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1 | /* |
2 | * CFQ, or complete fairness queueing, disk scheduler. |
3 | * |
4 | * Based on ideas from a previously unfinished io |
5 | * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. |
6 | * |
7 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
8 | */ |
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> |
17 | #include "cfq.h" |
18 | |
19 | /* |
20 | * tunables |
21 | */ |
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; |
36 | |
37 | /* |
38 | * offset from end of service tree |
39 | */ |
40 | #define CFQ_IDLE_DELAY (HZ / 5) |
41 | |
42 | /* |
43 | * below this threshold, we consider thinktime immediate |
44 | */ |
45 | #define CFQ_MIN_TT (2) |
46 | |
47 | #define CFQ_SLICE_SCALE (5) |
48 | #define CFQ_HW_QUEUE_MIN (5) |
49 | #define CFQ_SERVICE_SHIFT 12 |
50 | |
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) |
55 | |
56 | #define RQ_CIC(rq) \ |
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]) |
60 | |
61 | static struct kmem_cache *cfq_pool; |
62 | static struct kmem_cache *cfq_ioc_pool; |
63 | |
64 | static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); |
65 | static struct completion *ioc_gone; |
66 | static DEFINE_SPINLOCK(ioc_gone_lock); |
67 | |
68 | static DEFINE_SPINLOCK(cic_index_lock); |
69 | static DEFINE_IDA(cic_index_ida); |
70 | |
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) |
74 | |
75 | #define sample_valid(samples) ((samples) > 80) |
76 | #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) |
77 | |
78 | /* |
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. |
83 | */ |
84 | struct cfq_rb_root { |
85 | struct rb_root rb; |
86 | struct rb_node *left; |
87 | unsigned count; |
88 | unsigned total_weight; |
89 | u64 min_vdisktime; |
90 | }; |
91 | #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \ |
92 | .count = 0, .min_vdisktime = 0, } |
93 | |
94 | /* |
95 | * Per process-grouping structure |
96 | */ |
97 | struct cfq_queue { |
98 | /* reference count */ |
99 | int ref; |
100 | /* various state flags, see below */ |
101 | unsigned int flags; |
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 */ |
117 | int queued[2]; |
118 | /* currently allocated requests */ |
119 | int allocated[2]; |
120 | /* fifo list of requests in sort_list */ |
121 | struct list_head fifo; |
122 | |
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; |
130 | long slice_resid; |
131 | |
132 | /* pending metadata requests */ |
133 | int meta_pending; |
134 | /* number of requests that are on the dispatch list or inside driver */ |
135 | int dispatched; |
136 | |
137 | /* io prio of this group */ |
138 | unsigned short ioprio, org_ioprio; |
139 | unsigned short ioprio_class, org_ioprio_class; |
140 | |
141 | pid_t pid; |
142 | |
143 | u32 seek_history; |
144 | sector_t last_request_pos; |
145 | |
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; |
151 | }; |
152 | |
153 | /* |
154 | * First index in the service_trees. |
155 | * IDLE is handled separately, so it has negative index |
156 | */ |
157 | enum wl_prio_t { |
158 | BE_WORKLOAD = 0, |
159 | RT_WORKLOAD = 1, |
160 | IDLE_WORKLOAD = 2, |
161 | CFQ_PRIO_NR, |
162 | }; |
163 | |
164 | /* |
165 | * Second index in the service_trees. |
166 | */ |
167 | enum wl_type_t { |
168 | ASYNC_WORKLOAD = 0, |
169 | SYNC_NOIDLE_WORKLOAD = 1, |
170 | SYNC_WORKLOAD = 2 |
171 | }; |
172 | |
173 | /* This is per cgroup per device grouping structure */ |
174 | struct cfq_group { |
175 | /* group service_tree member */ |
176 | struct rb_node rb_node; |
177 | |
178 | /* group service_tree key */ |
179 | u64 vdisktime; |
180 | unsigned int weight; |
181 | unsigned int new_weight; |
182 | bool needs_update; |
183 | |
184 | /* number of cfqq currently on this group */ |
185 | int nr_cfqq; |
186 | |
187 | /* |
188 | * Per group busy queues average. Useful for workload slice calc. We |
189 | * create the array for each prio class but at run time it is used |
190 | * only for RT and BE class and slot for IDLE class remains unused. |
191 | * This is primarily done to avoid confusion and a gcc warning. |
192 | */ |
193 | unsigned int busy_queues_avg[CFQ_PRIO_NR]; |
194 | /* |
195 | * rr lists of queues with requests. We maintain service trees for |
196 | * RT and BE classes. These trees are subdivided in subclasses |
197 | * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE |
198 | * class there is no subclassification and all the cfq queues go on |
199 | * a single tree service_tree_idle. |
200 | * Counts are embedded in the cfq_rb_root |
201 | */ |
202 | struct cfq_rb_root service_trees[2][3]; |
203 | struct cfq_rb_root service_tree_idle; |
204 | |
205 | unsigned long saved_workload_slice; |
206 | enum wl_type_t saved_workload; |
207 | enum wl_prio_t saved_serving_prio; |
208 | struct blkio_group blkg; |
209 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
210 | struct hlist_node cfqd_node; |
211 | int ref; |
212 | #endif |
213 | /* number of requests that are on the dispatch list or inside driver */ |
214 | int dispatched; |
215 | }; |
216 | |
217 | /* |
218 | * Per block device queue structure |
219 | */ |
220 | struct cfq_data { |
221 | struct request_queue *queue; |
222 | /* Root service tree for cfq_groups */ |
223 | struct cfq_rb_root grp_service_tree; |
224 | struct cfq_group root_group; |
225 | |
226 | /* |
227 | * The priority currently being served |
228 | */ |
229 | enum wl_prio_t serving_prio; |
230 | enum wl_type_t serving_type; |
231 | unsigned long workload_expires; |
232 | struct cfq_group *serving_group; |
233 | |
234 | /* |
235 | * Each priority tree is sorted by next_request position. These |
236 | * trees are used when determining if two or more queues are |
237 | * interleaving requests (see cfq_close_cooperator). |
238 | */ |
239 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; |
240 | |
241 | unsigned int busy_queues; |
242 | unsigned int busy_sync_queues; |
243 | |
244 | int rq_in_driver; |
245 | int rq_in_flight[2]; |
246 | |
247 | /* |
248 | * queue-depth detection |
249 | */ |
250 | int rq_queued; |
251 | int hw_tag; |
252 | /* |
253 | * hw_tag can be |
254 | * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) |
255 | * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) |
256 | * 0 => no NCQ |
257 | */ |
258 | int hw_tag_est_depth; |
259 | unsigned int hw_tag_samples; |
260 | |
261 | /* |
262 | * idle window management |
263 | */ |
264 | struct timer_list idle_slice_timer; |
265 | struct work_struct unplug_work; |
266 | |
267 | struct cfq_queue *active_queue; |
268 | struct cfq_io_context *active_cic; |
269 | |
270 | /* |
271 | * async queue for each priority case |
272 | */ |
273 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; |
274 | struct cfq_queue *async_idle_cfqq; |
275 | |
276 | sector_t last_position; |
277 | |
278 | /* |
279 | * tunables, see top of file |
280 | */ |
281 | unsigned int cfq_quantum; |
282 | unsigned int cfq_fifo_expire[2]; |
283 | unsigned int cfq_back_penalty; |
284 | unsigned int cfq_back_max; |
285 | unsigned int cfq_slice[2]; |
286 | unsigned int cfq_slice_async_rq; |
287 | unsigned int cfq_slice_idle; |
288 | unsigned int cfq_group_idle; |
289 | unsigned int cfq_latency; |
290 | |
291 | unsigned int cic_index; |
292 | struct list_head cic_list; |
293 | |
294 | /* |
295 | * Fallback dummy cfqq for extreme OOM conditions |
296 | */ |
297 | struct cfq_queue oom_cfqq; |
298 | |
299 | unsigned long last_delayed_sync; |
300 | |
301 | /* List of cfq groups being managed on this device*/ |
302 | struct hlist_head cfqg_list; |
303 | |
304 | /* Number of groups which are on blkcg->blkg_list */ |
305 | unsigned int nr_blkcg_linked_grps; |
306 | }; |
307 | |
308 | static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); |
309 | |
310 | static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, |
311 | enum wl_prio_t prio, |
312 | enum wl_type_t type) |
313 | { |
314 | if (!cfqg) |
315 | return NULL; |
316 | |
317 | if (prio == IDLE_WORKLOAD) |
318 | return &cfqg->service_tree_idle; |
319 | |
320 | return &cfqg->service_trees[prio][type]; |
321 | } |
322 | |
323 | enum cfqq_state_flags { |
324 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
325 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ |
326 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
327 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
328 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
329 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ |
330 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ |
331 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
332 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
333 | CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ |
334 | CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ |
335 | CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ |
336 | CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ |
337 | }; |
338 | |
339 | #define CFQ_CFQQ_FNS(name) \ |
340 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ |
341 | { \ |
342 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
343 | } \ |
344 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ |
345 | { \ |
346 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
347 | } \ |
348 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ |
349 | { \ |
350 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
351 | } |
352 | |
353 | CFQ_CFQQ_FNS(on_rr); |
354 | CFQ_CFQQ_FNS(wait_request); |
355 | CFQ_CFQQ_FNS(must_dispatch); |
356 | CFQ_CFQQ_FNS(must_alloc_slice); |
357 | CFQ_CFQQ_FNS(fifo_expire); |
358 | CFQ_CFQQ_FNS(idle_window); |
359 | CFQ_CFQQ_FNS(prio_changed); |
360 | CFQ_CFQQ_FNS(slice_new); |
361 | CFQ_CFQQ_FNS(sync); |
362 | CFQ_CFQQ_FNS(coop); |
363 | CFQ_CFQQ_FNS(split_coop); |
364 | CFQ_CFQQ_FNS(deep); |
365 | CFQ_CFQQ_FNS(wait_busy); |
366 | #undef CFQ_CFQQ_FNS |
367 | |
368 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
369 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
370 | blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ |
371 | cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ |
372 | blkg_path(&(cfqq)->cfqg->blkg), ##args) |
373 | |
374 | #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ |
375 | blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ |
376 | blkg_path(&(cfqg)->blkg), ##args) \ |
377 | |
378 | #else |
379 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
380 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) |
381 | #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) |
382 | #endif |
383 | #define cfq_log(cfqd, fmt, args...) \ |
384 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) |
385 | |
386 | /* Traverses through cfq group service trees */ |
387 | #define for_each_cfqg_st(cfqg, i, j, st) \ |
388 | for (i = 0; i <= IDLE_WORKLOAD; i++) \ |
389 | for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ |
390 | : &cfqg->service_tree_idle; \ |
391 | (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ |
392 | (i == IDLE_WORKLOAD && j == 0); \ |
393 | j++, st = i < IDLE_WORKLOAD ? \ |
394 | &cfqg->service_trees[i][j]: NULL) \ |
395 | |
396 | |
397 | static inline bool iops_mode(struct cfq_data *cfqd) |
398 | { |
399 | /* |
400 | * If we are not idling on queues and it is a NCQ drive, parallel |
401 | * execution of requests is on and measuring time is not possible |
402 | * in most of the cases until and unless we drive shallower queue |
403 | * depths and that becomes a performance bottleneck. In such cases |
404 | * switch to start providing fairness in terms of number of IOs. |
405 | */ |
406 | if (!cfqd->cfq_slice_idle && cfqd->hw_tag) |
407 | return true; |
408 | else |
409 | return false; |
410 | } |
411 | |
412 | static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) |
413 | { |
414 | if (cfq_class_idle(cfqq)) |
415 | return IDLE_WORKLOAD; |
416 | if (cfq_class_rt(cfqq)) |
417 | return RT_WORKLOAD; |
418 | return BE_WORKLOAD; |
419 | } |
420 | |
421 | |
422 | static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) |
423 | { |
424 | if (!cfq_cfqq_sync(cfqq)) |
425 | return ASYNC_WORKLOAD; |
426 | if (!cfq_cfqq_idle_window(cfqq)) |
427 | return SYNC_NOIDLE_WORKLOAD; |
428 | return SYNC_WORKLOAD; |
429 | } |
430 | |
431 | static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, |
432 | struct cfq_data *cfqd, |
433 | struct cfq_group *cfqg) |
434 | { |
435 | if (wl == IDLE_WORKLOAD) |
436 | return cfqg->service_tree_idle.count; |
437 | |
438 | return cfqg->service_trees[wl][ASYNC_WORKLOAD].count |
439 | + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count |
440 | + cfqg->service_trees[wl][SYNC_WORKLOAD].count; |
441 | } |
442 | |
443 | static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, |
444 | struct cfq_group *cfqg) |
445 | { |
446 | return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count |
447 | + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; |
448 | } |
449 | |
450 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
451 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, |
452 | struct io_context *, gfp_t); |
453 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
454 | struct io_context *); |
455 | |
456 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, |
457 | bool is_sync) |
458 | { |
459 | return cic->cfqq[is_sync]; |
460 | } |
461 | |
462 | static inline void cic_set_cfqq(struct cfq_io_context *cic, |
463 | struct cfq_queue *cfqq, bool is_sync) |
464 | { |
465 | cic->cfqq[is_sync] = cfqq; |
466 | } |
467 | |
468 | #define CIC_DEAD_KEY 1ul |
469 | #define CIC_DEAD_INDEX_SHIFT 1 |
470 | |
471 | static inline void *cfqd_dead_key(struct cfq_data *cfqd) |
472 | { |
473 | return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY); |
474 | } |
475 | |
476 | static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic) |
477 | { |
478 | struct cfq_data *cfqd = cic->key; |
479 | |
480 | if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY)) |
481 | return NULL; |
482 | |
483 | return cfqd; |
484 | } |
485 | |
486 | /* |
487 | * We regard a request as SYNC, if it's either a read or has the SYNC bit |
488 | * set (in which case it could also be direct WRITE). |
489 | */ |
490 | static inline bool cfq_bio_sync(struct bio *bio) |
491 | { |
492 | return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); |
493 | } |
494 | |
495 | /* |
496 | * scheduler run of queue, if there are requests pending and no one in the |
497 | * driver that will restart queueing |
498 | */ |
499 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) |
500 | { |
501 | if (cfqd->busy_queues) { |
502 | cfq_log(cfqd, "schedule dispatch"); |
503 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
504 | } |
505 | } |
506 | |
507 | /* |
508 | * Scale schedule slice based on io priority. Use the sync time slice only |
509 | * if a queue is marked sync and has sync io queued. A sync queue with async |
510 | * io only, should not get full sync slice length. |
511 | */ |
512 | static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, |
513 | unsigned short prio) |
514 | { |
515 | const int base_slice = cfqd->cfq_slice[sync]; |
516 | |
517 | WARN_ON(prio >= IOPRIO_BE_NR); |
518 | |
519 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); |
520 | } |
521 | |
522 | static inline int |
523 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
524 | { |
525 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); |
526 | } |
527 | |
528 | static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) |
529 | { |
530 | u64 d = delta << CFQ_SERVICE_SHIFT; |
531 | |
532 | d = d * BLKIO_WEIGHT_DEFAULT; |
533 | do_div(d, cfqg->weight); |
534 | return d; |
535 | } |
536 | |
537 | static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) |
538 | { |
539 | s64 delta = (s64)(vdisktime - min_vdisktime); |
540 | if (delta > 0) |
541 | min_vdisktime = vdisktime; |
542 | |
543 | return min_vdisktime; |
544 | } |
545 | |
546 | static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) |
547 | { |
548 | s64 delta = (s64)(vdisktime - min_vdisktime); |
549 | if (delta < 0) |
550 | min_vdisktime = vdisktime; |
551 | |
552 | return min_vdisktime; |
553 | } |
554 | |
555 | static void update_min_vdisktime(struct cfq_rb_root *st) |
556 | { |
557 | struct cfq_group *cfqg; |
558 | |
559 | if (st->left) { |
560 | cfqg = rb_entry_cfqg(st->left); |
561 | st->min_vdisktime = max_vdisktime(st->min_vdisktime, |
562 | cfqg->vdisktime); |
563 | } |
564 | } |
565 | |
566 | /* |
567 | * get averaged number of queues of RT/BE priority. |
568 | * average is updated, with a formula that gives more weight to higher numbers, |
569 | * to quickly follows sudden increases and decrease slowly |
570 | */ |
571 | |
572 | static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, |
573 | struct cfq_group *cfqg, bool rt) |
574 | { |
575 | unsigned min_q, max_q; |
576 | unsigned mult = cfq_hist_divisor - 1; |
577 | unsigned round = cfq_hist_divisor / 2; |
578 | unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); |
579 | |
580 | min_q = min(cfqg->busy_queues_avg[rt], busy); |
581 | max_q = max(cfqg->busy_queues_avg[rt], busy); |
582 | cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / |
583 | cfq_hist_divisor; |
584 | return cfqg->busy_queues_avg[rt]; |
585 | } |
586 | |
587 | static inline unsigned |
588 | cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) |
589 | { |
590 | struct cfq_rb_root *st = &cfqd->grp_service_tree; |
591 | |
592 | return cfq_target_latency * cfqg->weight / st->total_weight; |
593 | } |
594 | |
595 | static inline unsigned |
596 | cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
597 | { |
598 | unsigned slice = cfq_prio_to_slice(cfqd, cfqq); |
599 | if (cfqd->cfq_latency) { |
600 | /* |
601 | * interested queues (we consider only the ones with the same |
602 | * priority class in the cfq group) |
603 | */ |
604 | unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, |
605 | cfq_class_rt(cfqq)); |
606 | unsigned sync_slice = cfqd->cfq_slice[1]; |
607 | unsigned expect_latency = sync_slice * iq; |
608 | unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); |
609 | |
610 | if (expect_latency > group_slice) { |
611 | unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; |
612 | /* scale low_slice according to IO priority |
613 | * and sync vs async */ |
614 | unsigned low_slice = |
615 | min(slice, base_low_slice * slice / sync_slice); |
616 | /* the adapted slice value is scaled to fit all iqs |
617 | * into the target latency */ |
618 | slice = max(slice * group_slice / expect_latency, |
619 | low_slice); |
620 | } |
621 | } |
622 | return slice; |
623 | } |
624 | |
625 | static inline void |
626 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
627 | { |
628 | unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); |
629 | |
630 | cfqq->slice_start = jiffies; |
631 | cfqq->slice_end = jiffies + slice; |
632 | cfqq->allocated_slice = slice; |
633 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
634 | } |
635 | |
636 | /* |
637 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end |
638 | * isn't valid until the first request from the dispatch is activated |
639 | * and the slice time set. |
640 | */ |
641 | static inline bool cfq_slice_used(struct cfq_queue *cfqq) |
642 | { |
643 | if (cfq_cfqq_slice_new(cfqq)) |
644 | return false; |
645 | if (time_before(jiffies, cfqq->slice_end)) |
646 | return false; |
647 | |
648 | return true; |
649 | } |
650 | |
651 | /* |
652 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
653 | * We choose the request that is closest to the head right now. Distance |
654 | * behind the head is penalized and only allowed to a certain extent. |
655 | */ |
656 | static struct request * |
657 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) |
658 | { |
659 | sector_t s1, s2, d1 = 0, d2 = 0; |
660 | unsigned long back_max; |
661 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
662 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ |
663 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ |
664 | |
665 | if (rq1 == NULL || rq1 == rq2) |
666 | return rq2; |
667 | if (rq2 == NULL) |
668 | return rq1; |
669 | |
670 | if (rq_is_sync(rq1) != rq_is_sync(rq2)) |
671 | return rq_is_sync(rq1) ? rq1 : rq2; |
672 | |
673 | if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_META) |
674 | return rq1->cmd_flags & REQ_META ? rq1 : rq2; |
675 | |
676 | s1 = blk_rq_pos(rq1); |
677 | s2 = blk_rq_pos(rq2); |
678 | |
679 | /* |
680 | * by definition, 1KiB is 2 sectors |
681 | */ |
682 | back_max = cfqd->cfq_back_max * 2; |
683 | |
684 | /* |
685 | * Strict one way elevator _except_ in the case where we allow |
686 | * short backward seeks which are biased as twice the cost of a |
687 | * similar forward seek. |
688 | */ |
689 | if (s1 >= last) |
690 | d1 = s1 - last; |
691 | else if (s1 + back_max >= last) |
692 | d1 = (last - s1) * cfqd->cfq_back_penalty; |
693 | else |
694 | wrap |= CFQ_RQ1_WRAP; |
695 | |
696 | if (s2 >= last) |
697 | d2 = s2 - last; |
698 | else if (s2 + back_max >= last) |
699 | d2 = (last - s2) * cfqd->cfq_back_penalty; |
700 | else |
701 | wrap |= CFQ_RQ2_WRAP; |
702 | |
703 | /* Found required data */ |
704 | |
705 | /* |
706 | * By doing switch() on the bit mask "wrap" we avoid having to |
707 | * check two variables for all permutations: --> faster! |
708 | */ |
709 | switch (wrap) { |
710 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
711 | if (d1 < d2) |
712 | return rq1; |
713 | else if (d2 < d1) |
714 | return rq2; |
715 | else { |
716 | if (s1 >= s2) |
717 | return rq1; |
718 | else |
719 | return rq2; |
720 | } |
721 | |
722 | case CFQ_RQ2_WRAP: |
723 | return rq1; |
724 | case CFQ_RQ1_WRAP: |
725 | return rq2; |
726 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ |
727 | default: |
728 | /* |
729 | * Since both rqs are wrapped, |
730 | * start with the one that's further behind head |
731 | * (--> only *one* back seek required), |
732 | * since back seek takes more time than forward. |
733 | */ |
734 | if (s1 <= s2) |
735 | return rq1; |
736 | else |
737 | return rq2; |
738 | } |
739 | } |
740 | |
741 | /* |
742 | * The below is leftmost cache rbtree addon |
743 | */ |
744 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
745 | { |
746 | /* Service tree is empty */ |
747 | if (!root->count) |
748 | return NULL; |
749 | |
750 | if (!root->left) |
751 | root->left = rb_first(&root->rb); |
752 | |
753 | if (root->left) |
754 | return rb_entry(root->left, struct cfq_queue, rb_node); |
755 | |
756 | return NULL; |
757 | } |
758 | |
759 | static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) |
760 | { |
761 | if (!root->left) |
762 | root->left = rb_first(&root->rb); |
763 | |
764 | if (root->left) |
765 | return rb_entry_cfqg(root->left); |
766 | |
767 | return NULL; |
768 | } |
769 | |
770 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
771 | { |
772 | rb_erase(n, root); |
773 | RB_CLEAR_NODE(n); |
774 | } |
775 | |
776 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
777 | { |
778 | if (root->left == n) |
779 | root->left = NULL; |
780 | rb_erase_init(n, &root->rb); |
781 | --root->count; |
782 | } |
783 | |
784 | /* |
785 | * would be nice to take fifo expire time into account as well |
786 | */ |
787 | static struct request * |
788 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
789 | struct request *last) |
790 | { |
791 | struct rb_node *rbnext = rb_next(&last->rb_node); |
792 | struct rb_node *rbprev = rb_prev(&last->rb_node); |
793 | struct request *next = NULL, *prev = NULL; |
794 | |
795 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
796 | |
797 | if (rbprev) |
798 | prev = rb_entry_rq(rbprev); |
799 | |
800 | if (rbnext) |
801 | next = rb_entry_rq(rbnext); |
802 | else { |
803 | rbnext = rb_first(&cfqq->sort_list); |
804 | if (rbnext && rbnext != &last->rb_node) |
805 | next = rb_entry_rq(rbnext); |
806 | } |
807 | |
808 | return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); |
809 | } |
810 | |
811 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
812 | struct cfq_queue *cfqq) |
813 | { |
814 | /* |
815 | * just an approximation, should be ok. |
816 | */ |
817 | return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
818 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); |
819 | } |
820 | |
821 | static inline s64 |
822 | cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) |
823 | { |
824 | return cfqg->vdisktime - st->min_vdisktime; |
825 | } |
826 | |
827 | static void |
828 | __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) |
829 | { |
830 | struct rb_node **node = &st->rb.rb_node; |
831 | struct rb_node *parent = NULL; |
832 | struct cfq_group *__cfqg; |
833 | s64 key = cfqg_key(st, cfqg); |
834 | int left = 1; |
835 | |
836 | while (*node != NULL) { |
837 | parent = *node; |
838 | __cfqg = rb_entry_cfqg(parent); |
839 | |
840 | if (key < cfqg_key(st, __cfqg)) |
841 | node = &parent->rb_left; |
842 | else { |
843 | node = &parent->rb_right; |
844 | left = 0; |
845 | } |
846 | } |
847 | |
848 | if (left) |
849 | st->left = &cfqg->rb_node; |
850 | |
851 | rb_link_node(&cfqg->rb_node, parent, node); |
852 | rb_insert_color(&cfqg->rb_node, &st->rb); |
853 | } |
854 | |
855 | static void |
856 | cfq_update_group_weight(struct cfq_group *cfqg) |
857 | { |
858 | BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); |
859 | if (cfqg->needs_update) { |
860 | cfqg->weight = cfqg->new_weight; |
861 | cfqg->needs_update = false; |
862 | } |
863 | } |
864 | |
865 | static void |
866 | cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) |
867 | { |
868 | BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); |
869 | |
870 | cfq_update_group_weight(cfqg); |
871 | __cfq_group_service_tree_add(st, cfqg); |
872 | st->total_weight += cfqg->weight; |
873 | } |
874 | |
875 | static void |
876 | cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) |
877 | { |
878 | struct cfq_rb_root *st = &cfqd->grp_service_tree; |
879 | struct cfq_group *__cfqg; |
880 | struct rb_node *n; |
881 | |
882 | cfqg->nr_cfqq++; |
883 | if (!RB_EMPTY_NODE(&cfqg->rb_node)) |
884 | return; |
885 | |
886 | /* |
887 | * Currently put the group at the end. Later implement something |
888 | * so that groups get lesser vtime based on their weights, so that |
889 | * if group does not loose all if it was not continuously backlogged. |
890 | */ |
891 | n = rb_last(&st->rb); |
892 | if (n) { |
893 | __cfqg = rb_entry_cfqg(n); |
894 | cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; |
895 | } else |
896 | cfqg->vdisktime = st->min_vdisktime; |
897 | cfq_group_service_tree_add(st, cfqg); |
898 | } |
899 | |
900 | static void |
901 | cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) |
902 | { |
903 | st->total_weight -= cfqg->weight; |
904 | if (!RB_EMPTY_NODE(&cfqg->rb_node)) |
905 | cfq_rb_erase(&cfqg->rb_node, st); |
906 | } |
907 | |
908 | static void |
909 | cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) |
910 | { |
911 | struct cfq_rb_root *st = &cfqd->grp_service_tree; |
912 | |
913 | BUG_ON(cfqg->nr_cfqq < 1); |
914 | cfqg->nr_cfqq--; |
915 | |
916 | /* If there are other cfq queues under this group, don't delete it */ |
917 | if (cfqg->nr_cfqq) |
918 | return; |
919 | |
920 | cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); |
921 | cfq_group_service_tree_del(st, cfqg); |
922 | cfqg->saved_workload_slice = 0; |
923 | cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); |
924 | } |
925 | |
926 | static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, |
927 | unsigned int *unaccounted_time) |
928 | { |
929 | unsigned int slice_used; |
930 | |
931 | /* |
932 | * Queue got expired before even a single request completed or |
933 | * got expired immediately after first request completion. |
934 | */ |
935 | if (!cfqq->slice_start || cfqq->slice_start == jiffies) { |
936 | /* |
937 | * Also charge the seek time incurred to the group, otherwise |
938 | * if there are mutiple queues in the group, each can dispatch |
939 | * a single request on seeky media and cause lots of seek time |
940 | * and group will never know it. |
941 | */ |
942 | slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), |
943 | 1); |
944 | } else { |
945 | slice_used = jiffies - cfqq->slice_start; |
946 | if (slice_used > cfqq->allocated_slice) { |
947 | *unaccounted_time = slice_used - cfqq->allocated_slice; |
948 | slice_used = cfqq->allocated_slice; |
949 | } |
950 | if (time_after(cfqq->slice_start, cfqq->dispatch_start)) |
951 | *unaccounted_time += cfqq->slice_start - |
952 | cfqq->dispatch_start; |
953 | } |
954 | |
955 | return slice_used; |
956 | } |
957 | |
958 | static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, |
959 | struct cfq_queue *cfqq) |
960 | { |
961 | struct cfq_rb_root *st = &cfqd->grp_service_tree; |
962 | unsigned int used_sl, charge, unaccounted_sl = 0; |
963 | int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) |
964 | - cfqg->service_tree_idle.count; |
965 | |
966 | BUG_ON(nr_sync < 0); |
967 | used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); |
968 | |
969 | if (iops_mode(cfqd)) |
970 | charge = cfqq->slice_dispatch; |
971 | else if (!cfq_cfqq_sync(cfqq) && !nr_sync) |
972 | charge = cfqq->allocated_slice; |
973 | |
974 | /* Can't update vdisktime while group is on service tree */ |
975 | cfq_group_service_tree_del(st, cfqg); |
976 | cfqg->vdisktime += cfq_scale_slice(charge, cfqg); |
977 | /* If a new weight was requested, update now, off tree */ |
978 | cfq_group_service_tree_add(st, cfqg); |
979 | |
980 | /* This group is being expired. Save the context */ |
981 | if (time_after(cfqd->workload_expires, jiffies)) { |
982 | cfqg->saved_workload_slice = cfqd->workload_expires |
983 | - jiffies; |
984 | cfqg->saved_workload = cfqd->serving_type; |
985 | cfqg->saved_serving_prio = cfqd->serving_prio; |
986 | } else |
987 | cfqg->saved_workload_slice = 0; |
988 | |
989 | cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, |
990 | st->min_vdisktime); |
991 | cfq_log_cfqq(cfqq->cfqd, cfqq, |
992 | "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", |
993 | used_sl, cfqq->slice_dispatch, charge, |
994 | iops_mode(cfqd), cfqq->nr_sectors); |
995 | cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl, |
996 | unaccounted_sl); |
997 | cfq_blkiocg_set_start_empty_time(&cfqg->blkg); |
998 | } |
999 | |
1000 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
1001 | static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) |
1002 | { |
1003 | if (blkg) |
1004 | return container_of(blkg, struct cfq_group, blkg); |
1005 | return NULL; |
1006 | } |
1007 | |
1008 | void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, |
1009 | unsigned int weight) |
1010 | { |
1011 | struct cfq_group *cfqg = cfqg_of_blkg(blkg); |
1012 | cfqg->new_weight = weight; |
1013 | cfqg->needs_update = true; |
1014 | } |
1015 | |
1016 | static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd, |
1017 | struct cfq_group *cfqg, struct blkio_cgroup *blkcg) |
1018 | { |
1019 | struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; |
1020 | unsigned int major, minor; |
1021 | |
1022 | /* |
1023 | * Add group onto cgroup list. It might happen that bdi->dev is |
1024 | * not initialized yet. Initialize this new group without major |
1025 | * and minor info and this info will be filled in once a new thread |
1026 | * comes for IO. |
1027 | */ |
1028 | if (bdi->dev) { |
1029 | sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); |
1030 | cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, |
1031 | (void *)cfqd, MKDEV(major, minor)); |
1032 | } else |
1033 | cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, |
1034 | (void *)cfqd, 0); |
1035 | |
1036 | cfqd->nr_blkcg_linked_grps++; |
1037 | cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); |
1038 | |
1039 | /* Add group on cfqd list */ |
1040 | hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); |
1041 | } |
1042 | |
1043 | /* |
1044 | * Should be called from sleepable context. No request queue lock as per |
1045 | * cpu stats are allocated dynamically and alloc_percpu needs to be called |
1046 | * from sleepable context. |
1047 | */ |
1048 | static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd) |
1049 | { |
1050 | struct cfq_group *cfqg = NULL; |
1051 | int i, j, ret; |
1052 | struct cfq_rb_root *st; |
1053 | |
1054 | cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); |
1055 | if (!cfqg) |
1056 | return NULL; |
1057 | |
1058 | for_each_cfqg_st(cfqg, i, j, st) |
1059 | *st = CFQ_RB_ROOT; |
1060 | RB_CLEAR_NODE(&cfqg->rb_node); |
1061 | |
1062 | /* |
1063 | * Take the initial reference that will be released on destroy |
1064 | * This can be thought of a joint reference by cgroup and |
1065 | * elevator which will be dropped by either elevator exit |
1066 | * or cgroup deletion path depending on who is exiting first. |
1067 | */ |
1068 | cfqg->ref = 1; |
1069 | |
1070 | ret = blkio_alloc_blkg_stats(&cfqg->blkg); |
1071 | if (ret) { |
1072 | kfree(cfqg); |
1073 | return NULL; |
1074 | } |
1075 | |
1076 | return cfqg; |
1077 | } |
1078 | |
1079 | static struct cfq_group * |
1080 | cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg) |
1081 | { |
1082 | struct cfq_group *cfqg = NULL; |
1083 | void *key = cfqd; |
1084 | struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; |
1085 | unsigned int major, minor; |
1086 | |
1087 | /* |
1088 | * This is the common case when there are no blkio cgroups. |
1089 | * Avoid lookup in this case |
1090 | */ |
1091 | if (blkcg == &blkio_root_cgroup) |
1092 | cfqg = &cfqd->root_group; |
1093 | else |
1094 | cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); |
1095 | |
1096 | if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { |
1097 | sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); |
1098 | cfqg->blkg.dev = MKDEV(major, minor); |
1099 | } |
1100 | |
1101 | return cfqg; |
1102 | } |
1103 | |
1104 | /* |
1105 | * Search for the cfq group current task belongs to. request_queue lock must |
1106 | * be held. |
1107 | */ |
1108 | static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) |
1109 | { |
1110 | struct blkio_cgroup *blkcg; |
1111 | struct cfq_group *cfqg = NULL, *__cfqg = NULL; |
1112 | struct request_queue *q = cfqd->queue; |
1113 | |
1114 | rcu_read_lock(); |
1115 | blkcg = task_blkio_cgroup(current); |
1116 | cfqg = cfq_find_cfqg(cfqd, blkcg); |
1117 | if (cfqg) { |
1118 | rcu_read_unlock(); |
1119 | return cfqg; |
1120 | } |
1121 | |
1122 | /* |
1123 | * Need to allocate a group. Allocation of group also needs allocation |
1124 | * of per cpu stats which in-turn takes a mutex() and can block. Hence |
1125 | * we need to drop rcu lock and queue_lock before we call alloc. |
1126 | * |
1127 | * Not taking any queue reference here and assuming that queue is |
1128 | * around by the time we return. CFQ queue allocation code does |
1129 | * the same. It might be racy though. |
1130 | */ |
1131 | |
1132 | rcu_read_unlock(); |
1133 | spin_unlock_irq(q->queue_lock); |
1134 | |
1135 | cfqg = cfq_alloc_cfqg(cfqd); |
1136 | |
1137 | spin_lock_irq(q->queue_lock); |
1138 | |
1139 | rcu_read_lock(); |
1140 | blkcg = task_blkio_cgroup(current); |
1141 | |
1142 | /* |
1143 | * If some other thread already allocated the group while we were |
1144 | * not holding queue lock, free up the group |
1145 | */ |
1146 | __cfqg = cfq_find_cfqg(cfqd, blkcg); |
1147 | |
1148 | if (__cfqg) { |
1149 | kfree(cfqg); |
1150 | rcu_read_unlock(); |
1151 | return __cfqg; |
1152 | } |
1153 | |
1154 | if (!cfqg) |
1155 | cfqg = &cfqd->root_group; |
1156 | |
1157 | cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg); |
1158 | rcu_read_unlock(); |
1159 | return cfqg; |
1160 | } |
1161 | |
1162 | static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) |
1163 | { |
1164 | cfqg->ref++; |
1165 | return cfqg; |
1166 | } |
1167 | |
1168 | static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) |
1169 | { |
1170 | /* Currently, all async queues are mapped to root group */ |
1171 | if (!cfq_cfqq_sync(cfqq)) |
1172 | cfqg = &cfqq->cfqd->root_group; |
1173 | |
1174 | cfqq->cfqg = cfqg; |
1175 | /* cfqq reference on cfqg */ |
1176 | cfqq->cfqg->ref++; |
1177 | } |
1178 | |
1179 | static void cfq_put_cfqg(struct cfq_group *cfqg) |
1180 | { |
1181 | struct cfq_rb_root *st; |
1182 | int i, j; |
1183 | |
1184 | BUG_ON(cfqg->ref <= 0); |
1185 | cfqg->ref--; |
1186 | if (cfqg->ref) |
1187 | return; |
1188 | for_each_cfqg_st(cfqg, i, j, st) |
1189 | BUG_ON(!RB_EMPTY_ROOT(&st->rb)); |
1190 | free_percpu(cfqg->blkg.stats_cpu); |
1191 | kfree(cfqg); |
1192 | } |
1193 | |
1194 | static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) |
1195 | { |
1196 | /* Something wrong if we are trying to remove same group twice */ |
1197 | BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); |
1198 | |
1199 | hlist_del_init(&cfqg->cfqd_node); |
1200 | |
1201 | /* |
1202 | * Put the reference taken at the time of creation so that when all |
1203 | * queues are gone, group can be destroyed. |
1204 | */ |
1205 | cfq_put_cfqg(cfqg); |
1206 | } |
1207 | |
1208 | static void cfq_release_cfq_groups(struct cfq_data *cfqd) |
1209 | { |
1210 | struct hlist_node *pos, *n; |
1211 | struct cfq_group *cfqg; |
1212 | |
1213 | hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { |
1214 | /* |
1215 | * If cgroup removal path got to blk_group first and removed |
1216 | * it from cgroup list, then it will take care of destroying |
1217 | * cfqg also. |
1218 | */ |
1219 | if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg)) |
1220 | cfq_destroy_cfqg(cfqd, cfqg); |
1221 | } |
1222 | } |
1223 | |
1224 | /* |
1225 | * Blk cgroup controller notification saying that blkio_group object is being |
1226 | * delinked as associated cgroup object is going away. That also means that |
1227 | * no new IO will come in this group. So get rid of this group as soon as |
1228 | * any pending IO in the group is finished. |
1229 | * |
1230 | * This function is called under rcu_read_lock(). key is the rcu protected |
1231 | * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu |
1232 | * read lock. |
1233 | * |
1234 | * "key" was fetched from blkio_group under blkio_cgroup->lock. That means |
1235 | * it should not be NULL as even if elevator was exiting, cgroup deltion |
1236 | * path got to it first. |
1237 | */ |
1238 | void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) |
1239 | { |
1240 | unsigned long flags; |
1241 | struct cfq_data *cfqd = key; |
1242 | |
1243 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
1244 | cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); |
1245 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
1246 | } |
1247 | |
1248 | #else /* GROUP_IOSCHED */ |
1249 | static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) |
1250 | { |
1251 | return &cfqd->root_group; |
1252 | } |
1253 | |
1254 | static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) |
1255 | { |
1256 | return cfqg; |
1257 | } |
1258 | |
1259 | static inline void |
1260 | cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { |
1261 | cfqq->cfqg = cfqg; |
1262 | } |
1263 | |
1264 | static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} |
1265 | static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} |
1266 | |
1267 | #endif /* GROUP_IOSCHED */ |
1268 | |
1269 | /* |
1270 | * The cfqd->service_trees holds all pending cfq_queue's that have |
1271 | * requests waiting to be processed. It is sorted in the order that |
1272 | * we will service the queues. |
1273 | */ |
1274 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1275 | bool add_front) |
1276 | { |
1277 | struct rb_node **p, *parent; |
1278 | struct cfq_queue *__cfqq; |
1279 | unsigned long rb_key; |
1280 | struct cfq_rb_root *service_tree; |
1281 | int left; |
1282 | int new_cfqq = 1; |
1283 | |
1284 | service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), |
1285 | cfqq_type(cfqq)); |
1286 | if (cfq_class_idle(cfqq)) { |
1287 | rb_key = CFQ_IDLE_DELAY; |
1288 | parent = rb_last(&service_tree->rb); |
1289 | if (parent && parent != &cfqq->rb_node) { |
1290 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
1291 | rb_key += __cfqq->rb_key; |
1292 | } else |
1293 | rb_key += jiffies; |
1294 | } else if (!add_front) { |
1295 | /* |
1296 | * Get our rb key offset. Subtract any residual slice |
1297 | * value carried from last service. A negative resid |
1298 | * count indicates slice overrun, and this should position |
1299 | * the next service time further away in the tree. |
1300 | */ |
1301 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
1302 | rb_key -= cfqq->slice_resid; |
1303 | cfqq->slice_resid = 0; |
1304 | } else { |
1305 | rb_key = -HZ; |
1306 | __cfqq = cfq_rb_first(service_tree); |
1307 | rb_key += __cfqq ? __cfqq->rb_key : jiffies; |
1308 | } |
1309 | |
1310 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
1311 | new_cfqq = 0; |
1312 | /* |
1313 | * same position, nothing more to do |
1314 | */ |
1315 | if (rb_key == cfqq->rb_key && |
1316 | cfqq->service_tree == service_tree) |
1317 | return; |
1318 | |
1319 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
1320 | cfqq->service_tree = NULL; |
1321 | } |
1322 | |
1323 | left = 1; |
1324 | parent = NULL; |
1325 | cfqq->service_tree = service_tree; |
1326 | p = &service_tree->rb.rb_node; |
1327 | while (*p) { |
1328 | struct rb_node **n; |
1329 | |
1330 | parent = *p; |
1331 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
1332 | |
1333 | /* |
1334 | * sort by key, that represents service time. |
1335 | */ |
1336 | if (time_before(rb_key, __cfqq->rb_key)) |
1337 | n = &(*p)->rb_left; |
1338 | else { |
1339 | n = &(*p)->rb_right; |
1340 | left = 0; |
1341 | } |
1342 | |
1343 | p = n; |
1344 | } |
1345 | |
1346 | if (left) |
1347 | service_tree->left = &cfqq->rb_node; |
1348 | |
1349 | cfqq->rb_key = rb_key; |
1350 | rb_link_node(&cfqq->rb_node, parent, p); |
1351 | rb_insert_color(&cfqq->rb_node, &service_tree->rb); |
1352 | service_tree->count++; |
1353 | if (add_front || !new_cfqq) |
1354 | return; |
1355 | cfq_group_notify_queue_add(cfqd, cfqq->cfqg); |
1356 | } |
1357 | |
1358 | static struct cfq_queue * |
1359 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
1360 | sector_t sector, struct rb_node **ret_parent, |
1361 | struct rb_node ***rb_link) |
1362 | { |
1363 | struct rb_node **p, *parent; |
1364 | struct cfq_queue *cfqq = NULL; |
1365 | |
1366 | parent = NULL; |
1367 | p = &root->rb_node; |
1368 | while (*p) { |
1369 | struct rb_node **n; |
1370 | |
1371 | parent = *p; |
1372 | cfqq = rb_entry(parent, struct cfq_queue, p_node); |
1373 | |
1374 | /* |
1375 | * Sort strictly based on sector. Smallest to the left, |
1376 | * largest to the right. |
1377 | */ |
1378 | if (sector > blk_rq_pos(cfqq->next_rq)) |
1379 | n = &(*p)->rb_right; |
1380 | else if (sector < blk_rq_pos(cfqq->next_rq)) |
1381 | n = &(*p)->rb_left; |
1382 | else |
1383 | break; |
1384 | p = n; |
1385 | cfqq = NULL; |
1386 | } |
1387 | |
1388 | *ret_parent = parent; |
1389 | if (rb_link) |
1390 | *rb_link = p; |
1391 | return cfqq; |
1392 | } |
1393 | |
1394 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1395 | { |
1396 | struct rb_node **p, *parent; |
1397 | struct cfq_queue *__cfqq; |
1398 | |
1399 | if (cfqq->p_root) { |
1400 | rb_erase(&cfqq->p_node, cfqq->p_root); |
1401 | cfqq->p_root = NULL; |
1402 | } |
1403 | |
1404 | if (cfq_class_idle(cfqq)) |
1405 | return; |
1406 | if (!cfqq->next_rq) |
1407 | return; |
1408 | |
1409 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
1410 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
1411 | blk_rq_pos(cfqq->next_rq), &parent, &p); |
1412 | if (!__cfqq) { |
1413 | rb_link_node(&cfqq->p_node, parent, p); |
1414 | rb_insert_color(&cfqq->p_node, cfqq->p_root); |
1415 | } else |
1416 | cfqq->p_root = NULL; |
1417 | } |
1418 | |
1419 | /* |
1420 | * Update cfqq's position in the service tree. |
1421 | */ |
1422 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1423 | { |
1424 | /* |
1425 | * Resorting requires the cfqq to be on the RR list already. |
1426 | */ |
1427 | if (cfq_cfqq_on_rr(cfqq)) { |
1428 | cfq_service_tree_add(cfqd, cfqq, 0); |
1429 | cfq_prio_tree_add(cfqd, cfqq); |
1430 | } |
1431 | } |
1432 | |
1433 | /* |
1434 | * add to busy list of queues for service, trying to be fair in ordering |
1435 | * the pending list according to last request service |
1436 | */ |
1437 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1438 | { |
1439 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
1440 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1441 | cfq_mark_cfqq_on_rr(cfqq); |
1442 | cfqd->busy_queues++; |
1443 | if (cfq_cfqq_sync(cfqq)) |
1444 | cfqd->busy_sync_queues++; |
1445 | |
1446 | cfq_resort_rr_list(cfqd, cfqq); |
1447 | } |
1448 | |
1449 | /* |
1450 | * Called when the cfqq no longer has requests pending, remove it from |
1451 | * the service tree. |
1452 | */ |
1453 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1454 | { |
1455 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
1456 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
1457 | cfq_clear_cfqq_on_rr(cfqq); |
1458 | |
1459 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
1460 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
1461 | cfqq->service_tree = NULL; |
1462 | } |
1463 | if (cfqq->p_root) { |
1464 | rb_erase(&cfqq->p_node, cfqq->p_root); |
1465 | cfqq->p_root = NULL; |
1466 | } |
1467 | |
1468 | cfq_group_notify_queue_del(cfqd, cfqq->cfqg); |
1469 | BUG_ON(!cfqd->busy_queues); |
1470 | cfqd->busy_queues--; |
1471 | if (cfq_cfqq_sync(cfqq)) |
1472 | cfqd->busy_sync_queues--; |
1473 | } |
1474 | |
1475 | /* |
1476 | * rb tree support functions |
1477 | */ |
1478 | static void cfq_del_rq_rb(struct request *rq) |
1479 | { |
1480 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1481 | const int sync = rq_is_sync(rq); |
1482 | |
1483 | BUG_ON(!cfqq->queued[sync]); |
1484 | cfqq->queued[sync]--; |
1485 | |
1486 | elv_rb_del(&cfqq->sort_list, rq); |
1487 | |
1488 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { |
1489 | /* |
1490 | * Queue will be deleted from service tree when we actually |
1491 | * expire it later. Right now just remove it from prio tree |
1492 | * as it is empty. |
1493 | */ |
1494 | if (cfqq->p_root) { |
1495 | rb_erase(&cfqq->p_node, cfqq->p_root); |
1496 | cfqq->p_root = NULL; |
1497 | } |
1498 | } |
1499 | } |
1500 | |
1501 | static void cfq_add_rq_rb(struct request *rq) |
1502 | { |
1503 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1504 | struct cfq_data *cfqd = cfqq->cfqd; |
1505 | struct request *__alias, *prev; |
1506 | |
1507 | cfqq->queued[rq_is_sync(rq)]++; |
1508 | |
1509 | /* |
1510 | * looks a little odd, but the first insert might return an alias. |
1511 | * if that happens, put the alias on the dispatch list |
1512 | */ |
1513 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
1514 | cfq_dispatch_insert(cfqd->queue, __alias); |
1515 | |
1516 | if (!cfq_cfqq_on_rr(cfqq)) |
1517 | cfq_add_cfqq_rr(cfqd, cfqq); |
1518 | |
1519 | /* |
1520 | * check if this request is a better next-serve candidate |
1521 | */ |
1522 | prev = cfqq->next_rq; |
1523 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); |
1524 | |
1525 | /* |
1526 | * adjust priority tree position, if ->next_rq changes |
1527 | */ |
1528 | if (prev != cfqq->next_rq) |
1529 | cfq_prio_tree_add(cfqd, cfqq); |
1530 | |
1531 | BUG_ON(!cfqq->next_rq); |
1532 | } |
1533 | |
1534 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1535 | { |
1536 | elv_rb_del(&cfqq->sort_list, rq); |
1537 | cfqq->queued[rq_is_sync(rq)]--; |
1538 | cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, |
1539 | rq_data_dir(rq), rq_is_sync(rq)); |
1540 | cfq_add_rq_rb(rq); |
1541 | cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, |
1542 | &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), |
1543 | rq_is_sync(rq)); |
1544 | } |
1545 | |
1546 | static struct request * |
1547 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) |
1548 | { |
1549 | struct task_struct *tsk = current; |
1550 | struct cfq_io_context *cic; |
1551 | struct cfq_queue *cfqq; |
1552 | |
1553 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
1554 | if (!cic) |
1555 | return NULL; |
1556 | |
1557 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
1558 | if (cfqq) { |
1559 | sector_t sector = bio->bi_sector + bio_sectors(bio); |
1560 | |
1561 | return elv_rb_find(&cfqq->sort_list, sector); |
1562 | } |
1563 | |
1564 | return NULL; |
1565 | } |
1566 | |
1567 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1568 | { |
1569 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1570 | |
1571 | cfqd->rq_in_driver++; |
1572 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
1573 | cfqd->rq_in_driver); |
1574 | |
1575 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
1576 | } |
1577 | |
1578 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1579 | { |
1580 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1581 | |
1582 | WARN_ON(!cfqd->rq_in_driver); |
1583 | cfqd->rq_in_driver--; |
1584 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
1585 | cfqd->rq_in_driver); |
1586 | } |
1587 | |
1588 | static void cfq_remove_request(struct request *rq) |
1589 | { |
1590 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1591 | |
1592 | if (cfqq->next_rq == rq) |
1593 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); |
1594 | |
1595 | list_del_init(&rq->queuelist); |
1596 | cfq_del_rq_rb(rq); |
1597 | |
1598 | cfqq->cfqd->rq_queued--; |
1599 | cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, |
1600 | rq_data_dir(rq), rq_is_sync(rq)); |
1601 | if (rq->cmd_flags & REQ_META) { |
1602 | WARN_ON(!cfqq->meta_pending); |
1603 | cfqq->meta_pending--; |
1604 | } |
1605 | } |
1606 | |
1607 | static int cfq_merge(struct request_queue *q, struct request **req, |
1608 | struct bio *bio) |
1609 | { |
1610 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1611 | struct request *__rq; |
1612 | |
1613 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
1614 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
1615 | *req = __rq; |
1616 | return ELEVATOR_FRONT_MERGE; |
1617 | } |
1618 | |
1619 | return ELEVATOR_NO_MERGE; |
1620 | } |
1621 | |
1622 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
1623 | int type) |
1624 | { |
1625 | if (type == ELEVATOR_FRONT_MERGE) { |
1626 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1627 | |
1628 | cfq_reposition_rq_rb(cfqq, req); |
1629 | } |
1630 | } |
1631 | |
1632 | static void cfq_bio_merged(struct request_queue *q, struct request *req, |
1633 | struct bio *bio) |
1634 | { |
1635 | cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, |
1636 | bio_data_dir(bio), cfq_bio_sync(bio)); |
1637 | } |
1638 | |
1639 | static void |
1640 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1641 | struct request *next) |
1642 | { |
1643 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1644 | /* |
1645 | * reposition in fifo if next is older than rq |
1646 | */ |
1647 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && |
1648 | time_before(rq_fifo_time(next), rq_fifo_time(rq))) { |
1649 | list_move(&rq->queuelist, &next->queuelist); |
1650 | rq_set_fifo_time(rq, rq_fifo_time(next)); |
1651 | } |
1652 | |
1653 | if (cfqq->next_rq == next) |
1654 | cfqq->next_rq = rq; |
1655 | cfq_remove_request(next); |
1656 | cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, |
1657 | rq_data_dir(next), rq_is_sync(next)); |
1658 | } |
1659 | |
1660 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
1661 | struct bio *bio) |
1662 | { |
1663 | struct cfq_data *cfqd = q->elevator->elevator_data; |
1664 | struct cfq_io_context *cic; |
1665 | struct cfq_queue *cfqq; |
1666 | |
1667 | /* |
1668 | * Disallow merge of a sync bio into an async request. |
1669 | */ |
1670 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
1671 | return false; |
1672 | |
1673 | /* |
1674 | * Lookup the cfqq that this bio will be queued with. Allow |
1675 | * merge only if rq is queued there. |
1676 | */ |
1677 | cic = cfq_cic_lookup(cfqd, current->io_context); |
1678 | if (!cic) |
1679 | return false; |
1680 | |
1681 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
1682 | return cfqq == RQ_CFQQ(rq); |
1683 | } |
1684 | |
1685 | static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1686 | { |
1687 | del_timer(&cfqd->idle_slice_timer); |
1688 | cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); |
1689 | } |
1690 | |
1691 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
1692 | struct cfq_queue *cfqq) |
1693 | { |
1694 | if (cfqq) { |
1695 | cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", |
1696 | cfqd->serving_prio, cfqd->serving_type); |
1697 | cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); |
1698 | cfqq->slice_start = 0; |
1699 | cfqq->dispatch_start = jiffies; |
1700 | cfqq->allocated_slice = 0; |
1701 | cfqq->slice_end = 0; |
1702 | cfqq->slice_dispatch = 0; |
1703 | cfqq->nr_sectors = 0; |
1704 | |
1705 | cfq_clear_cfqq_wait_request(cfqq); |
1706 | cfq_clear_cfqq_must_dispatch(cfqq); |
1707 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
1708 | cfq_clear_cfqq_fifo_expire(cfqq); |
1709 | cfq_mark_cfqq_slice_new(cfqq); |
1710 | |
1711 | cfq_del_timer(cfqd, cfqq); |
1712 | } |
1713 | |
1714 | cfqd->active_queue = cfqq; |
1715 | } |
1716 | |
1717 | /* |
1718 | * current cfqq expired its slice (or was too idle), select new one |
1719 | */ |
1720 | static void |
1721 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1722 | bool timed_out) |
1723 | { |
1724 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
1725 | |
1726 | if (cfq_cfqq_wait_request(cfqq)) |
1727 | cfq_del_timer(cfqd, cfqq); |
1728 | |
1729 | cfq_clear_cfqq_wait_request(cfqq); |
1730 | cfq_clear_cfqq_wait_busy(cfqq); |
1731 | |
1732 | /* |
1733 | * If this cfqq is shared between multiple processes, check to |
1734 | * make sure that those processes are still issuing I/Os within |
1735 | * the mean seek distance. If not, it may be time to break the |
1736 | * queues apart again. |
1737 | */ |
1738 | if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) |
1739 | cfq_mark_cfqq_split_coop(cfqq); |
1740 | |
1741 | /* |
1742 | * store what was left of this slice, if the queue idled/timed out |
1743 | */ |
1744 | if (timed_out) { |
1745 | if (cfq_cfqq_slice_new(cfqq)) |
1746 | cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); |
1747 | else |
1748 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
1749 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
1750 | } |
1751 | |
1752 | cfq_group_served(cfqd, cfqq->cfqg, cfqq); |
1753 | |
1754 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
1755 | cfq_del_cfqq_rr(cfqd, cfqq); |
1756 | |
1757 | cfq_resort_rr_list(cfqd, cfqq); |
1758 | |
1759 | if (cfqq == cfqd->active_queue) |
1760 | cfqd->active_queue = NULL; |
1761 | |
1762 | if (cfqd->active_cic) { |
1763 | put_io_context(cfqd->active_cic->ioc); |
1764 | cfqd->active_cic = NULL; |
1765 | } |
1766 | } |
1767 | |
1768 | static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) |
1769 | { |
1770 | struct cfq_queue *cfqq = cfqd->active_queue; |
1771 | |
1772 | if (cfqq) |
1773 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
1774 | } |
1775 | |
1776 | /* |
1777 | * Get next queue for service. Unless we have a queue preemption, |
1778 | * we'll simply select the first cfqq in the service tree. |
1779 | */ |
1780 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
1781 | { |
1782 | struct cfq_rb_root *service_tree = |
1783 | service_tree_for(cfqd->serving_group, cfqd->serving_prio, |
1784 | cfqd->serving_type); |
1785 | |
1786 | if (!cfqd->rq_queued) |
1787 | return NULL; |
1788 | |
1789 | /* There is nothing to dispatch */ |
1790 | if (!service_tree) |
1791 | return NULL; |
1792 | if (RB_EMPTY_ROOT(&service_tree->rb)) |
1793 | return NULL; |
1794 | return cfq_rb_first(service_tree); |
1795 | } |
1796 | |
1797 | static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) |
1798 | { |
1799 | struct cfq_group *cfqg; |
1800 | struct cfq_queue *cfqq; |
1801 | int i, j; |
1802 | struct cfq_rb_root *st; |
1803 | |
1804 | if (!cfqd->rq_queued) |
1805 | return NULL; |
1806 | |
1807 | cfqg = cfq_get_next_cfqg(cfqd); |
1808 | if (!cfqg) |
1809 | return NULL; |
1810 | |
1811 | for_each_cfqg_st(cfqg, i, j, st) |
1812 | if ((cfqq = cfq_rb_first(st)) != NULL) |
1813 | return cfqq; |
1814 | return NULL; |
1815 | } |
1816 | |
1817 | /* |
1818 | * Get and set a new active queue for service. |
1819 | */ |
1820 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
1821 | struct cfq_queue *cfqq) |
1822 | { |
1823 | if (!cfqq) |
1824 | cfqq = cfq_get_next_queue(cfqd); |
1825 | |
1826 | __cfq_set_active_queue(cfqd, cfqq); |
1827 | return cfqq; |
1828 | } |
1829 | |
1830 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
1831 | struct request *rq) |
1832 | { |
1833 | if (blk_rq_pos(rq) >= cfqd->last_position) |
1834 | return blk_rq_pos(rq) - cfqd->last_position; |
1835 | else |
1836 | return cfqd->last_position - blk_rq_pos(rq); |
1837 | } |
1838 | |
1839 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1840 | struct request *rq) |
1841 | { |
1842 | return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; |
1843 | } |
1844 | |
1845 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
1846 | struct cfq_queue *cur_cfqq) |
1847 | { |
1848 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
1849 | struct rb_node *parent, *node; |
1850 | struct cfq_queue *__cfqq; |
1851 | sector_t sector = cfqd->last_position; |
1852 | |
1853 | if (RB_EMPTY_ROOT(root)) |
1854 | return NULL; |
1855 | |
1856 | /* |
1857 | * First, if we find a request starting at the end of the last |
1858 | * request, choose it. |
1859 | */ |
1860 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
1861 | if (__cfqq) |
1862 | return __cfqq; |
1863 | |
1864 | /* |
1865 | * If the exact sector wasn't found, the parent of the NULL leaf |
1866 | * will contain the closest sector. |
1867 | */ |
1868 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); |
1869 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
1870 | return __cfqq; |
1871 | |
1872 | if (blk_rq_pos(__cfqq->next_rq) < sector) |
1873 | node = rb_next(&__cfqq->p_node); |
1874 | else |
1875 | node = rb_prev(&__cfqq->p_node); |
1876 | if (!node) |
1877 | return NULL; |
1878 | |
1879 | __cfqq = rb_entry(node, struct cfq_queue, p_node); |
1880 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
1881 | return __cfqq; |
1882 | |
1883 | return NULL; |
1884 | } |
1885 | |
1886 | /* |
1887 | * cfqd - obvious |
1888 | * cur_cfqq - passed in so that we don't decide that the current queue is |
1889 | * closely cooperating with itself. |
1890 | * |
1891 | * So, basically we're assuming that that cur_cfqq has dispatched at least |
1892 | * one request, and that cfqd->last_position reflects a position on the disk |
1893 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid |
1894 | * assumption. |
1895 | */ |
1896 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, |
1897 | struct cfq_queue *cur_cfqq) |
1898 | { |
1899 | struct cfq_queue *cfqq; |
1900 | |
1901 | if (cfq_class_idle(cur_cfqq)) |
1902 | return NULL; |
1903 | if (!cfq_cfqq_sync(cur_cfqq)) |
1904 | return NULL; |
1905 | if (CFQQ_SEEKY(cur_cfqq)) |
1906 | return NULL; |
1907 | |
1908 | /* |
1909 | * Don't search priority tree if it's the only queue in the group. |
1910 | */ |
1911 | if (cur_cfqq->cfqg->nr_cfqq == 1) |
1912 | return NULL; |
1913 | |
1914 | /* |
1915 | * We should notice if some of the queues are cooperating, eg |
1916 | * working closely on the same area of the disk. In that case, |
1917 | * we can group them together and don't waste time idling. |
1918 | */ |
1919 | cfqq = cfqq_close(cfqd, cur_cfqq); |
1920 | if (!cfqq) |
1921 | return NULL; |
1922 | |
1923 | /* If new queue belongs to different cfq_group, don't choose it */ |
1924 | if (cur_cfqq->cfqg != cfqq->cfqg) |
1925 | return NULL; |
1926 | |
1927 | /* |
1928 | * It only makes sense to merge sync queues. |
1929 | */ |
1930 | if (!cfq_cfqq_sync(cfqq)) |
1931 | return NULL; |
1932 | if (CFQQ_SEEKY(cfqq)) |
1933 | return NULL; |
1934 | |
1935 | /* |
1936 | * Do not merge queues of different priority classes |
1937 | */ |
1938 | if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) |
1939 | return NULL; |
1940 | |
1941 | return cfqq; |
1942 | } |
1943 | |
1944 | /* |
1945 | * Determine whether we should enforce idle window for this queue. |
1946 | */ |
1947 | |
1948 | static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1949 | { |
1950 | enum wl_prio_t prio = cfqq_prio(cfqq); |
1951 | struct cfq_rb_root *service_tree = cfqq->service_tree; |
1952 | |
1953 | BUG_ON(!service_tree); |
1954 | BUG_ON(!service_tree->count); |
1955 | |
1956 | if (!cfqd->cfq_slice_idle) |
1957 | return false; |
1958 | |
1959 | /* We never do for idle class queues. */ |
1960 | if (prio == IDLE_WORKLOAD) |
1961 | return false; |
1962 | |
1963 | /* We do for queues that were marked with idle window flag. */ |
1964 | if (cfq_cfqq_idle_window(cfqq) && |
1965 | !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) |
1966 | return true; |
1967 | |
1968 | /* |
1969 | * Otherwise, we do only if they are the last ones |
1970 | * in their service tree. |
1971 | */ |
1972 | if (service_tree->count == 1 && cfq_cfqq_sync(cfqq)) |
1973 | return true; |
1974 | cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", |
1975 | service_tree->count); |
1976 | return false; |
1977 | } |
1978 | |
1979 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
1980 | { |
1981 | struct cfq_queue *cfqq = cfqd->active_queue; |
1982 | struct cfq_io_context *cic; |
1983 | unsigned long sl, group_idle = 0; |
1984 | |
1985 | /* |
1986 | * SSD device without seek penalty, disable idling. But only do so |
1987 | * for devices that support queuing, otherwise we still have a problem |
1988 | * with sync vs async workloads. |
1989 | */ |
1990 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
1991 | return; |
1992 | |
1993 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
1994 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
1995 | |
1996 | /* |
1997 | * idle is disabled, either manually or by past process history |
1998 | */ |
1999 | if (!cfq_should_idle(cfqd, cfqq)) { |
2000 | /* no queue idling. Check for group idling */ |
2001 | if (cfqd->cfq_group_idle) |
2002 | group_idle = cfqd->cfq_group_idle; |
2003 | else |
2004 | return; |
2005 | } |
2006 | |
2007 | /* |
2008 | * still active requests from this queue, don't idle |
2009 | */ |
2010 | if (cfqq->dispatched) |
2011 | return; |
2012 | |
2013 | /* |
2014 | * task has exited, don't wait |
2015 | */ |
2016 | cic = cfqd->active_cic; |
2017 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
2018 | return; |
2019 | |
2020 | /* |
2021 | * If our average think time is larger than the remaining time |
2022 | * slice, then don't idle. This avoids overrunning the allotted |
2023 | * time slice. |
2024 | */ |
2025 | if (sample_valid(cic->ttime_samples) && |
2026 | (cfqq->slice_end - jiffies < cic->ttime_mean)) { |
2027 | cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", |
2028 | cic->ttime_mean); |
2029 | return; |
2030 | } |
2031 | |
2032 | /* There are other queues in the group, don't do group idle */ |
2033 | if (group_idle && cfqq->cfqg->nr_cfqq > 1) |
2034 | return; |
2035 | |
2036 | cfq_mark_cfqq_wait_request(cfqq); |
2037 | |
2038 | if (group_idle) |
2039 | sl = cfqd->cfq_group_idle; |
2040 | else |
2041 | sl = cfqd->cfq_slice_idle; |
2042 | |
2043 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
2044 | cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); |
2045 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, |
2046 | group_idle ? 1 : 0); |
2047 | } |
2048 | |
2049 | /* |
2050 | * Move request from internal lists to the request queue dispatch list. |
2051 | */ |
2052 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
2053 | { |
2054 | struct cfq_data *cfqd = q->elevator->elevator_data; |
2055 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
2056 | |
2057 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
2058 | |
2059 | cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
2060 | cfq_remove_request(rq); |
2061 | cfqq->dispatched++; |
2062 | (RQ_CFQG(rq))->dispatched++; |
2063 | elv_dispatch_sort(q, rq); |
2064 | |
2065 | cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; |
2066 | cfqq->nr_sectors += blk_rq_sectors(rq); |
2067 | cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), |
2068 | rq_data_dir(rq), rq_is_sync(rq)); |
2069 | } |
2070 | |
2071 | /* |
2072 | * return expired entry, or NULL to just start from scratch in rbtree |
2073 | */ |
2074 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
2075 | { |
2076 | struct request *rq = NULL; |
2077 | |
2078 | if (cfq_cfqq_fifo_expire(cfqq)) |
2079 | return NULL; |
2080 | |
2081 | cfq_mark_cfqq_fifo_expire(cfqq); |
2082 | |
2083 | if (list_empty(&cfqq->fifo)) |
2084 | return NULL; |
2085 | |
2086 | rq = rq_entry_fifo(cfqq->fifo.next); |
2087 | if (time_before(jiffies, rq_fifo_time(rq))) |
2088 | rq = NULL; |
2089 | |
2090 | cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); |
2091 | return rq; |
2092 | } |
2093 | |
2094 | static inline int |
2095 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2096 | { |
2097 | const int base_rq = cfqd->cfq_slice_async_rq; |
2098 | |
2099 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
2100 | |
2101 | return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); |
2102 | } |
2103 | |
2104 | /* |
2105 | * Must be called with the queue_lock held. |
2106 | */ |
2107 | static int cfqq_process_refs(struct cfq_queue *cfqq) |
2108 | { |
2109 | int process_refs, io_refs; |
2110 | |
2111 | io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; |
2112 | process_refs = cfqq->ref - io_refs; |
2113 | BUG_ON(process_refs < 0); |
2114 | return process_refs; |
2115 | } |
2116 | |
2117 | static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) |
2118 | { |
2119 | int process_refs, new_process_refs; |
2120 | struct cfq_queue *__cfqq; |
2121 | |
2122 | /* |
2123 | * If there are no process references on the new_cfqq, then it is |
2124 | * unsafe to follow the ->new_cfqq chain as other cfqq's in the |
2125 | * chain may have dropped their last reference (not just their |
2126 | * last process reference). |
2127 | */ |
2128 | if (!cfqq_process_refs(new_cfqq)) |
2129 | return; |
2130 | |
2131 | /* Avoid a circular list and skip interim queue merges */ |
2132 | while ((__cfqq = new_cfqq->new_cfqq)) { |
2133 | if (__cfqq == cfqq) |
2134 | return; |
2135 | new_cfqq = __cfqq; |
2136 | } |
2137 | |
2138 | process_refs = cfqq_process_refs(cfqq); |
2139 | new_process_refs = cfqq_process_refs(new_cfqq); |
2140 | /* |
2141 | * If the process for the cfqq has gone away, there is no |
2142 | * sense in merging the queues. |
2143 | */ |
2144 | if (process_refs == 0 || new_process_refs == 0) |
2145 | return; |
2146 | |
2147 | /* |
2148 | * Merge in the direction of the lesser amount of work. |
2149 | */ |
2150 | if (new_process_refs >= process_refs) { |
2151 | cfqq->new_cfqq = new_cfqq; |
2152 | new_cfqq->ref += process_refs; |
2153 | } else { |
2154 | new_cfqq->new_cfqq = cfqq; |
2155 | cfqq->ref += new_process_refs; |
2156 | } |
2157 | } |
2158 | |
2159 | static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, |
2160 | struct cfq_group *cfqg, enum wl_prio_t prio) |
2161 | { |
2162 | struct cfq_queue *queue; |
2163 | int i; |
2164 | bool key_valid = false; |
2165 | unsigned long lowest_key = 0; |
2166 | enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; |
2167 | |
2168 | for (i = 0; i <= SYNC_WORKLOAD; ++i) { |
2169 | /* select the one with lowest rb_key */ |
2170 | queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); |
2171 | if (queue && |
2172 | (!key_valid || time_before(queue->rb_key, lowest_key))) { |
2173 | lowest_key = queue->rb_key; |
2174 | cur_best = i; |
2175 | key_valid = true; |
2176 | } |
2177 | } |
2178 | |
2179 | return cur_best; |
2180 | } |
2181 | |
2182 | static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) |
2183 | { |
2184 | unsigned slice; |
2185 | unsigned count; |
2186 | struct cfq_rb_root *st; |
2187 | unsigned group_slice; |
2188 | enum wl_prio_t original_prio = cfqd->serving_prio; |
2189 | |
2190 | /* Choose next priority. RT > BE > IDLE */ |
2191 | if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) |
2192 | cfqd->serving_prio = RT_WORKLOAD; |
2193 | else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) |
2194 | cfqd->serving_prio = BE_WORKLOAD; |
2195 | else { |
2196 | cfqd->serving_prio = IDLE_WORKLOAD; |
2197 | cfqd->workload_expires = jiffies + 1; |
2198 | return; |
2199 | } |
2200 | |
2201 | if (original_prio != cfqd->serving_prio) |
2202 | goto new_workload; |
2203 | |
2204 | /* |
2205 | * For RT and BE, we have to choose also the type |
2206 | * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload |
2207 | * expiration time |
2208 | */ |
2209 | st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); |
2210 | count = st->count; |
2211 | |
2212 | /* |
2213 | * check workload expiration, and that we still have other queues ready |
2214 | */ |
2215 | if (count && !time_after(jiffies, cfqd->workload_expires)) |
2216 | return; |
2217 | |
2218 | new_workload: |
2219 | /* otherwise select new workload type */ |
2220 | cfqd->serving_type = |
2221 | cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); |
2222 | st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); |
2223 | count = st->count; |
2224 | |
2225 | /* |
2226 | * the workload slice is computed as a fraction of target latency |
2227 | * proportional to the number of queues in that workload, over |
2228 | * all the queues in the same priority class |
2229 | */ |
2230 | group_slice = cfq_group_slice(cfqd, cfqg); |
2231 | |
2232 | slice = group_slice * count / |
2233 | max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], |
2234 | cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); |
2235 | |
2236 | if (cfqd->serving_type == ASYNC_WORKLOAD) { |
2237 | unsigned int tmp; |
2238 | |
2239 | /* |
2240 | * Async queues are currently system wide. Just taking |
2241 | * proportion of queues with-in same group will lead to higher |
2242 | * async ratio system wide as generally root group is going |
2243 | * to have higher weight. A more accurate thing would be to |
2244 | * calculate system wide asnc/sync ratio. |
2245 | */ |
2246 | tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); |
2247 | tmp = tmp/cfqd->busy_queues; |
2248 | slice = min_t(unsigned, slice, tmp); |
2249 | |
2250 | /* async workload slice is scaled down according to |
2251 | * the sync/async slice ratio. */ |
2252 | slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; |
2253 | } else |
2254 | /* sync workload slice is at least 2 * cfq_slice_idle */ |
2255 | slice = max(slice, 2 * cfqd->cfq_slice_idle); |
2256 | |
2257 | slice = max_t(unsigned, slice, CFQ_MIN_TT); |
2258 | cfq_log(cfqd, "workload slice:%d", slice); |
2259 | cfqd->workload_expires = jiffies + slice; |
2260 | } |
2261 | |
2262 | static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) |
2263 | { |
2264 | struct cfq_rb_root *st = &cfqd->grp_service_tree; |
2265 | struct cfq_group *cfqg; |
2266 | |
2267 | if (RB_EMPTY_ROOT(&st->rb)) |
2268 | return NULL; |
2269 | cfqg = cfq_rb_first_group(st); |
2270 | update_min_vdisktime(st); |
2271 | return cfqg; |
2272 | } |
2273 | |
2274 | static void cfq_choose_cfqg(struct cfq_data *cfqd) |
2275 | { |
2276 | struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); |
2277 | |
2278 | cfqd->serving_group = cfqg; |
2279 | |
2280 | /* Restore the workload type data */ |
2281 | if (cfqg->saved_workload_slice) { |
2282 | cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; |
2283 | cfqd->serving_type = cfqg->saved_workload; |
2284 | cfqd->serving_prio = cfqg->saved_serving_prio; |
2285 | } else |
2286 | cfqd->workload_expires = jiffies - 1; |
2287 | |
2288 | choose_service_tree(cfqd, cfqg); |
2289 | } |
2290 | |
2291 | /* |
2292 | * Select a queue for service. If we have a current active queue, |
2293 | * check whether to continue servicing it, or retrieve and set a new one. |
2294 | */ |
2295 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
2296 | { |
2297 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
2298 | |
2299 | cfqq = cfqd->active_queue; |
2300 | if (!cfqq) |
2301 | goto new_queue; |
2302 | |
2303 | if (!cfqd->rq_queued) |
2304 | return NULL; |
2305 | |
2306 | /* |
2307 | * We were waiting for group to get backlogged. Expire the queue |
2308 | */ |
2309 | if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) |
2310 | goto expire; |
2311 | |
2312 | /* |
2313 | * The active queue has run out of time, expire it and select new. |
2314 | */ |
2315 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { |
2316 | /* |
2317 | * If slice had not expired at the completion of last request |
2318 | * we might not have turned on wait_busy flag. Don't expire |
2319 | * the queue yet. Allow the group to get backlogged. |
2320 | * |
2321 | * The very fact that we have used the slice, that means we |
2322 | * have been idling all along on this queue and it should be |
2323 | * ok to wait for this request to complete. |
2324 | */ |
2325 | if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) |
2326 | && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { |
2327 | cfqq = NULL; |
2328 | goto keep_queue; |
2329 | } else |
2330 | goto check_group_idle; |
2331 | } |
2332 | |
2333 | /* |
2334 | * The active queue has requests and isn't expired, allow it to |
2335 | * dispatch. |
2336 | */ |
2337 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
2338 | goto keep_queue; |
2339 | |
2340 | /* |
2341 | * If another queue has a request waiting within our mean seek |
2342 | * distance, let it run. The expire code will check for close |
2343 | * cooperators and put the close queue at the front of the service |
2344 | * tree. If possible, merge the expiring queue with the new cfqq. |
2345 | */ |
2346 | new_cfqq = cfq_close_cooperator(cfqd, cfqq); |
2347 | if (new_cfqq) { |
2348 | if (!cfqq->new_cfqq) |
2349 | cfq_setup_merge(cfqq, new_cfqq); |
2350 | goto expire; |
2351 | } |
2352 | |
2353 | /* |
2354 | * No requests pending. If the active queue still has requests in |
2355 | * flight or is idling for a new request, allow either of these |
2356 | * conditions to happen (or time out) before selecting a new queue. |
2357 | */ |
2358 | if (timer_pending(&cfqd->idle_slice_timer)) { |
2359 | cfqq = NULL; |
2360 | goto keep_queue; |
2361 | } |
2362 | |
2363 | /* |
2364 | * This is a deep seek queue, but the device is much faster than |
2365 | * the queue can deliver, don't idle |
2366 | **/ |
2367 | if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && |
2368 | (cfq_cfqq_slice_new(cfqq) || |
2369 | (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { |
2370 | cfq_clear_cfqq_deep(cfqq); |
2371 | cfq_clear_cfqq_idle_window(cfqq); |
2372 | } |
2373 | |
2374 | if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { |
2375 | cfqq = NULL; |
2376 | goto keep_queue; |
2377 | } |
2378 | |
2379 | /* |
2380 | * If group idle is enabled and there are requests dispatched from |
2381 | * this group, wait for requests to complete. |
2382 | */ |
2383 | check_group_idle: |
2384 | if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 |
2385 | && cfqq->cfqg->dispatched) { |
2386 | cfqq = NULL; |
2387 | goto keep_queue; |
2388 | } |
2389 | |
2390 | expire: |
2391 | cfq_slice_expired(cfqd, 0); |
2392 | new_queue: |
2393 | /* |
2394 | * Current queue expired. Check if we have to switch to a new |
2395 | * service tree |
2396 | */ |
2397 | if (!new_cfqq) |
2398 | cfq_choose_cfqg(cfqd); |
2399 | |
2400 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
2401 | keep_queue: |
2402 | return cfqq; |
2403 | } |
2404 | |
2405 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
2406 | { |
2407 | int dispatched = 0; |
2408 | |
2409 | while (cfqq->next_rq) { |
2410 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); |
2411 | dispatched++; |
2412 | } |
2413 | |
2414 | BUG_ON(!list_empty(&cfqq->fifo)); |
2415 | |
2416 | /* By default cfqq is not expired if it is empty. Do it explicitly */ |
2417 | __cfq_slice_expired(cfqq->cfqd, cfqq, 0); |
2418 | return dispatched; |
2419 | } |
2420 | |
2421 | /* |
2422 | * Drain our current requests. Used for barriers and when switching |
2423 | * io schedulers on-the-fly. |
2424 | */ |
2425 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
2426 | { |
2427 | struct cfq_queue *cfqq; |
2428 | int dispatched = 0; |
2429 | |
2430 | /* Expire the timeslice of the current active queue first */ |
2431 | cfq_slice_expired(cfqd, 0); |
2432 | while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { |
2433 | __cfq_set_active_queue(cfqd, cfqq); |
2434 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
2435 | } |
2436 | |
2437 | BUG_ON(cfqd->busy_queues); |
2438 | |
2439 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
2440 | return dispatched; |
2441 | } |
2442 | |
2443 | static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, |
2444 | struct cfq_queue *cfqq) |
2445 | { |
2446 | /* the queue hasn't finished any request, can't estimate */ |
2447 | if (cfq_cfqq_slice_new(cfqq)) |
2448 | return true; |
2449 | if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, |
2450 | cfqq->slice_end)) |
2451 | return true; |
2452 | |
2453 | return false; |
2454 | } |
2455 | |
2456 | static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2457 | { |
2458 | unsigned int max_dispatch; |
2459 | |
2460 | /* |
2461 | * Drain async requests before we start sync IO |
2462 | */ |
2463 | if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) |
2464 | return false; |
2465 | |
2466 | /* |
2467 | * If this is an async queue and we have sync IO in flight, let it wait |
2468 | */ |
2469 | if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) |
2470 | return false; |
2471 | |
2472 | max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); |
2473 | if (cfq_class_idle(cfqq)) |
2474 | max_dispatch = 1; |
2475 | |
2476 | /* |
2477 | * Does this cfqq already have too much IO in flight? |
2478 | */ |
2479 | if (cfqq->dispatched >= max_dispatch) { |
2480 | bool promote_sync = false; |
2481 | /* |
2482 | * idle queue must always only have a single IO in flight |
2483 | */ |
2484 | if (cfq_class_idle(cfqq)) |
2485 | return false; |
2486 | |
2487 | /* |
2488 | * If there is only one sync queue |
2489 | * we can ignore async queue here and give the sync |
2490 | * queue no dispatch limit. The reason is a sync queue can |
2491 | * preempt async queue, limiting the sync queue doesn't make |
2492 | * sense. This is useful for aiostress test. |
2493 | */ |
2494 | if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) |
2495 | promote_sync = true; |
2496 | |
2497 | /* |
2498 | * We have other queues, don't allow more IO from this one |
2499 | */ |
2500 | if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && |
2501 | !promote_sync) |
2502 | return false; |
2503 | |
2504 | /* |
2505 | * Sole queue user, no limit |
2506 | */ |
2507 | if (cfqd->busy_queues == 1 || promote_sync) |
2508 | max_dispatch = -1; |
2509 | else |
2510 | /* |
2511 | * Normally we start throttling cfqq when cfq_quantum/2 |
2512 | * requests have been dispatched. But we can drive |
2513 | * deeper queue depths at the beginning of slice |
2514 | * subjected to upper limit of cfq_quantum. |
2515 | * */ |
2516 | max_dispatch = cfqd->cfq_quantum; |
2517 | } |
2518 | |
2519 | /* |
2520 | * Async queues must wait a bit before being allowed dispatch. |
2521 | * We also ramp up the dispatch depth gradually for async IO, |
2522 | * based on the last sync IO we serviced |
2523 | */ |
2524 | if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
2525 | unsigned long last_sync = jiffies - cfqd->last_delayed_sync; |
2526 | unsigned int depth; |
2527 | |
2528 | depth = last_sync / cfqd->cfq_slice[1]; |
2529 | if (!depth && !cfqq->dispatched) |
2530 | depth = 1; |
2531 | if (depth < max_dispatch) |
2532 | max_dispatch = depth; |
2533 | } |
2534 | |
2535 | /* |
2536 | * If we're below the current max, allow a dispatch |
2537 | */ |
2538 | return cfqq->dispatched < max_dispatch; |
2539 | } |
2540 | |
2541 | /* |
2542 | * Dispatch a request from cfqq, moving them to the request queue |
2543 | * dispatch list. |
2544 | */ |
2545 | static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2546 | { |
2547 | struct request *rq; |
2548 | |
2549 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
2550 | |
2551 | if (!cfq_may_dispatch(cfqd, cfqq)) |
2552 | return false; |
2553 | |
2554 | /* |
2555 | * follow expired path, else get first next available |
2556 | */ |
2557 | rq = cfq_check_fifo(cfqq); |
2558 | if (!rq) |
2559 | rq = cfqq->next_rq; |
2560 | |
2561 | /* |
2562 | * insert request into driver dispatch list |
2563 | */ |
2564 | cfq_dispatch_insert(cfqd->queue, rq); |
2565 | |
2566 | if (!cfqd->active_cic) { |
2567 | struct cfq_io_context *cic = RQ_CIC(rq); |
2568 | |
2569 | atomic_long_inc(&cic->ioc->refcount); |
2570 | cfqd->active_cic = cic; |
2571 | } |
2572 | |
2573 | return true; |
2574 | } |
2575 | |
2576 | /* |
2577 | * Find the cfqq that we need to service and move a request from that to the |
2578 | * dispatch list |
2579 | */ |
2580 | static int cfq_dispatch_requests(struct request_queue *q, int force) |
2581 | { |
2582 | struct cfq_data *cfqd = q->elevator->elevator_data; |
2583 | struct cfq_queue *cfqq; |
2584 | |
2585 | if (!cfqd->busy_queues) |
2586 | return 0; |
2587 | |
2588 | if (unlikely(force)) |
2589 | return cfq_forced_dispatch(cfqd); |
2590 | |
2591 | cfqq = cfq_select_queue(cfqd); |
2592 | if (!cfqq) |
2593 | return 0; |
2594 | |
2595 | /* |
2596 | * Dispatch a request from this cfqq, if it is allowed |
2597 | */ |
2598 | if (!cfq_dispatch_request(cfqd, cfqq)) |
2599 | return 0; |
2600 | |
2601 | cfqq->slice_dispatch++; |
2602 | cfq_clear_cfqq_must_dispatch(cfqq); |
2603 | |
2604 | /* |
2605 | * expire an async queue immediately if it has used up its slice. idle |
2606 | * queue always expire after 1 dispatch round. |
2607 | */ |
2608 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && |
2609 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || |
2610 | cfq_class_idle(cfqq))) { |
2611 | cfqq->slice_end = jiffies + 1; |
2612 | cfq_slice_expired(cfqd, 0); |
2613 | } |
2614 | |
2615 | cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
2616 | return 1; |
2617 | } |
2618 | |
2619 | /* |
2620 | * task holds one reference to the queue, dropped when task exits. each rq |
2621 | * in-flight on this queue also holds a reference, dropped when rq is freed. |
2622 | * |
2623 | * Each cfq queue took a reference on the parent group. Drop it now. |
2624 | * queue lock must be held here. |
2625 | */ |
2626 | static void cfq_put_queue(struct cfq_queue *cfqq) |
2627 | { |
2628 | struct cfq_data *cfqd = cfqq->cfqd; |
2629 | struct cfq_group *cfqg; |
2630 | |
2631 | BUG_ON(cfqq->ref <= 0); |
2632 | |
2633 | cfqq->ref--; |
2634 | if (cfqq->ref) |
2635 | return; |
2636 | |
2637 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
2638 | BUG_ON(rb_first(&cfqq->sort_list)); |
2639 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
2640 | cfqg = cfqq->cfqg; |
2641 | |
2642 | if (unlikely(cfqd->active_queue == cfqq)) { |
2643 | __cfq_slice_expired(cfqd, cfqq, 0); |
2644 | cfq_schedule_dispatch(cfqd); |
2645 | } |
2646 | |
2647 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
2648 | kmem_cache_free(cfq_pool, cfqq); |
2649 | cfq_put_cfqg(cfqg); |
2650 | } |
2651 | |
2652 | /* |
2653 | * Call func for each cic attached to this ioc. |
2654 | */ |
2655 | static void |
2656 | call_for_each_cic(struct io_context *ioc, |
2657 | void (*func)(struct io_context *, struct cfq_io_context *)) |
2658 | { |
2659 | struct cfq_io_context *cic; |
2660 | struct hlist_node *n; |
2661 | |
2662 | rcu_read_lock(); |
2663 | |
2664 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) |
2665 | func(ioc, cic); |
2666 | |
2667 | rcu_read_unlock(); |
2668 | } |
2669 | |
2670 | static void cfq_cic_free_rcu(struct rcu_head *head) |
2671 | { |
2672 | struct cfq_io_context *cic; |
2673 | |
2674 | cic = container_of(head, struct cfq_io_context, rcu_head); |
2675 | |
2676 | kmem_cache_free(cfq_ioc_pool, cic); |
2677 | elv_ioc_count_dec(cfq_ioc_count); |
2678 | |
2679 | if (ioc_gone) { |
2680 | /* |
2681 | * CFQ scheduler is exiting, grab exit lock and check |
2682 | * the pending io context count. If it hits zero, |
2683 | * complete ioc_gone and set it back to NULL |
2684 | */ |
2685 | spin_lock(&ioc_gone_lock); |
2686 | if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { |
2687 | complete(ioc_gone); |
2688 | ioc_gone = NULL; |
2689 | } |
2690 | spin_unlock(&ioc_gone_lock); |
2691 | } |
2692 | } |
2693 | |
2694 | static void cfq_cic_free(struct cfq_io_context *cic) |
2695 | { |
2696 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); |
2697 | } |
2698 | |
2699 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) |
2700 | { |
2701 | unsigned long flags; |
2702 | unsigned long dead_key = (unsigned long) cic->key; |
2703 | |
2704 | BUG_ON(!(dead_key & CIC_DEAD_KEY)); |
2705 | |
2706 | spin_lock_irqsave(&ioc->lock, flags); |
2707 | radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT); |
2708 | hlist_del_rcu(&cic->cic_list); |
2709 | spin_unlock_irqrestore(&ioc->lock, flags); |
2710 | |
2711 | cfq_cic_free(cic); |
2712 | } |
2713 | |
2714 | /* |
2715 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. |
2716 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), |
2717 | * and ->trim() which is called with the task lock held |
2718 | */ |
2719 | static void cfq_free_io_context(struct io_context *ioc) |
2720 | { |
2721 | /* |
2722 | * ioc->refcount is zero here, or we are called from elv_unregister(), |
2723 | * so no more cic's are allowed to be linked into this ioc. So it |
2724 | * should be ok to iterate over the known list, we will see all cic's |
2725 | * since no new ones are added. |
2726 | */ |
2727 | call_for_each_cic(ioc, cic_free_func); |
2728 | } |
2729 | |
2730 | static void cfq_put_cooperator(struct cfq_queue *cfqq) |
2731 | { |
2732 | struct cfq_queue *__cfqq, *next; |
2733 | |
2734 | /* |
2735 | * If this queue was scheduled to merge with another queue, be |
2736 | * sure to drop the reference taken on that queue (and others in |
2737 | * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. |
2738 | */ |
2739 | __cfqq = cfqq->new_cfqq; |
2740 | while (__cfqq) { |
2741 | if (__cfqq == cfqq) { |
2742 | WARN(1, "cfqq->new_cfqq loop detected\n"); |
2743 | break; |
2744 | } |
2745 | next = __cfqq->new_cfqq; |
2746 | cfq_put_queue(__cfqq); |
2747 | __cfqq = next; |
2748 | } |
2749 | } |
2750 | |
2751 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2752 | { |
2753 | if (unlikely(cfqq == cfqd->active_queue)) { |
2754 | __cfq_slice_expired(cfqd, cfqq, 0); |
2755 | cfq_schedule_dispatch(cfqd); |
2756 | } |
2757 | |
2758 | cfq_put_cooperator(cfqq); |
2759 | |
2760 | cfq_put_queue(cfqq); |
2761 | } |
2762 | |
2763 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
2764 | struct cfq_io_context *cic) |
2765 | { |
2766 | struct io_context *ioc = cic->ioc; |
2767 | |
2768 | list_del_init(&cic->queue_list); |
2769 | |
2770 | /* |
2771 | * Make sure dead mark is seen for dead queues |
2772 | */ |
2773 | smp_wmb(); |
2774 | cic->key = cfqd_dead_key(cfqd); |
2775 | |
2776 | rcu_read_lock(); |
2777 | if (rcu_dereference(ioc->ioc_data) == cic) { |
2778 | rcu_read_unlock(); |
2779 | spin_lock(&ioc->lock); |
2780 | rcu_assign_pointer(ioc->ioc_data, NULL); |
2781 | spin_unlock(&ioc->lock); |
2782 | } else |
2783 | rcu_read_unlock(); |
2784 | |
2785 | if (cic->cfqq[BLK_RW_ASYNC]) { |
2786 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); |
2787 | cic->cfqq[BLK_RW_ASYNC] = NULL; |
2788 | } |
2789 | |
2790 | if (cic->cfqq[BLK_RW_SYNC]) { |
2791 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); |
2792 | cic->cfqq[BLK_RW_SYNC] = NULL; |
2793 | } |
2794 | } |
2795 | |
2796 | static void cfq_exit_single_io_context(struct io_context *ioc, |
2797 | struct cfq_io_context *cic) |
2798 | { |
2799 | struct cfq_data *cfqd = cic_to_cfqd(cic); |
2800 | |
2801 | if (cfqd) { |
2802 | struct request_queue *q = cfqd->queue; |
2803 | unsigned long flags; |
2804 | |
2805 | spin_lock_irqsave(q->queue_lock, flags); |
2806 | |
2807 | /* |
2808 | * Ensure we get a fresh copy of the ->key to prevent |
2809 | * race between exiting task and queue |
2810 | */ |
2811 | smp_read_barrier_depends(); |
2812 | if (cic->key == cfqd) |
2813 | __cfq_exit_single_io_context(cfqd, cic); |
2814 | |
2815 | spin_unlock_irqrestore(q->queue_lock, flags); |
2816 | } |
2817 | } |
2818 | |
2819 | /* |
2820 | * The process that ioc belongs to has exited, we need to clean up |
2821 | * and put the internal structures we have that belongs to that process. |
2822 | */ |
2823 | static void cfq_exit_io_context(struct io_context *ioc) |
2824 | { |
2825 | call_for_each_cic(ioc, cfq_exit_single_io_context); |
2826 | } |
2827 | |
2828 | static struct cfq_io_context * |
2829 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
2830 | { |
2831 | struct cfq_io_context *cic; |
2832 | |
2833 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
2834 | cfqd->queue->node); |
2835 | if (cic) { |
2836 | cic->last_end_request = jiffies; |
2837 | INIT_LIST_HEAD(&cic->queue_list); |
2838 | INIT_HLIST_NODE(&cic->cic_list); |
2839 | cic->dtor = cfq_free_io_context; |
2840 | cic->exit = cfq_exit_io_context; |
2841 | elv_ioc_count_inc(cfq_ioc_count); |
2842 | } |
2843 | |
2844 | return cic; |
2845 | } |
2846 | |
2847 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
2848 | { |
2849 | struct task_struct *tsk = current; |
2850 | int ioprio_class; |
2851 | |
2852 | if (!cfq_cfqq_prio_changed(cfqq)) |
2853 | return; |
2854 | |
2855 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
2856 | switch (ioprio_class) { |
2857 | default: |
2858 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); |
2859 | case IOPRIO_CLASS_NONE: |
2860 | /* |
2861 | * no prio set, inherit CPU scheduling settings |
2862 | */ |
2863 | cfqq->ioprio = task_nice_ioprio(tsk); |
2864 | cfqq->ioprio_class = task_nice_ioclass(tsk); |
2865 | break; |
2866 | case IOPRIO_CLASS_RT: |
2867 | cfqq->ioprio = task_ioprio(ioc); |
2868 | cfqq->ioprio_class = IOPRIO_CLASS_RT; |
2869 | break; |
2870 | case IOPRIO_CLASS_BE: |
2871 | cfqq->ioprio = task_ioprio(ioc); |
2872 | cfqq->ioprio_class = IOPRIO_CLASS_BE; |
2873 | break; |
2874 | case IOPRIO_CLASS_IDLE: |
2875 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; |
2876 | cfqq->ioprio = 7; |
2877 | cfq_clear_cfqq_idle_window(cfqq); |
2878 | break; |
2879 | } |
2880 | |
2881 | /* |
2882 | * keep track of original prio settings in case we have to temporarily |
2883 | * elevate the priority of this queue |
2884 | */ |
2885 | cfqq->org_ioprio = cfqq->ioprio; |
2886 | cfqq->org_ioprio_class = cfqq->ioprio_class; |
2887 | cfq_clear_cfqq_prio_changed(cfqq); |
2888 | } |
2889 | |
2890 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
2891 | { |
2892 | struct cfq_data *cfqd = cic_to_cfqd(cic); |
2893 | struct cfq_queue *cfqq; |
2894 | unsigned long flags; |
2895 | |
2896 | if (unlikely(!cfqd)) |
2897 | return; |
2898 | |
2899 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
2900 | |
2901 | cfqq = cic->cfqq[BLK_RW_ASYNC]; |
2902 | if (cfqq) { |
2903 | struct cfq_queue *new_cfqq; |
2904 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
2905 | GFP_ATOMIC); |
2906 | if (new_cfqq) { |
2907 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
2908 | cfq_put_queue(cfqq); |
2909 | } |
2910 | } |
2911 | |
2912 | cfqq = cic->cfqq[BLK_RW_SYNC]; |
2913 | if (cfqq) |
2914 | cfq_mark_cfqq_prio_changed(cfqq); |
2915 | |
2916 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
2917 | } |
2918 | |
2919 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
2920 | { |
2921 | call_for_each_cic(ioc, changed_ioprio); |
2922 | ioc->ioprio_changed = 0; |
2923 | } |
2924 | |
2925 | static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
2926 | pid_t pid, bool is_sync) |
2927 | { |
2928 | RB_CLEAR_NODE(&cfqq->rb_node); |
2929 | RB_CLEAR_NODE(&cfqq->p_node); |
2930 | INIT_LIST_HEAD(&cfqq->fifo); |
2931 | |
2932 | cfqq->ref = 0; |
2933 | cfqq->cfqd = cfqd; |
2934 | |
2935 | cfq_mark_cfqq_prio_changed(cfqq); |
2936 | |
2937 | if (is_sync) { |
2938 | if (!cfq_class_idle(cfqq)) |
2939 | cfq_mark_cfqq_idle_window(cfqq); |
2940 | cfq_mark_cfqq_sync(cfqq); |
2941 | } |
2942 | cfqq->pid = pid; |
2943 | } |
2944 | |
2945 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
2946 | static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic) |
2947 | { |
2948 | struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); |
2949 | struct cfq_data *cfqd = cic_to_cfqd(cic); |
2950 | unsigned long flags; |
2951 | struct request_queue *q; |
2952 | |
2953 | if (unlikely(!cfqd)) |
2954 | return; |
2955 | |
2956 | q = cfqd->queue; |
2957 | |
2958 | spin_lock_irqsave(q->queue_lock, flags); |
2959 | |
2960 | if (sync_cfqq) { |
2961 | /* |
2962 | * Drop reference to sync queue. A new sync queue will be |
2963 | * assigned in new group upon arrival of a fresh request. |
2964 | */ |
2965 | cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); |
2966 | cic_set_cfqq(cic, NULL, 1); |
2967 | cfq_put_queue(sync_cfqq); |
2968 | } |
2969 | |
2970 | spin_unlock_irqrestore(q->queue_lock, flags); |
2971 | } |
2972 | |
2973 | static void cfq_ioc_set_cgroup(struct io_context *ioc) |
2974 | { |
2975 | call_for_each_cic(ioc, changed_cgroup); |
2976 | ioc->cgroup_changed = 0; |
2977 | } |
2978 | #endif /* CONFIG_CFQ_GROUP_IOSCHED */ |
2979 | |
2980 | static struct cfq_queue * |
2981 | cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, |
2982 | struct io_context *ioc, gfp_t gfp_mask) |
2983 | { |
2984 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
2985 | struct cfq_io_context *cic; |
2986 | struct cfq_group *cfqg; |
2987 | |
2988 | retry: |
2989 | cfqg = cfq_get_cfqg(cfqd); |
2990 | cic = cfq_cic_lookup(cfqd, ioc); |
2991 | /* cic always exists here */ |
2992 | cfqq = cic_to_cfqq(cic, is_sync); |
2993 | |
2994 | /* |
2995 | * Always try a new alloc if we fell back to the OOM cfqq |
2996 | * originally, since it should just be a temporary situation. |
2997 | */ |
2998 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
2999 | cfqq = NULL; |
3000 | if (new_cfqq) { |
3001 | cfqq = new_cfqq; |
3002 | new_cfqq = NULL; |
3003 | } else if (gfp_mask & __GFP_WAIT) { |
3004 | spin_unlock_irq(cfqd->queue->queue_lock); |
3005 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
3006 | gfp_mask | __GFP_ZERO, |
3007 | cfqd->queue->node); |
3008 | spin_lock_irq(cfqd->queue->queue_lock); |
3009 | if (new_cfqq) |
3010 | goto retry; |
3011 | } else { |
3012 | cfqq = kmem_cache_alloc_node(cfq_pool, |
3013 | gfp_mask | __GFP_ZERO, |
3014 | cfqd->queue->node); |
3015 | } |
3016 | |
3017 | if (cfqq) { |
3018 | cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); |
3019 | cfq_init_prio_data(cfqq, ioc); |
3020 | cfq_link_cfqq_cfqg(cfqq, cfqg); |
3021 | cfq_log_cfqq(cfqd, cfqq, "alloced"); |
3022 | } else |
3023 | cfqq = &cfqd->oom_cfqq; |
3024 | } |
3025 | |
3026 | if (new_cfqq) |
3027 | kmem_cache_free(cfq_pool, new_cfqq); |
3028 | |
3029 | return cfqq; |
3030 | } |
3031 | |
3032 | static struct cfq_queue ** |
3033 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) |
3034 | { |
3035 | switch (ioprio_class) { |
3036 | case IOPRIO_CLASS_RT: |
3037 | return &cfqd->async_cfqq[0][ioprio]; |
3038 | case IOPRIO_CLASS_BE: |
3039 | return &cfqd->async_cfqq[1][ioprio]; |
3040 | case IOPRIO_CLASS_IDLE: |
3041 | return &cfqd->async_idle_cfqq; |
3042 | default: |
3043 | BUG(); |
3044 | } |
3045 | } |
3046 | |
3047 | static struct cfq_queue * |
3048 | cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, |
3049 | gfp_t gfp_mask) |
3050 | { |
3051 | const int ioprio = task_ioprio(ioc); |
3052 | const int ioprio_class = task_ioprio_class(ioc); |
3053 | struct cfq_queue **async_cfqq = NULL; |
3054 | struct cfq_queue *cfqq = NULL; |
3055 | |
3056 | if (!is_sync) { |
3057 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); |
3058 | cfqq = *async_cfqq; |
3059 | } |
3060 | |
3061 | if (!cfqq) |
3062 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
3063 | |
3064 | /* |
3065 | * pin the queue now that it's allocated, scheduler exit will prune it |
3066 | */ |
3067 | if (!is_sync && !(*async_cfqq)) { |
3068 | cfqq->ref++; |
3069 | *async_cfqq = cfqq; |
3070 | } |
3071 | |
3072 | cfqq->ref++; |
3073 | return cfqq; |
3074 | } |
3075 | |
3076 | /* |
3077 | * We drop cfq io contexts lazily, so we may find a dead one. |
3078 | */ |
3079 | static void |
3080 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
3081 | struct cfq_io_context *cic) |
3082 | { |
3083 | unsigned long flags; |
3084 | |
3085 | WARN_ON(!list_empty(&cic->queue_list)); |
3086 | BUG_ON(cic->key != cfqd_dead_key(cfqd)); |
3087 | |
3088 | spin_lock_irqsave(&ioc->lock, flags); |
3089 | |
3090 | BUG_ON(rcu_dereference_check(ioc->ioc_data, |
3091 | lockdep_is_held(&ioc->lock)) == cic); |
3092 | |
3093 | radix_tree_delete(&ioc->radix_root, cfqd->cic_index); |
3094 | hlist_del_rcu(&cic->cic_list); |
3095 | spin_unlock_irqrestore(&ioc->lock, flags); |
3096 | |
3097 | cfq_cic_free(cic); |
3098 | } |
3099 | |
3100 | static struct cfq_io_context * |
3101 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
3102 | { |
3103 | struct cfq_io_context *cic; |
3104 | unsigned long flags; |
3105 | |
3106 | if (unlikely(!ioc)) |
3107 | return NULL; |
3108 | |
3109 | rcu_read_lock(); |
3110 | |
3111 | /* |
3112 | * we maintain a last-hit cache, to avoid browsing over the tree |
3113 | */ |
3114 | cic = rcu_dereference(ioc->ioc_data); |
3115 | if (cic && cic->key == cfqd) { |
3116 | rcu_read_unlock(); |
3117 | return cic; |
3118 | } |
3119 | |
3120 | do { |
3121 | cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index); |
3122 | rcu_read_unlock(); |
3123 | if (!cic) |
3124 | break; |
3125 | if (unlikely(cic->key != cfqd)) { |
3126 | cfq_drop_dead_cic(cfqd, ioc, cic); |
3127 | rcu_read_lock(); |
3128 | continue; |
3129 | } |
3130 | |
3131 | spin_lock_irqsave(&ioc->lock, flags); |
3132 | rcu_assign_pointer(ioc->ioc_data, cic); |
3133 | spin_unlock_irqrestore(&ioc->lock, flags); |
3134 | break; |
3135 | } while (1); |
3136 | |
3137 | return cic; |
3138 | } |
3139 | |
3140 | /* |
3141 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup |
3142 | * the process specific cfq io context when entered from the block layer. |
3143 | * Also adds the cic to a per-cfqd list, used when this queue is removed. |
3144 | */ |
3145 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
3146 | struct cfq_io_context *cic, gfp_t gfp_mask) |
3147 | { |
3148 | unsigned long flags; |
3149 | int ret; |
3150 | |
3151 | ret = radix_tree_preload(gfp_mask); |
3152 | if (!ret) { |
3153 | cic->ioc = ioc; |
3154 | cic->key = cfqd; |
3155 | |
3156 | spin_lock_irqsave(&ioc->lock, flags); |
3157 | ret = radix_tree_insert(&ioc->radix_root, |
3158 | cfqd->cic_index, cic); |
3159 | if (!ret) |
3160 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); |
3161 | spin_unlock_irqrestore(&ioc->lock, flags); |
3162 | |
3163 | radix_tree_preload_end(); |
3164 | |
3165 | if (!ret) { |
3166 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
3167 | list_add(&cic->queue_list, &cfqd->cic_list); |
3168 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
3169 | } |
3170 | } |
3171 | |
3172 | if (ret) |
3173 | printk(KERN_ERR "cfq: cic link failed!\n"); |
3174 | |
3175 | return ret; |
3176 | } |
3177 | |
3178 | /* |
3179 | * Setup general io context and cfq io context. There can be several cfq |
3180 | * io contexts per general io context, if this process is doing io to more |
3181 | * than one device managed by cfq. |
3182 | */ |
3183 | static struct cfq_io_context * |
3184 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
3185 | { |
3186 | struct io_context *ioc = NULL; |
3187 | struct cfq_io_context *cic; |
3188 | |
3189 | might_sleep_if(gfp_mask & __GFP_WAIT); |
3190 | |
3191 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
3192 | if (!ioc) |
3193 | return NULL; |
3194 | |
3195 | cic = cfq_cic_lookup(cfqd, ioc); |
3196 | if (cic) |
3197 | goto out; |
3198 | |
3199 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
3200 | if (cic == NULL) |
3201 | goto err; |
3202 | |
3203 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
3204 | goto err_free; |
3205 | |
3206 | out: |
3207 | smp_read_barrier_depends(); |
3208 | if (unlikely(ioc->ioprio_changed)) |
3209 | cfq_ioc_set_ioprio(ioc); |
3210 | |
3211 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
3212 | if (unlikely(ioc->cgroup_changed)) |
3213 | cfq_ioc_set_cgroup(ioc); |
3214 | #endif |
3215 | return cic; |
3216 | err_free: |
3217 | cfq_cic_free(cic); |
3218 | err: |
3219 | put_io_context(ioc); |
3220 | return NULL; |
3221 | } |
3222 | |
3223 | static void |
3224 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) |
3225 | { |
3226 | unsigned long elapsed = jiffies - cic->last_end_request; |
3227 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); |
3228 | |
3229 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
3230 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; |
3231 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; |
3232 | } |
3233 | |
3234 | static void |
3235 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
3236 | struct request *rq) |
3237 | { |
3238 | sector_t sdist = 0; |
3239 | sector_t n_sec = blk_rq_sectors(rq); |
3240 | if (cfqq->last_request_pos) { |
3241 | if (cfqq->last_request_pos < blk_rq_pos(rq)) |
3242 | sdist = blk_rq_pos(rq) - cfqq->last_request_pos; |
3243 | else |
3244 | sdist = cfqq->last_request_pos - blk_rq_pos(rq); |
3245 | } |
3246 | |
3247 | cfqq->seek_history <<= 1; |
3248 | if (blk_queue_nonrot(cfqd->queue)) |
3249 | cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); |
3250 | else |
3251 | cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); |
3252 | } |
3253 | |
3254 | /* |
3255 | * Disable idle window if the process thinks too long or seeks so much that |
3256 | * it doesn't matter |
3257 | */ |
3258 | static void |
3259 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
3260 | struct cfq_io_context *cic) |
3261 | { |
3262 | int old_idle, enable_idle; |
3263 | |
3264 | /* |
3265 | * Don't idle for async or idle io prio class |
3266 | */ |
3267 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) |
3268 | return; |
3269 | |
3270 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
3271 | |
3272 | if (cfqq->queued[0] + cfqq->queued[1] >= 4) |
3273 | cfq_mark_cfqq_deep(cfqq); |
3274 | |
3275 | if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) |
3276 | enable_idle = 0; |
3277 | else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
3278 | (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) |
3279 | enable_idle = 0; |
3280 | else if (sample_valid(cic->ttime_samples)) { |
3281 | if (cic->ttime_mean > cfqd->cfq_slice_idle) |
3282 | enable_idle = 0; |
3283 | else |
3284 | enable_idle = 1; |
3285 | } |
3286 | |
3287 | if (old_idle != enable_idle) { |
3288 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); |
3289 | if (enable_idle) |
3290 | cfq_mark_cfqq_idle_window(cfqq); |
3291 | else |
3292 | cfq_clear_cfqq_idle_window(cfqq); |
3293 | } |
3294 | } |
3295 | |
3296 | /* |
3297 | * Check if new_cfqq should preempt the currently active queue. Return 0 for |
3298 | * no or if we aren't sure, a 1 will cause a preempt. |
3299 | */ |
3300 | static bool |
3301 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
3302 | struct request *rq) |
3303 | { |
3304 | struct cfq_queue *cfqq; |
3305 | |
3306 | cfqq = cfqd->active_queue; |
3307 | if (!cfqq) |
3308 | return false; |
3309 | |
3310 | if (cfq_class_idle(new_cfqq)) |
3311 | return false; |
3312 | |
3313 | if (cfq_class_idle(cfqq)) |
3314 | return true; |
3315 | |
3316 | /* |
3317 | * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. |
3318 | */ |
3319 | if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) |
3320 | return false; |
3321 | |
3322 | /* |
3323 | * if the new request is sync, but the currently running queue is |
3324 | * not, let the sync request have priority. |
3325 | */ |
3326 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
3327 | return true; |
3328 | |
3329 | if (new_cfqq->cfqg != cfqq->cfqg) |
3330 | return false; |
3331 | |
3332 | if (cfq_slice_used(cfqq)) |
3333 | return true; |
3334 | |
3335 | /* Allow preemption only if we are idling on sync-noidle tree */ |
3336 | if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && |
3337 | cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && |
3338 | new_cfqq->service_tree->count == 2 && |
3339 | RB_EMPTY_ROOT(&cfqq->sort_list)) |
3340 | return true; |
3341 | |
3342 | /* |
3343 | * So both queues are sync. Let the new request get disk time if |
3344 | * it's a metadata request and the current queue is doing regular IO. |
3345 | */ |
3346 | if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending) |
3347 | return true; |
3348 | |
3349 | /* |
3350 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. |
3351 | */ |
3352 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) |
3353 | return true; |
3354 | |
3355 | /* An idle queue should not be idle now for some reason */ |
3356 | if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) |
3357 | return true; |
3358 | |
3359 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
3360 | return false; |
3361 | |
3362 | /* |
3363 | * if this request is as-good as one we would expect from the |
3364 | * current cfqq, let it preempt |
3365 | */ |
3366 | if (cfq_rq_close(cfqd, cfqq, rq)) |
3367 | return true; |
3368 | |
3369 | return false; |
3370 | } |
3371 | |
3372 | /* |
3373 | * cfqq preempts the active queue. if we allowed preempt with no slice left, |
3374 | * let it have half of its nominal slice. |
3375 | */ |
3376 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
3377 | { |
3378 | struct cfq_queue *old_cfqq = cfqd->active_queue; |
3379 | |
3380 | cfq_log_cfqq(cfqd, cfqq, "preempt"); |
3381 | cfq_slice_expired(cfqd, 1); |
3382 | |
3383 | /* |
3384 | * workload type is changed, don't save slice, otherwise preempt |
3385 | * doesn't happen |
3386 | */ |
3387 | if (cfqq_type(old_cfqq) != cfqq_type(cfqq)) |
3388 | cfqq->cfqg->saved_workload_slice = 0; |
3389 | |
3390 | /* |
3391 | * Put the new queue at the front of the of the current list, |
3392 | * so we know that it will be selected next. |
3393 | */ |
3394 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
3395 | |
3396 | cfq_service_tree_add(cfqd, cfqq, 1); |
3397 | |
3398 | cfqq->slice_end = 0; |
3399 | cfq_mark_cfqq_slice_new(cfqq); |
3400 | } |
3401 | |
3402 | /* |
3403 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
3404 | * something we should do about it |
3405 | */ |
3406 | static void |
3407 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
3408 | struct request *rq) |
3409 | { |
3410 | struct cfq_io_context *cic = RQ_CIC(rq); |
3411 | |
3412 | cfqd->rq_queued++; |
3413 | if (rq->cmd_flags & REQ_META) |
3414 | cfqq->meta_pending++; |
3415 | |
3416 | cfq_update_io_thinktime(cfqd, cic); |
3417 | cfq_update_io_seektime(cfqd, cfqq, rq); |
3418 | cfq_update_idle_window(cfqd, cfqq, cic); |
3419 | |
3420 | cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
3421 | |
3422 | if (cfqq == cfqd->active_queue) { |
3423 | /* |
3424 | * Remember that we saw a request from this process, but |
3425 | * don't start queuing just yet. Otherwise we risk seeing lots |
3426 | * of tiny requests, because we disrupt the normal plugging |
3427 | * and merging. If the request is already larger than a single |
3428 | * page, let it rip immediately. For that case we assume that |
3429 | * merging is already done. Ditto for a busy system that |
3430 | * has other work pending, don't risk delaying until the |
3431 | * idle timer unplug to continue working. |
3432 | */ |
3433 | if (cfq_cfqq_wait_request(cfqq)) { |
3434 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
3435 | cfqd->busy_queues > 1) { |
3436 | cfq_del_timer(cfqd, cfqq); |
3437 | cfq_clear_cfqq_wait_request(cfqq); |
3438 | __blk_run_queue(cfqd->queue); |
3439 | } else { |
3440 | cfq_blkiocg_update_idle_time_stats( |
3441 | &cfqq->cfqg->blkg); |
3442 | cfq_mark_cfqq_must_dispatch(cfqq); |
3443 | } |
3444 | } |
3445 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
3446 | /* |
3447 | * not the active queue - expire current slice if it is |
3448 | * idle and has expired it's mean thinktime or this new queue |
3449 | * has some old slice time left and is of higher priority or |
3450 | * this new queue is RT and the current one is BE |
3451 | */ |
3452 | cfq_preempt_queue(cfqd, cfqq); |
3453 | __blk_run_queue(cfqd->queue); |
3454 | } |
3455 | } |
3456 | |
3457 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
3458 | { |
3459 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3460 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
3461 | |
3462 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
3463 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
3464 | |
3465 | rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); |
3466 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
3467 | cfq_add_rq_rb(rq); |
3468 | cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, |
3469 | &cfqd->serving_group->blkg, rq_data_dir(rq), |
3470 | rq_is_sync(rq)); |
3471 | cfq_rq_enqueued(cfqd, cfqq, rq); |
3472 | } |
3473 | |
3474 | /* |
3475 | * Update hw_tag based on peak queue depth over 50 samples under |
3476 | * sufficient load. |
3477 | */ |
3478 | static void cfq_update_hw_tag(struct cfq_data *cfqd) |
3479 | { |
3480 | struct cfq_queue *cfqq = cfqd->active_queue; |
3481 | |
3482 | if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth) |
3483 | cfqd->hw_tag_est_depth = cfqd->rq_in_driver; |
3484 | |
3485 | if (cfqd->hw_tag == 1) |
3486 | return; |
3487 | |
3488 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && |
3489 | cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN) |
3490 | return; |
3491 | |
3492 | /* |
3493 | * If active queue hasn't enough requests and can idle, cfq might not |
3494 | * dispatch sufficient requests to hardware. Don't zero hw_tag in this |
3495 | * case |
3496 | */ |
3497 | if (cfqq && cfq_cfqq_idle_window(cfqq) && |
3498 | cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < |
3499 | CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN) |
3500 | return; |
3501 | |
3502 | if (cfqd->hw_tag_samples++ < 50) |
3503 | return; |
3504 | |
3505 | if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) |
3506 | cfqd->hw_tag = 1; |
3507 | else |
3508 | cfqd->hw_tag = 0; |
3509 | } |
3510 | |
3511 | static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
3512 | { |
3513 | struct cfq_io_context *cic = cfqd->active_cic; |
3514 | |
3515 | /* If the queue already has requests, don't wait */ |
3516 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
3517 | return false; |
3518 | |
3519 | /* If there are other queues in the group, don't wait */ |
3520 | if (cfqq->cfqg->nr_cfqq > 1) |
3521 | return false; |
3522 | |
3523 | if (cfq_slice_used(cfqq)) |
3524 | return true; |
3525 | |
3526 | /* if slice left is less than think time, wait busy */ |
3527 | if (cic && sample_valid(cic->ttime_samples) |
3528 | && (cfqq->slice_end - jiffies < cic->ttime_mean)) |
3529 | return true; |
3530 | |
3531 | /* |
3532 | * If think times is less than a jiffy than ttime_mean=0 and above |
3533 | * will not be true. It might happen that slice has not expired yet |
3534 | * but will expire soon (4-5 ns) during select_queue(). To cover the |
3535 | * case where think time is less than a jiffy, mark the queue wait |
3536 | * busy if only 1 jiffy is left in the slice. |
3537 | */ |
3538 | if (cfqq->slice_end - jiffies == 1) |
3539 | return true; |
3540 | |
3541 | return false; |
3542 | } |
3543 | |
3544 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
3545 | { |
3546 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
3547 | struct cfq_data *cfqd = cfqq->cfqd; |
3548 | const int sync = rq_is_sync(rq); |
3549 | unsigned long now; |
3550 | |
3551 | now = jiffies; |
3552 | cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", |
3553 | !!(rq->cmd_flags & REQ_NOIDLE)); |
3554 | |
3555 | cfq_update_hw_tag(cfqd); |
3556 | |
3557 | WARN_ON(!cfqd->rq_in_driver); |
3558 | WARN_ON(!cfqq->dispatched); |
3559 | cfqd->rq_in_driver--; |
3560 | cfqq->dispatched--; |
3561 | (RQ_CFQG(rq))->dispatched--; |
3562 | cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg, |
3563 | rq_start_time_ns(rq), rq_io_start_time_ns(rq), |
3564 | rq_data_dir(rq), rq_is_sync(rq)); |
3565 | |
3566 | cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--; |
3567 | |
3568 | if (sync) { |
3569 | RQ_CIC(rq)->last_end_request = now; |
3570 | if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now)) |
3571 | cfqd->last_delayed_sync = now; |
3572 | } |
3573 | |
3574 | /* |
3575 | * If this is the active queue, check if it needs to be expired, |
3576 | * or if we want to idle in case it has no pending requests. |
3577 | */ |
3578 | if (cfqd->active_queue == cfqq) { |
3579 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
3580 | |
3581 | if (cfq_cfqq_slice_new(cfqq)) { |
3582 | cfq_set_prio_slice(cfqd, cfqq); |
3583 | cfq_clear_cfqq_slice_new(cfqq); |
3584 | } |
3585 | |
3586 | /* |
3587 | * Should we wait for next request to come in before we expire |
3588 | * the queue. |
3589 | */ |
3590 | if (cfq_should_wait_busy(cfqd, cfqq)) { |
3591 | unsigned long extend_sl = cfqd->cfq_slice_idle; |
3592 | if (!cfqd->cfq_slice_idle) |
3593 | extend_sl = cfqd->cfq_group_idle; |
3594 | cfqq->slice_end = jiffies + extend_sl; |
3595 | cfq_mark_cfqq_wait_busy(cfqq); |
3596 | cfq_log_cfqq(cfqd, cfqq, "will busy wait"); |
3597 | } |
3598 | |
3599 | /* |
3600 | * Idling is not enabled on: |
3601 | * - expired queues |
3602 | * - idle-priority queues |
3603 | * - async queues |
3604 | * - queues with still some requests queued |
3605 | * - when there is a close cooperator |
3606 | */ |
3607 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
3608 | cfq_slice_expired(cfqd, 1); |
3609 | else if (sync && cfqq_empty && |
3610 | !cfq_close_cooperator(cfqd, cfqq)) { |
3611 | cfq_arm_slice_timer(cfqd); |
3612 | } |
3613 | } |
3614 | |
3615 | if (!cfqd->rq_in_driver) |
3616 | cfq_schedule_dispatch(cfqd); |
3617 | } |
3618 | |
3619 | /* |
3620 | * we temporarily boost lower priority queues if they are holding fs exclusive |
3621 | * resources. they are boosted to normal prio (CLASS_BE/4) |
3622 | */ |
3623 | static void cfq_prio_boost(struct cfq_queue *cfqq) |
3624 | { |
3625 | if (has_fs_excl()) { |
3626 | /* |
3627 | * boost idle prio on transactions that would lock out other |
3628 | * users of the filesystem |
3629 | */ |
3630 | if (cfq_class_idle(cfqq)) |
3631 | cfqq->ioprio_class = IOPRIO_CLASS_BE; |
3632 | if (cfqq->ioprio > IOPRIO_NORM) |
3633 | cfqq->ioprio = IOPRIO_NORM; |
3634 | } else { |
3635 | /* |
3636 | * unboost the queue (if needed) |
3637 | */ |
3638 | cfqq->ioprio_class = cfqq->org_ioprio_class; |
3639 | cfqq->ioprio = cfqq->org_ioprio; |
3640 | } |
3641 | } |
3642 | |
3643 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
3644 | { |
3645 | if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { |
3646 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
3647 | return ELV_MQUEUE_MUST; |
3648 | } |
3649 | |
3650 | return ELV_MQUEUE_MAY; |
3651 | } |
3652 | |
3653 | static int cfq_may_queue(struct request_queue *q, int rw) |
3654 | { |
3655 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3656 | struct task_struct *tsk = current; |
3657 | struct cfq_io_context *cic; |
3658 | struct cfq_queue *cfqq; |
3659 | |
3660 | /* |
3661 | * don't force setup of a queue from here, as a call to may_queue |
3662 | * does not necessarily imply that a request actually will be queued. |
3663 | * so just lookup a possibly existing queue, or return 'may queue' |
3664 | * if that fails |
3665 | */ |
3666 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
3667 | if (!cic) |
3668 | return ELV_MQUEUE_MAY; |
3669 | |
3670 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
3671 | if (cfqq) { |
3672 | cfq_init_prio_data(cfqq, cic->ioc); |
3673 | cfq_prio_boost(cfqq); |
3674 | |
3675 | return __cfq_may_queue(cfqq); |
3676 | } |
3677 | |
3678 | return ELV_MQUEUE_MAY; |
3679 | } |
3680 | |
3681 | /* |
3682 | * queue lock held here |
3683 | */ |
3684 | static void cfq_put_request(struct request *rq) |
3685 | { |
3686 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
3687 | |
3688 | if (cfqq) { |
3689 | const int rw = rq_data_dir(rq); |
3690 | |
3691 | BUG_ON(!cfqq->allocated[rw]); |
3692 | cfqq->allocated[rw]--; |
3693 | |
3694 | put_io_context(RQ_CIC(rq)->ioc); |
3695 | |
3696 | rq->elevator_private[0] = NULL; |
3697 | rq->elevator_private[1] = NULL; |
3698 | |
3699 | /* Put down rq reference on cfqg */ |
3700 | cfq_put_cfqg(RQ_CFQG(rq)); |
3701 | rq->elevator_private[2] = NULL; |
3702 | |
3703 | cfq_put_queue(cfqq); |
3704 | } |
3705 | } |
3706 | |
3707 | static struct cfq_queue * |
3708 | cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, |
3709 | struct cfq_queue *cfqq) |
3710 | { |
3711 | cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); |
3712 | cic_set_cfqq(cic, cfqq->new_cfqq, 1); |
3713 | cfq_mark_cfqq_coop(cfqq->new_cfqq); |
3714 | cfq_put_queue(cfqq); |
3715 | return cic_to_cfqq(cic, 1); |
3716 | } |
3717 | |
3718 | /* |
3719 | * Returns NULL if a new cfqq should be allocated, or the old cfqq if this |
3720 | * was the last process referring to said cfqq. |
3721 | */ |
3722 | static struct cfq_queue * |
3723 | split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) |
3724 | { |
3725 | if (cfqq_process_refs(cfqq) == 1) { |
3726 | cfqq->pid = current->pid; |
3727 | cfq_clear_cfqq_coop(cfqq); |
3728 | cfq_clear_cfqq_split_coop(cfqq); |
3729 | return cfqq; |
3730 | } |
3731 | |
3732 | cic_set_cfqq(cic, NULL, 1); |
3733 | |
3734 | cfq_put_cooperator(cfqq); |
3735 | |
3736 | cfq_put_queue(cfqq); |
3737 | return NULL; |
3738 | } |
3739 | /* |
3740 | * Allocate cfq data structures associated with this request. |
3741 | */ |
3742 | static int |
3743 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
3744 | { |
3745 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3746 | struct cfq_io_context *cic; |
3747 | const int rw = rq_data_dir(rq); |
3748 | const bool is_sync = rq_is_sync(rq); |
3749 | struct cfq_queue *cfqq; |
3750 | unsigned long flags; |
3751 | |
3752 | might_sleep_if(gfp_mask & __GFP_WAIT); |
3753 | |
3754 | cic = cfq_get_io_context(cfqd, gfp_mask); |
3755 | |
3756 | spin_lock_irqsave(q->queue_lock, flags); |
3757 | |
3758 | if (!cic) |
3759 | goto queue_fail; |
3760 | |
3761 | new_queue: |
3762 | cfqq = cic_to_cfqq(cic, is_sync); |
3763 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
3764 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
3765 | cic_set_cfqq(cic, cfqq, is_sync); |
3766 | } else { |
3767 | /* |
3768 | * If the queue was seeky for too long, break it apart. |
3769 | */ |
3770 | if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) { |
3771 | cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); |
3772 | cfqq = split_cfqq(cic, cfqq); |
3773 | if (!cfqq) |
3774 | goto new_queue; |
3775 | } |
3776 | |
3777 | /* |
3778 | * Check to see if this queue is scheduled to merge with |
3779 | * another, closely cooperating queue. The merging of |
3780 | * queues happens here as it must be done in process context. |
3781 | * The reference on new_cfqq was taken in merge_cfqqs. |
3782 | */ |
3783 | if (cfqq->new_cfqq) |
3784 | cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); |
3785 | } |
3786 | |
3787 | cfqq->allocated[rw]++; |
3788 | |
3789 | cfqq->ref++; |
3790 | rq->elevator_private[0] = cic; |
3791 | rq->elevator_private[1] = cfqq; |
3792 | rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg); |
3793 | spin_unlock_irqrestore(q->queue_lock, flags); |
3794 | return 0; |
3795 | |
3796 | queue_fail: |
3797 | cfq_schedule_dispatch(cfqd); |
3798 | spin_unlock_irqrestore(q->queue_lock, flags); |
3799 | cfq_log(cfqd, "set_request fail"); |
3800 | return 1; |
3801 | } |
3802 | |
3803 | static void cfq_kick_queue(struct work_struct *work) |
3804 | { |
3805 | struct cfq_data *cfqd = |
3806 | container_of(work, struct cfq_data, unplug_work); |
3807 | struct request_queue *q = cfqd->queue; |
3808 | |
3809 | spin_lock_irq(q->queue_lock); |
3810 | __blk_run_queue(cfqd->queue); |
3811 | spin_unlock_irq(q->queue_lock); |
3812 | } |
3813 | |
3814 | /* |
3815 | * Timer running if the active_queue is currently idling inside its time slice |
3816 | */ |
3817 | static void cfq_idle_slice_timer(unsigned long data) |
3818 | { |
3819 | struct cfq_data *cfqd = (struct cfq_data *) data; |
3820 | struct cfq_queue *cfqq; |
3821 | unsigned long flags; |
3822 | int timed_out = 1; |
3823 | |
3824 | cfq_log(cfqd, "idle timer fired"); |
3825 | |
3826 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
3827 | |
3828 | cfqq = cfqd->active_queue; |
3829 | if (cfqq) { |
3830 | timed_out = 0; |
3831 | |
3832 | /* |
3833 | * We saw a request before the queue expired, let it through |
3834 | */ |
3835 | if (cfq_cfqq_must_dispatch(cfqq)) |
3836 | goto out_kick; |
3837 | |
3838 | /* |
3839 | * expired |
3840 | */ |
3841 | if (cfq_slice_used(cfqq)) |
3842 | goto expire; |
3843 | |
3844 | /* |
3845 | * only expire and reinvoke request handler, if there are |
3846 | * other queues with pending requests |
3847 | */ |
3848 | if (!cfqd->busy_queues) |
3849 | goto out_cont; |
3850 | |
3851 | /* |
3852 | * not expired and it has a request pending, let it dispatch |
3853 | */ |
3854 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
3855 | goto out_kick; |
3856 | |
3857 | /* |
3858 | * Queue depth flag is reset only when the idle didn't succeed |
3859 | */ |
3860 | cfq_clear_cfqq_deep(cfqq); |
3861 | } |
3862 | expire: |
3863 | cfq_slice_expired(cfqd, timed_out); |
3864 | out_kick: |
3865 | cfq_schedule_dispatch(cfqd); |
3866 | out_cont: |
3867 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
3868 | } |
3869 | |
3870 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
3871 | { |
3872 | del_timer_sync(&cfqd->idle_slice_timer); |
3873 | cancel_work_sync(&cfqd->unplug_work); |
3874 | } |
3875 | |
3876 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
3877 | { |
3878 | int i; |
3879 | |
3880 | for (i = 0; i < IOPRIO_BE_NR; i++) { |
3881 | if (cfqd->async_cfqq[0][i]) |
3882 | cfq_put_queue(cfqd->async_cfqq[0][i]); |
3883 | if (cfqd->async_cfqq[1][i]) |
3884 | cfq_put_queue(cfqd->async_cfqq[1][i]); |
3885 | } |
3886 | |
3887 | if (cfqd->async_idle_cfqq) |
3888 | cfq_put_queue(cfqd->async_idle_cfqq); |
3889 | } |
3890 | |
3891 | static void cfq_exit_queue(struct elevator_queue *e) |
3892 | { |
3893 | struct cfq_data *cfqd = e->elevator_data; |
3894 | struct request_queue *q = cfqd->queue; |
3895 | bool wait = false; |
3896 | |
3897 | cfq_shutdown_timer_wq(cfqd); |
3898 | |
3899 | spin_lock_irq(q->queue_lock); |
3900 | |
3901 | if (cfqd->active_queue) |
3902 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
3903 | |
3904 | while (!list_empty(&cfqd->cic_list)) { |
3905 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
3906 | struct cfq_io_context, |
3907 | queue_list); |
3908 | |
3909 | __cfq_exit_single_io_context(cfqd, cic); |
3910 | } |
3911 | |
3912 | cfq_put_async_queues(cfqd); |
3913 | cfq_release_cfq_groups(cfqd); |
3914 | |
3915 | /* |
3916 | * If there are groups which we could not unlink from blkcg list, |
3917 | * wait for a rcu period for them to be freed. |
3918 | */ |
3919 | if (cfqd->nr_blkcg_linked_grps) |
3920 | wait = true; |
3921 | |
3922 | spin_unlock_irq(q->queue_lock); |
3923 | |
3924 | cfq_shutdown_timer_wq(cfqd); |
3925 | |
3926 | spin_lock(&cic_index_lock); |
3927 | ida_remove(&cic_index_ida, cfqd->cic_index); |
3928 | spin_unlock(&cic_index_lock); |
3929 | |
3930 | /* |
3931 | * Wait for cfqg->blkg->key accessors to exit their grace periods. |
3932 | * Do this wait only if there are other unlinked groups out |
3933 | * there. This can happen if cgroup deletion path claimed the |
3934 | * responsibility of cleaning up a group before queue cleanup code |
3935 | * get to the group. |
3936 | * |
3937 | * Do not call synchronize_rcu() unconditionally as there are drivers |
3938 | * which create/delete request queue hundreds of times during scan/boot |
3939 | * and synchronize_rcu() can take significant time and slow down boot. |
3940 | */ |
3941 | if (wait) |
3942 | synchronize_rcu(); |
3943 | |
3944 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
3945 | /* Free up per cpu stats for root group */ |
3946 | free_percpu(cfqd->root_group.blkg.stats_cpu); |
3947 | #endif |
3948 | kfree(cfqd); |
3949 | } |
3950 | |
3951 | static int cfq_alloc_cic_index(void) |
3952 | { |
3953 | int index, error; |
3954 | |
3955 | do { |
3956 | if (!ida_pre_get(&cic_index_ida, GFP_KERNEL)) |
3957 | return -ENOMEM; |
3958 | |
3959 | spin_lock(&cic_index_lock); |
3960 | error = ida_get_new(&cic_index_ida, &index); |
3961 | spin_unlock(&cic_index_lock); |
3962 | if (error && error != -EAGAIN) |
3963 | return error; |
3964 | } while (error); |
3965 | |
3966 | return index; |
3967 | } |
3968 | |
3969 | static void *cfq_init_queue(struct request_queue *q) |
3970 | { |
3971 | struct cfq_data *cfqd; |
3972 | int i, j; |
3973 | struct cfq_group *cfqg; |
3974 | struct cfq_rb_root *st; |
3975 | |
3976 | i = cfq_alloc_cic_index(); |
3977 | if (i < 0) |
3978 | return NULL; |
3979 | |
3980 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
3981 | if (!cfqd) { |
3982 | spin_lock(&cic_index_lock); |
3983 | ida_remove(&cic_index_ida, i); |
3984 | spin_unlock(&cic_index_lock); |
3985 | return NULL; |
3986 | } |
3987 | |
3988 | /* |
3989 | * Don't need take queue_lock in the routine, since we are |
3990 | * initializing the ioscheduler, and nobody is using cfqd |
3991 | */ |
3992 | cfqd->cic_index = i; |
3993 | |
3994 | /* Init root service tree */ |
3995 | cfqd->grp_service_tree = CFQ_RB_ROOT; |
3996 | |
3997 | /* Init root group */ |
3998 | cfqg = &cfqd->root_group; |
3999 | for_each_cfqg_st(cfqg, i, j, st) |
4000 | *st = CFQ_RB_ROOT; |
4001 | RB_CLEAR_NODE(&cfqg->rb_node); |
4002 | |
4003 | /* Give preference to root group over other groups */ |
4004 | cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT; |
4005 | |
4006 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
4007 | /* |
4008 | * Set root group reference to 2. One reference will be dropped when |
4009 | * all groups on cfqd->cfqg_list are being deleted during queue exit. |
4010 | * Other reference will remain there as we don't want to delete this |
4011 | * group as it is statically allocated and gets destroyed when |
4012 | * throtl_data goes away. |
4013 | */ |
4014 | cfqg->ref = 2; |
4015 | |
4016 | if (blkio_alloc_blkg_stats(&cfqg->blkg)) { |
4017 | kfree(cfqg); |
4018 | kfree(cfqd); |
4019 | return NULL; |
4020 | } |
4021 | |
4022 | rcu_read_lock(); |
4023 | |
4024 | cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, |
4025 | (void *)cfqd, 0); |
4026 | rcu_read_unlock(); |
4027 | cfqd->nr_blkcg_linked_grps++; |
4028 | |
4029 | /* Add group on cfqd->cfqg_list */ |
4030 | hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); |
4031 | #endif |
4032 | /* |
4033 | * Not strictly needed (since RB_ROOT just clears the node and we |
4034 | * zeroed cfqd on alloc), but better be safe in case someone decides |
4035 | * to add magic to the rb code |
4036 | */ |
4037 | for (i = 0; i < CFQ_PRIO_LISTS; i++) |
4038 | cfqd->prio_trees[i] = RB_ROOT; |
4039 | |
4040 | /* |
4041 | * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. |
4042 | * Grab a permanent reference to it, so that the normal code flow |
4043 | * will not attempt to free it. |
4044 | */ |
4045 | cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); |
4046 | cfqd->oom_cfqq.ref++; |
4047 | cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); |
4048 | |
4049 | INIT_LIST_HEAD(&cfqd->cic_list); |
4050 | |
4051 | cfqd->queue = q; |
4052 | |
4053 | init_timer(&cfqd->idle_slice_timer); |
4054 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; |
4055 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; |
4056 | |
4057 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
4058 | |
4059 | cfqd->cfq_quantum = cfq_quantum; |
4060 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
4061 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; |
4062 | cfqd->cfq_back_max = cfq_back_max; |
4063 | cfqd->cfq_back_penalty = cfq_back_penalty; |
4064 | cfqd->cfq_slice[0] = cfq_slice_async; |
4065 | cfqd->cfq_slice[1] = cfq_slice_sync; |
4066 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; |
4067 | cfqd->cfq_slice_idle = cfq_slice_idle; |
4068 | cfqd->cfq_group_idle = cfq_group_idle; |
4069 | cfqd->cfq_latency = 1; |
4070 | cfqd->hw_tag = -1; |
4071 | /* |
4072 | * we optimistically start assuming sync ops weren't delayed in last |
4073 | * second, in order to have larger depth for async operations. |
4074 | */ |
4075 | cfqd->last_delayed_sync = jiffies - HZ; |
4076 | return cfqd; |
4077 | } |
4078 | |
4079 | static void cfq_slab_kill(void) |
4080 | { |
4081 | /* |
4082 | * Caller already ensured that pending RCU callbacks are completed, |
4083 | * so we should have no busy allocations at this point. |
4084 | */ |
4085 | if (cfq_pool) |
4086 | kmem_cache_destroy(cfq_pool); |
4087 | if (cfq_ioc_pool) |
4088 | kmem_cache_destroy(cfq_ioc_pool); |
4089 | } |
4090 | |
4091 | static int __init cfq_slab_setup(void) |
4092 | { |
4093 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
4094 | if (!cfq_pool) |
4095 | goto fail; |
4096 | |
4097 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
4098 | if (!cfq_ioc_pool) |
4099 | goto fail; |
4100 | |
4101 | return 0; |
4102 | fail: |
4103 | cfq_slab_kill(); |
4104 | return -ENOMEM; |
4105 | } |
4106 | |
4107 | /* |
4108 | * sysfs parts below --> |
4109 | */ |
4110 | static ssize_t |
4111 | cfq_var_show(unsigned int var, char *page) |
4112 | { |
4113 | return sprintf(page, "%d\n", var); |
4114 | } |
4115 | |
4116 | static ssize_t |
4117 | cfq_var_store(unsigned int *var, const char *page, size_t count) |
4118 | { |
4119 | char *p = (char *) page; |
4120 | |
4121 | *var = simple_strtoul(p, &p, 10); |
4122 | return count; |
4123 | } |
4124 | |
4125 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
4126 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
4127 | { \ |
4128 | struct cfq_data *cfqd = e->elevator_data; \ |
4129 | unsigned int __data = __VAR; \ |
4130 | if (__CONV) \ |
4131 | __data = jiffies_to_msecs(__data); \ |
4132 | return cfq_var_show(__data, (page)); \ |
4133 | } |
4134 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); |
4135 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
4136 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); |
4137 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
4138 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); |
4139 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
4140 | SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1); |
4141 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); |
4142 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); |
4143 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); |
4144 | SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); |
4145 | #undef SHOW_FUNCTION |
4146 | |
4147 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ |
4148 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
4149 | { \ |
4150 | struct cfq_data *cfqd = e->elevator_data; \ |
4151 | unsigned int __data; \ |
4152 | int ret = cfq_var_store(&__data, (page), count); \ |
4153 | if (__data < (MIN)) \ |
4154 | __data = (MIN); \ |
4155 | else if (__data > (MAX)) \ |
4156 | __data = (MAX); \ |
4157 | if (__CONV) \ |
4158 | *(__PTR) = msecs_to_jiffies(__data); \ |
4159 | else \ |
4160 | *(__PTR) = __data; \ |
4161 | return ret; \ |
4162 | } |
4163 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); |
4164 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
4165 | UINT_MAX, 1); |
4166 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, |
4167 | UINT_MAX, 1); |
4168 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
4169 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
4170 | UINT_MAX, 0); |
4171 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
4172 | STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1); |
4173 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); |
4174 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); |
4175 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
4176 | UINT_MAX, 0); |
4177 | STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); |
4178 | #undef STORE_FUNCTION |
4179 | |
4180 | #define CFQ_ATTR(name) \ |
4181 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) |
4182 | |
4183 | static struct elv_fs_entry cfq_attrs[] = { |
4184 | CFQ_ATTR(quantum), |
4185 | CFQ_ATTR(fifo_expire_sync), |
4186 | CFQ_ATTR(fifo_expire_async), |
4187 | CFQ_ATTR(back_seek_max), |
4188 | CFQ_ATTR(back_seek_penalty), |
4189 | CFQ_ATTR(slice_sync), |
4190 | CFQ_ATTR(slice_async), |
4191 | CFQ_ATTR(slice_async_rq), |
4192 | CFQ_ATTR(slice_idle), |
4193 | CFQ_ATTR(group_idle), |
4194 | CFQ_ATTR(low_latency), |
4195 | __ATTR_NULL |
4196 | }; |
4197 | |
4198 | static struct elevator_type iosched_cfq = { |
4199 | .ops = { |
4200 | .elevator_merge_fn = cfq_merge, |
4201 | .elevator_merged_fn = cfq_merged_request, |
4202 | .elevator_merge_req_fn = cfq_merged_requests, |
4203 | .elevator_allow_merge_fn = cfq_allow_merge, |
4204 | .elevator_bio_merged_fn = cfq_bio_merged, |
4205 | .elevator_dispatch_fn = cfq_dispatch_requests, |
4206 | .elevator_add_req_fn = cfq_insert_request, |
4207 | .elevator_activate_req_fn = cfq_activate_request, |
4208 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
4209 | .elevator_completed_req_fn = cfq_completed_request, |
4210 | .elevator_former_req_fn = elv_rb_former_request, |
4211 | .elevator_latter_req_fn = elv_rb_latter_request, |
4212 | .elevator_set_req_fn = cfq_set_request, |
4213 | .elevator_put_req_fn = cfq_put_request, |
4214 | .elevator_may_queue_fn = cfq_may_queue, |
4215 | .elevator_init_fn = cfq_init_queue, |
4216 | .elevator_exit_fn = cfq_exit_queue, |
4217 | .trim = cfq_free_io_context, |
4218 | }, |
4219 | .elevator_attrs = cfq_attrs, |
4220 | .elevator_name = "cfq", |
4221 | .elevator_owner = THIS_MODULE, |
4222 | }; |
4223 | |
4224 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
4225 | static struct blkio_policy_type blkio_policy_cfq = { |
4226 | .ops = { |
4227 | .blkio_unlink_group_fn = cfq_unlink_blkio_group, |
4228 | .blkio_update_group_weight_fn = cfq_update_blkio_group_weight, |
4229 | }, |
4230 | .plid = BLKIO_POLICY_PROP, |
4231 | }; |
4232 | #else |
4233 | static struct blkio_policy_type blkio_policy_cfq; |
4234 | #endif |
4235 | |
4236 | static int __init cfq_init(void) |
4237 | { |
4238 | /* |
4239 | * could be 0 on HZ < 1000 setups |
4240 | */ |
4241 | if (!cfq_slice_async) |
4242 | cfq_slice_async = 1; |
4243 | if (!cfq_slice_idle) |
4244 | cfq_slice_idle = 1; |
4245 | |
4246 | #ifdef CONFIG_CFQ_GROUP_IOSCHED |
4247 | if (!cfq_group_idle) |
4248 | cfq_group_idle = 1; |
4249 | #else |
4250 | cfq_group_idle = 0; |
4251 | #endif |
4252 | if (cfq_slab_setup()) |
4253 | return -ENOMEM; |
4254 | |
4255 | elv_register(&iosched_cfq); |
4256 | blkio_policy_register(&blkio_policy_cfq); |
4257 | |
4258 | return 0; |
4259 | } |
4260 | |
4261 | static void __exit cfq_exit(void) |
4262 | { |
4263 | DECLARE_COMPLETION_ONSTACK(all_gone); |
4264 | blkio_policy_unregister(&blkio_policy_cfq); |
4265 | elv_unregister(&iosched_cfq); |
4266 | ioc_gone = &all_gone; |
4267 | /* ioc_gone's update must be visible before reading ioc_count */ |
4268 | smp_wmb(); |
4269 | |
4270 | /* |
4271 | * this also protects us from entering cfq_slab_kill() with |
4272 | * pending RCU callbacks |
4273 | */ |
4274 | if (elv_ioc_count_read(cfq_ioc_count)) |
4275 | wait_for_completion(&all_gone); |
4276 | ida_destroy(&cic_index_ida); |
4277 | cfq_slab_kill(); |
4278 | } |
4279 | |
4280 | module_init(cfq_init); |
4281 | module_exit(cfq_exit); |
4282 | |
4283 | MODULE_AUTHOR("Jens Axboe"); |
4284 | MODULE_LICENSE("GPL"); |
4285 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |
4286 |
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