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Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
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 | * | |
0fe23479 | 7 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
1da177e4 | 8 | */ |
1da177e4 | 9 | #include <linux/module.h> |
1cc9be68 AV |
10 | #include <linux/blkdev.h> |
11 | #include <linux/elevator.h> | |
ad5ebd2f | 12 | #include <linux/jiffies.h> |
1da177e4 | 13 | #include <linux/rbtree.h> |
22e2c507 | 14 | #include <linux/ioprio.h> |
7b679138 | 15 | #include <linux/blktrace_api.h> |
1da177e4 LT |
16 | |
17 | /* | |
18 | * tunables | |
19 | */ | |
fe094d98 JA |
20 | /* max queue in one round of service */ |
21 | static const int cfq_quantum = 4; | |
64100099 | 22 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
fe094d98 JA |
23 | /* maximum backwards seek, in KiB */ |
24 | static const int cfq_back_max = 16 * 1024; | |
25 | /* penalty of a backwards seek */ | |
26 | static const int cfq_back_penalty = 2; | |
64100099 | 27 | static const int cfq_slice_sync = HZ / 10; |
3b18152c | 28 | static int cfq_slice_async = HZ / 25; |
64100099 | 29 | static const int cfq_slice_async_rq = 2; |
caaa5f9f | 30 | static int cfq_slice_idle = HZ / 125; |
5db5d642 CZ |
31 | static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ |
32 | static const int cfq_hist_divisor = 4; | |
22e2c507 | 33 | |
d9e7620e | 34 | /* |
0871714e | 35 | * offset from end of service tree |
d9e7620e | 36 | */ |
0871714e | 37 | #define CFQ_IDLE_DELAY (HZ / 5) |
d9e7620e JA |
38 | |
39 | /* | |
40 | * below this threshold, we consider thinktime immediate | |
41 | */ | |
42 | #define CFQ_MIN_TT (2) | |
43 | ||
e6c5bc73 JM |
44 | /* |
45 | * Allow merged cfqqs to perform this amount of seeky I/O before | |
46 | * deciding to break the queues up again. | |
47 | */ | |
48 | #define CFQQ_COOP_TOUT (HZ) | |
49 | ||
22e2c507 | 50 | #define CFQ_SLICE_SCALE (5) |
45333d5a | 51 | #define CFQ_HW_QUEUE_MIN (5) |
22e2c507 | 52 | |
fe094d98 JA |
53 | #define RQ_CIC(rq) \ |
54 | ((struct cfq_io_context *) (rq)->elevator_private) | |
7b679138 | 55 | #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) |
1da177e4 | 56 | |
e18b890b CL |
57 | static struct kmem_cache *cfq_pool; |
58 | static struct kmem_cache *cfq_ioc_pool; | |
1da177e4 | 59 | |
245b2e70 | 60 | static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); |
334e94de | 61 | static struct completion *ioc_gone; |
9a11b4ed | 62 | static DEFINE_SPINLOCK(ioc_gone_lock); |
334e94de | 63 | |
22e2c507 JA |
64 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
65 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
22e2c507 JA |
66 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
67 | ||
206dc69b JA |
68 | #define sample_valid(samples) ((samples) > 80) |
69 | ||
cc09e299 JA |
70 | /* |
71 | * Most of our rbtree usage is for sorting with min extraction, so | |
72 | * if we cache the leftmost node we don't have to walk down the tree | |
73 | * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should | |
74 | * move this into the elevator for the rq sorting as well. | |
75 | */ | |
76 | struct cfq_rb_root { | |
77 | struct rb_root rb; | |
78 | struct rb_node *left; | |
aa6f6a3d | 79 | unsigned count; |
cc09e299 | 80 | }; |
aa6f6a3d | 81 | #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, } |
cc09e299 | 82 | |
6118b70b JA |
83 | /* |
84 | * Per process-grouping structure | |
85 | */ | |
86 | struct cfq_queue { | |
87 | /* reference count */ | |
88 | atomic_t ref; | |
89 | /* various state flags, see below */ | |
90 | unsigned int flags; | |
91 | /* parent cfq_data */ | |
92 | struct cfq_data *cfqd; | |
93 | /* service_tree member */ | |
94 | struct rb_node rb_node; | |
95 | /* service_tree key */ | |
96 | unsigned long rb_key; | |
97 | /* prio tree member */ | |
98 | struct rb_node p_node; | |
99 | /* prio tree root we belong to, if any */ | |
100 | struct rb_root *p_root; | |
101 | /* sorted list of pending requests */ | |
102 | struct rb_root sort_list; | |
103 | /* if fifo isn't expired, next request to serve */ | |
104 | struct request *next_rq; | |
105 | /* requests queued in sort_list */ | |
106 | int queued[2]; | |
107 | /* currently allocated requests */ | |
108 | int allocated[2]; | |
109 | /* fifo list of requests in sort_list */ | |
110 | struct list_head fifo; | |
111 | ||
112 | unsigned long slice_end; | |
113 | long slice_resid; | |
114 | unsigned int slice_dispatch; | |
115 | ||
116 | /* pending metadata requests */ | |
117 | int meta_pending; | |
118 | /* number of requests that are on the dispatch list or inside driver */ | |
119 | int dispatched; | |
120 | ||
121 | /* io prio of this group */ | |
122 | unsigned short ioprio, org_ioprio; | |
123 | unsigned short ioprio_class, org_ioprio_class; | |
124 | ||
b2c18e1e JM |
125 | unsigned int seek_samples; |
126 | u64 seek_total; | |
127 | sector_t seek_mean; | |
128 | sector_t last_request_pos; | |
e6c5bc73 | 129 | unsigned long seeky_start; |
b2c18e1e | 130 | |
6118b70b | 131 | pid_t pid; |
df5fe3e8 | 132 | |
aa6f6a3d | 133 | struct cfq_rb_root *service_tree; |
df5fe3e8 | 134 | struct cfq_queue *new_cfqq; |
cdb16e8f | 135 | struct cfq_group *cfqg; |
6118b70b JA |
136 | }; |
137 | ||
c0324a02 | 138 | /* |
718eee05 | 139 | * First index in the service_trees. |
c0324a02 CZ |
140 | * IDLE is handled separately, so it has negative index |
141 | */ | |
142 | enum wl_prio_t { | |
c0324a02 | 143 | BE_WORKLOAD = 0, |
615f0259 VG |
144 | RT_WORKLOAD = 1, |
145 | IDLE_WORKLOAD = 2, | |
c0324a02 CZ |
146 | }; |
147 | ||
718eee05 CZ |
148 | /* |
149 | * Second index in the service_trees. | |
150 | */ | |
151 | enum wl_type_t { | |
152 | ASYNC_WORKLOAD = 0, | |
153 | SYNC_NOIDLE_WORKLOAD = 1, | |
154 | SYNC_WORKLOAD = 2 | |
155 | }; | |
156 | ||
cdb16e8f VG |
157 | /* This is per cgroup per device grouping structure */ |
158 | struct cfq_group { | |
159 | /* | |
160 | * rr lists of queues with requests, onle rr for each priority class. | |
161 | * Counts are embedded in the cfq_rb_root | |
162 | */ | |
163 | struct cfq_rb_root service_trees[2][3]; | |
164 | struct cfq_rb_root service_tree_idle; | |
165 | }; | |
718eee05 | 166 | |
22e2c507 JA |
167 | /* |
168 | * Per block device queue structure | |
169 | */ | |
1da177e4 | 170 | struct cfq_data { |
165125e1 | 171 | struct request_queue *queue; |
cdb16e8f | 172 | struct cfq_group root_group; |
22e2c507 | 173 | |
c0324a02 CZ |
174 | /* |
175 | * The priority currently being served | |
22e2c507 | 176 | */ |
c0324a02 | 177 | enum wl_prio_t serving_prio; |
718eee05 CZ |
178 | enum wl_type_t serving_type; |
179 | unsigned long workload_expires; | |
cdb16e8f | 180 | struct cfq_group *serving_group; |
8e550632 | 181 | bool noidle_tree_requires_idle; |
a36e71f9 JA |
182 | |
183 | /* | |
184 | * Each priority tree is sorted by next_request position. These | |
185 | * trees are used when determining if two or more queues are | |
186 | * interleaving requests (see cfq_close_cooperator). | |
187 | */ | |
188 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; | |
189 | ||
22e2c507 | 190 | unsigned int busy_queues; |
5db5d642 | 191 | unsigned int busy_queues_avg[2]; |
22e2c507 | 192 | |
5ad531db | 193 | int rq_in_driver[2]; |
3ed9a296 | 194 | int sync_flight; |
45333d5a AC |
195 | |
196 | /* | |
197 | * queue-depth detection | |
198 | */ | |
199 | int rq_queued; | |
25776e35 | 200 | int hw_tag; |
e459dd08 CZ |
201 | /* |
202 | * hw_tag can be | |
203 | * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) | |
204 | * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) | |
205 | * 0 => no NCQ | |
206 | */ | |
207 | int hw_tag_est_depth; | |
208 | unsigned int hw_tag_samples; | |
1da177e4 | 209 | |
22e2c507 JA |
210 | /* |
211 | * idle window management | |
212 | */ | |
213 | struct timer_list idle_slice_timer; | |
23e018a1 | 214 | struct work_struct unplug_work; |
1da177e4 | 215 | |
22e2c507 JA |
216 | struct cfq_queue *active_queue; |
217 | struct cfq_io_context *active_cic; | |
22e2c507 | 218 | |
c2dea2d1 VT |
219 | /* |
220 | * async queue for each priority case | |
221 | */ | |
222 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; | |
223 | struct cfq_queue *async_idle_cfqq; | |
15c31be4 | 224 | |
6d048f53 | 225 | sector_t last_position; |
1da177e4 | 226 | |
1da177e4 LT |
227 | /* |
228 | * tunables, see top of file | |
229 | */ | |
230 | unsigned int cfq_quantum; | |
22e2c507 | 231 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
232 | unsigned int cfq_back_penalty; |
233 | unsigned int cfq_back_max; | |
22e2c507 JA |
234 | unsigned int cfq_slice[2]; |
235 | unsigned int cfq_slice_async_rq; | |
236 | unsigned int cfq_slice_idle; | |
963b72fc | 237 | unsigned int cfq_latency; |
d9ff4187 AV |
238 | |
239 | struct list_head cic_list; | |
1da177e4 | 240 | |
6118b70b JA |
241 | /* |
242 | * Fallback dummy cfqq for extreme OOM conditions | |
243 | */ | |
244 | struct cfq_queue oom_cfqq; | |
365722bb VG |
245 | |
246 | unsigned long last_end_sync_rq; | |
1da177e4 LT |
247 | }; |
248 | ||
cdb16e8f VG |
249 | static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, |
250 | enum wl_prio_t prio, | |
718eee05 | 251 | enum wl_type_t type, |
c0324a02 CZ |
252 | struct cfq_data *cfqd) |
253 | { | |
254 | if (prio == IDLE_WORKLOAD) | |
cdb16e8f | 255 | return &cfqg->service_tree_idle; |
c0324a02 | 256 | |
cdb16e8f | 257 | return &cfqg->service_trees[prio][type]; |
c0324a02 CZ |
258 | } |
259 | ||
3b18152c | 260 | enum cfqq_state_flags { |
b0b8d749 JA |
261 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
262 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
b029195d | 263 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
b0b8d749 | 264 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
b0b8d749 JA |
265 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
266 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
267 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
44f7c160 | 268 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
91fac317 | 269 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
b3b6d040 | 270 | CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ |
76280aff | 271 | CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ |
3b18152c JA |
272 | }; |
273 | ||
274 | #define CFQ_CFQQ_FNS(name) \ | |
275 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
276 | { \ | |
fe094d98 | 277 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
278 | } \ |
279 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
280 | { \ | |
fe094d98 | 281 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
282 | } \ |
283 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
284 | { \ | |
fe094d98 | 285 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
3b18152c JA |
286 | } |
287 | ||
288 | CFQ_CFQQ_FNS(on_rr); | |
289 | CFQ_CFQQ_FNS(wait_request); | |
b029195d | 290 | CFQ_CFQQ_FNS(must_dispatch); |
3b18152c | 291 | CFQ_CFQQ_FNS(must_alloc_slice); |
3b18152c JA |
292 | CFQ_CFQQ_FNS(fifo_expire); |
293 | CFQ_CFQQ_FNS(idle_window); | |
294 | CFQ_CFQQ_FNS(prio_changed); | |
44f7c160 | 295 | CFQ_CFQQ_FNS(slice_new); |
91fac317 | 296 | CFQ_CFQQ_FNS(sync); |
a36e71f9 | 297 | CFQ_CFQQ_FNS(coop); |
76280aff | 298 | CFQ_CFQQ_FNS(deep); |
3b18152c JA |
299 | #undef CFQ_CFQQ_FNS |
300 | ||
7b679138 JA |
301 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
302 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) | |
303 | #define cfq_log(cfqd, fmt, args...) \ | |
304 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) | |
305 | ||
615f0259 VG |
306 | /* Traverses through cfq group service trees */ |
307 | #define for_each_cfqg_st(cfqg, i, j, st) \ | |
308 | for (i = 0; i <= IDLE_WORKLOAD; i++) \ | |
309 | for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ | |
310 | : &cfqg->service_tree_idle; \ | |
311 | (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ | |
312 | (i == IDLE_WORKLOAD && j == 0); \ | |
313 | j++, st = i < IDLE_WORKLOAD ? \ | |
314 | &cfqg->service_trees[i][j]: NULL) \ | |
315 | ||
316 | ||
c0324a02 CZ |
317 | static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) |
318 | { | |
319 | if (cfq_class_idle(cfqq)) | |
320 | return IDLE_WORKLOAD; | |
321 | if (cfq_class_rt(cfqq)) | |
322 | return RT_WORKLOAD; | |
323 | return BE_WORKLOAD; | |
324 | } | |
325 | ||
718eee05 CZ |
326 | |
327 | static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) | |
328 | { | |
329 | if (!cfq_cfqq_sync(cfqq)) | |
330 | return ASYNC_WORKLOAD; | |
331 | if (!cfq_cfqq_idle_window(cfqq)) | |
332 | return SYNC_NOIDLE_WORKLOAD; | |
333 | return SYNC_WORKLOAD; | |
334 | } | |
335 | ||
c0324a02 CZ |
336 | static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd) |
337 | { | |
cdb16e8f VG |
338 | struct cfq_group *cfqg = &cfqd->root_group; |
339 | ||
c0324a02 | 340 | if (wl == IDLE_WORKLOAD) |
cdb16e8f | 341 | return cfqg->service_tree_idle.count; |
c0324a02 | 342 | |
cdb16e8f VG |
343 | return cfqg->service_trees[wl][ASYNC_WORKLOAD].count |
344 | + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count | |
345 | + cfqg->service_trees[wl][SYNC_WORKLOAD].count; | |
c0324a02 CZ |
346 | } |
347 | ||
165125e1 | 348 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
a6151c3a | 349 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, |
fd0928df | 350 | struct io_context *, gfp_t); |
4ac845a2 | 351 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
91fac317 VT |
352 | struct io_context *); |
353 | ||
5ad531db JA |
354 | static inline int rq_in_driver(struct cfq_data *cfqd) |
355 | { | |
356 | return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1]; | |
357 | } | |
358 | ||
91fac317 | 359 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, |
a6151c3a | 360 | bool is_sync) |
91fac317 | 361 | { |
a6151c3a | 362 | return cic->cfqq[is_sync]; |
91fac317 VT |
363 | } |
364 | ||
365 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
a6151c3a | 366 | struct cfq_queue *cfqq, bool is_sync) |
91fac317 | 367 | { |
a6151c3a | 368 | cic->cfqq[is_sync] = cfqq; |
91fac317 VT |
369 | } |
370 | ||
371 | /* | |
372 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
373 | * set (in which case it could also be direct WRITE). | |
374 | */ | |
a6151c3a | 375 | static inline bool cfq_bio_sync(struct bio *bio) |
91fac317 | 376 | { |
a6151c3a | 377 | return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO); |
91fac317 | 378 | } |
1da177e4 | 379 | |
99f95e52 AM |
380 | /* |
381 | * scheduler run of queue, if there are requests pending and no one in the | |
382 | * driver that will restart queueing | |
383 | */ | |
23e018a1 | 384 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) |
99f95e52 | 385 | { |
7b679138 JA |
386 | if (cfqd->busy_queues) { |
387 | cfq_log(cfqd, "schedule dispatch"); | |
23e018a1 | 388 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
7b679138 | 389 | } |
99f95e52 AM |
390 | } |
391 | ||
165125e1 | 392 | static int cfq_queue_empty(struct request_queue *q) |
99f95e52 AM |
393 | { |
394 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
395 | ||
b4878f24 | 396 | return !cfqd->busy_queues; |
99f95e52 AM |
397 | } |
398 | ||
44f7c160 JA |
399 | /* |
400 | * Scale schedule slice based on io priority. Use the sync time slice only | |
401 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
402 | * io only, should not get full sync slice length. | |
403 | */ | |
a6151c3a | 404 | static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, |
d9e7620e | 405 | unsigned short prio) |
44f7c160 | 406 | { |
d9e7620e | 407 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 408 | |
d9e7620e JA |
409 | WARN_ON(prio >= IOPRIO_BE_NR); |
410 | ||
411 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
412 | } | |
44f7c160 | 413 | |
d9e7620e JA |
414 | static inline int |
415 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
416 | { | |
417 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
418 | } |
419 | ||
5db5d642 CZ |
420 | /* |
421 | * get averaged number of queues of RT/BE priority. | |
422 | * average is updated, with a formula that gives more weight to higher numbers, | |
423 | * to quickly follows sudden increases and decrease slowly | |
424 | */ | |
425 | ||
5869619c JA |
426 | static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt) |
427 | { | |
5db5d642 CZ |
428 | unsigned min_q, max_q; |
429 | unsigned mult = cfq_hist_divisor - 1; | |
430 | unsigned round = cfq_hist_divisor / 2; | |
c0324a02 | 431 | unsigned busy = cfq_busy_queues_wl(rt, cfqd); |
5db5d642 CZ |
432 | |
433 | min_q = min(cfqd->busy_queues_avg[rt], busy); | |
434 | max_q = max(cfqd->busy_queues_avg[rt], busy); | |
435 | cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) / | |
436 | cfq_hist_divisor; | |
437 | return cfqd->busy_queues_avg[rt]; | |
438 | } | |
439 | ||
44f7c160 JA |
440 | static inline void |
441 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
442 | { | |
5db5d642 CZ |
443 | unsigned slice = cfq_prio_to_slice(cfqd, cfqq); |
444 | if (cfqd->cfq_latency) { | |
445 | /* interested queues (we consider only the ones with the same | |
446 | * priority class) */ | |
447 | unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq)); | |
448 | unsigned sync_slice = cfqd->cfq_slice[1]; | |
449 | unsigned expect_latency = sync_slice * iq; | |
450 | if (expect_latency > cfq_target_latency) { | |
451 | unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; | |
452 | /* scale low_slice according to IO priority | |
453 | * and sync vs async */ | |
454 | unsigned low_slice = | |
455 | min(slice, base_low_slice * slice / sync_slice); | |
456 | /* the adapted slice value is scaled to fit all iqs | |
457 | * into the target latency */ | |
458 | slice = max(slice * cfq_target_latency / expect_latency, | |
459 | low_slice); | |
460 | } | |
461 | } | |
462 | cfqq->slice_end = jiffies + slice; | |
7b679138 | 463 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
44f7c160 JA |
464 | } |
465 | ||
466 | /* | |
467 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
468 | * isn't valid until the first request from the dispatch is activated | |
469 | * and the slice time set. | |
470 | */ | |
a6151c3a | 471 | static inline bool cfq_slice_used(struct cfq_queue *cfqq) |
44f7c160 JA |
472 | { |
473 | if (cfq_cfqq_slice_new(cfqq)) | |
474 | return 0; | |
475 | if (time_before(jiffies, cfqq->slice_end)) | |
476 | return 0; | |
477 | ||
478 | return 1; | |
479 | } | |
480 | ||
1da177e4 | 481 | /* |
5e705374 | 482 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 483 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 484 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 485 | */ |
5e705374 | 486 | static struct request * |
cf7c25cf | 487 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) |
1da177e4 | 488 | { |
cf7c25cf | 489 | sector_t s1, s2, d1 = 0, d2 = 0; |
1da177e4 | 490 | unsigned long back_max; |
e8a99053 AM |
491 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
492 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
493 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 494 | |
5e705374 JA |
495 | if (rq1 == NULL || rq1 == rq2) |
496 | return rq2; | |
497 | if (rq2 == NULL) | |
498 | return rq1; | |
9c2c38a1 | 499 | |
5e705374 JA |
500 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
501 | return rq1; | |
502 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
503 | return rq2; | |
374f84ac JA |
504 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
505 | return rq1; | |
506 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
507 | return rq2; | |
1da177e4 | 508 | |
83096ebf TH |
509 | s1 = blk_rq_pos(rq1); |
510 | s2 = blk_rq_pos(rq2); | |
1da177e4 | 511 | |
1da177e4 LT |
512 | /* |
513 | * by definition, 1KiB is 2 sectors | |
514 | */ | |
515 | back_max = cfqd->cfq_back_max * 2; | |
516 | ||
517 | /* | |
518 | * Strict one way elevator _except_ in the case where we allow | |
519 | * short backward seeks which are biased as twice the cost of a | |
520 | * similar forward seek. | |
521 | */ | |
522 | if (s1 >= last) | |
523 | d1 = s1 - last; | |
524 | else if (s1 + back_max >= last) | |
525 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
526 | else | |
e8a99053 | 527 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
528 | |
529 | if (s2 >= last) | |
530 | d2 = s2 - last; | |
531 | else if (s2 + back_max >= last) | |
532 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
533 | else | |
e8a99053 | 534 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
535 | |
536 | /* Found required data */ | |
e8a99053 AM |
537 | |
538 | /* | |
539 | * By doing switch() on the bit mask "wrap" we avoid having to | |
540 | * check two variables for all permutations: --> faster! | |
541 | */ | |
542 | switch (wrap) { | |
5e705374 | 543 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 544 | if (d1 < d2) |
5e705374 | 545 | return rq1; |
e8a99053 | 546 | else if (d2 < d1) |
5e705374 | 547 | return rq2; |
e8a99053 AM |
548 | else { |
549 | if (s1 >= s2) | |
5e705374 | 550 | return rq1; |
e8a99053 | 551 | else |
5e705374 | 552 | return rq2; |
e8a99053 | 553 | } |
1da177e4 | 554 | |
e8a99053 | 555 | case CFQ_RQ2_WRAP: |
5e705374 | 556 | return rq1; |
e8a99053 | 557 | case CFQ_RQ1_WRAP: |
5e705374 JA |
558 | return rq2; |
559 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
560 | default: |
561 | /* | |
562 | * Since both rqs are wrapped, | |
563 | * start with the one that's further behind head | |
564 | * (--> only *one* back seek required), | |
565 | * since back seek takes more time than forward. | |
566 | */ | |
567 | if (s1 <= s2) | |
5e705374 | 568 | return rq1; |
1da177e4 | 569 | else |
5e705374 | 570 | return rq2; |
1da177e4 LT |
571 | } |
572 | } | |
573 | ||
498d3aa2 JA |
574 | /* |
575 | * The below is leftmost cache rbtree addon | |
576 | */ | |
0871714e | 577 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
cc09e299 | 578 | { |
615f0259 VG |
579 | /* Service tree is empty */ |
580 | if (!root->count) | |
581 | return NULL; | |
582 | ||
cc09e299 JA |
583 | if (!root->left) |
584 | root->left = rb_first(&root->rb); | |
585 | ||
0871714e JA |
586 | if (root->left) |
587 | return rb_entry(root->left, struct cfq_queue, rb_node); | |
588 | ||
589 | return NULL; | |
cc09e299 JA |
590 | } |
591 | ||
a36e71f9 JA |
592 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
593 | { | |
594 | rb_erase(n, root); | |
595 | RB_CLEAR_NODE(n); | |
596 | } | |
597 | ||
cc09e299 JA |
598 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
599 | { | |
600 | if (root->left == n) | |
601 | root->left = NULL; | |
a36e71f9 | 602 | rb_erase_init(n, &root->rb); |
aa6f6a3d | 603 | --root->count; |
cc09e299 JA |
604 | } |
605 | ||
1da177e4 LT |
606 | /* |
607 | * would be nice to take fifo expire time into account as well | |
608 | */ | |
5e705374 JA |
609 | static struct request * |
610 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
611 | struct request *last) | |
1da177e4 | 612 | { |
21183b07 JA |
613 | struct rb_node *rbnext = rb_next(&last->rb_node); |
614 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 615 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 616 | |
21183b07 | 617 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
618 | |
619 | if (rbprev) | |
5e705374 | 620 | prev = rb_entry_rq(rbprev); |
1da177e4 | 621 | |
21183b07 | 622 | if (rbnext) |
5e705374 | 623 | next = rb_entry_rq(rbnext); |
21183b07 JA |
624 | else { |
625 | rbnext = rb_first(&cfqq->sort_list); | |
626 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 627 | next = rb_entry_rq(rbnext); |
21183b07 | 628 | } |
1da177e4 | 629 | |
cf7c25cf | 630 | return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); |
1da177e4 LT |
631 | } |
632 | ||
d9e7620e JA |
633 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
634 | struct cfq_queue *cfqq) | |
1da177e4 | 635 | { |
d9e7620e JA |
636 | /* |
637 | * just an approximation, should be ok. | |
638 | */ | |
cdb16e8f | 639 | return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
464191c6 | 640 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); |
d9e7620e JA |
641 | } |
642 | ||
498d3aa2 | 643 | /* |
c0324a02 | 644 | * The cfqd->service_trees holds all pending cfq_queue's that have |
498d3aa2 JA |
645 | * requests waiting to be processed. It is sorted in the order that |
646 | * we will service the queues. | |
647 | */ | |
a36e71f9 | 648 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 649 | bool add_front) |
d9e7620e | 650 | { |
0871714e JA |
651 | struct rb_node **p, *parent; |
652 | struct cfq_queue *__cfqq; | |
d9e7620e | 653 | unsigned long rb_key; |
c0324a02 | 654 | struct cfq_rb_root *service_tree; |
498d3aa2 | 655 | int left; |
d9e7620e | 656 | |
cdb16e8f VG |
657 | service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), |
658 | cfqq_type(cfqq), cfqd); | |
0871714e JA |
659 | if (cfq_class_idle(cfqq)) { |
660 | rb_key = CFQ_IDLE_DELAY; | |
aa6f6a3d | 661 | parent = rb_last(&service_tree->rb); |
0871714e JA |
662 | if (parent && parent != &cfqq->rb_node) { |
663 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
664 | rb_key += __cfqq->rb_key; | |
665 | } else | |
666 | rb_key += jiffies; | |
667 | } else if (!add_front) { | |
b9c8946b JA |
668 | /* |
669 | * Get our rb key offset. Subtract any residual slice | |
670 | * value carried from last service. A negative resid | |
671 | * count indicates slice overrun, and this should position | |
672 | * the next service time further away in the tree. | |
673 | */ | |
edd75ffd | 674 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
b9c8946b | 675 | rb_key -= cfqq->slice_resid; |
edd75ffd | 676 | cfqq->slice_resid = 0; |
48e025e6 CZ |
677 | } else { |
678 | rb_key = -HZ; | |
aa6f6a3d | 679 | __cfqq = cfq_rb_first(service_tree); |
48e025e6 CZ |
680 | rb_key += __cfqq ? __cfqq->rb_key : jiffies; |
681 | } | |
1da177e4 | 682 | |
d9e7620e | 683 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 684 | /* |
d9e7620e | 685 | * same position, nothing more to do |
99f9628a | 686 | */ |
c0324a02 CZ |
687 | if (rb_key == cfqq->rb_key && |
688 | cfqq->service_tree == service_tree) | |
d9e7620e | 689 | return; |
1da177e4 | 690 | |
aa6f6a3d CZ |
691 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
692 | cfqq->service_tree = NULL; | |
1da177e4 | 693 | } |
d9e7620e | 694 | |
498d3aa2 | 695 | left = 1; |
0871714e | 696 | parent = NULL; |
aa6f6a3d CZ |
697 | cfqq->service_tree = service_tree; |
698 | p = &service_tree->rb.rb_node; | |
d9e7620e | 699 | while (*p) { |
67060e37 | 700 | struct rb_node **n; |
cc09e299 | 701 | |
d9e7620e JA |
702 | parent = *p; |
703 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
704 | ||
0c534e0a | 705 | /* |
c0324a02 | 706 | * sort by key, that represents service time. |
0c534e0a | 707 | */ |
c0324a02 | 708 | if (time_before(rb_key, __cfqq->rb_key)) |
67060e37 | 709 | n = &(*p)->rb_left; |
c0324a02 | 710 | else { |
67060e37 | 711 | n = &(*p)->rb_right; |
cc09e299 | 712 | left = 0; |
c0324a02 | 713 | } |
67060e37 JA |
714 | |
715 | p = n; | |
d9e7620e JA |
716 | } |
717 | ||
cc09e299 | 718 | if (left) |
aa6f6a3d | 719 | service_tree->left = &cfqq->rb_node; |
cc09e299 | 720 | |
d9e7620e JA |
721 | cfqq->rb_key = rb_key; |
722 | rb_link_node(&cfqq->rb_node, parent, p); | |
aa6f6a3d CZ |
723 | rb_insert_color(&cfqq->rb_node, &service_tree->rb); |
724 | service_tree->count++; | |
1da177e4 LT |
725 | } |
726 | ||
a36e71f9 | 727 | static struct cfq_queue * |
f2d1f0ae JA |
728 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
729 | sector_t sector, struct rb_node **ret_parent, | |
730 | struct rb_node ***rb_link) | |
a36e71f9 | 731 | { |
a36e71f9 JA |
732 | struct rb_node **p, *parent; |
733 | struct cfq_queue *cfqq = NULL; | |
734 | ||
735 | parent = NULL; | |
736 | p = &root->rb_node; | |
737 | while (*p) { | |
738 | struct rb_node **n; | |
739 | ||
740 | parent = *p; | |
741 | cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
742 | ||
743 | /* | |
744 | * Sort strictly based on sector. Smallest to the left, | |
745 | * largest to the right. | |
746 | */ | |
2e46e8b2 | 747 | if (sector > blk_rq_pos(cfqq->next_rq)) |
a36e71f9 | 748 | n = &(*p)->rb_right; |
2e46e8b2 | 749 | else if (sector < blk_rq_pos(cfqq->next_rq)) |
a36e71f9 JA |
750 | n = &(*p)->rb_left; |
751 | else | |
752 | break; | |
753 | p = n; | |
3ac6c9f8 | 754 | cfqq = NULL; |
a36e71f9 JA |
755 | } |
756 | ||
757 | *ret_parent = parent; | |
758 | if (rb_link) | |
759 | *rb_link = p; | |
3ac6c9f8 | 760 | return cfqq; |
a36e71f9 JA |
761 | } |
762 | ||
763 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
764 | { | |
a36e71f9 JA |
765 | struct rb_node **p, *parent; |
766 | struct cfq_queue *__cfqq; | |
767 | ||
f2d1f0ae JA |
768 | if (cfqq->p_root) { |
769 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
770 | cfqq->p_root = NULL; | |
771 | } | |
a36e71f9 JA |
772 | |
773 | if (cfq_class_idle(cfqq)) | |
774 | return; | |
775 | if (!cfqq->next_rq) | |
776 | return; | |
777 | ||
f2d1f0ae | 778 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
2e46e8b2 TH |
779 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
780 | blk_rq_pos(cfqq->next_rq), &parent, &p); | |
3ac6c9f8 JA |
781 | if (!__cfqq) { |
782 | rb_link_node(&cfqq->p_node, parent, p); | |
f2d1f0ae JA |
783 | rb_insert_color(&cfqq->p_node, cfqq->p_root); |
784 | } else | |
785 | cfqq->p_root = NULL; | |
a36e71f9 JA |
786 | } |
787 | ||
498d3aa2 JA |
788 | /* |
789 | * Update cfqq's position in the service tree. | |
790 | */ | |
edd75ffd | 791 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
6d048f53 | 792 | { |
6d048f53 JA |
793 | /* |
794 | * Resorting requires the cfqq to be on the RR list already. | |
795 | */ | |
a36e71f9 | 796 | if (cfq_cfqq_on_rr(cfqq)) { |
edd75ffd | 797 | cfq_service_tree_add(cfqd, cfqq, 0); |
a36e71f9 JA |
798 | cfq_prio_tree_add(cfqd, cfqq); |
799 | } | |
6d048f53 JA |
800 | } |
801 | ||
1da177e4 LT |
802 | /* |
803 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 804 | * the pending list according to last request service |
1da177e4 | 805 | */ |
febffd61 | 806 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 807 | { |
7b679138 | 808 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
3b18152c JA |
809 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
810 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
811 | cfqd->busy_queues++; |
812 | ||
edd75ffd | 813 | cfq_resort_rr_list(cfqd, cfqq); |
1da177e4 LT |
814 | } |
815 | ||
498d3aa2 JA |
816 | /* |
817 | * Called when the cfqq no longer has requests pending, remove it from | |
818 | * the service tree. | |
819 | */ | |
febffd61 | 820 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 821 | { |
7b679138 | 822 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
3b18152c JA |
823 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
824 | cfq_clear_cfqq_on_rr(cfqq); | |
1da177e4 | 825 | |
aa6f6a3d CZ |
826 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
827 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); | |
828 | cfqq->service_tree = NULL; | |
829 | } | |
f2d1f0ae JA |
830 | if (cfqq->p_root) { |
831 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
832 | cfqq->p_root = NULL; | |
833 | } | |
d9e7620e | 834 | |
1da177e4 LT |
835 | BUG_ON(!cfqd->busy_queues); |
836 | cfqd->busy_queues--; | |
837 | } | |
838 | ||
839 | /* | |
840 | * rb tree support functions | |
841 | */ | |
febffd61 | 842 | static void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 843 | { |
5e705374 | 844 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 845 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 846 | const int sync = rq_is_sync(rq); |
1da177e4 | 847 | |
b4878f24 JA |
848 | BUG_ON(!cfqq->queued[sync]); |
849 | cfqq->queued[sync]--; | |
1da177e4 | 850 | |
5e705374 | 851 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 852 | |
dd67d051 | 853 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 854 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
855 | } |
856 | ||
5e705374 | 857 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 858 | { |
5e705374 | 859 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 860 | struct cfq_data *cfqd = cfqq->cfqd; |
a36e71f9 | 861 | struct request *__alias, *prev; |
1da177e4 | 862 | |
5380a101 | 863 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
864 | |
865 | /* | |
866 | * looks a little odd, but the first insert might return an alias. | |
867 | * if that happens, put the alias on the dispatch list | |
868 | */ | |
21183b07 | 869 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 870 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
871 | |
872 | if (!cfq_cfqq_on_rr(cfqq)) | |
873 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
874 | |
875 | /* | |
876 | * check if this request is a better next-serve candidate | |
877 | */ | |
a36e71f9 | 878 | prev = cfqq->next_rq; |
cf7c25cf | 879 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); |
a36e71f9 JA |
880 | |
881 | /* | |
882 | * adjust priority tree position, if ->next_rq changes | |
883 | */ | |
884 | if (prev != cfqq->next_rq) | |
885 | cfq_prio_tree_add(cfqd, cfqq); | |
886 | ||
5044eed4 | 887 | BUG_ON(!cfqq->next_rq); |
1da177e4 LT |
888 | } |
889 | ||
febffd61 | 890 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 891 | { |
5380a101 JA |
892 | elv_rb_del(&cfqq->sort_list, rq); |
893 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 894 | cfq_add_rq_rb(rq); |
1da177e4 LT |
895 | } |
896 | ||
206dc69b JA |
897 | static struct request * |
898 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 899 | { |
206dc69b | 900 | struct task_struct *tsk = current; |
91fac317 | 901 | struct cfq_io_context *cic; |
206dc69b | 902 | struct cfq_queue *cfqq; |
1da177e4 | 903 | |
4ac845a2 | 904 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
905 | if (!cic) |
906 | return NULL; | |
907 | ||
908 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
89850f7e JA |
909 | if (cfqq) { |
910 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
911 | ||
21183b07 | 912 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 913 | } |
1da177e4 | 914 | |
1da177e4 LT |
915 | return NULL; |
916 | } | |
917 | ||
165125e1 | 918 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 919 | { |
22e2c507 | 920 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 921 | |
5ad531db | 922 | cfqd->rq_in_driver[rq_is_sync(rq)]++; |
7b679138 | 923 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
5ad531db | 924 | rq_in_driver(cfqd)); |
25776e35 | 925 | |
5b93629b | 926 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
1da177e4 LT |
927 | } |
928 | ||
165125e1 | 929 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 930 | { |
b4878f24 | 931 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5ad531db | 932 | const int sync = rq_is_sync(rq); |
b4878f24 | 933 | |
5ad531db JA |
934 | WARN_ON(!cfqd->rq_in_driver[sync]); |
935 | cfqd->rq_in_driver[sync]--; | |
7b679138 | 936 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
5ad531db | 937 | rq_in_driver(cfqd)); |
1da177e4 LT |
938 | } |
939 | ||
b4878f24 | 940 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 941 | { |
5e705374 | 942 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 943 | |
5e705374 JA |
944 | if (cfqq->next_rq == rq) |
945 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 946 | |
b4878f24 | 947 | list_del_init(&rq->queuelist); |
5e705374 | 948 | cfq_del_rq_rb(rq); |
374f84ac | 949 | |
45333d5a | 950 | cfqq->cfqd->rq_queued--; |
374f84ac JA |
951 | if (rq_is_meta(rq)) { |
952 | WARN_ON(!cfqq->meta_pending); | |
953 | cfqq->meta_pending--; | |
954 | } | |
1da177e4 LT |
955 | } |
956 | ||
165125e1 JA |
957 | static int cfq_merge(struct request_queue *q, struct request **req, |
958 | struct bio *bio) | |
1da177e4 LT |
959 | { |
960 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
961 | struct request *__rq; | |
1da177e4 | 962 | |
206dc69b | 963 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 964 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
965 | *req = __rq; |
966 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
967 | } |
968 | ||
969 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
970 | } |
971 | ||
165125e1 | 972 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
21183b07 | 973 | int type) |
1da177e4 | 974 | { |
21183b07 | 975 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 976 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 977 | |
5e705374 | 978 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 979 | } |
1da177e4 LT |
980 | } |
981 | ||
982 | static void | |
165125e1 | 983 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
984 | struct request *next) |
985 | { | |
cf7c25cf | 986 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 JA |
987 | /* |
988 | * reposition in fifo if next is older than rq | |
989 | */ | |
990 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
30996f40 | 991 | time_before(rq_fifo_time(next), rq_fifo_time(rq))) { |
22e2c507 | 992 | list_move(&rq->queuelist, &next->queuelist); |
30996f40 JA |
993 | rq_set_fifo_time(rq, rq_fifo_time(next)); |
994 | } | |
22e2c507 | 995 | |
cf7c25cf CZ |
996 | if (cfqq->next_rq == next) |
997 | cfqq->next_rq = rq; | |
b4878f24 | 998 | cfq_remove_request(next); |
22e2c507 JA |
999 | } |
1000 | ||
165125e1 | 1001 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
da775265 JA |
1002 | struct bio *bio) |
1003 | { | |
1004 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
91fac317 | 1005 | struct cfq_io_context *cic; |
da775265 | 1006 | struct cfq_queue *cfqq; |
da775265 JA |
1007 | |
1008 | /* | |
ec8acb69 | 1009 | * Disallow merge of a sync bio into an async request. |
da775265 | 1010 | */ |
91fac317 | 1011 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
a6151c3a | 1012 | return false; |
da775265 JA |
1013 | |
1014 | /* | |
719d3402 JA |
1015 | * Lookup the cfqq that this bio will be queued with. Allow |
1016 | * merge only if rq is queued there. | |
da775265 | 1017 | */ |
4ac845a2 | 1018 | cic = cfq_cic_lookup(cfqd, current->io_context); |
91fac317 | 1019 | if (!cic) |
a6151c3a | 1020 | return false; |
719d3402 | 1021 | |
91fac317 | 1022 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
a6151c3a | 1023 | return cfqq == RQ_CFQQ(rq); |
da775265 JA |
1024 | } |
1025 | ||
febffd61 JA |
1026 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
1027 | struct cfq_queue *cfqq) | |
22e2c507 JA |
1028 | { |
1029 | if (cfqq) { | |
7b679138 | 1030 | cfq_log_cfqq(cfqd, cfqq, "set_active"); |
22e2c507 | 1031 | cfqq->slice_end = 0; |
2f5cb738 JA |
1032 | cfqq->slice_dispatch = 0; |
1033 | ||
2f5cb738 | 1034 | cfq_clear_cfqq_wait_request(cfqq); |
b029195d | 1035 | cfq_clear_cfqq_must_dispatch(cfqq); |
3b18152c JA |
1036 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
1037 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 1038 | cfq_mark_cfqq_slice_new(cfqq); |
2f5cb738 JA |
1039 | |
1040 | del_timer(&cfqd->idle_slice_timer); | |
22e2c507 JA |
1041 | } |
1042 | ||
1043 | cfqd->active_queue = cfqq; | |
1044 | } | |
1045 | ||
7b14e3b5 JA |
1046 | /* |
1047 | * current cfqq expired its slice (or was too idle), select new one | |
1048 | */ | |
1049 | static void | |
1050 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
a6151c3a | 1051 | bool timed_out) |
7b14e3b5 | 1052 | { |
7b679138 JA |
1053 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
1054 | ||
7b14e3b5 JA |
1055 | if (cfq_cfqq_wait_request(cfqq)) |
1056 | del_timer(&cfqd->idle_slice_timer); | |
1057 | ||
7b14e3b5 JA |
1058 | cfq_clear_cfqq_wait_request(cfqq); |
1059 | ||
1060 | /* | |
6084cdda | 1061 | * store what was left of this slice, if the queue idled/timed out |
7b14e3b5 | 1062 | */ |
7b679138 | 1063 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) { |
c5b680f3 | 1064 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b679138 JA |
1065 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
1066 | } | |
7b14e3b5 | 1067 | |
edd75ffd | 1068 | cfq_resort_rr_list(cfqd, cfqq); |
7b14e3b5 JA |
1069 | |
1070 | if (cfqq == cfqd->active_queue) | |
1071 | cfqd->active_queue = NULL; | |
1072 | ||
1073 | if (cfqd->active_cic) { | |
1074 | put_io_context(cfqd->active_cic->ioc); | |
1075 | cfqd->active_cic = NULL; | |
1076 | } | |
7b14e3b5 JA |
1077 | } |
1078 | ||
a6151c3a | 1079 | static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) |
7b14e3b5 JA |
1080 | { |
1081 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1082 | ||
1083 | if (cfqq) | |
6084cdda | 1084 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
7b14e3b5 JA |
1085 | } |
1086 | ||
498d3aa2 JA |
1087 | /* |
1088 | * Get next queue for service. Unless we have a queue preemption, | |
1089 | * we'll simply select the first cfqq in the service tree. | |
1090 | */ | |
6d048f53 | 1091 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 1092 | { |
c0324a02 | 1093 | struct cfq_rb_root *service_tree = |
cdb16e8f VG |
1094 | service_tree_for(cfqd->serving_group, cfqd->serving_prio, |
1095 | cfqd->serving_type, cfqd); | |
d9e7620e | 1096 | |
c0324a02 CZ |
1097 | if (RB_EMPTY_ROOT(&service_tree->rb)) |
1098 | return NULL; | |
1099 | return cfq_rb_first(service_tree); | |
6d048f53 JA |
1100 | } |
1101 | ||
498d3aa2 JA |
1102 | /* |
1103 | * Get and set a new active queue for service. | |
1104 | */ | |
a36e71f9 JA |
1105 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
1106 | struct cfq_queue *cfqq) | |
6d048f53 | 1107 | { |
e00ef799 | 1108 | if (!cfqq) |
a36e71f9 | 1109 | cfqq = cfq_get_next_queue(cfqd); |
6d048f53 | 1110 | |
22e2c507 | 1111 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 1112 | return cfqq; |
22e2c507 JA |
1113 | } |
1114 | ||
d9e7620e JA |
1115 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
1116 | struct request *rq) | |
1117 | { | |
83096ebf TH |
1118 | if (blk_rq_pos(rq) >= cfqd->last_position) |
1119 | return blk_rq_pos(rq) - cfqd->last_position; | |
d9e7620e | 1120 | else |
83096ebf | 1121 | return cfqd->last_position - blk_rq_pos(rq); |
d9e7620e JA |
1122 | } |
1123 | ||
b2c18e1e JM |
1124 | #define CFQQ_SEEK_THR 8 * 1024 |
1125 | #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR) | |
04dc6e71 | 1126 | |
b2c18e1e JM |
1127 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1128 | struct request *rq) | |
6d048f53 | 1129 | { |
b2c18e1e | 1130 | sector_t sdist = cfqq->seek_mean; |
6d048f53 | 1131 | |
b2c18e1e JM |
1132 | if (!sample_valid(cfqq->seek_samples)) |
1133 | sdist = CFQQ_SEEK_THR; | |
6d048f53 | 1134 | |
04dc6e71 | 1135 | return cfq_dist_from_last(cfqd, rq) <= sdist; |
6d048f53 JA |
1136 | } |
1137 | ||
a36e71f9 JA |
1138 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
1139 | struct cfq_queue *cur_cfqq) | |
1140 | { | |
f2d1f0ae | 1141 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
a36e71f9 JA |
1142 | struct rb_node *parent, *node; |
1143 | struct cfq_queue *__cfqq; | |
1144 | sector_t sector = cfqd->last_position; | |
1145 | ||
1146 | if (RB_EMPTY_ROOT(root)) | |
1147 | return NULL; | |
1148 | ||
1149 | /* | |
1150 | * First, if we find a request starting at the end of the last | |
1151 | * request, choose it. | |
1152 | */ | |
f2d1f0ae | 1153 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
a36e71f9 JA |
1154 | if (__cfqq) |
1155 | return __cfqq; | |
1156 | ||
1157 | /* | |
1158 | * If the exact sector wasn't found, the parent of the NULL leaf | |
1159 | * will contain the closest sector. | |
1160 | */ | |
1161 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
b2c18e1e | 1162 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1163 | return __cfqq; |
1164 | ||
2e46e8b2 | 1165 | if (blk_rq_pos(__cfqq->next_rq) < sector) |
a36e71f9 JA |
1166 | node = rb_next(&__cfqq->p_node); |
1167 | else | |
1168 | node = rb_prev(&__cfqq->p_node); | |
1169 | if (!node) | |
1170 | return NULL; | |
1171 | ||
1172 | __cfqq = rb_entry(node, struct cfq_queue, p_node); | |
b2c18e1e | 1173 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1174 | return __cfqq; |
1175 | ||
1176 | return NULL; | |
1177 | } | |
1178 | ||
1179 | /* | |
1180 | * cfqd - obvious | |
1181 | * cur_cfqq - passed in so that we don't decide that the current queue is | |
1182 | * closely cooperating with itself. | |
1183 | * | |
1184 | * So, basically we're assuming that that cur_cfqq has dispatched at least | |
1185 | * one request, and that cfqd->last_position reflects a position on the disk | |
1186 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid | |
1187 | * assumption. | |
1188 | */ | |
1189 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, | |
b3b6d040 | 1190 | struct cfq_queue *cur_cfqq) |
6d048f53 | 1191 | { |
a36e71f9 JA |
1192 | struct cfq_queue *cfqq; |
1193 | ||
e6c5bc73 JM |
1194 | if (!cfq_cfqq_sync(cur_cfqq)) |
1195 | return NULL; | |
1196 | if (CFQQ_SEEKY(cur_cfqq)) | |
1197 | return NULL; | |
1198 | ||
6d048f53 | 1199 | /* |
d9e7620e JA |
1200 | * We should notice if some of the queues are cooperating, eg |
1201 | * working closely on the same area of the disk. In that case, | |
1202 | * we can group them together and don't waste time idling. | |
6d048f53 | 1203 | */ |
a36e71f9 JA |
1204 | cfqq = cfqq_close(cfqd, cur_cfqq); |
1205 | if (!cfqq) | |
1206 | return NULL; | |
1207 | ||
df5fe3e8 JM |
1208 | /* |
1209 | * It only makes sense to merge sync queues. | |
1210 | */ | |
1211 | if (!cfq_cfqq_sync(cfqq)) | |
1212 | return NULL; | |
e6c5bc73 JM |
1213 | if (CFQQ_SEEKY(cfqq)) |
1214 | return NULL; | |
df5fe3e8 | 1215 | |
c0324a02 CZ |
1216 | /* |
1217 | * Do not merge queues of different priority classes | |
1218 | */ | |
1219 | if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) | |
1220 | return NULL; | |
1221 | ||
a36e71f9 | 1222 | return cfqq; |
6d048f53 JA |
1223 | } |
1224 | ||
a6d44e98 CZ |
1225 | /* |
1226 | * Determine whether we should enforce idle window for this queue. | |
1227 | */ | |
1228 | ||
1229 | static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1230 | { | |
1231 | enum wl_prio_t prio = cfqq_prio(cfqq); | |
718eee05 | 1232 | struct cfq_rb_root *service_tree = cfqq->service_tree; |
a6d44e98 CZ |
1233 | |
1234 | /* We never do for idle class queues. */ | |
1235 | if (prio == IDLE_WORKLOAD) | |
1236 | return false; | |
1237 | ||
1238 | /* We do for queues that were marked with idle window flag. */ | |
1239 | if (cfq_cfqq_idle_window(cfqq)) | |
1240 | return true; | |
1241 | ||
1242 | /* | |
1243 | * Otherwise, we do only if they are the last ones | |
1244 | * in their service tree. | |
1245 | */ | |
718eee05 | 1246 | if (!service_tree) |
cdb16e8f VG |
1247 | service_tree = service_tree_for(cfqq->cfqg, prio, |
1248 | cfqq_type(cfqq), cfqd); | |
718eee05 | 1249 | |
a6d44e98 CZ |
1250 | if (service_tree->count == 0) |
1251 | return true; | |
1252 | ||
1253 | return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq); | |
1254 | } | |
1255 | ||
6d048f53 | 1256 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 1257 | { |
1792669c | 1258 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 1259 | struct cfq_io_context *cic; |
7b14e3b5 JA |
1260 | unsigned long sl; |
1261 | ||
a68bbddb | 1262 | /* |
f7d7b7a7 JA |
1263 | * SSD device without seek penalty, disable idling. But only do so |
1264 | * for devices that support queuing, otherwise we still have a problem | |
1265 | * with sync vs async workloads. | |
a68bbddb | 1266 | */ |
f7d7b7a7 | 1267 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
a68bbddb JA |
1268 | return; |
1269 | ||
dd67d051 | 1270 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 1271 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
1272 | |
1273 | /* | |
1274 | * idle is disabled, either manually or by past process history | |
1275 | */ | |
a6d44e98 | 1276 | if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq)) |
6d048f53 JA |
1277 | return; |
1278 | ||
7b679138 | 1279 | /* |
8e550632 | 1280 | * still active requests from this queue, don't idle |
7b679138 | 1281 | */ |
8e550632 | 1282 | if (cfqq->dispatched) |
7b679138 JA |
1283 | return; |
1284 | ||
22e2c507 JA |
1285 | /* |
1286 | * task has exited, don't wait | |
1287 | */ | |
206dc69b | 1288 | cic = cfqd->active_cic; |
66dac98e | 1289 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
6d048f53 JA |
1290 | return; |
1291 | ||
355b659c CZ |
1292 | /* |
1293 | * If our average think time is larger than the remaining time | |
1294 | * slice, then don't idle. This avoids overrunning the allotted | |
1295 | * time slice. | |
1296 | */ | |
1297 | if (sample_valid(cic->ttime_samples) && | |
1298 | (cfqq->slice_end - jiffies < cic->ttime_mean)) | |
1299 | return; | |
1300 | ||
3b18152c | 1301 | cfq_mark_cfqq_wait_request(cfqq); |
22e2c507 | 1302 | |
6d048f53 | 1303 | sl = cfqd->cfq_slice_idle; |
206dc69b | 1304 | |
7b14e3b5 | 1305 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
9481ffdc | 1306 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); |
1da177e4 LT |
1307 | } |
1308 | ||
498d3aa2 JA |
1309 | /* |
1310 | * Move request from internal lists to the request queue dispatch list. | |
1311 | */ | |
165125e1 | 1312 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
1da177e4 | 1313 | { |
3ed9a296 | 1314 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1315 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 1316 | |
7b679138 JA |
1317 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
1318 | ||
06d21886 | 1319 | cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
5380a101 | 1320 | cfq_remove_request(rq); |
6d048f53 | 1321 | cfqq->dispatched++; |
5380a101 | 1322 | elv_dispatch_sort(q, rq); |
3ed9a296 JA |
1323 | |
1324 | if (cfq_cfqq_sync(cfqq)) | |
1325 | cfqd->sync_flight++; | |
1da177e4 LT |
1326 | } |
1327 | ||
1328 | /* | |
1329 | * return expired entry, or NULL to just start from scratch in rbtree | |
1330 | */ | |
febffd61 | 1331 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 | 1332 | { |
30996f40 | 1333 | struct request *rq = NULL; |
1da177e4 | 1334 | |
3b18152c | 1335 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 1336 | return NULL; |
cb887411 JA |
1337 | |
1338 | cfq_mark_cfqq_fifo_expire(cfqq); | |
1339 | ||
89850f7e JA |
1340 | if (list_empty(&cfqq->fifo)) |
1341 | return NULL; | |
1da177e4 | 1342 | |
89850f7e | 1343 | rq = rq_entry_fifo(cfqq->fifo.next); |
30996f40 | 1344 | if (time_before(jiffies, rq_fifo_time(rq))) |
7b679138 | 1345 | rq = NULL; |
1da177e4 | 1346 | |
30996f40 | 1347 | cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); |
6d048f53 | 1348 | return rq; |
1da177e4 LT |
1349 | } |
1350 | ||
22e2c507 JA |
1351 | static inline int |
1352 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1353 | { | |
1354 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1355 | |
22e2c507 | 1356 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1357 | |
22e2c507 | 1358 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1359 | } |
1360 | ||
df5fe3e8 JM |
1361 | /* |
1362 | * Must be called with the queue_lock held. | |
1363 | */ | |
1364 | static int cfqq_process_refs(struct cfq_queue *cfqq) | |
1365 | { | |
1366 | int process_refs, io_refs; | |
1367 | ||
1368 | io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; | |
1369 | process_refs = atomic_read(&cfqq->ref) - io_refs; | |
1370 | BUG_ON(process_refs < 0); | |
1371 | return process_refs; | |
1372 | } | |
1373 | ||
1374 | static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) | |
1375 | { | |
e6c5bc73 | 1376 | int process_refs, new_process_refs; |
df5fe3e8 JM |
1377 | struct cfq_queue *__cfqq; |
1378 | ||
1379 | /* Avoid a circular list and skip interim queue merges */ | |
1380 | while ((__cfqq = new_cfqq->new_cfqq)) { | |
1381 | if (__cfqq == cfqq) | |
1382 | return; | |
1383 | new_cfqq = __cfqq; | |
1384 | } | |
1385 | ||
1386 | process_refs = cfqq_process_refs(cfqq); | |
1387 | /* | |
1388 | * If the process for the cfqq has gone away, there is no | |
1389 | * sense in merging the queues. | |
1390 | */ | |
1391 | if (process_refs == 0) | |
1392 | return; | |
1393 | ||
e6c5bc73 JM |
1394 | /* |
1395 | * Merge in the direction of the lesser amount of work. | |
1396 | */ | |
1397 | new_process_refs = cfqq_process_refs(new_cfqq); | |
1398 | if (new_process_refs >= process_refs) { | |
1399 | cfqq->new_cfqq = new_cfqq; | |
1400 | atomic_add(process_refs, &new_cfqq->ref); | |
1401 | } else { | |
1402 | new_cfqq->new_cfqq = cfqq; | |
1403 | atomic_add(new_process_refs, &cfqq->ref); | |
1404 | } | |
df5fe3e8 JM |
1405 | } |
1406 | ||
cdb16e8f VG |
1407 | static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, |
1408 | struct cfq_group *cfqg, enum wl_prio_t prio, | |
1409 | bool prio_changed) | |
718eee05 CZ |
1410 | { |
1411 | struct cfq_queue *queue; | |
1412 | int i; | |
1413 | bool key_valid = false; | |
1414 | unsigned long lowest_key = 0; | |
1415 | enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; | |
1416 | ||
1417 | if (prio_changed) { | |
1418 | /* | |
1419 | * When priorities switched, we prefer starting | |
1420 | * from SYNC_NOIDLE (first choice), or just SYNC | |
1421 | * over ASYNC | |
1422 | */ | |
cdb16e8f | 1423 | if (service_tree_for(cfqg, prio, cur_best, cfqd)->count) |
718eee05 CZ |
1424 | return cur_best; |
1425 | cur_best = SYNC_WORKLOAD; | |
cdb16e8f | 1426 | if (service_tree_for(cfqg, prio, cur_best, cfqd)->count) |
718eee05 CZ |
1427 | return cur_best; |
1428 | ||
1429 | return ASYNC_WORKLOAD; | |
1430 | } | |
1431 | ||
1432 | for (i = 0; i < 3; ++i) { | |
1433 | /* otherwise, select the one with lowest rb_key */ | |
cdb16e8f | 1434 | queue = cfq_rb_first(service_tree_for(cfqg, prio, i, cfqd)); |
718eee05 CZ |
1435 | if (queue && |
1436 | (!key_valid || time_before(queue->rb_key, lowest_key))) { | |
1437 | lowest_key = queue->rb_key; | |
1438 | cur_best = i; | |
1439 | key_valid = true; | |
1440 | } | |
1441 | } | |
1442 | ||
1443 | return cur_best; | |
1444 | } | |
1445 | ||
cdb16e8f | 1446 | static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) |
718eee05 CZ |
1447 | { |
1448 | enum wl_prio_t previous_prio = cfqd->serving_prio; | |
1449 | bool prio_changed; | |
1450 | unsigned slice; | |
1451 | unsigned count; | |
cdb16e8f | 1452 | struct cfq_rb_root *st; |
718eee05 CZ |
1453 | |
1454 | /* Choose next priority. RT > BE > IDLE */ | |
1455 | if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd)) | |
1456 | cfqd->serving_prio = RT_WORKLOAD; | |
1457 | else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd)) | |
1458 | cfqd->serving_prio = BE_WORKLOAD; | |
1459 | else { | |
1460 | cfqd->serving_prio = IDLE_WORKLOAD; | |
1461 | cfqd->workload_expires = jiffies + 1; | |
1462 | return; | |
1463 | } | |
1464 | ||
1465 | /* | |
1466 | * For RT and BE, we have to choose also the type | |
1467 | * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload | |
1468 | * expiration time | |
1469 | */ | |
1470 | prio_changed = (cfqd->serving_prio != previous_prio); | |
cdb16e8f VG |
1471 | st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type, |
1472 | cfqd); | |
1473 | count = st->count; | |
718eee05 CZ |
1474 | |
1475 | /* | |
1476 | * If priority didn't change, check workload expiration, | |
1477 | * and that we still have other queues ready | |
1478 | */ | |
1479 | if (!prio_changed && count && | |
1480 | !time_after(jiffies, cfqd->workload_expires)) | |
1481 | return; | |
1482 | ||
1483 | /* otherwise select new workload type */ | |
1484 | cfqd->serving_type = | |
cdb16e8f VG |
1485 | cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio, prio_changed); |
1486 | st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type, | |
1487 | cfqd); | |
1488 | count = st->count; | |
718eee05 CZ |
1489 | |
1490 | /* | |
1491 | * the workload slice is computed as a fraction of target latency | |
1492 | * proportional to the number of queues in that workload, over | |
1493 | * all the queues in the same priority class | |
1494 | */ | |
1495 | slice = cfq_target_latency * count / | |
1496 | max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio], | |
1497 | cfq_busy_queues_wl(cfqd->serving_prio, cfqd)); | |
1498 | ||
1499 | if (cfqd->serving_type == ASYNC_WORKLOAD) | |
1500 | /* async workload slice is scaled down according to | |
1501 | * the sync/async slice ratio. */ | |
1502 | slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; | |
1503 | else | |
1504 | /* sync workload slice is at least 2 * cfq_slice_idle */ | |
1505 | slice = max(slice, 2 * cfqd->cfq_slice_idle); | |
1506 | ||
1507 | slice = max_t(unsigned, slice, CFQ_MIN_TT); | |
1508 | cfqd->workload_expires = jiffies + slice; | |
8e550632 | 1509 | cfqd->noidle_tree_requires_idle = false; |
718eee05 CZ |
1510 | } |
1511 | ||
cdb16e8f VG |
1512 | static void cfq_choose_cfqg(struct cfq_data *cfqd) |
1513 | { | |
1514 | cfqd->serving_group = &cfqd->root_group; | |
1515 | choose_service_tree(cfqd, &cfqd->root_group); | |
1516 | } | |
1517 | ||
22e2c507 | 1518 | /* |
498d3aa2 JA |
1519 | * Select a queue for service. If we have a current active queue, |
1520 | * check whether to continue servicing it, or retrieve and set a new one. | |
22e2c507 | 1521 | */ |
1b5ed5e1 | 1522 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1523 | { |
a36e71f9 | 1524 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
1da177e4 | 1525 | |
22e2c507 JA |
1526 | cfqq = cfqd->active_queue; |
1527 | if (!cfqq) | |
1528 | goto new_queue; | |
1da177e4 | 1529 | |
22e2c507 | 1530 | /* |
6d048f53 | 1531 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 1532 | */ |
b029195d | 1533 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) |
3b18152c | 1534 | goto expire; |
1da177e4 | 1535 | |
22e2c507 | 1536 | /* |
6d048f53 JA |
1537 | * The active queue has requests and isn't expired, allow it to |
1538 | * dispatch. | |
22e2c507 | 1539 | */ |
dd67d051 | 1540 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 1541 | goto keep_queue; |
6d048f53 | 1542 | |
a36e71f9 JA |
1543 | /* |
1544 | * If another queue has a request waiting within our mean seek | |
1545 | * distance, let it run. The expire code will check for close | |
1546 | * cooperators and put the close queue at the front of the service | |
df5fe3e8 | 1547 | * tree. If possible, merge the expiring queue with the new cfqq. |
a36e71f9 | 1548 | */ |
b3b6d040 | 1549 | new_cfqq = cfq_close_cooperator(cfqd, cfqq); |
df5fe3e8 JM |
1550 | if (new_cfqq) { |
1551 | if (!cfqq->new_cfqq) | |
1552 | cfq_setup_merge(cfqq, new_cfqq); | |
a36e71f9 | 1553 | goto expire; |
df5fe3e8 | 1554 | } |
a36e71f9 | 1555 | |
6d048f53 JA |
1556 | /* |
1557 | * No requests pending. If the active queue still has requests in | |
1558 | * flight or is idling for a new request, allow either of these | |
1559 | * conditions to happen (or time out) before selecting a new queue. | |
1560 | */ | |
cc197479 | 1561 | if (timer_pending(&cfqd->idle_slice_timer) || |
a6d44e98 | 1562 | (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) { |
caaa5f9f JA |
1563 | cfqq = NULL; |
1564 | goto keep_queue; | |
22e2c507 JA |
1565 | } |
1566 | ||
3b18152c | 1567 | expire: |
6084cdda | 1568 | cfq_slice_expired(cfqd, 0); |
3b18152c | 1569 | new_queue: |
718eee05 CZ |
1570 | /* |
1571 | * Current queue expired. Check if we have to switch to a new | |
1572 | * service tree | |
1573 | */ | |
1574 | if (!new_cfqq) | |
cdb16e8f | 1575 | cfq_choose_cfqg(cfqd); |
718eee05 | 1576 | |
a36e71f9 | 1577 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
22e2c507 | 1578 | keep_queue: |
3b18152c | 1579 | return cfqq; |
22e2c507 JA |
1580 | } |
1581 | ||
febffd61 | 1582 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
d9e7620e JA |
1583 | { |
1584 | int dispatched = 0; | |
1585 | ||
1586 | while (cfqq->next_rq) { | |
1587 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1588 | dispatched++; | |
1589 | } | |
1590 | ||
1591 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1592 | return dispatched; | |
1593 | } | |
1594 | ||
498d3aa2 JA |
1595 | /* |
1596 | * Drain our current requests. Used for barriers and when switching | |
1597 | * io schedulers on-the-fly. | |
1598 | */ | |
d9e7620e | 1599 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1600 | { |
0871714e | 1601 | struct cfq_queue *cfqq; |
d9e7620e | 1602 | int dispatched = 0; |
718eee05 | 1603 | int i, j; |
cdb16e8f | 1604 | struct cfq_group *cfqg = &cfqd->root_group; |
615f0259 | 1605 | struct cfq_rb_root *st; |
cdb16e8f | 1606 | |
615f0259 VG |
1607 | for_each_cfqg_st(cfqg, i, j, st) { |
1608 | while ((cfqq = cfq_rb_first(st)) != NULL) | |
1609 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); | |
1610 | } | |
1b5ed5e1 | 1611 | |
6084cdda | 1612 | cfq_slice_expired(cfqd, 0); |
1b5ed5e1 TH |
1613 | BUG_ON(cfqd->busy_queues); |
1614 | ||
6923715a | 1615 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
1b5ed5e1 TH |
1616 | return dispatched; |
1617 | } | |
1618 | ||
0b182d61 | 1619 | static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2f5cb738 | 1620 | { |
2f5cb738 | 1621 | unsigned int max_dispatch; |
22e2c507 | 1622 | |
5ad531db JA |
1623 | /* |
1624 | * Drain async requests before we start sync IO | |
1625 | */ | |
a6d44e98 | 1626 | if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) |
0b182d61 | 1627 | return false; |
5ad531db | 1628 | |
2f5cb738 JA |
1629 | /* |
1630 | * If this is an async queue and we have sync IO in flight, let it wait | |
1631 | */ | |
1632 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) | |
0b182d61 | 1633 | return false; |
2f5cb738 JA |
1634 | |
1635 | max_dispatch = cfqd->cfq_quantum; | |
1636 | if (cfq_class_idle(cfqq)) | |
1637 | max_dispatch = 1; | |
b4878f24 | 1638 | |
2f5cb738 JA |
1639 | /* |
1640 | * Does this cfqq already have too much IO in flight? | |
1641 | */ | |
1642 | if (cfqq->dispatched >= max_dispatch) { | |
1643 | /* | |
1644 | * idle queue must always only have a single IO in flight | |
1645 | */ | |
3ed9a296 | 1646 | if (cfq_class_idle(cfqq)) |
0b182d61 | 1647 | return false; |
3ed9a296 | 1648 | |
2f5cb738 JA |
1649 | /* |
1650 | * We have other queues, don't allow more IO from this one | |
1651 | */ | |
1652 | if (cfqd->busy_queues > 1) | |
0b182d61 | 1653 | return false; |
9ede209e | 1654 | |
365722bb | 1655 | /* |
474b18cc | 1656 | * Sole queue user, no limit |
365722bb | 1657 | */ |
474b18cc | 1658 | max_dispatch = -1; |
8e296755 JA |
1659 | } |
1660 | ||
1661 | /* | |
1662 | * Async queues must wait a bit before being allowed dispatch. | |
1663 | * We also ramp up the dispatch depth gradually for async IO, | |
1664 | * based on the last sync IO we serviced | |
1665 | */ | |
963b72fc | 1666 | if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
8e296755 JA |
1667 | unsigned long last_sync = jiffies - cfqd->last_end_sync_rq; |
1668 | unsigned int depth; | |
365722bb | 1669 | |
61f0c1dc | 1670 | depth = last_sync / cfqd->cfq_slice[1]; |
e00c54c3 JA |
1671 | if (!depth && !cfqq->dispatched) |
1672 | depth = 1; | |
8e296755 JA |
1673 | if (depth < max_dispatch) |
1674 | max_dispatch = depth; | |
2f5cb738 | 1675 | } |
3ed9a296 | 1676 | |
0b182d61 JA |
1677 | /* |
1678 | * If we're below the current max, allow a dispatch | |
1679 | */ | |
1680 | return cfqq->dispatched < max_dispatch; | |
1681 | } | |
1682 | ||
1683 | /* | |
1684 | * Dispatch a request from cfqq, moving them to the request queue | |
1685 | * dispatch list. | |
1686 | */ | |
1687 | static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1688 | { | |
1689 | struct request *rq; | |
1690 | ||
1691 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); | |
1692 | ||
1693 | if (!cfq_may_dispatch(cfqd, cfqq)) | |
1694 | return false; | |
1695 | ||
1696 | /* | |
1697 | * follow expired path, else get first next available | |
1698 | */ | |
1699 | rq = cfq_check_fifo(cfqq); | |
1700 | if (!rq) | |
1701 | rq = cfqq->next_rq; | |
1702 | ||
1703 | /* | |
1704 | * insert request into driver dispatch list | |
1705 | */ | |
1706 | cfq_dispatch_insert(cfqd->queue, rq); | |
1707 | ||
1708 | if (!cfqd->active_cic) { | |
1709 | struct cfq_io_context *cic = RQ_CIC(rq); | |
1710 | ||
1711 | atomic_long_inc(&cic->ioc->refcount); | |
1712 | cfqd->active_cic = cic; | |
1713 | } | |
1714 | ||
1715 | return true; | |
1716 | } | |
1717 | ||
1718 | /* | |
1719 | * Find the cfqq that we need to service and move a request from that to the | |
1720 | * dispatch list | |
1721 | */ | |
1722 | static int cfq_dispatch_requests(struct request_queue *q, int force) | |
1723 | { | |
1724 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1725 | struct cfq_queue *cfqq; | |
1726 | ||
1727 | if (!cfqd->busy_queues) | |
1728 | return 0; | |
1729 | ||
1730 | if (unlikely(force)) | |
1731 | return cfq_forced_dispatch(cfqd); | |
1732 | ||
1733 | cfqq = cfq_select_queue(cfqd); | |
1734 | if (!cfqq) | |
8e296755 JA |
1735 | return 0; |
1736 | ||
2f5cb738 | 1737 | /* |
0b182d61 | 1738 | * Dispatch a request from this cfqq, if it is allowed |
2f5cb738 | 1739 | */ |
0b182d61 JA |
1740 | if (!cfq_dispatch_request(cfqd, cfqq)) |
1741 | return 0; | |
1742 | ||
2f5cb738 | 1743 | cfqq->slice_dispatch++; |
b029195d | 1744 | cfq_clear_cfqq_must_dispatch(cfqq); |
22e2c507 | 1745 | |
2f5cb738 JA |
1746 | /* |
1747 | * expire an async queue immediately if it has used up its slice. idle | |
1748 | * queue always expire after 1 dispatch round. | |
1749 | */ | |
1750 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && | |
1751 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1752 | cfq_class_idle(cfqq))) { | |
1753 | cfqq->slice_end = jiffies + 1; | |
1754 | cfq_slice_expired(cfqd, 0); | |
1da177e4 LT |
1755 | } |
1756 | ||
b217a903 | 1757 | cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
2f5cb738 | 1758 | return 1; |
1da177e4 LT |
1759 | } |
1760 | ||
1da177e4 | 1761 | /* |
5e705374 JA |
1762 | * task holds one reference to the queue, dropped when task exits. each rq |
1763 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1764 | * |
1765 | * queue lock must be held here. | |
1766 | */ | |
1767 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1768 | { | |
22e2c507 JA |
1769 | struct cfq_data *cfqd = cfqq->cfqd; |
1770 | ||
1771 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1772 | |
1773 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1774 | return; | |
1775 | ||
7b679138 | 1776 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
1da177e4 | 1777 | BUG_ON(rb_first(&cfqq->sort_list)); |
22e2c507 | 1778 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1779 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1780 | |
28f95cbc | 1781 | if (unlikely(cfqd->active_queue == cfqq)) { |
6084cdda | 1782 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1783 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1784 | } |
22e2c507 | 1785 | |
1da177e4 LT |
1786 | kmem_cache_free(cfq_pool, cfqq); |
1787 | } | |
1788 | ||
d6de8be7 JA |
1789 | /* |
1790 | * Must always be called with the rcu_read_lock() held | |
1791 | */ | |
07416d29 JA |
1792 | static void |
1793 | __call_for_each_cic(struct io_context *ioc, | |
1794 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1795 | { | |
1796 | struct cfq_io_context *cic; | |
1797 | struct hlist_node *n; | |
1798 | ||
1799 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) | |
1800 | func(ioc, cic); | |
1801 | } | |
1802 | ||
4ac845a2 | 1803 | /* |
34e6bbf2 | 1804 | * Call func for each cic attached to this ioc. |
4ac845a2 | 1805 | */ |
34e6bbf2 | 1806 | static void |
4ac845a2 JA |
1807 | call_for_each_cic(struct io_context *ioc, |
1808 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1da177e4 | 1809 | { |
4ac845a2 | 1810 | rcu_read_lock(); |
07416d29 | 1811 | __call_for_each_cic(ioc, func); |
4ac845a2 | 1812 | rcu_read_unlock(); |
34e6bbf2 FC |
1813 | } |
1814 | ||
1815 | static void cfq_cic_free_rcu(struct rcu_head *head) | |
1816 | { | |
1817 | struct cfq_io_context *cic; | |
1818 | ||
1819 | cic = container_of(head, struct cfq_io_context, rcu_head); | |
1820 | ||
1821 | kmem_cache_free(cfq_ioc_pool, cic); | |
245b2e70 | 1822 | elv_ioc_count_dec(cfq_ioc_count); |
34e6bbf2 | 1823 | |
9a11b4ed JA |
1824 | if (ioc_gone) { |
1825 | /* | |
1826 | * CFQ scheduler is exiting, grab exit lock and check | |
1827 | * the pending io context count. If it hits zero, | |
1828 | * complete ioc_gone and set it back to NULL | |
1829 | */ | |
1830 | spin_lock(&ioc_gone_lock); | |
245b2e70 | 1831 | if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { |
9a11b4ed JA |
1832 | complete(ioc_gone); |
1833 | ioc_gone = NULL; | |
1834 | } | |
1835 | spin_unlock(&ioc_gone_lock); | |
1836 | } | |
34e6bbf2 | 1837 | } |
4ac845a2 | 1838 | |
34e6bbf2 FC |
1839 | static void cfq_cic_free(struct cfq_io_context *cic) |
1840 | { | |
1841 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); | |
4ac845a2 JA |
1842 | } |
1843 | ||
1844 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) | |
1845 | { | |
1846 | unsigned long flags; | |
1847 | ||
1848 | BUG_ON(!cic->dead_key); | |
1849 | ||
1850 | spin_lock_irqsave(&ioc->lock, flags); | |
1851 | radix_tree_delete(&ioc->radix_root, cic->dead_key); | |
ffc4e759 | 1852 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
1853 | spin_unlock_irqrestore(&ioc->lock, flags); |
1854 | ||
34e6bbf2 | 1855 | cfq_cic_free(cic); |
4ac845a2 JA |
1856 | } |
1857 | ||
d6de8be7 JA |
1858 | /* |
1859 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. | |
1860 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), | |
1861 | * and ->trim() which is called with the task lock held | |
1862 | */ | |
4ac845a2 JA |
1863 | static void cfq_free_io_context(struct io_context *ioc) |
1864 | { | |
4ac845a2 | 1865 | /* |
34e6bbf2 FC |
1866 | * ioc->refcount is zero here, or we are called from elv_unregister(), |
1867 | * so no more cic's are allowed to be linked into this ioc. So it | |
1868 | * should be ok to iterate over the known list, we will see all cic's | |
1869 | * since no new ones are added. | |
4ac845a2 | 1870 | */ |
07416d29 | 1871 | __call_for_each_cic(ioc, cic_free_func); |
1da177e4 LT |
1872 | } |
1873 | ||
89850f7e | 1874 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1875 | { |
df5fe3e8 JM |
1876 | struct cfq_queue *__cfqq, *next; |
1877 | ||
28f95cbc | 1878 | if (unlikely(cfqq == cfqd->active_queue)) { |
6084cdda | 1879 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1880 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1881 | } |
22e2c507 | 1882 | |
df5fe3e8 JM |
1883 | /* |
1884 | * If this queue was scheduled to merge with another queue, be | |
1885 | * sure to drop the reference taken on that queue (and others in | |
1886 | * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. | |
1887 | */ | |
1888 | __cfqq = cfqq->new_cfqq; | |
1889 | while (__cfqq) { | |
1890 | if (__cfqq == cfqq) { | |
1891 | WARN(1, "cfqq->new_cfqq loop detected\n"); | |
1892 | break; | |
1893 | } | |
1894 | next = __cfqq->new_cfqq; | |
1895 | cfq_put_queue(__cfqq); | |
1896 | __cfqq = next; | |
1897 | } | |
1898 | ||
89850f7e JA |
1899 | cfq_put_queue(cfqq); |
1900 | } | |
22e2c507 | 1901 | |
89850f7e JA |
1902 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1903 | struct cfq_io_context *cic) | |
1904 | { | |
4faa3c81 FC |
1905 | struct io_context *ioc = cic->ioc; |
1906 | ||
fc46379d | 1907 | list_del_init(&cic->queue_list); |
4ac845a2 JA |
1908 | |
1909 | /* | |
1910 | * Make sure key == NULL is seen for dead queues | |
1911 | */ | |
fc46379d | 1912 | smp_wmb(); |
4ac845a2 | 1913 | cic->dead_key = (unsigned long) cic->key; |
fc46379d JA |
1914 | cic->key = NULL; |
1915 | ||
4faa3c81 FC |
1916 | if (ioc->ioc_data == cic) |
1917 | rcu_assign_pointer(ioc->ioc_data, NULL); | |
1918 | ||
ff6657c6 JA |
1919 | if (cic->cfqq[BLK_RW_ASYNC]) { |
1920 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); | |
1921 | cic->cfqq[BLK_RW_ASYNC] = NULL; | |
12a05732 AV |
1922 | } |
1923 | ||
ff6657c6 JA |
1924 | if (cic->cfqq[BLK_RW_SYNC]) { |
1925 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); | |
1926 | cic->cfqq[BLK_RW_SYNC] = NULL; | |
12a05732 | 1927 | } |
89850f7e JA |
1928 | } |
1929 | ||
4ac845a2 JA |
1930 | static void cfq_exit_single_io_context(struct io_context *ioc, |
1931 | struct cfq_io_context *cic) | |
89850f7e JA |
1932 | { |
1933 | struct cfq_data *cfqd = cic->key; | |
1934 | ||
89850f7e | 1935 | if (cfqd) { |
165125e1 | 1936 | struct request_queue *q = cfqd->queue; |
4ac845a2 | 1937 | unsigned long flags; |
89850f7e | 1938 | |
4ac845a2 | 1939 | spin_lock_irqsave(q->queue_lock, flags); |
62c1fe9d JA |
1940 | |
1941 | /* | |
1942 | * Ensure we get a fresh copy of the ->key to prevent | |
1943 | * race between exiting task and queue | |
1944 | */ | |
1945 | smp_read_barrier_depends(); | |
1946 | if (cic->key) | |
1947 | __cfq_exit_single_io_context(cfqd, cic); | |
1948 | ||
4ac845a2 | 1949 | spin_unlock_irqrestore(q->queue_lock, flags); |
89850f7e | 1950 | } |
1da177e4 LT |
1951 | } |
1952 | ||
498d3aa2 JA |
1953 | /* |
1954 | * The process that ioc belongs to has exited, we need to clean up | |
1955 | * and put the internal structures we have that belongs to that process. | |
1956 | */ | |
e2d74ac0 | 1957 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1958 | { |
4ac845a2 | 1959 | call_for_each_cic(ioc, cfq_exit_single_io_context); |
1da177e4 LT |
1960 | } |
1961 | ||
22e2c507 | 1962 | static struct cfq_io_context * |
8267e268 | 1963 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1964 | { |
b5deef90 | 1965 | struct cfq_io_context *cic; |
1da177e4 | 1966 | |
94f6030c CL |
1967 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
1968 | cfqd->queue->node); | |
1da177e4 | 1969 | if (cic) { |
22e2c507 | 1970 | cic->last_end_request = jiffies; |
553698f9 | 1971 | INIT_LIST_HEAD(&cic->queue_list); |
ffc4e759 | 1972 | INIT_HLIST_NODE(&cic->cic_list); |
22e2c507 JA |
1973 | cic->dtor = cfq_free_io_context; |
1974 | cic->exit = cfq_exit_io_context; | |
245b2e70 | 1975 | elv_ioc_count_inc(cfq_ioc_count); |
1da177e4 LT |
1976 | } |
1977 | ||
1978 | return cic; | |
1979 | } | |
1980 | ||
fd0928df | 1981 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
22e2c507 JA |
1982 | { |
1983 | struct task_struct *tsk = current; | |
1984 | int ioprio_class; | |
1985 | ||
3b18152c | 1986 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1987 | return; |
1988 | ||
fd0928df | 1989 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
22e2c507 | 1990 | switch (ioprio_class) { |
fe094d98 JA |
1991 | default: |
1992 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1993 | case IOPRIO_CLASS_NONE: | |
1994 | /* | |
6d63c275 | 1995 | * no prio set, inherit CPU scheduling settings |
fe094d98 JA |
1996 | */ |
1997 | cfqq->ioprio = task_nice_ioprio(tsk); | |
6d63c275 | 1998 | cfqq->ioprio_class = task_nice_ioclass(tsk); |
fe094d98 JA |
1999 | break; |
2000 | case IOPRIO_CLASS_RT: | |
2001 | cfqq->ioprio = task_ioprio(ioc); | |
2002 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
2003 | break; | |
2004 | case IOPRIO_CLASS_BE: | |
2005 | cfqq->ioprio = task_ioprio(ioc); | |
2006 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
2007 | break; | |
2008 | case IOPRIO_CLASS_IDLE: | |
2009 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
2010 | cfqq->ioprio = 7; | |
2011 | cfq_clear_cfqq_idle_window(cfqq); | |
2012 | break; | |
22e2c507 JA |
2013 | } |
2014 | ||
2015 | /* | |
2016 | * keep track of original prio settings in case we have to temporarily | |
2017 | * elevate the priority of this queue | |
2018 | */ | |
2019 | cfqq->org_ioprio = cfqq->ioprio; | |
2020 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 2021 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
2022 | } |
2023 | ||
febffd61 | 2024 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
22e2c507 | 2025 | { |
478a82b0 AV |
2026 | struct cfq_data *cfqd = cic->key; |
2027 | struct cfq_queue *cfqq; | |
c1b707d2 | 2028 | unsigned long flags; |
35e6077c | 2029 | |
caaa5f9f JA |
2030 | if (unlikely(!cfqd)) |
2031 | return; | |
2032 | ||
c1b707d2 | 2033 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f | 2034 | |
ff6657c6 | 2035 | cfqq = cic->cfqq[BLK_RW_ASYNC]; |
caaa5f9f JA |
2036 | if (cfqq) { |
2037 | struct cfq_queue *new_cfqq; | |
ff6657c6 JA |
2038 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
2039 | GFP_ATOMIC); | |
caaa5f9f | 2040 | if (new_cfqq) { |
ff6657c6 | 2041 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
caaa5f9f JA |
2042 | cfq_put_queue(cfqq); |
2043 | } | |
22e2c507 | 2044 | } |
caaa5f9f | 2045 | |
ff6657c6 | 2046 | cfqq = cic->cfqq[BLK_RW_SYNC]; |
caaa5f9f JA |
2047 | if (cfqq) |
2048 | cfq_mark_cfqq_prio_changed(cfqq); | |
2049 | ||
c1b707d2 | 2050 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
2051 | } |
2052 | ||
fc46379d | 2053 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 2054 | { |
4ac845a2 | 2055 | call_for_each_cic(ioc, changed_ioprio); |
fc46379d | 2056 | ioc->ioprio_changed = 0; |
22e2c507 JA |
2057 | } |
2058 | ||
d5036d77 | 2059 | static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 2060 | pid_t pid, bool is_sync) |
d5036d77 JA |
2061 | { |
2062 | RB_CLEAR_NODE(&cfqq->rb_node); | |
2063 | RB_CLEAR_NODE(&cfqq->p_node); | |
2064 | INIT_LIST_HEAD(&cfqq->fifo); | |
2065 | ||
2066 | atomic_set(&cfqq->ref, 0); | |
2067 | cfqq->cfqd = cfqd; | |
2068 | ||
2069 | cfq_mark_cfqq_prio_changed(cfqq); | |
2070 | ||
2071 | if (is_sync) { | |
2072 | if (!cfq_class_idle(cfqq)) | |
2073 | cfq_mark_cfqq_idle_window(cfqq); | |
2074 | cfq_mark_cfqq_sync(cfqq); | |
2075 | } | |
2076 | cfqq->pid = pid; | |
2077 | } | |
2078 | ||
cdb16e8f VG |
2079 | static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) |
2080 | { | |
2081 | cfqq->cfqg = cfqg; | |
2082 | } | |
2083 | ||
2084 | static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create) | |
2085 | { | |
2086 | return &cfqd->root_group; | |
2087 | } | |
2088 | ||
22e2c507 | 2089 | static struct cfq_queue * |
a6151c3a | 2090 | cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, |
fd0928df | 2091 | struct io_context *ioc, gfp_t gfp_mask) |
22e2c507 | 2092 | { |
22e2c507 | 2093 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
91fac317 | 2094 | struct cfq_io_context *cic; |
cdb16e8f | 2095 | struct cfq_group *cfqg; |
22e2c507 JA |
2096 | |
2097 | retry: | |
cdb16e8f | 2098 | cfqg = cfq_get_cfqg(cfqd, 1); |
4ac845a2 | 2099 | cic = cfq_cic_lookup(cfqd, ioc); |
91fac317 VT |
2100 | /* cic always exists here */ |
2101 | cfqq = cic_to_cfqq(cic, is_sync); | |
22e2c507 | 2102 | |
6118b70b JA |
2103 | /* |
2104 | * Always try a new alloc if we fell back to the OOM cfqq | |
2105 | * originally, since it should just be a temporary situation. | |
2106 | */ | |
2107 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { | |
2108 | cfqq = NULL; | |
22e2c507 JA |
2109 | if (new_cfqq) { |
2110 | cfqq = new_cfqq; | |
2111 | new_cfqq = NULL; | |
2112 | } else if (gfp_mask & __GFP_WAIT) { | |
2113 | spin_unlock_irq(cfqd->queue->queue_lock); | |
94f6030c | 2114 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
6118b70b | 2115 | gfp_mask | __GFP_ZERO, |
94f6030c | 2116 | cfqd->queue->node); |
22e2c507 | 2117 | spin_lock_irq(cfqd->queue->queue_lock); |
6118b70b JA |
2118 | if (new_cfqq) |
2119 | goto retry; | |
22e2c507 | 2120 | } else { |
94f6030c CL |
2121 | cfqq = kmem_cache_alloc_node(cfq_pool, |
2122 | gfp_mask | __GFP_ZERO, | |
2123 | cfqd->queue->node); | |
22e2c507 JA |
2124 | } |
2125 | ||
6118b70b JA |
2126 | if (cfqq) { |
2127 | cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); | |
2128 | cfq_init_prio_data(cfqq, ioc); | |
cdb16e8f | 2129 | cfq_link_cfqq_cfqg(cfqq, cfqg); |
6118b70b JA |
2130 | cfq_log_cfqq(cfqd, cfqq, "alloced"); |
2131 | } else | |
2132 | cfqq = &cfqd->oom_cfqq; | |
22e2c507 JA |
2133 | } |
2134 | ||
2135 | if (new_cfqq) | |
2136 | kmem_cache_free(cfq_pool, new_cfqq); | |
2137 | ||
22e2c507 JA |
2138 | return cfqq; |
2139 | } | |
2140 | ||
c2dea2d1 VT |
2141 | static struct cfq_queue ** |
2142 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
2143 | { | |
fe094d98 | 2144 | switch (ioprio_class) { |
c2dea2d1 VT |
2145 | case IOPRIO_CLASS_RT: |
2146 | return &cfqd->async_cfqq[0][ioprio]; | |
2147 | case IOPRIO_CLASS_BE: | |
2148 | return &cfqd->async_cfqq[1][ioprio]; | |
2149 | case IOPRIO_CLASS_IDLE: | |
2150 | return &cfqd->async_idle_cfqq; | |
2151 | default: | |
2152 | BUG(); | |
2153 | } | |
2154 | } | |
2155 | ||
15c31be4 | 2156 | static struct cfq_queue * |
a6151c3a | 2157 | cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, |
15c31be4 JA |
2158 | gfp_t gfp_mask) |
2159 | { | |
fd0928df JA |
2160 | const int ioprio = task_ioprio(ioc); |
2161 | const int ioprio_class = task_ioprio_class(ioc); | |
c2dea2d1 | 2162 | struct cfq_queue **async_cfqq = NULL; |
15c31be4 JA |
2163 | struct cfq_queue *cfqq = NULL; |
2164 | ||
c2dea2d1 VT |
2165 | if (!is_sync) { |
2166 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
2167 | cfqq = *async_cfqq; | |
2168 | } | |
2169 | ||
6118b70b | 2170 | if (!cfqq) |
fd0928df | 2171 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
15c31be4 JA |
2172 | |
2173 | /* | |
2174 | * pin the queue now that it's allocated, scheduler exit will prune it | |
2175 | */ | |
c2dea2d1 | 2176 | if (!is_sync && !(*async_cfqq)) { |
15c31be4 | 2177 | atomic_inc(&cfqq->ref); |
c2dea2d1 | 2178 | *async_cfqq = cfqq; |
15c31be4 JA |
2179 | } |
2180 | ||
2181 | atomic_inc(&cfqq->ref); | |
2182 | return cfqq; | |
2183 | } | |
2184 | ||
498d3aa2 JA |
2185 | /* |
2186 | * We drop cfq io contexts lazily, so we may find a dead one. | |
2187 | */ | |
dbecf3ab | 2188 | static void |
4ac845a2 JA |
2189 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
2190 | struct cfq_io_context *cic) | |
dbecf3ab | 2191 | { |
4ac845a2 JA |
2192 | unsigned long flags; |
2193 | ||
fc46379d | 2194 | WARN_ON(!list_empty(&cic->queue_list)); |
597bc485 | 2195 | |
4ac845a2 JA |
2196 | spin_lock_irqsave(&ioc->lock, flags); |
2197 | ||
4faa3c81 | 2198 | BUG_ON(ioc->ioc_data == cic); |
597bc485 | 2199 | |
4ac845a2 | 2200 | radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
ffc4e759 | 2201 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
2202 | spin_unlock_irqrestore(&ioc->lock, flags); |
2203 | ||
2204 | cfq_cic_free(cic); | |
dbecf3ab OH |
2205 | } |
2206 | ||
e2d74ac0 | 2207 | static struct cfq_io_context * |
4ac845a2 | 2208 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
e2d74ac0 | 2209 | { |
e2d74ac0 | 2210 | struct cfq_io_context *cic; |
d6de8be7 | 2211 | unsigned long flags; |
4ac845a2 | 2212 | void *k; |
e2d74ac0 | 2213 | |
91fac317 VT |
2214 | if (unlikely(!ioc)) |
2215 | return NULL; | |
2216 | ||
d6de8be7 JA |
2217 | rcu_read_lock(); |
2218 | ||
597bc485 JA |
2219 | /* |
2220 | * we maintain a last-hit cache, to avoid browsing over the tree | |
2221 | */ | |
4ac845a2 | 2222 | cic = rcu_dereference(ioc->ioc_data); |
d6de8be7 JA |
2223 | if (cic && cic->key == cfqd) { |
2224 | rcu_read_unlock(); | |
597bc485 | 2225 | return cic; |
d6de8be7 | 2226 | } |
597bc485 | 2227 | |
4ac845a2 | 2228 | do { |
4ac845a2 JA |
2229 | cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); |
2230 | rcu_read_unlock(); | |
2231 | if (!cic) | |
2232 | break; | |
be3b0753 OH |
2233 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
2234 | k = cic->key; | |
2235 | if (unlikely(!k)) { | |
4ac845a2 | 2236 | cfq_drop_dead_cic(cfqd, ioc, cic); |
d6de8be7 | 2237 | rcu_read_lock(); |
4ac845a2 | 2238 | continue; |
dbecf3ab | 2239 | } |
e2d74ac0 | 2240 | |
d6de8be7 | 2241 | spin_lock_irqsave(&ioc->lock, flags); |
4ac845a2 | 2242 | rcu_assign_pointer(ioc->ioc_data, cic); |
d6de8be7 | 2243 | spin_unlock_irqrestore(&ioc->lock, flags); |
4ac845a2 JA |
2244 | break; |
2245 | } while (1); | |
e2d74ac0 | 2246 | |
4ac845a2 | 2247 | return cic; |
e2d74ac0 JA |
2248 | } |
2249 | ||
4ac845a2 JA |
2250 | /* |
2251 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup | |
2252 | * the process specific cfq io context when entered from the block layer. | |
2253 | * Also adds the cic to a per-cfqd list, used when this queue is removed. | |
2254 | */ | |
febffd61 JA |
2255 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
2256 | struct cfq_io_context *cic, gfp_t gfp_mask) | |
e2d74ac0 | 2257 | { |
0261d688 | 2258 | unsigned long flags; |
4ac845a2 | 2259 | int ret; |
e2d74ac0 | 2260 | |
4ac845a2 JA |
2261 | ret = radix_tree_preload(gfp_mask); |
2262 | if (!ret) { | |
2263 | cic->ioc = ioc; | |
2264 | cic->key = cfqd; | |
e2d74ac0 | 2265 | |
4ac845a2 JA |
2266 | spin_lock_irqsave(&ioc->lock, flags); |
2267 | ret = radix_tree_insert(&ioc->radix_root, | |
2268 | (unsigned long) cfqd, cic); | |
ffc4e759 JA |
2269 | if (!ret) |
2270 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); | |
4ac845a2 | 2271 | spin_unlock_irqrestore(&ioc->lock, flags); |
e2d74ac0 | 2272 | |
4ac845a2 JA |
2273 | radix_tree_preload_end(); |
2274 | ||
2275 | if (!ret) { | |
2276 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2277 | list_add(&cic->queue_list, &cfqd->cic_list); | |
2278 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2279 | } | |
e2d74ac0 JA |
2280 | } |
2281 | ||
4ac845a2 JA |
2282 | if (ret) |
2283 | printk(KERN_ERR "cfq: cic link failed!\n"); | |
fc46379d | 2284 | |
4ac845a2 | 2285 | return ret; |
e2d74ac0 JA |
2286 | } |
2287 | ||
1da177e4 LT |
2288 | /* |
2289 | * Setup general io context and cfq io context. There can be several cfq | |
2290 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 2291 | * than one device managed by cfq. |
1da177e4 LT |
2292 | */ |
2293 | static struct cfq_io_context * | |
e2d74ac0 | 2294 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 2295 | { |
22e2c507 | 2296 | struct io_context *ioc = NULL; |
1da177e4 | 2297 | struct cfq_io_context *cic; |
1da177e4 | 2298 | |
22e2c507 | 2299 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 2300 | |
b5deef90 | 2301 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
2302 | if (!ioc) |
2303 | return NULL; | |
2304 | ||
4ac845a2 | 2305 | cic = cfq_cic_lookup(cfqd, ioc); |
e2d74ac0 JA |
2306 | if (cic) |
2307 | goto out; | |
1da177e4 | 2308 | |
e2d74ac0 JA |
2309 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
2310 | if (cic == NULL) | |
2311 | goto err; | |
1da177e4 | 2312 | |
4ac845a2 JA |
2313 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
2314 | goto err_free; | |
2315 | ||
1da177e4 | 2316 | out: |
fc46379d JA |
2317 | smp_read_barrier_depends(); |
2318 | if (unlikely(ioc->ioprio_changed)) | |
2319 | cfq_ioc_set_ioprio(ioc); | |
2320 | ||
1da177e4 | 2321 | return cic; |
4ac845a2 JA |
2322 | err_free: |
2323 | cfq_cic_free(cic); | |
1da177e4 LT |
2324 | err: |
2325 | put_io_context(ioc); | |
2326 | return NULL; | |
2327 | } | |
2328 | ||
22e2c507 JA |
2329 | static void |
2330 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 2331 | { |
aaf1228d JA |
2332 | unsigned long elapsed = jiffies - cic->last_end_request; |
2333 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 2334 | |
22e2c507 JA |
2335 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
2336 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
2337 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
2338 | } | |
1da177e4 | 2339 | |
206dc69b | 2340 | static void |
b2c18e1e | 2341 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
6d048f53 | 2342 | struct request *rq) |
206dc69b JA |
2343 | { |
2344 | sector_t sdist; | |
2345 | u64 total; | |
2346 | ||
b2c18e1e | 2347 | if (!cfqq->last_request_pos) |
4d00aa47 | 2348 | sdist = 0; |
b2c18e1e JM |
2349 | else if (cfqq->last_request_pos < blk_rq_pos(rq)) |
2350 | sdist = blk_rq_pos(rq) - cfqq->last_request_pos; | |
206dc69b | 2351 | else |
b2c18e1e | 2352 | sdist = cfqq->last_request_pos - blk_rq_pos(rq); |
206dc69b JA |
2353 | |
2354 | /* | |
2355 | * Don't allow the seek distance to get too large from the | |
2356 | * odd fragment, pagein, etc | |
2357 | */ | |
b2c18e1e JM |
2358 | if (cfqq->seek_samples <= 60) /* second&third seek */ |
2359 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024); | |
206dc69b | 2360 | else |
b2c18e1e | 2361 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64); |
206dc69b | 2362 | |
b2c18e1e JM |
2363 | cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8; |
2364 | cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8; | |
2365 | total = cfqq->seek_total + (cfqq->seek_samples/2); | |
2366 | do_div(total, cfqq->seek_samples); | |
2367 | cfqq->seek_mean = (sector_t)total; | |
e6c5bc73 JM |
2368 | |
2369 | /* | |
2370 | * If this cfqq is shared between multiple processes, check to | |
2371 | * make sure that those processes are still issuing I/Os within | |
2372 | * the mean seek distance. If not, it may be time to break the | |
2373 | * queues apart again. | |
2374 | */ | |
2375 | if (cfq_cfqq_coop(cfqq)) { | |
2376 | if (CFQQ_SEEKY(cfqq) && !cfqq->seeky_start) | |
2377 | cfqq->seeky_start = jiffies; | |
2378 | else if (!CFQQ_SEEKY(cfqq)) | |
2379 | cfqq->seeky_start = 0; | |
2380 | } | |
206dc69b | 2381 | } |
1da177e4 | 2382 | |
22e2c507 JA |
2383 | /* |
2384 | * Disable idle window if the process thinks too long or seeks so much that | |
2385 | * it doesn't matter | |
2386 | */ | |
2387 | static void | |
2388 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
2389 | struct cfq_io_context *cic) | |
2390 | { | |
7b679138 | 2391 | int old_idle, enable_idle; |
1be92f2f | 2392 | |
0871714e JA |
2393 | /* |
2394 | * Don't idle for async or idle io prio class | |
2395 | */ | |
2396 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) | |
1be92f2f JA |
2397 | return; |
2398 | ||
c265a7f4 | 2399 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 2400 | |
76280aff CZ |
2401 | if (cfqq->queued[0] + cfqq->queued[1] >= 4) |
2402 | cfq_mark_cfqq_deep(cfqq); | |
2403 | ||
66dac98e | 2404 | if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
76280aff CZ |
2405 | (!cfq_cfqq_deep(cfqq) && sample_valid(cfqq->seek_samples) |
2406 | && CFQQ_SEEKY(cfqq))) | |
22e2c507 JA |
2407 | enable_idle = 0; |
2408 | else if (sample_valid(cic->ttime_samples)) { | |
718eee05 | 2409 | if (cic->ttime_mean > cfqd->cfq_slice_idle) |
22e2c507 JA |
2410 | enable_idle = 0; |
2411 | else | |
2412 | enable_idle = 1; | |
1da177e4 LT |
2413 | } |
2414 | ||
7b679138 JA |
2415 | if (old_idle != enable_idle) { |
2416 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); | |
2417 | if (enable_idle) | |
2418 | cfq_mark_cfqq_idle_window(cfqq); | |
2419 | else | |
2420 | cfq_clear_cfqq_idle_window(cfqq); | |
2421 | } | |
22e2c507 | 2422 | } |
1da177e4 | 2423 | |
22e2c507 JA |
2424 | /* |
2425 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
2426 | * no or if we aren't sure, a 1 will cause a preempt. | |
2427 | */ | |
a6151c3a | 2428 | static bool |
22e2c507 | 2429 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
5e705374 | 2430 | struct request *rq) |
22e2c507 | 2431 | { |
6d048f53 | 2432 | struct cfq_queue *cfqq; |
22e2c507 | 2433 | |
6d048f53 JA |
2434 | cfqq = cfqd->active_queue; |
2435 | if (!cfqq) | |
a6151c3a | 2436 | return false; |
22e2c507 | 2437 | |
6d048f53 | 2438 | if (cfq_slice_used(cfqq)) |
a6151c3a | 2439 | return true; |
6d048f53 JA |
2440 | |
2441 | if (cfq_class_idle(new_cfqq)) | |
a6151c3a | 2442 | return false; |
22e2c507 JA |
2443 | |
2444 | if (cfq_class_idle(cfqq)) | |
a6151c3a | 2445 | return true; |
1e3335de | 2446 | |
e4a22919 CZ |
2447 | if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && |
2448 | cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && | |
2449 | new_cfqq->service_tree->count == 1) | |
718eee05 CZ |
2450 | return true; |
2451 | ||
374f84ac JA |
2452 | /* |
2453 | * if the new request is sync, but the currently running queue is | |
2454 | * not, let the sync request have priority. | |
2455 | */ | |
5e705374 | 2456 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
a6151c3a | 2457 | return true; |
1e3335de | 2458 | |
374f84ac JA |
2459 | /* |
2460 | * So both queues are sync. Let the new request get disk time if | |
2461 | * it's a metadata request and the current queue is doing regular IO. | |
2462 | */ | |
2463 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
e6ec4fe2 | 2464 | return true; |
22e2c507 | 2465 | |
3a9a3f6c DS |
2466 | /* |
2467 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. | |
2468 | */ | |
2469 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) | |
a6151c3a | 2470 | return true; |
3a9a3f6c | 2471 | |
1e3335de | 2472 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
a6151c3a | 2473 | return false; |
1e3335de JA |
2474 | |
2475 | /* | |
2476 | * if this request is as-good as one we would expect from the | |
2477 | * current cfqq, let it preempt | |
2478 | */ | |
e00ef799 | 2479 | if (cfq_rq_close(cfqd, cfqq, rq)) |
a6151c3a | 2480 | return true; |
1e3335de | 2481 | |
a6151c3a | 2482 | return false; |
22e2c507 JA |
2483 | } |
2484 | ||
2485 | /* | |
2486 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
2487 | * let it have half of its nominal slice. | |
2488 | */ | |
2489 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2490 | { | |
7b679138 | 2491 | cfq_log_cfqq(cfqd, cfqq, "preempt"); |
6084cdda | 2492 | cfq_slice_expired(cfqd, 1); |
22e2c507 | 2493 | |
bf572256 JA |
2494 | /* |
2495 | * Put the new queue at the front of the of the current list, | |
2496 | * so we know that it will be selected next. | |
2497 | */ | |
2498 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
edd75ffd JA |
2499 | |
2500 | cfq_service_tree_add(cfqd, cfqq, 1); | |
bf572256 | 2501 | |
44f7c160 JA |
2502 | cfqq->slice_end = 0; |
2503 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
2504 | } |
2505 | ||
22e2c507 | 2506 | /* |
5e705374 | 2507 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
2508 | * something we should do about it |
2509 | */ | |
2510 | static void | |
5e705374 JA |
2511 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
2512 | struct request *rq) | |
22e2c507 | 2513 | { |
5e705374 | 2514 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 2515 | |
45333d5a | 2516 | cfqd->rq_queued++; |
374f84ac JA |
2517 | if (rq_is_meta(rq)) |
2518 | cfqq->meta_pending++; | |
2519 | ||
9c2c38a1 | 2520 | cfq_update_io_thinktime(cfqd, cic); |
b2c18e1e | 2521 | cfq_update_io_seektime(cfqd, cfqq, rq); |
9c2c38a1 JA |
2522 | cfq_update_idle_window(cfqd, cfqq, cic); |
2523 | ||
b2c18e1e | 2524 | cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
22e2c507 JA |
2525 | |
2526 | if (cfqq == cfqd->active_queue) { | |
2527 | /* | |
b029195d JA |
2528 | * Remember that we saw a request from this process, but |
2529 | * don't start queuing just yet. Otherwise we risk seeing lots | |
2530 | * of tiny requests, because we disrupt the normal plugging | |
d6ceb25e JA |
2531 | * and merging. If the request is already larger than a single |
2532 | * page, let it rip immediately. For that case we assume that | |
2d870722 JA |
2533 | * merging is already done. Ditto for a busy system that |
2534 | * has other work pending, don't risk delaying until the | |
2535 | * idle timer unplug to continue working. | |
22e2c507 | 2536 | */ |
d6ceb25e | 2537 | if (cfq_cfqq_wait_request(cfqq)) { |
2d870722 JA |
2538 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
2539 | cfqd->busy_queues > 1) { | |
d6ceb25e | 2540 | del_timer(&cfqd->idle_slice_timer); |
bf791937 VG |
2541 | __blk_run_queue(cfqd->queue); |
2542 | } else | |
2543 | cfq_mark_cfqq_must_dispatch(cfqq); | |
d6ceb25e | 2544 | } |
5e705374 | 2545 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
2546 | /* |
2547 | * not the active queue - expire current slice if it is | |
2548 | * idle and has expired it's mean thinktime or this new queue | |
3a9a3f6c DS |
2549 | * has some old slice time left and is of higher priority or |
2550 | * this new queue is RT and the current one is BE | |
22e2c507 JA |
2551 | */ |
2552 | cfq_preempt_queue(cfqd, cfqq); | |
a7f55792 | 2553 | __blk_run_queue(cfqd->queue); |
22e2c507 | 2554 | } |
1da177e4 LT |
2555 | } |
2556 | ||
165125e1 | 2557 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2558 | { |
b4878f24 | 2559 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 2560 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 2561 | |
7b679138 | 2562 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
fd0928df | 2563 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
1da177e4 | 2564 | |
30996f40 | 2565 | rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); |
22e2c507 | 2566 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
aa6f6a3d | 2567 | cfq_add_rq_rb(rq); |
22e2c507 | 2568 | |
5e705374 | 2569 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
2570 | } |
2571 | ||
45333d5a AC |
2572 | /* |
2573 | * Update hw_tag based on peak queue depth over 50 samples under | |
2574 | * sufficient load. | |
2575 | */ | |
2576 | static void cfq_update_hw_tag(struct cfq_data *cfqd) | |
2577 | { | |
1a1238a7 SL |
2578 | struct cfq_queue *cfqq = cfqd->active_queue; |
2579 | ||
e459dd08 CZ |
2580 | if (rq_in_driver(cfqd) > cfqd->hw_tag_est_depth) |
2581 | cfqd->hw_tag_est_depth = rq_in_driver(cfqd); | |
2582 | ||
2583 | if (cfqd->hw_tag == 1) | |
2584 | return; | |
45333d5a AC |
2585 | |
2586 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && | |
5ad531db | 2587 | rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN) |
45333d5a AC |
2588 | return; |
2589 | ||
1a1238a7 SL |
2590 | /* |
2591 | * If active queue hasn't enough requests and can idle, cfq might not | |
2592 | * dispatch sufficient requests to hardware. Don't zero hw_tag in this | |
2593 | * case | |
2594 | */ | |
2595 | if (cfqq && cfq_cfqq_idle_window(cfqq) && | |
2596 | cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < | |
2597 | CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN) | |
2598 | return; | |
2599 | ||
45333d5a AC |
2600 | if (cfqd->hw_tag_samples++ < 50) |
2601 | return; | |
2602 | ||
e459dd08 | 2603 | if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) |
45333d5a AC |
2604 | cfqd->hw_tag = 1; |
2605 | else | |
2606 | cfqd->hw_tag = 0; | |
45333d5a AC |
2607 | } |
2608 | ||
165125e1 | 2609 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2610 | { |
5e705374 | 2611 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 2612 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 2613 | const int sync = rq_is_sync(rq); |
b4878f24 | 2614 | unsigned long now; |
1da177e4 | 2615 | |
b4878f24 | 2616 | now = jiffies; |
7b679138 | 2617 | cfq_log_cfqq(cfqd, cfqq, "complete"); |
1da177e4 | 2618 | |
45333d5a AC |
2619 | cfq_update_hw_tag(cfqd); |
2620 | ||
5ad531db | 2621 | WARN_ON(!cfqd->rq_in_driver[sync]); |
6d048f53 | 2622 | WARN_ON(!cfqq->dispatched); |
5ad531db | 2623 | cfqd->rq_in_driver[sync]--; |
6d048f53 | 2624 | cfqq->dispatched--; |
1da177e4 | 2625 | |
3ed9a296 JA |
2626 | if (cfq_cfqq_sync(cfqq)) |
2627 | cfqd->sync_flight--; | |
2628 | ||
365722bb | 2629 | if (sync) { |
5e705374 | 2630 | RQ_CIC(rq)->last_end_request = now; |
365722bb VG |
2631 | cfqd->last_end_sync_rq = now; |
2632 | } | |
caaa5f9f JA |
2633 | |
2634 | /* | |
2635 | * If this is the active queue, check if it needs to be expired, | |
2636 | * or if we want to idle in case it has no pending requests. | |
2637 | */ | |
2638 | if (cfqd->active_queue == cfqq) { | |
a36e71f9 JA |
2639 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
2640 | ||
44f7c160 JA |
2641 | if (cfq_cfqq_slice_new(cfqq)) { |
2642 | cfq_set_prio_slice(cfqd, cfqq); | |
2643 | cfq_clear_cfqq_slice_new(cfqq); | |
2644 | } | |
a36e71f9 | 2645 | /* |
8e550632 CZ |
2646 | * Idling is not enabled on: |
2647 | * - expired queues | |
2648 | * - idle-priority queues | |
2649 | * - async queues | |
2650 | * - queues with still some requests queued | |
2651 | * - when there is a close cooperator | |
a36e71f9 | 2652 | */ |
0871714e | 2653 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
6084cdda | 2654 | cfq_slice_expired(cfqd, 1); |
8e550632 CZ |
2655 | else if (sync && cfqq_empty && |
2656 | !cfq_close_cooperator(cfqd, cfqq)) { | |
2657 | cfqd->noidle_tree_requires_idle |= !rq_noidle(rq); | |
2658 | /* | |
2659 | * Idling is enabled for SYNC_WORKLOAD. | |
2660 | * SYNC_NOIDLE_WORKLOAD idles at the end of the tree | |
2661 | * only if we processed at least one !rq_noidle request | |
2662 | */ | |
2663 | if (cfqd->serving_type == SYNC_WORKLOAD | |
2664 | || cfqd->noidle_tree_requires_idle) | |
2665 | cfq_arm_slice_timer(cfqd); | |
2666 | } | |
caaa5f9f | 2667 | } |
6d048f53 | 2668 | |
5ad531db | 2669 | if (!rq_in_driver(cfqd)) |
23e018a1 | 2670 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
2671 | } |
2672 | ||
22e2c507 JA |
2673 | /* |
2674 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
2675 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
2676 | */ | |
2677 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 2678 | { |
22e2c507 JA |
2679 | if (has_fs_excl()) { |
2680 | /* | |
2681 | * boost idle prio on transactions that would lock out other | |
2682 | * users of the filesystem | |
2683 | */ | |
2684 | if (cfq_class_idle(cfqq)) | |
2685 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
2686 | if (cfqq->ioprio > IOPRIO_NORM) | |
2687 | cfqq->ioprio = IOPRIO_NORM; | |
2688 | } else { | |
2689 | /* | |
dddb7451 | 2690 | * unboost the queue (if needed) |
22e2c507 | 2691 | */ |
dddb7451 CZ |
2692 | cfqq->ioprio_class = cfqq->org_ioprio_class; |
2693 | cfqq->ioprio = cfqq->org_ioprio; | |
22e2c507 | 2694 | } |
22e2c507 | 2695 | } |
1da177e4 | 2696 | |
89850f7e | 2697 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 2698 | { |
1b379d8d | 2699 | if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 2700 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 2701 | return ELV_MQUEUE_MUST; |
3b18152c | 2702 | } |
1da177e4 | 2703 | |
22e2c507 | 2704 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
2705 | } |
2706 | ||
165125e1 | 2707 | static int cfq_may_queue(struct request_queue *q, int rw) |
22e2c507 JA |
2708 | { |
2709 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2710 | struct task_struct *tsk = current; | |
91fac317 | 2711 | struct cfq_io_context *cic; |
22e2c507 JA |
2712 | struct cfq_queue *cfqq; |
2713 | ||
2714 | /* | |
2715 | * don't force setup of a queue from here, as a call to may_queue | |
2716 | * does not necessarily imply that a request actually will be queued. | |
2717 | * so just lookup a possibly existing queue, or return 'may queue' | |
2718 | * if that fails | |
2719 | */ | |
4ac845a2 | 2720 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
2721 | if (!cic) |
2722 | return ELV_MQUEUE_MAY; | |
2723 | ||
b0b78f81 | 2724 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
22e2c507 | 2725 | if (cfqq) { |
fd0928df | 2726 | cfq_init_prio_data(cfqq, cic->ioc); |
22e2c507 JA |
2727 | cfq_prio_boost(cfqq); |
2728 | ||
89850f7e | 2729 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
2730 | } |
2731 | ||
2732 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
2733 | } |
2734 | ||
1da177e4 LT |
2735 | /* |
2736 | * queue lock held here | |
2737 | */ | |
bb37b94c | 2738 | static void cfq_put_request(struct request *rq) |
1da177e4 | 2739 | { |
5e705374 | 2740 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 2741 | |
5e705374 | 2742 | if (cfqq) { |
22e2c507 | 2743 | const int rw = rq_data_dir(rq); |
1da177e4 | 2744 | |
22e2c507 JA |
2745 | BUG_ON(!cfqq->allocated[rw]); |
2746 | cfqq->allocated[rw]--; | |
1da177e4 | 2747 | |
5e705374 | 2748 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 2749 | |
1da177e4 | 2750 | rq->elevator_private = NULL; |
5e705374 | 2751 | rq->elevator_private2 = NULL; |
1da177e4 | 2752 | |
1da177e4 LT |
2753 | cfq_put_queue(cfqq); |
2754 | } | |
2755 | } | |
2756 | ||
df5fe3e8 JM |
2757 | static struct cfq_queue * |
2758 | cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
2759 | struct cfq_queue *cfqq) | |
2760 | { | |
2761 | cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); | |
2762 | cic_set_cfqq(cic, cfqq->new_cfqq, 1); | |
b3b6d040 | 2763 | cfq_mark_cfqq_coop(cfqq->new_cfqq); |
df5fe3e8 JM |
2764 | cfq_put_queue(cfqq); |
2765 | return cic_to_cfqq(cic, 1); | |
2766 | } | |
2767 | ||
e6c5bc73 JM |
2768 | static int should_split_cfqq(struct cfq_queue *cfqq) |
2769 | { | |
2770 | if (cfqq->seeky_start && | |
2771 | time_after(jiffies, cfqq->seeky_start + CFQQ_COOP_TOUT)) | |
2772 | return 1; | |
2773 | return 0; | |
2774 | } | |
2775 | ||
2776 | /* | |
2777 | * Returns NULL if a new cfqq should be allocated, or the old cfqq if this | |
2778 | * was the last process referring to said cfqq. | |
2779 | */ | |
2780 | static struct cfq_queue * | |
2781 | split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) | |
2782 | { | |
2783 | if (cfqq_process_refs(cfqq) == 1) { | |
2784 | cfqq->seeky_start = 0; | |
2785 | cfqq->pid = current->pid; | |
2786 | cfq_clear_cfqq_coop(cfqq); | |
2787 | return cfqq; | |
2788 | } | |
2789 | ||
2790 | cic_set_cfqq(cic, NULL, 1); | |
2791 | cfq_put_queue(cfqq); | |
2792 | return NULL; | |
2793 | } | |
1da177e4 | 2794 | /* |
22e2c507 | 2795 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2796 | */ |
22e2c507 | 2797 | static int |
165125e1 | 2798 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
2799 | { |
2800 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2801 | struct cfq_io_context *cic; | |
2802 | const int rw = rq_data_dir(rq); | |
a6151c3a | 2803 | const bool is_sync = rq_is_sync(rq); |
22e2c507 | 2804 | struct cfq_queue *cfqq; |
1da177e4 LT |
2805 | unsigned long flags; |
2806 | ||
2807 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2808 | ||
e2d74ac0 | 2809 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2810 | |
1da177e4 LT |
2811 | spin_lock_irqsave(q->queue_lock, flags); |
2812 | ||
22e2c507 JA |
2813 | if (!cic) |
2814 | goto queue_fail; | |
2815 | ||
e6c5bc73 | 2816 | new_queue: |
91fac317 | 2817 | cfqq = cic_to_cfqq(cic, is_sync); |
32f2e807 | 2818 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
fd0928df | 2819 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
91fac317 | 2820 | cic_set_cfqq(cic, cfqq, is_sync); |
df5fe3e8 | 2821 | } else { |
e6c5bc73 JM |
2822 | /* |
2823 | * If the queue was seeky for too long, break it apart. | |
2824 | */ | |
2825 | if (cfq_cfqq_coop(cfqq) && should_split_cfqq(cfqq)) { | |
2826 | cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); | |
2827 | cfqq = split_cfqq(cic, cfqq); | |
2828 | if (!cfqq) | |
2829 | goto new_queue; | |
2830 | } | |
2831 | ||
df5fe3e8 JM |
2832 | /* |
2833 | * Check to see if this queue is scheduled to merge with | |
2834 | * another, closely cooperating queue. The merging of | |
2835 | * queues happens here as it must be done in process context. | |
2836 | * The reference on new_cfqq was taken in merge_cfqqs. | |
2837 | */ | |
2838 | if (cfqq->new_cfqq) | |
2839 | cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); | |
91fac317 | 2840 | } |
1da177e4 LT |
2841 | |
2842 | cfqq->allocated[rw]++; | |
22e2c507 | 2843 | atomic_inc(&cfqq->ref); |
1da177e4 | 2844 | |
5e705374 | 2845 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 2846 | |
5e705374 JA |
2847 | rq->elevator_private = cic; |
2848 | rq->elevator_private2 = cfqq; | |
2849 | return 0; | |
1da177e4 | 2850 | |
22e2c507 JA |
2851 | queue_fail: |
2852 | if (cic) | |
2853 | put_io_context(cic->ioc); | |
89850f7e | 2854 | |
23e018a1 | 2855 | cfq_schedule_dispatch(cfqd); |
1da177e4 | 2856 | spin_unlock_irqrestore(q->queue_lock, flags); |
7b679138 | 2857 | cfq_log(cfqd, "set_request fail"); |
1da177e4 LT |
2858 | return 1; |
2859 | } | |
2860 | ||
65f27f38 | 2861 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 2862 | { |
65f27f38 | 2863 | struct cfq_data *cfqd = |
23e018a1 | 2864 | container_of(work, struct cfq_data, unplug_work); |
165125e1 | 2865 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2866 | |
40bb54d1 | 2867 | spin_lock_irq(q->queue_lock); |
a7f55792 | 2868 | __blk_run_queue(cfqd->queue); |
40bb54d1 | 2869 | spin_unlock_irq(q->queue_lock); |
22e2c507 JA |
2870 | } |
2871 | ||
2872 | /* | |
2873 | * Timer running if the active_queue is currently idling inside its time slice | |
2874 | */ | |
2875 | static void cfq_idle_slice_timer(unsigned long data) | |
2876 | { | |
2877 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2878 | struct cfq_queue *cfqq; | |
2879 | unsigned long flags; | |
3c6bd2f8 | 2880 | int timed_out = 1; |
22e2c507 | 2881 | |
7b679138 JA |
2882 | cfq_log(cfqd, "idle timer fired"); |
2883 | ||
22e2c507 JA |
2884 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
2885 | ||
fe094d98 JA |
2886 | cfqq = cfqd->active_queue; |
2887 | if (cfqq) { | |
3c6bd2f8 JA |
2888 | timed_out = 0; |
2889 | ||
b029195d JA |
2890 | /* |
2891 | * We saw a request before the queue expired, let it through | |
2892 | */ | |
2893 | if (cfq_cfqq_must_dispatch(cfqq)) | |
2894 | goto out_kick; | |
2895 | ||
22e2c507 JA |
2896 | /* |
2897 | * expired | |
2898 | */ | |
44f7c160 | 2899 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
2900 | goto expire; |
2901 | ||
2902 | /* | |
2903 | * only expire and reinvoke request handler, if there are | |
2904 | * other queues with pending requests | |
2905 | */ | |
caaa5f9f | 2906 | if (!cfqd->busy_queues) |
22e2c507 | 2907 | goto out_cont; |
22e2c507 JA |
2908 | |
2909 | /* | |
2910 | * not expired and it has a request pending, let it dispatch | |
2911 | */ | |
75e50984 | 2912 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 2913 | goto out_kick; |
76280aff CZ |
2914 | |
2915 | /* | |
2916 | * Queue depth flag is reset only when the idle didn't succeed | |
2917 | */ | |
2918 | cfq_clear_cfqq_deep(cfqq); | |
22e2c507 JA |
2919 | } |
2920 | expire: | |
6084cdda | 2921 | cfq_slice_expired(cfqd, timed_out); |
22e2c507 | 2922 | out_kick: |
23e018a1 | 2923 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2924 | out_cont: |
2925 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2926 | } | |
2927 | ||
3b18152c JA |
2928 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2929 | { | |
2930 | del_timer_sync(&cfqd->idle_slice_timer); | |
23e018a1 | 2931 | cancel_work_sync(&cfqd->unplug_work); |
3b18152c | 2932 | } |
22e2c507 | 2933 | |
c2dea2d1 VT |
2934 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
2935 | { | |
2936 | int i; | |
2937 | ||
2938 | for (i = 0; i < IOPRIO_BE_NR; i++) { | |
2939 | if (cfqd->async_cfqq[0][i]) | |
2940 | cfq_put_queue(cfqd->async_cfqq[0][i]); | |
2941 | if (cfqd->async_cfqq[1][i]) | |
2942 | cfq_put_queue(cfqd->async_cfqq[1][i]); | |
c2dea2d1 | 2943 | } |
2389d1ef ON |
2944 | |
2945 | if (cfqd->async_idle_cfqq) | |
2946 | cfq_put_queue(cfqd->async_idle_cfqq); | |
c2dea2d1 VT |
2947 | } |
2948 | ||
b374d18a | 2949 | static void cfq_exit_queue(struct elevator_queue *e) |
1da177e4 | 2950 | { |
22e2c507 | 2951 | struct cfq_data *cfqd = e->elevator_data; |
165125e1 | 2952 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2953 | |
3b18152c | 2954 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2955 | |
d9ff4187 | 2956 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2957 | |
d9ff4187 | 2958 | if (cfqd->active_queue) |
6084cdda | 2959 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
e2d74ac0 JA |
2960 | |
2961 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2962 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2963 | struct cfq_io_context, | |
2964 | queue_list); | |
89850f7e JA |
2965 | |
2966 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 2967 | } |
e2d74ac0 | 2968 | |
c2dea2d1 | 2969 | cfq_put_async_queues(cfqd); |
15c31be4 | 2970 | |
d9ff4187 | 2971 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
2972 | |
2973 | cfq_shutdown_timer_wq(cfqd); | |
2974 | ||
a90d742e | 2975 | kfree(cfqd); |
1da177e4 LT |
2976 | } |
2977 | ||
165125e1 | 2978 | static void *cfq_init_queue(struct request_queue *q) |
1da177e4 LT |
2979 | { |
2980 | struct cfq_data *cfqd; | |
718eee05 | 2981 | int i, j; |
cdb16e8f | 2982 | struct cfq_group *cfqg; |
615f0259 | 2983 | struct cfq_rb_root *st; |
1da177e4 | 2984 | |
94f6030c | 2985 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
1da177e4 | 2986 | if (!cfqd) |
bc1c1169 | 2987 | return NULL; |
1da177e4 | 2988 | |
cdb16e8f VG |
2989 | /* Init root group */ |
2990 | cfqg = &cfqd->root_group; | |
615f0259 VG |
2991 | for_each_cfqg_st(cfqg, i, j, st) |
2992 | *st = CFQ_RB_ROOT; | |
26a2ac00 JA |
2993 | |
2994 | /* | |
2995 | * Not strictly needed (since RB_ROOT just clears the node and we | |
2996 | * zeroed cfqd on alloc), but better be safe in case someone decides | |
2997 | * to add magic to the rb code | |
2998 | */ | |
2999 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
3000 | cfqd->prio_trees[i] = RB_ROOT; | |
3001 | ||
6118b70b JA |
3002 | /* |
3003 | * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. | |
3004 | * Grab a permanent reference to it, so that the normal code flow | |
3005 | * will not attempt to free it. | |
3006 | */ | |
3007 | cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); | |
3008 | atomic_inc(&cfqd->oom_cfqq.ref); | |
cdb16e8f | 3009 | cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group); |
6118b70b | 3010 | |
d9ff4187 | 3011 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 3012 | |
1da177e4 | 3013 | cfqd->queue = q; |
1da177e4 | 3014 | |
22e2c507 JA |
3015 | init_timer(&cfqd->idle_slice_timer); |
3016 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
3017 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
3018 | ||
23e018a1 | 3019 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 3020 | |
1da177e4 | 3021 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
3022 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
3023 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
3024 | cfqd->cfq_back_max = cfq_back_max; |
3025 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
3026 | cfqd->cfq_slice[0] = cfq_slice_async; |
3027 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
3028 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
3029 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
963b72fc | 3030 | cfqd->cfq_latency = 1; |
e459dd08 | 3031 | cfqd->hw_tag = -1; |
365722bb | 3032 | cfqd->last_end_sync_rq = jiffies; |
bc1c1169 | 3033 | return cfqd; |
1da177e4 LT |
3034 | } |
3035 | ||
3036 | static void cfq_slab_kill(void) | |
3037 | { | |
d6de8be7 JA |
3038 | /* |
3039 | * Caller already ensured that pending RCU callbacks are completed, | |
3040 | * so we should have no busy allocations at this point. | |
3041 | */ | |
1da177e4 LT |
3042 | if (cfq_pool) |
3043 | kmem_cache_destroy(cfq_pool); | |
3044 | if (cfq_ioc_pool) | |
3045 | kmem_cache_destroy(cfq_ioc_pool); | |
3046 | } | |
3047 | ||
3048 | static int __init cfq_slab_setup(void) | |
3049 | { | |
0a31bd5f | 3050 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
1da177e4 LT |
3051 | if (!cfq_pool) |
3052 | goto fail; | |
3053 | ||
34e6bbf2 | 3054 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
1da177e4 LT |
3055 | if (!cfq_ioc_pool) |
3056 | goto fail; | |
3057 | ||
3058 | return 0; | |
3059 | fail: | |
3060 | cfq_slab_kill(); | |
3061 | return -ENOMEM; | |
3062 | } | |
3063 | ||
1da177e4 LT |
3064 | /* |
3065 | * sysfs parts below --> | |
3066 | */ | |
1da177e4 LT |
3067 | static ssize_t |
3068 | cfq_var_show(unsigned int var, char *page) | |
3069 | { | |
3070 | return sprintf(page, "%d\n", var); | |
3071 | } | |
3072 | ||
3073 | static ssize_t | |
3074 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
3075 | { | |
3076 | char *p = (char *) page; | |
3077 | ||
3078 | *var = simple_strtoul(p, &p, 10); | |
3079 | return count; | |
3080 | } | |
3081 | ||
1da177e4 | 3082 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
b374d18a | 3083 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
1da177e4 | 3084 | { \ |
3d1ab40f | 3085 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
3086 | unsigned int __data = __VAR; \ |
3087 | if (__CONV) \ | |
3088 | __data = jiffies_to_msecs(__data); \ | |
3089 | return cfq_var_show(__data, (page)); \ | |
3090 | } | |
3091 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
3092 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
3093 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
3094 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
3095 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
3096 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
3097 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
3098 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
3099 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
963b72fc | 3100 | SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); |
1da177e4 LT |
3101 | #undef SHOW_FUNCTION |
3102 | ||
3103 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
b374d18a | 3104 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
1da177e4 | 3105 | { \ |
3d1ab40f | 3106 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
3107 | unsigned int __data; \ |
3108 | int ret = cfq_var_store(&__data, (page), count); \ | |
3109 | if (__data < (MIN)) \ | |
3110 | __data = (MIN); \ | |
3111 | else if (__data > (MAX)) \ | |
3112 | __data = (MAX); \ | |
3113 | if (__CONV) \ | |
3114 | *(__PTR) = msecs_to_jiffies(__data); \ | |
3115 | else \ | |
3116 | *(__PTR) = __data; \ | |
3117 | return ret; \ | |
3118 | } | |
3119 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
fe094d98 JA |
3120 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
3121 | UINT_MAX, 1); | |
3122 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, | |
3123 | UINT_MAX, 1); | |
e572ec7e | 3124 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
fe094d98 JA |
3125 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
3126 | UINT_MAX, 0); | |
22e2c507 JA |
3127 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
3128 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
3129 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
fe094d98 JA |
3130 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
3131 | UINT_MAX, 0); | |
963b72fc | 3132 | STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); |
1da177e4 LT |
3133 | #undef STORE_FUNCTION |
3134 | ||
e572ec7e AV |
3135 | #define CFQ_ATTR(name) \ |
3136 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
3137 | ||
3138 | static struct elv_fs_entry cfq_attrs[] = { | |
3139 | CFQ_ATTR(quantum), | |
e572ec7e AV |
3140 | CFQ_ATTR(fifo_expire_sync), |
3141 | CFQ_ATTR(fifo_expire_async), | |
3142 | CFQ_ATTR(back_seek_max), | |
3143 | CFQ_ATTR(back_seek_penalty), | |
3144 | CFQ_ATTR(slice_sync), | |
3145 | CFQ_ATTR(slice_async), | |
3146 | CFQ_ATTR(slice_async_rq), | |
3147 | CFQ_ATTR(slice_idle), | |
963b72fc | 3148 | CFQ_ATTR(low_latency), |
e572ec7e | 3149 | __ATTR_NULL |
1da177e4 LT |
3150 | }; |
3151 | ||
1da177e4 LT |
3152 | static struct elevator_type iosched_cfq = { |
3153 | .ops = { | |
3154 | .elevator_merge_fn = cfq_merge, | |
3155 | .elevator_merged_fn = cfq_merged_request, | |
3156 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 3157 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 3158 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 3159 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 3160 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
3161 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
3162 | .elevator_queue_empty_fn = cfq_queue_empty, | |
3163 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
3164 | .elevator_former_req_fn = elv_rb_former_request, |
3165 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
3166 | .elevator_set_req_fn = cfq_set_request, |
3167 | .elevator_put_req_fn = cfq_put_request, | |
3168 | .elevator_may_queue_fn = cfq_may_queue, | |
3169 | .elevator_init_fn = cfq_init_queue, | |
3170 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 3171 | .trim = cfq_free_io_context, |
1da177e4 | 3172 | }, |
3d1ab40f | 3173 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
3174 | .elevator_name = "cfq", |
3175 | .elevator_owner = THIS_MODULE, | |
3176 | }; | |
3177 | ||
3178 | static int __init cfq_init(void) | |
3179 | { | |
22e2c507 JA |
3180 | /* |
3181 | * could be 0 on HZ < 1000 setups | |
3182 | */ | |
3183 | if (!cfq_slice_async) | |
3184 | cfq_slice_async = 1; | |
3185 | if (!cfq_slice_idle) | |
3186 | cfq_slice_idle = 1; | |
3187 | ||
1da177e4 LT |
3188 | if (cfq_slab_setup()) |
3189 | return -ENOMEM; | |
3190 | ||
2fdd82bd | 3191 | elv_register(&iosched_cfq); |
1da177e4 | 3192 | |
2fdd82bd | 3193 | return 0; |
1da177e4 LT |
3194 | } |
3195 | ||
3196 | static void __exit cfq_exit(void) | |
3197 | { | |
6e9a4738 | 3198 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 3199 | elv_unregister(&iosched_cfq); |
334e94de | 3200 | ioc_gone = &all_gone; |
fba82272 OH |
3201 | /* ioc_gone's update must be visible before reading ioc_count */ |
3202 | smp_wmb(); | |
d6de8be7 JA |
3203 | |
3204 | /* | |
3205 | * this also protects us from entering cfq_slab_kill() with | |
3206 | * pending RCU callbacks | |
3207 | */ | |
245b2e70 | 3208 | if (elv_ioc_count_read(cfq_ioc_count)) |
9a11b4ed | 3209 | wait_for_completion(&all_gone); |
83521d3e | 3210 | cfq_slab_kill(); |
1da177e4 LT |
3211 | } |
3212 | ||
3213 | module_init(cfq_init); | |
3214 | module_exit(cfq_exit); | |
3215 | ||
3216 | MODULE_AUTHOR("Jens Axboe"); | |
3217 | MODULE_LICENSE("GPL"); | |
3218 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |