cfqq
= cfq_get_next_queue_forced(cfqd
)) != NULL
) {
2333 __cfq_set_active_queue(cfqd
, cfqq
);
2334 dispatched
+= __cfq_forced_dispatch_cfqq(cfqq
);
2337 BUG_ON(cfqd
->busy_queues
);
2339 cfq_log(cfqd
, "forced_dispatch=%d", dispatched
);
2343 static inline bool cfq_slice_used_soon(struct cfq_data
*cfqd
,
2344 struct cfq_queue
*cfqq
)
2346 /* the queue hasn't finished any request, can't estimate */
2347 if (cfq_cfqq_slice_new(cfqq
))
2349 if (time_after(jiffies
+ cfqd
->cfq_slice_idle
* cfqq
->dispatched
,
2356 static bool cfq_may_dispatch(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2358 unsigned int max_dispatch
;
2361 * Drain async requests before we start sync IO
2363 if (cfq_should_idle(cfqd
, cfqq
) && cfqd
->rq_in_flight
[BLK_RW_ASYNC
])
2367 * If this is an async queue and we have sync IO in flight, let it wait
2369 if (cfqd
->rq_in_flight
[BLK_RW_SYNC
] && !cfq_cfqq_sync(cfqq
))
2372 max_dispatch
= max_t(unsigned int, cfqd
->cfq_quantum
/ 2, 1);
2373 if (cfq_class_idle(cfqq
))
2377 * Does this cfqq already have too much IO in flight?
2379 if (cfqq
->dispatched
>= max_dispatch
) {
2381 * idle queue must always only have a single IO in flight
2383 if (cfq_class_idle(cfqq
))
2387 * We have other queues, don't allow more IO from this one
2389 if (cfqd
->busy_queues
> 1 && cfq_slice_used_soon(cfqd
, cfqq
))
2393 * Sole queue user, no limit
2395 if (cfqd
->busy_queues
== 1)
2399 * Normally we start throttling cfqq when cfq_quantum/2
2400 * requests have been dispatched. But we can drive
2401 * deeper queue depths at the beginning of slice
2402 * subjected to upper limit of cfq_quantum.
2404 max_dispatch
= cfqd
->cfq_quantum
;
2408 * Async queues must wait a bit before being allowed dispatch.
2409 * We also ramp up the dispatch depth gradually for async IO,
2410 * based on the last sync IO we serviced
2412 if (!cfq_cfqq_sync(cfqq
) && cfqd
->cfq_latency
) {
2413 unsigned long last_sync
= jiffies
- cfqd
->last_delayed_sync
;
2416 depth
= last_sync
/ cfqd
->cfq_slice
[1];
2417 if (!depth
&& !cfqq
->dispatched
)
2419 if (depth
< max_dispatch
)
2420 max_dispatch
= depth
;
2424 * If we're below the current max, allow a dispatch
2426 return cfqq
->dispatched
< max_dispatch
;
2430 * Dispatch a request from cfqq, moving them to the request queue
2433 static bool cfq_dispatch_request(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2437 BUG_ON(RB_EMPTY_ROOT(&cfqq
->sort_list
));
2439 if (!cfq_may_dispatch(cfqd
, cfqq
))
2443 * follow expired path, else get first next available
2445 rq
= cfq_check_fifo(cfqq
);
2450 * insert request into driver dispatch list
2452 cfq_dispatch_insert(cfqd
->queue
, rq
);
2454 if (!cfqd
->active_cic
) {
2455 struct cfq_io_context
*cic
= RQ_CIC(rq
);
2457 atomic_long_inc(&cic
->ioc
->refcount
);
2458 cfqd
->active_cic
= cic
;
2465 * Find the cfqq that we need to service and move a request from that to the
2468 static int cfq_dispatch_requests(struct request_queue
*q
, int force
)
2470 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
2471 struct cfq_queue
*cfqq
;
2473 if (!cfqd
->busy_queues
)
2476 if (unlikely(force
))
2477 return cfq_forced_dispatch(cfqd
);
2479 cfqq
= cfq_select_queue(cfqd
);
2484 * Dispatch a request from this cfqq, if it is allowed
2486 if (!cfq_dispatch_request(cfqd
, cfqq
))
2489 cfqq
->slice_dispatch
++;
2490 cfq_clear_cfqq_must_dispatch(cfqq
);
2493 * expire an async queue immediately if it has used up its slice. idle
2494 * queue always expire after 1 dispatch round.
2496 if (cfqd
->busy_queues
> 1 && ((!cfq_cfqq_sync(cfqq
) &&
2497 cfqq
->slice_dispatch
>= cfq_prio_to_maxrq(cfqd
, cfqq
)) ||
2498 cfq_class_idle(cfqq
))) {
2499 cfqq
->slice_end
= jiffies
+ 1;
2500 cfq_slice_expired(cfqd
, 0);
2503 cfq_log_cfqq(cfqd
, cfqq
, "dispatched a request");
2508 * task holds one reference to the queue, dropped when task exits. each rq
2509 * in-flight on this queue also holds a reference, dropped when rq is freed.
2511 * Each cfq queue took a reference on the parent group. Drop it now.
2512 * queue lock must be held here.
2514 static void cfq_put_queue(struct cfq_queue
*cfqq
)
2516 struct cfq_data
*cfqd
= cfqq
->cfqd
;
2517 struct cfq_group
*cfqg
;
2519 BUG_ON(cfqq
->ref
<= 0);
2525 cfq_log_cfqq(cfqd
, cfqq
, "put_queue");
2526 BUG_ON(rb_first(&cfqq
->sort_list
));
2527 BUG_ON(cfqq
->allocated
[READ
] + cfqq
->allocated
[WRITE
]);
2530 if (unlikely(cfqd
->active_queue
== cfqq
)) {
2531 __cfq_slice_expired(cfqd
, cfqq
, 0);
2532 cfq_schedule_dispatch(cfqd
);
2535 BUG_ON(cfq_cfqq_on_rr(cfqq
));
2536 kmem_cache_free(cfq_pool
, cfqq
);
2541 * Must always be called with the rcu_read_lock() held
2544 __call_for_each_cic(struct io_context
*ioc
,
2545 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2547 struct cfq_io_context
*cic
;
2548 struct hlist_node
*n
;
2550 hlist_for_each_entry_rcu(cic
, n
, &ioc
->cic_list
, cic_list
)
2555 * Call func for each cic attached to this ioc.
2558 call_for_each_cic(struct io_context
*ioc
,
2559 void (*func
)(struct io_context
*, struct cfq_io_context
*))
2562 __call_for_each_cic(ioc
, func
);
2566 static void cfq_cic_free_rcu(struct rcu_head
*head
)
2568 struct cfq_io_context
*cic
;
2570 cic
= container_of(head
, struct cfq_io_context
, rcu_head
);
2572 kmem_cache_free(cfq_ioc_pool
, cic
);
2573 elv_ioc_count_dec(cfq_ioc_count
);
2577 * CFQ scheduler is exiting, grab exit lock and check
2578 * the pending io context count. If it hits zero,
2579 * complete ioc_gone and set it back to NULL
2581 spin_lock(&ioc_gone_lock
);
2582 if (ioc_gone
&& !elv_ioc_count_read(cfq_ioc_count
)) {
2586 spin_unlock(&ioc_gone_lock
);
2590 static void cfq_cic_free(struct cfq_io_context
*cic
)
2592 call_rcu(&cic
->rcu_head
, cfq_cic_free_rcu
);
2595 static void cic_free_func(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2597 unsigned long flags
;
2598 unsigned long dead_key
= (unsigned long) cic
->key
;
2600 BUG_ON(!(dead_key
& CIC_DEAD_KEY
));
2602 spin_lock_irqsave(&ioc
->lock
, flags
);
2603 radix_tree_delete(&ioc
->radix_root
, dead_key
>> CIC_DEAD_INDEX_SHIFT
);
2604 hlist_del_rcu(&cic
->cic_list
);
2605 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2611 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2612 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2613 * and ->trim() which is called with the task lock held
2615 static void cfq_free_io_context(struct io_context
*ioc
)
2618 * ioc->refcount is zero here, or we are called from elv_unregister(),
2619 * so no more cic's are allowed to be linked into this ioc. So it
2620 * should be ok to iterate over the known list, we will see all cic's
2621 * since no new ones are added.
2623 __call_for_each_cic(ioc
, cic_free_func
);
2626 static void cfq_put_cooperator(struct cfq_queue
*cfqq
)
2628 struct cfq_queue
*__cfqq
, *next
;
2631 * If this queue was scheduled to merge with another queue, be
2632 * sure to drop the reference taken on that queue (and others in
2633 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2635 __cfqq
= cfqq
->new_cfqq
;
2637 if (__cfqq
== cfqq
) {
2638 WARN(1, "cfqq->new_cfqq loop detected\n");
2641 next
= __cfqq
->new_cfqq
;
2642 cfq_put_queue(__cfqq
);
2647 static void cfq_exit_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
2649 if (unlikely(cfqq
== cfqd
->active_queue
)) {
2650 __cfq_slice_expired(cfqd
, cfqq
, 0);
2651 cfq_schedule_dispatch(cfqd
);
2654 cfq_put_cooperator(cfqq
);
2656 cfq_put_queue(cfqq
);
2659 static void __cfq_exit_single_io_context(struct cfq_data
*cfqd
,
2660 struct cfq_io_context
*cic
)
2662 struct io_context
*ioc
= cic
->ioc
;
2664 list_del_init(&cic
->queue_list
);
2667 * Make sure dead mark is seen for dead queues
2670 cic
->key
= cfqd_dead_key(cfqd
);
2672 if (ioc
->ioc_data
== cic
)
2673 rcu_assign_pointer(ioc
->ioc_data
, NULL
);
2675 if (cic
->cfqq
[BLK_RW_ASYNC
]) {
2676 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_ASYNC
]);
2677 cic
->cfqq
[BLK_RW_ASYNC
] = NULL
;
2680 if (cic
->cfqq
[BLK_RW_SYNC
]) {
2681 cfq_exit_cfqq(cfqd
, cic
->cfqq
[BLK_RW_SYNC
]);
2682 cic
->cfqq
[BLK_RW_SYNC
] = NULL
;
2686 static void cfq_exit_single_io_context(struct io_context
*ioc
,
2687 struct cfq_io_context
*cic
)
2689 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2692 struct request_queue
*q
= cfqd
->queue
;
2693 unsigned long flags
;
2695 spin_lock_irqsave(q
->queue_lock
, flags
);
2698 * Ensure we get a fresh copy of the ->key to prevent
2699 * race between exiting task and queue
2701 smp_read_barrier_depends();
2702 if (cic
->key
== cfqd
)
2703 __cfq_exit_single_io_context(cfqd
, cic
);
2705 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2710 * The process that ioc belongs to has exited, we need to clean up
2711 * and put the internal structures we have that belongs to that process.
2713 static void cfq_exit_io_context(struct io_context
*ioc
)
2715 call_for_each_cic(ioc
, cfq_exit_single_io_context
);
2718 static struct cfq_io_context
*
2719 cfq_alloc_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
2721 struct cfq_io_context
*cic
;
2723 cic
= kmem_cache_alloc_node(cfq_ioc_pool
, gfp_mask
| __GFP_ZERO
,
2726 cic
->last_end_request
= jiffies
;
2727 INIT_LIST_HEAD(&cic
->queue_list
);
2728 INIT_HLIST_NODE(&cic
->cic_list
);
2729 cic
->dtor
= cfq_free_io_context
;
2730 cic
->exit
= cfq_exit_io_context
;
2731 elv_ioc_count_inc(cfq_ioc_count
);
2737 static void cfq_init_prio_data(struct cfq_queue
*cfqq
, struct io_context
*ioc
)
2739 struct task_struct
*tsk
= current
;
2742 if (!cfq_cfqq_prio_changed(cfqq
))
2745 ioprio_class
= IOPRIO_PRIO_CLASS(ioc
->ioprio
);
2746 switch (ioprio_class
) {
2748 printk(KERN_ERR
"cfq: bad prio %x\n", ioprio_class
);
2749 case IOPRIO_CLASS_NONE
:
2751 * no prio set, inherit CPU scheduling settings
2753 cfqq
->ioprio
= task_nice_ioprio(tsk
);
2754 cfqq
->ioprio_class
= task_nice_ioclass(tsk
);
2756 case IOPRIO_CLASS_RT
:
2757 cfqq
->ioprio
= task_ioprio(ioc
);
2758 cfqq
->ioprio_class
= IOPRIO_CLASS_RT
;
2760 case IOPRIO_CLASS_BE
:
2761 cfqq
->ioprio
= task_ioprio(ioc
);
2762 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
2764 case IOPRIO_CLASS_IDLE
:
2765 cfqq
->ioprio_class
= IOPRIO_CLASS_IDLE
;
2767 cfq_clear_cfqq_idle_window(cfqq
);
2772 * keep track of original prio settings in case we have to temporarily
2773 * elevate the priority of this queue
2775 cfqq
->org_ioprio
= cfqq
->ioprio
;
2776 cfqq
->org_ioprio_class
= cfqq
->ioprio_class
;
2777 cfq_clear_cfqq_prio_changed(cfqq
);
2780 static void changed_ioprio(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2782 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2783 struct cfq_queue
*cfqq
;
2784 unsigned long flags
;
2786 if (unlikely(!cfqd
))
2789 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
2791 cfqq
= cic
->cfqq
[BLK_RW_ASYNC
];
2793 struct cfq_queue
*new_cfqq
;
2794 new_cfqq
= cfq_get_queue(cfqd
, BLK_RW_ASYNC
, cic
->ioc
,
2797 cic
->cfqq
[BLK_RW_ASYNC
] = new_cfqq
;
2798 cfq_put_queue(cfqq
);
2802 cfqq
= cic
->cfqq
[BLK_RW_SYNC
];
2804 cfq_mark_cfqq_prio_changed(cfqq
);
2806 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
2809 static void cfq_ioc_set_ioprio(struct io_context
*ioc
)
2811 call_for_each_cic(ioc
, changed_ioprio
);
2812 ioc
->ioprio_changed
= 0;
2815 static void cfq_init_cfqq(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
2816 pid_t pid
, bool is_sync
)
2818 RB_CLEAR_NODE(&cfqq
->rb_node
);
2819 RB_CLEAR_NODE(&cfqq
->p_node
);
2820 INIT_LIST_HEAD(&cfqq
->fifo
);
2825 cfq_mark_cfqq_prio_changed(cfqq
);
2828 if (!cfq_class_idle(cfqq
))
2829 cfq_mark_cfqq_idle_window(cfqq
);
2830 cfq_mark_cfqq_sync(cfqq
);
2835 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2836 static void changed_cgroup(struct io_context
*ioc
, struct cfq_io_context
*cic
)
2838 struct cfq_queue
*sync_cfqq
= cic_to_cfqq(cic
, 1);
2839 struct cfq_data
*cfqd
= cic_to_cfqd(cic
);
2840 unsigned long flags
;
2841 struct request_queue
*q
;
2843 if (unlikely(!cfqd
))
2848 spin_lock_irqsave(q
->queue_lock
, flags
);
2852 * Drop reference to sync queue. A new sync queue will be
2853 * assigned in new group upon arrival of a fresh request.
2855 cfq_log_cfqq(cfqd
, sync_cfqq
, "changed cgroup");
2856 cic_set_cfqq(cic
, NULL
, 1);
2857 cfq_put_queue(sync_cfqq
);
2860 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2863 static void cfq_ioc_set_cgroup(struct io_context
*ioc
)
2865 call_for_each_cic(ioc
, changed_cgroup
);
2866 ioc
->cgroup_changed
= 0;
2868 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2870 static struct cfq_queue
*
2871 cfq_find_alloc_queue(struct cfq_data
*cfqd
, bool is_sync
,
2872 struct io_context
*ioc
, gfp_t gfp_mask
)
2874 struct cfq_queue
*cfqq
, *new_cfqq
= NULL
;
2875 struct cfq_io_context
*cic
;
2876 struct cfq_group
*cfqg
;
2879 cfqg
= cfq_get_cfqg(cfqd
, 1);
2880 cic
= cfq_cic_lookup(cfqd
, ioc
);
2881 /* cic always exists here */
2882 cfqq
= cic_to_cfqq(cic
, is_sync
);
2885 * Always try a new alloc if we fell back to the OOM cfqq
2886 * originally, since it should just be a temporary situation.
2888 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
2893 } else if (gfp_mask
& __GFP_WAIT
) {
2894 spin_unlock_irq(cfqd
->queue
->queue_lock
);
2895 new_cfqq
= kmem_cache_alloc_node(cfq_pool
,
2896 gfp_mask
| __GFP_ZERO
,
2898 spin_lock_irq(cfqd
->queue
->queue_lock
);
2902 cfqq
= kmem_cache_alloc_node(cfq_pool
,
2903 gfp_mask
| __GFP_ZERO
,
2908 cfq_init_cfqq(cfqd
, cfqq
, current
->pid
, is_sync
);
2909 cfq_init_prio_data(cfqq
, ioc
);
2910 cfq_link_cfqq_cfqg(cfqq
, cfqg
);
2911 cfq_log_cfqq(cfqd
, cfqq
, "alloced");
2913 cfqq
= &cfqd
->oom_cfqq
;
2917 kmem_cache_free(cfq_pool
, new_cfqq
);
2922 static struct cfq_queue
**
2923 cfq_async_queue_prio(struct cfq_data
*cfqd
, int ioprio_class
, int ioprio
)
2925 switch (ioprio_class
) {
2926 case IOPRIO_CLASS_RT
:
2927 return &cfqd
->async_cfqq
[0][ioprio
];
2928 case IOPRIO_CLASS_BE
:
2929 return &cfqd
->async_cfqq
[1][ioprio
];
2930 case IOPRIO_CLASS_IDLE
:
2931 return &cfqd
->async_idle_cfqq
;
2937 static struct cfq_queue
*
2938 cfq_get_queue(struct cfq_data
*cfqd
, bool is_sync
, struct io_context
*ioc
,
2941 const int ioprio
= task_ioprio(ioc
);
2942 const int ioprio_class
= task_ioprio_class(ioc
);
2943 struct cfq_queue
**async_cfqq
= NULL
;
2944 struct cfq_queue
*cfqq
= NULL
;
2947 async_cfqq
= cfq_async_queue_prio(cfqd
, ioprio_class
, ioprio
);
2952 cfqq
= cfq_find_alloc_queue(cfqd
, is_sync
, ioc
, gfp_mask
);
2955 * pin the queue now that it's allocated, scheduler exit will prune it
2957 if (!is_sync
&& !(*async_cfqq
)) {
2967 * We drop cfq io contexts lazily, so we may find a dead one.
2970 cfq_drop_dead_cic(struct cfq_data
*cfqd
, struct io_context
*ioc
,
2971 struct cfq_io_context
*cic
)
2973 unsigned long flags
;
2975 WARN_ON(!list_empty(&cic
->queue_list
));
2976 BUG_ON(cic
->key
!= cfqd_dead_key(cfqd
));
2978 spin_lock_irqsave(&ioc
->lock
, flags
);
2980 BUG_ON(ioc
->ioc_data
== cic
);
2982 radix_tree_delete(&ioc
->radix_root
, cfqd
->cic_index
);
2983 hlist_del_rcu(&cic
->cic_list
);
2984 spin_unlock_irqrestore(&ioc
->lock
, flags
);
2989 static struct cfq_io_context
*
2990 cfq_cic_lookup(struct cfq_data
*cfqd
, struct io_context
*ioc
)
2992 struct cfq_io_context
*cic
;
2993 unsigned long flags
;
3001 * we maintain a last-hit cache, to avoid browsing over the tree
3003 cic
= rcu_dereference(ioc
->ioc_data
);
3004 if (cic
&& cic
->key
== cfqd
) {
3010 cic
= radix_tree_lookup(&ioc
->radix_root
, cfqd
->cic_index
);
3014 if (unlikely(cic
->key
!= cfqd
)) {
3015 cfq_drop_dead_cic(cfqd
, ioc
, cic
);
3020 spin_lock_irqsave(&ioc
->lock
, flags
);
3021 rcu_assign_pointer(ioc
->ioc_data
, cic
);
3022 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3030 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
3031 * the process specific cfq io context when entered from the block layer.
3032 * Also adds the cic to a per-cfqd list, used when this queue is removed.
3034 static int cfq_cic_link(struct cfq_data
*cfqd
, struct io_context
*ioc
,
3035 struct cfq_io_context
*cic
, gfp_t gfp_mask
)
3037 unsigned long flags
;
3040 ret
= radix_tree_preload(gfp_mask
);
3045 spin_lock_irqsave(&ioc
->lock
, flags
);
3046 ret
= radix_tree_insert(&ioc
->radix_root
,
3047 cfqd
->cic_index
, cic
);
3049 hlist_add_head_rcu(&cic
->cic_list
, &ioc
->cic_list
);
3050 spin_unlock_irqrestore(&ioc
->lock
, flags
);
3052 radix_tree_preload_end();
3055 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3056 list_add(&cic
->queue_list
, &cfqd
->cic_list
);
3057 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3062 printk(KERN_ERR
"cfq: cic link failed!\n");
3068 * Setup general io context and cfq io context. There can be several cfq
3069 * io contexts per general io context, if this process is doing io to more
3070 * than one device managed by cfq.
3072 static struct cfq_io_context
*
3073 cfq_get_io_context(struct cfq_data
*cfqd
, gfp_t gfp_mask
)
3075 struct io_context
*ioc
= NULL
;
3076 struct cfq_io_context
*cic
;
3078 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3080 ioc
= get_io_context(gfp_mask
, cfqd
->queue
->node
);
3084 cic
= cfq_cic_lookup(cfqd
, ioc
);
3088 cic
= cfq_alloc_io_context(cfqd
, gfp_mask
);
3092 if (cfq_cic_link(cfqd
, ioc
, cic
, gfp_mask
))
3096 smp_read_barrier_depends();
3097 if (unlikely(ioc
->ioprio_changed
))
3098 cfq_ioc_set_ioprio(ioc
);
3100 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3101 if (unlikely(ioc
->cgroup_changed
))
3102 cfq_ioc_set_cgroup(ioc
);
3108 put_io_context(ioc
);
3113 cfq_update_io_thinktime(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
)
3115 unsigned long elapsed
= jiffies
- cic
->last_end_request
;
3116 unsigned long ttime
= min(elapsed
, 2UL * cfqd
->cfq_slice_idle
);
3118 cic
->ttime_samples
= (7*cic
->ttime_samples
+ 256) / 8;
3119 cic
->ttime_total
= (7*cic
->ttime_total
+ 256*ttime
) / 8;
3120 cic
->ttime_mean
= (cic
->ttime_total
+ 128) / cic
->ttime_samples
;
3124 cfq_update_io_seektime(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3128 sector_t n_sec
= blk_rq_sectors(rq
);
3129 if (cfqq
->last_request_pos
) {
3130 if (cfqq
->last_request_pos
< blk_rq_pos(rq
))
3131 sdist
= blk_rq_pos(rq
) - cfqq
->last_request_pos
;
3133 sdist
= cfqq
->last_request_pos
- blk_rq_pos(rq
);
3136 cfqq
->seek_history
<<= 1;
3137 if (blk_queue_nonrot(cfqd
->queue
))
3138 cfqq
->seek_history
|= (n_sec
< CFQQ_SECT_THR_NONROT
);
3140 cfqq
->seek_history
|= (sdist
> CFQQ_SEEK_THR
);
3144 * Disable idle window if the process thinks too long or seeks so much that
3148 cfq_update_idle_window(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3149 struct cfq_io_context
*cic
)
3151 int old_idle
, enable_idle
;
3154 * Don't idle for async or idle io prio class
3156 if (!cfq_cfqq_sync(cfqq
) || cfq_class_idle(cfqq
))
3159 enable_idle
= old_idle
= cfq_cfqq_idle_window(cfqq
);
3161 if (cfqq
->queued
[0] + cfqq
->queued
[1] >= 4)
3162 cfq_mark_cfqq_deep(cfqq
);
3164 if (cfqq
->next_rq
&& (cfqq
->next_rq
->cmd_flags
& REQ_NOIDLE
))
3166 else if (!atomic_read(&cic
->ioc
->nr_tasks
) || !cfqd
->cfq_slice_idle
||
3167 (!cfq_cfqq_deep(cfqq
) && CFQQ_SEEKY(cfqq
)))
3169 else if (sample_valid(cic
->ttime_samples
)) {
3170 if (cic
->ttime_mean
> cfqd
->cfq_slice_idle
)
3176 if (old_idle
!= enable_idle
) {
3177 cfq_log_cfqq(cfqd
, cfqq
, "idle=%d", enable_idle
);
3179 cfq_mark_cfqq_idle_window(cfqq
);
3181 cfq_clear_cfqq_idle_window(cfqq
);
3186 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3187 * no or if we aren't sure, a 1 will cause a preempt.
3190 cfq_should_preempt(struct cfq_data
*cfqd
, struct cfq_queue
*new_cfqq
,
3193 struct cfq_queue
*cfqq
;
3195 cfqq
= cfqd
->active_queue
;
3199 if (cfq_class_idle(new_cfqq
))
3202 if (cfq_class_idle(cfqq
))
3206 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3208 if (cfq_class_rt(cfqq
) && !cfq_class_rt(new_cfqq
))
3212 * if the new request is sync, but the currently running queue is
3213 * not, let the sync request have priority.
3215 if (rq_is_sync(rq
) && !cfq_cfqq_sync(cfqq
))
3218 if (new_cfqq
->cfqg
!= cfqq
->cfqg
)
3221 if (cfq_slice_used(cfqq
))
3224 /* Allow preemption only if we are idling on sync-noidle tree */
3225 if (cfqd
->serving_type
== SYNC_NOIDLE_WORKLOAD
&&
3226 cfqq_type(new_cfqq
) == SYNC_NOIDLE_WORKLOAD
&&
3227 new_cfqq
->service_tree
->count
== 2 &&
3228 RB_EMPTY_ROOT(&cfqq
->sort_list
))
3232 * So both queues are sync. Let the new request get disk time if
3233 * it's a metadata request and the current queue is doing regular IO.
3235 if ((rq
->cmd_flags
& REQ_META
) && !cfqq
->meta_pending
)
3239 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3241 if (cfq_class_rt(new_cfqq
) && !cfq_class_rt(cfqq
))
3244 /* An idle queue should not be idle now for some reason */
3245 if (RB_EMPTY_ROOT(&cfqq
->sort_list
) && !cfq_should_idle(cfqd
, cfqq
))
3248 if (!cfqd
->active_cic
|| !cfq_cfqq_wait_request(cfqq
))
3252 * if this request is as-good as one we would expect from the
3253 * current cfqq, let it preempt
3255 if (cfq_rq_close(cfqd
, cfqq
, rq
))
3262 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3263 * let it have half of its nominal slice.
3265 static void cfq_preempt_queue(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3267 struct cfq_queue
*old_cfqq
= cfqd
->active_queue
;
3269 cfq_log_cfqq(cfqd
, cfqq
, "preempt");
3270 cfq_slice_expired(cfqd
, 1);
3273 * workload type is changed, don't save slice, otherwise preempt
3276 if (cfqq_type(old_cfqq
) != cfqq_type(cfqq
))
3277 cfqq
->cfqg
->saved_workload_slice
= 0;
3280 * Put the new queue at the front of the of the current list,
3281 * so we know that it will be selected next.
3283 BUG_ON(!cfq_cfqq_on_rr(cfqq
));
3285 cfq_service_tree_add(cfqd
, cfqq
, 1);
3287 cfqq
->slice_end
= 0;
3288 cfq_mark_cfqq_slice_new(cfqq
);
3292 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3293 * something we should do about it
3296 cfq_rq_enqueued(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
,
3299 struct cfq_io_context
*cic
= RQ_CIC(rq
);
3302 if (rq
->cmd_flags
& REQ_META
)
3303 cfqq
->meta_pending
++;
3305 cfq_update_io_thinktime(cfqd
, cic
);
3306 cfq_update_io_seektime(cfqd
, cfqq
, rq
);
3307 cfq_update_idle_window(cfqd
, cfqq
, cic
);
3309 cfqq
->last_request_pos
= blk_rq_pos(rq
) + blk_rq_sectors(rq
);
3311 if (cfqq
== cfqd
->active_queue
) {
3313 * Remember that we saw a request from this process, but
3314 * don't start queuing just yet. Otherwise we risk seeing lots
3315 * of tiny requests, because we disrupt the normal plugging
3316 * and merging. If the request is already larger than a single
3317 * page, let it rip immediately. For that case we assume that
3318 * merging is already done. Ditto for a busy system that
3319 * has other work pending, don't risk delaying until the
3320 * idle timer unplug to continue working.
3322 if (cfq_cfqq_wait_request(cfqq
)) {
3323 if (blk_rq_bytes(rq
) > PAGE_CACHE_SIZE
||
3324 cfqd
->busy_queues
> 1) {
3325 cfq_del_timer(cfqd
, cfqq
);
3326 cfq_clear_cfqq_wait_request(cfqq
);
3327 __blk_run_queue(cfqd
->queue
);
3329 cfq_blkiocg_update_idle_time_stats(
3331 cfq_mark_cfqq_must_dispatch(cfqq
);
3334 } else if (cfq_should_preempt(cfqd
, cfqq
, rq
)) {
3336 * not the active queue - expire current slice if it is
3337 * idle and has expired it's mean thinktime or this new queue
3338 * has some old slice time left and is of higher priority or
3339 * this new queue is RT and the current one is BE
3341 cfq_preempt_queue(cfqd
, cfqq
);
3342 __blk_run_queue(cfqd
->queue
);
3346 static void cfq_insert_request(struct request_queue
*q
, struct request
*rq
)
3348 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3349 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3351 cfq_log_cfqq(cfqd
, cfqq
, "insert_request");
3352 cfq_init_prio_data(cfqq
, RQ_CIC(rq
)->ioc
);
3354 rq_set_fifo_time(rq
, jiffies
+ cfqd
->cfq_fifo_expire
[rq_is_sync(rq
)]);
3355 list_add_tail(&rq
->queuelist
, &cfqq
->fifo
);
3357 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq
))->blkg
,
3358 &cfqd
->serving_group
->blkg
, rq_data_dir(rq
),
3360 cfq_rq_enqueued(cfqd
, cfqq
, rq
);
3364 * Update hw_tag based on peak queue depth over 50 samples under
3367 static void cfq_update_hw_tag(struct cfq_data
*cfqd
)
3369 struct cfq_queue
*cfqq
= cfqd
->active_queue
;
3371 if (cfqd
->rq_in_driver
> cfqd
->hw_tag_est_depth
)
3372 cfqd
->hw_tag_est_depth
= cfqd
->rq_in_driver
;
3374 if (cfqd
->hw_tag
== 1)
3377 if (cfqd
->rq_queued
<= CFQ_HW_QUEUE_MIN
&&
3378 cfqd
->rq_in_driver
<= CFQ_HW_QUEUE_MIN
)
3382 * If active queue hasn't enough requests and can idle, cfq might not
3383 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3386 if (cfqq
&& cfq_cfqq_idle_window(cfqq
) &&
3387 cfqq
->dispatched
+ cfqq
->queued
[0] + cfqq
->queued
[1] <
3388 CFQ_HW_QUEUE_MIN
&& cfqd
->rq_in_driver
< CFQ_HW_QUEUE_MIN
)
3391 if (cfqd
->hw_tag_samples
++ < 50)
3394 if (cfqd
->hw_tag_est_depth
>= CFQ_HW_QUEUE_MIN
)
3400 static bool cfq_should_wait_busy(struct cfq_data
*cfqd
, struct cfq_queue
*cfqq
)
3402 struct cfq_io_context
*cic
= cfqd
->active_cic
;
3404 /* If the queue already has requests, don't wait */
3405 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3408 /* If there are other queues in the group, don't wait */
3409 if (cfqq
->cfqg
->nr_cfqq
> 1)
3412 if (cfq_slice_used(cfqq
))
3415 /* if slice left is less than think time, wait busy */
3416 if (cic
&& sample_valid(cic
->ttime_samples
)
3417 && (cfqq
->slice_end
- jiffies
< cic
->ttime_mean
))
3421 * If think times is less than a jiffy than ttime_mean=0 and above
3422 * will not be true. It might happen that slice has not expired yet
3423 * but will expire soon (4-5 ns) during select_queue(). To cover the
3424 * case where think time is less than a jiffy, mark the queue wait
3425 * busy if only 1 jiffy is left in the slice.
3427 if (cfqq
->slice_end
- jiffies
== 1)
3433 static void cfq_completed_request(struct request_queue
*q
, struct request
*rq
)
3435 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3436 struct cfq_data
*cfqd
= cfqq
->cfqd
;
3437 const int sync
= rq_is_sync(rq
);
3441 cfq_log_cfqq(cfqd
, cfqq
, "complete rqnoidle %d",
3442 !!(rq
->cmd_flags
& REQ_NOIDLE
));
3444 cfq_update_hw_tag(cfqd
);
3446 WARN_ON(!cfqd
->rq_in_driver
);
3447 WARN_ON(!cfqq
->dispatched
);
3448 cfqd
->rq_in_driver
--;
3450 (RQ_CFQG(rq
))->dispatched
--;
3451 cfq_blkiocg_update_completion_stats(&cfqq
->cfqg
->blkg
,
3452 rq_start_time_ns(rq
), rq_io_start_time_ns(rq
),
3453 rq_data_dir(rq
), rq_is_sync(rq
));
3455 cfqd
->rq_in_flight
[cfq_cfqq_sync(cfqq
)]--;
3458 RQ_CIC(rq
)->last_end_request
= now
;
3459 if (!time_after(rq
->start_time
+ cfqd
->cfq_fifo_expire
[1], now
))
3460 cfqd
->last_delayed_sync
= now
;
3464 * If this is the active queue, check if it needs to be expired,
3465 * or if we want to idle in case it has no pending requests.
3467 if (cfqd
->active_queue
== cfqq
) {
3468 const bool cfqq_empty
= RB_EMPTY_ROOT(&cfqq
->sort_list
);
3470 if (cfq_cfqq_slice_new(cfqq
)) {
3471 cfq_set_prio_slice(cfqd
, cfqq
);
3472 cfq_clear_cfqq_slice_new(cfqq
);
3476 * Should we wait for next request to come in before we expire
3479 if (cfq_should_wait_busy(cfqd
, cfqq
)) {
3480 unsigned long extend_sl
= cfqd
->cfq_slice_idle
;
3481 if (!cfqd
->cfq_slice_idle
)
3482 extend_sl
= cfqd
->cfq_group_idle
;
3483 cfqq
->slice_end
= jiffies
+ extend_sl
;
3484 cfq_mark_cfqq_wait_busy(cfqq
);
3485 cfq_log_cfqq(cfqd
, cfqq
, "will busy wait");
3489 * Idling is not enabled on:
3491 * - idle-priority queues
3493 * - queues with still some requests queued
3494 * - when there is a close cooperator
3496 if (cfq_slice_used(cfqq
) || cfq_class_idle(cfqq
))
3497 cfq_slice_expired(cfqd
, 1);
3498 else if (sync
&& cfqq_empty
&&
3499 !cfq_close_cooperator(cfqd
, cfqq
)) {
3500 cfq_arm_slice_timer(cfqd
);
3504 if (!cfqd
->rq_in_driver
)
3505 cfq_schedule_dispatch(cfqd
);
3509 * we temporarily boost lower priority queues if they are holding fs exclusive
3510 * resources. they are boosted to normal prio (CLASS_BE/4)
3512 static void cfq_prio_boost(struct cfq_queue
*cfqq
)
3514 if (has_fs_excl()) {
3516 * boost idle prio on transactions that would lock out other
3517 * users of the filesystem
3519 if (cfq_class_idle(cfqq
))
3520 cfqq
->ioprio_class
= IOPRIO_CLASS_BE
;
3521 if (cfqq
->ioprio
> IOPRIO_NORM
)
3522 cfqq
->ioprio
= IOPRIO_NORM
;
3525 * unboost the queue (if needed)
3527 cfqq
->ioprio_class
= cfqq
->org_ioprio_class
;
3528 cfqq
->ioprio
= cfqq
->org_ioprio
;
3532 static inline int __cfq_may_queue(struct cfq_queue
*cfqq
)
3534 if (cfq_cfqq_wait_request(cfqq
) && !cfq_cfqq_must_alloc_slice(cfqq
)) {
3535 cfq_mark_cfqq_must_alloc_slice(cfqq
);
3536 return ELV_MQUEUE_MUST
;
3539 return ELV_MQUEUE_MAY
;
3542 static int cfq_may_queue(struct request_queue
*q
, int rw
)
3544 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3545 struct task_struct
*tsk
= current
;
3546 struct cfq_io_context
*cic
;
3547 struct cfq_queue
*cfqq
;
3550 * don't force setup of a queue from here, as a call to may_queue
3551 * does not necessarily imply that a request actually will be queued.
3552 * so just lookup a possibly existing queue, or return 'may queue'
3555 cic
= cfq_cic_lookup(cfqd
, tsk
->io_context
);
3557 return ELV_MQUEUE_MAY
;
3559 cfqq
= cic_to_cfqq(cic
, rw_is_sync(rw
));
3561 cfq_init_prio_data(cfqq
, cic
->ioc
);
3562 cfq_prio_boost(cfqq
);
3564 return __cfq_may_queue(cfqq
);
3567 return ELV_MQUEUE_MAY
;
3571 * queue lock held here
3573 static void cfq_put_request(struct request
*rq
)
3575 struct cfq_queue
*cfqq
= RQ_CFQQ(rq
);
3578 const int rw
= rq_data_dir(rq
);
3580 BUG_ON(!cfqq
->allocated
[rw
]);
3581 cfqq
->allocated
[rw
]--;
3583 put_io_context(RQ_CIC(rq
)->ioc
);
3585 rq
->elevator_private
[0] = NULL
;
3586 rq
->elevator_private
[1] = NULL
;
3588 /* Put down rq reference on cfqg */
3589 cfq_put_cfqg(RQ_CFQG(rq
));
3590 rq
->elevator_private
[2] = NULL
;
3592 cfq_put_queue(cfqq
);
3596 static struct cfq_queue
*
3597 cfq_merge_cfqqs(struct cfq_data
*cfqd
, struct cfq_io_context
*cic
,
3598 struct cfq_queue
*cfqq
)
3600 cfq_log_cfqq(cfqd
, cfqq
, "merging with queue %p", cfqq
->new_cfqq
);
3601 cic_set_cfqq(cic
, cfqq
->new_cfqq
, 1);
3602 cfq_mark_cfqq_coop(cfqq
->new_cfqq
);
3603 cfq_put_queue(cfqq
);
3604 return cic_to_cfqq(cic
, 1);
3608 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3609 * was the last process referring to said cfqq.
3611 static struct cfq_queue
*
3612 split_cfqq(struct cfq_io_context
*cic
, struct cfq_queue
*cfqq
)
3614 if (cfqq_process_refs(cfqq
) == 1) {
3615 cfqq
->pid
= current
->pid
;
3616 cfq_clear_cfqq_coop(cfqq
);
3617 cfq_clear_cfqq_split_coop(cfqq
);
3621 cic_set_cfqq(cic
, NULL
, 1);
3623 cfq_put_cooperator(cfqq
);
3625 cfq_put_queue(cfqq
);
3629 * Allocate cfq data structures associated with this request.
3632 cfq_set_request(struct request_queue
*q
, struct request
*rq
, gfp_t gfp_mask
)
3634 struct cfq_data
*cfqd
= q
->elevator
->elevator_data
;
3635 struct cfq_io_context
*cic
;
3636 const int rw
= rq_data_dir(rq
);
3637 const bool is_sync
= rq_is_sync(rq
);
3638 struct cfq_queue
*cfqq
;
3639 unsigned long flags
;
3641 might_sleep_if(gfp_mask
& __GFP_WAIT
);
3643 cic
= cfq_get_io_context(cfqd
, gfp_mask
);
3645 spin_lock_irqsave(q
->queue_lock
, flags
);
3651 cfqq
= cic_to_cfqq(cic
, is_sync
);
3652 if (!cfqq
|| cfqq
== &cfqd
->oom_cfqq
) {
3653 cfqq
= cfq_get_queue(cfqd
, is_sync
, cic
->ioc
, gfp_mask
);
3654 cic_set_cfqq(cic
, cfqq
, is_sync
);
3657 * If the queue was seeky for too long, break it apart.
3659 if (cfq_cfqq_coop(cfqq
) && cfq_cfqq_split_coop(cfqq
)) {
3660 cfq_log_cfqq(cfqd
, cfqq
, "breaking apart cfqq");
3661 cfqq
= split_cfqq(cic
, cfqq
);
3667 * Check to see if this queue is scheduled to merge with
3668 * another, closely cooperating queue. The merging of
3669 * queues happens here as it must be done in process context.
3670 * The reference on new_cfqq was taken in merge_cfqqs.
3673 cfqq
= cfq_merge_cfqqs(cfqd
, cic
, cfqq
);
3676 cfqq
->allocated
[rw
]++;
3679 rq
->elevator_private
[0] = cic
;
3680 rq
->elevator_private
[1] = cfqq
;
3681 rq
->elevator_private
[2] = cfq_ref_get_cfqg(cfqq
->cfqg
);
3682 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3687 put_io_context(cic
->ioc
);
3689 cfq_schedule_dispatch(cfqd
);
3690 spin_unlock_irqrestore(q
->queue_lock
, flags
);
3691 cfq_log(cfqd
, "set_request fail");
3695 static void cfq_kick_queue(struct work_struct
*work
)
3697 struct cfq_data
*cfqd
=
3698 container_of(work
, struct cfq_data
, unplug_work
);
3699 struct request_queue
*q
= cfqd
->queue
;
3701 spin_lock_irq(q
->queue_lock
);
3702 __blk_run_queue(cfqd
->queue
);
3703 spin_unlock_irq(q
->queue_lock
);
3707 * Timer running if the active_queue is currently idling inside its time slice
3709 static void cfq_idle_slice_timer(unsigned long data
)
3711 struct cfq_data
*cfqd
= (struct cfq_data
*) data
;
3712 struct cfq_queue
*cfqq
;
3713 unsigned long flags
;
3716 cfq_log(cfqd
, "idle timer fired");
3718 spin_lock_irqsave(cfqd
->queue
->queue_lock
, flags
);
3720 cfqq
= cfqd
->active_queue
;
3725 * We saw a request before the queue expired, let it through
3727 if (cfq_cfqq_must_dispatch(cfqq
))
3733 if (cfq_slice_used(cfqq
))
3737 * only expire and reinvoke request handler, if there are
3738 * other queues with pending requests
3740 if (!cfqd
->busy_queues
)
3744 * not expired and it has a request pending, let it dispatch
3746 if (!RB_EMPTY_ROOT(&cfqq
->sort_list
))
3750 * Queue depth flag is reset only when the idle didn't succeed
3752 cfq_clear_cfqq_deep(cfqq
);
3755 cfq_slice_expired(cfqd
, timed_out
);
3757 cfq_schedule_dispatch(cfqd
);
3759 spin_unlock_irqrestore(cfqd
->queue
->queue_lock
, flags
);
3762 static void cfq_shutdown_timer_wq(struct cfq_data
*cfqd
)
3764 del_timer_sync(&cfqd
->idle_slice_timer
);
3765 cancel_work_sync(&cfqd
->unplug_work
);
3768 static void cfq_put_async_queues(struct cfq_data
*cfqd
)
3772 for (i
= 0; i
< IOPRIO_BE_NR
; i
++) {
3773 if (cfqd
->async_cfqq
[0][i
])
3774 cfq_put_queue(cfqd
->async_cfqq
[0][i
]);
3775 if (cfqd
->async_cfqq
[1][i
])
3776 cfq_put_queue(cfqd
->async_cfqq
[1][i
]);
3779 if (cfqd
->async_idle_cfqq
)
3780 cfq_put_queue(cfqd
->async_idle_cfqq
);
3783 static void cfq_cfqd_free(struct rcu_head
*head
)
3785 kfree(container_of(head
, struct cfq_data
, rcu
));
3788 static void cfq_exit_queue(struct elevator_queue
*e
)
3790 struct cfq_data
*cfqd
= e
->elevator_data
;
3791 struct request_queue
*q
= cfqd
->queue
;
3793 cfq_shutdown_timer_wq(cfqd
);
3795 spin_lock_irq(q
->queue_lock
);
3797 if (cfqd
->active_queue
)
3798 __cfq_slice_expired(cfqd
, cfqd
->active_queue
, 0);
3800 while (!list_empty(&cfqd
->cic_list
)) {
3801 struct cfq_io_context
*cic
= list_entry(cfqd
->cic_list
.next
,
3802 struct cfq_io_context
,
3805 __cfq_exit_single_io_context(cfqd
, cic
);
3808 cfq_put_async_queues(cfqd
);
3809 cfq_release_cfq_groups(cfqd
);
3810 cfq_blkiocg_del_blkio_group(&cfqd
->root_group
.blkg
);
3812 spin_unlock_irq(q
->queue_lock
);
3814 cfq_shutdown_timer_wq(cfqd
);
3816 spin_lock(&cic_index_lock
);
3817 ida_remove(&cic_index_ida
, cfqd
->cic_index
);
3818 spin_unlock(&cic_index_lock
);
3820 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3821 call_rcu(&cfqd
->rcu
, cfq_cfqd_free
);
3824 static int cfq_alloc_cic_index(void)
3829 if (!ida_pre_get(&cic_index_ida
, GFP_KERNEL
))
3832 spin_lock(&cic_index_lock
);
3833 error
= ida_get_new(&cic_index_ida
, &index
);
3834 spin_unlock(&cic_index_lock
);
3835 if (error
&& error
!= -EAGAIN
)
3842 static void *cfq_init_queue(struct request_queue
*q
)
3844 struct cfq_data
*cfqd
;
3846 struct cfq_group
*cfqg
;
3847 struct cfq_rb_root
*st
;
3849 i
= cfq_alloc_cic_index();
3853 cfqd
= kmalloc_node(sizeof(*cfqd
), GFP_KERNEL
| __GFP_ZERO
, q
->node
);
3858 * Don't need take queue_lock in the routine, since we are
3859 * initializing the ioscheduler, and nobody is using cfqd
3861 cfqd
->cic_index
= i
;
3863 /* Init root service tree */
3864 cfqd
->grp_service_tree
= CFQ_RB_ROOT
;
3866 /* Init root group */
3867 cfqg
= &cfqd
->root_group
;
3868 for_each_cfqg_st(cfqg
, i
, j
, st
)
3870 RB_CLEAR_NODE(&cfqg
->rb_node
);
3872 /* Give preference to root group over other groups */
3873 cfqg
->weight
= 2*BLKIO_WEIGHT_DEFAULT
;
3875 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3877 * Take a reference to root group which we never drop. This is just
3878 * to make sure that cfq_put_cfqg() does not try to kfree root group
3882 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup
, &cfqg
->blkg
,
3887 * Not strictly needed (since RB_ROOT just clears the node and we
3888 * zeroed cfqd on alloc), but better be safe in case someone decides
3889 * to add magic to the rb code
3891 for (i
= 0; i
< CFQ_PRIO_LISTS
; i
++)
3892 cfqd
->prio_trees
[i
] = RB_ROOT
;
3895 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3896 * Grab a permanent reference to it, so that the normal code flow
3897 * will not attempt to free it.
3899 cfq_init_cfqq(cfqd
, &cfqd
->oom_cfqq
, 1, 0);
3900 cfqd
->oom_cfqq
.ref
++;
3901 cfq_link_cfqq_cfqg(&cfqd
->oom_cfqq
, &cfqd
->root_group
);
3903 INIT_LIST_HEAD(&cfqd
->cic_list
);
3907 init_timer(&cfqd
->idle_slice_timer
);
3908 cfqd
->idle_slice_timer
.function
= cfq_idle_slice_timer
;
3909 cfqd
->idle_slice_timer
.data
= (unsigned long) cfqd
;
3911 INIT_WORK(&cfqd
->unplug_work
, cfq_kick_queue
);
3913 cfqd
->cfq_quantum
= cfq_quantum
;
3914 cfqd
->cfq_fifo_expire
[0] = cfq_fifo_expire
[0];
3915 cfqd
->cfq_fifo_expire
[1] = cfq_fifo_expire
[1];
3916 cfqd
->cfq_back_max
= cfq_back_max
;
3917 cfqd
->cfq_back_penalty
= cfq_back_penalty
;
3918 cfqd
->cfq_slice
[0] = cfq_slice_async
;
3919 cfqd
->cfq_slice
[1] = cfq_slice_sync
;
3920 cfqd
->cfq_slice_async_rq
= cfq_slice_async_rq
;
3921 cfqd
->cfq_slice_idle
= cfq_slice_idle
;
3922 cfqd
->cfq_group_idle
= cfq_group_idle
;
3923 cfqd
->cfq_latency
= 1;
3926 * we optimistically start assuming sync ops weren't delayed in last
3927 * second, in order to have larger depth for async operations.
3929 cfqd
->last_delayed_sync
= jiffies
- HZ
;
3933 static void cfq_slab_kill(void)
3936 * Caller already ensured that pending RCU callbacks are completed,
3937 * so we should have no busy allocations at this point.
3940 kmem_cache_destroy(cfq_pool
);
3942 kmem_cache_destroy(cfq_ioc_pool
);
3945 static int __init
cfq_slab_setup(void)
3947 cfq_pool
= KMEM_CACHE(cfq_queue
, 0);
3951 cfq_ioc_pool
= KMEM_CACHE(cfq_io_context
, 0);
3962 * sysfs parts below -->
3965 cfq_var_show(unsigned int var
, char *page
)
3967 return sprintf(page
, "%d\n", var
);
3971 cfq_var_store(unsigned int *var
, const char *page
, size_t count
)
3973 char *p
= (char *) page
;
3975 *var
= simple_strtoul(p
, &p
, 10);
3979 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3980 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3982 struct cfq_data *cfqd = e->elevator_data; \
3983 unsigned int __data = __VAR; \
3985 __data = jiffies_to_msecs(__data); \
3986 return cfq_var_show(__data, (page)); \
3988 SHOW_FUNCTION(cfq_quantum_show
, cfqd
->cfq_quantum
, 0);
3989 SHOW_FUNCTION(cfq_fifo_expire_sync_show
, cfqd
->cfq_fifo_expire
[1], 1);
3990 SHOW_FUNCTION(cfq_fifo_expire_async_show
, cfqd
->cfq_fifo_expire
[0], 1);
3991 SHOW_FUNCTION(cfq_back_seek_max_show
, cfqd
->cfq_back_max
, 0);
3992 SHOW_FUNCTION(cfq_back_seek_penalty_show
, cfqd
->cfq_back_penalty
, 0);
3993 SHOW_FUNCTION(cfq_slice_idle_show
, cfqd
->cfq_slice_idle
, 1);
3994 SHOW_FUNCTION(cfq_group_idle_show
, cfqd
->cfq_group_idle
, 1);
3995 SHOW_FUNCTION(cfq_slice_sync_show
, cfqd
->cfq_slice
[1], 1);
3996 SHOW_FUNCTION(cfq_slice_async_show
, cfqd
->cfq_slice
[0], 1);
3997 SHOW_FUNCTION(cfq_slice_async_rq_show
, cfqd
->cfq_slice_async_rq
, 0);
3998 SHOW_FUNCTION(cfq_low_latency_show
, cfqd
->cfq_latency
, 0);
3999 #undef SHOW_FUNCTION
4001 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
4002 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4004 struct cfq_data *cfqd = e->elevator_data; \
4005 unsigned int __data; \
4006 int ret = cfq_var_store(&__data, (page), count); \
4007 if (__data < (MIN)) \
4009 else if (__data > (MAX)) \
4012 *(__PTR) = msecs_to_jiffies(__data); \
4014 *(__PTR) = __data; \
4017 STORE_FUNCTION(cfq_quantum_store
, &cfqd
->cfq_quantum
, 1, UINT_MAX
, 0);
4018 STORE_FUNCTION(cfq_fifo_expire_sync_store
, &cfqd
->cfq_fifo_expire
[1], 1,
4020 STORE_FUNCTION(cfq_fifo_expire_async_store
, &cfqd
->cfq_fifo_expire
[0], 1,
4022 STORE_FUNCTION(cfq_back_seek_max_store
, &cfqd
->cfq_back_max
, 0, UINT_MAX
, 0);
4023 STORE_FUNCTION(cfq_back_seek_penalty_store
, &cfqd
->cfq_back_penalty
, 1,
4025 STORE_FUNCTION(cfq_slice_idle_store
, &cfqd
->cfq_slice_idle
, 0, UINT_MAX
, 1);
4026 STORE_FUNCTION(cfq_group_idle_store
, &cfqd
->cfq_group_idle
, 0, UINT_MAX
, 1);
4027 STORE_FUNCTION(cfq_slice_sync_store
, &cfqd
->cfq_slice
[1], 1, UINT_MAX
, 1);
4028 STORE_FUNCTION(cfq_slice_async_store
, &cfqd
->cfq_slice
[0], 1, UINT_MAX
, 1);
4029 STORE_FUNCTION(cfq_slice_async_rq_store
, &cfqd
->cfq_slice_async_rq
, 1,
4031 STORE_FUNCTION(cfq_low_latency_store
, &cfqd
->cfq_latency
, 0, 1, 0);
4032 #undef STORE_FUNCTION
4034 #define CFQ_ATTR(name) \
4035 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4037 static struct elv_fs_entry cfq_attrs
[] = {
4039 CFQ_ATTR(fifo_expire_sync
),
4040 CFQ_ATTR(fifo_expire_async
),
4041 CFQ_ATTR(back_seek_max
),
4042 CFQ_ATTR(back_seek_penalty
),
4043 CFQ_ATTR(slice_sync
),
4044 CFQ_ATTR(slice_async
),
4045 CFQ_ATTR(slice_async_rq
),
4046 CFQ_ATTR(slice_idle
),
4047 CFQ_ATTR(group_idle
),
4048 CFQ_ATTR(low_latency
),
4052 static struct elevator_type iosched_cfq
= {
4054 .elevator_merge_fn
= cfq_merge
,
4055 .elevator_merged_fn
= cfq_merged_request
,
4056 .elevator_merge_req_fn
= cfq_merged_requests
,
4057 .elevator_allow_merge_fn
= cfq_allow_merge
,
4058 .elevator_bio_merged_fn
= cfq_bio_merged
,
4059 .elevator_dispatch_fn
= cfq_dispatch_requests
,
4060 .elevator_add_req_fn
= cfq_insert_request
,
4061 .elevator_activate_req_fn
= cfq_activate_request
,
4062 .elevator_deactivate_req_fn
= cfq_deactivate_request
,
4063 .elevator_queue_empty_fn
= cfq_queue_empty
,
4064 .elevator_completed_req_fn
= cfq_completed_request
,
4065 .elevator_former_req_fn
= elv_rb_former_request
,
4066 .elevator_latter_req_fn
= elv_rb_latter_request
,
4067 .elevator_set_req_fn
= cfq_set_request
,
4068 .elevator_put_req_fn
= cfq_put_request
,
4069 .elevator_may_queue_fn
= cfq_may_queue
,
4070 .elevator_init_fn
= cfq_init_queue
,
4071 .elevator_exit_fn
= cfq_exit_queue
,
4072 .trim
= cfq_free_io_context
,
4074 .elevator_attrs
= cfq_attrs
,
4075 .elevator_name
= "cfq",
4076 .elevator_owner
= THIS_MODULE
,
4079 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4080 static struct blkio_policy_type blkio_policy_cfq
= {
4082 .blkio_unlink_group_fn
= cfq_unlink_blkio_group
,
4083 .blkio_update_group_weight_fn
= cfq_update_blkio_group_weight
,
4085 .plid
= BLKIO_POLICY_PROP
,
4088 static struct blkio_policy_type blkio_policy_cfq
;
4091 static int __init
cfq_init(void)
4094 * could be 0 on HZ < 1000 setups
4096 if (!cfq_slice_async
)
4097 cfq_slice_async
= 1;
4098 if (!cfq_slice_idle
)
4101 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4102 if (!cfq_group_idle
)
4107 if (cfq_slab_setup())
4110 elv_register(&iosched_cfq
);
4111 blkio_policy_register(&blkio_policy_cfq
);
4116 static void __exit
cfq_exit(void)
4118 DECLARE_COMPLETION_ONSTACK(all_gone
);
4119 blkio_policy_unregister(&blkio_policy_cfq
);
4120 elv_unregister(&iosched_cfq
);
4121 ioc_gone
= &all_gone
;
4122 /* ioc_gone's update must be visible before reading ioc_count */
4126 * this also protects us from entering cfq_slab_kill() with
4127 * pending RCU callbacks
4129 if (elv_ioc_count_read(cfq_ioc_count
))
4130 wait_for_completion(&all_gone
);
4131 ida_destroy(&cic_index_ida
);
4135 module_init(cfq_init
);
4136 module_exit(cfq_exit
);
4138 MODULE_AUTHOR("Jens Axboe");
4139 MODULE_LICENSE("GPL");
4140 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");