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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; |
6118b70b JA |
135 | }; |
136 | ||
c0324a02 | 137 | /* |
718eee05 | 138 | * First index in the service_trees. |
c0324a02 CZ |
139 | * IDLE is handled separately, so it has negative index |
140 | */ | |
141 | enum wl_prio_t { | |
142 | IDLE_WORKLOAD = -1, | |
143 | BE_WORKLOAD = 0, | |
144 | RT_WORKLOAD = 1 | |
145 | }; | |
146 | ||
718eee05 CZ |
147 | /* |
148 | * Second index in the service_trees. | |
149 | */ | |
150 | enum wl_type_t { | |
151 | ASYNC_WORKLOAD = 0, | |
152 | SYNC_NOIDLE_WORKLOAD = 1, | |
153 | SYNC_WORKLOAD = 2 | |
154 | }; | |
155 | ||
156 | ||
22e2c507 JA |
157 | /* |
158 | * Per block device queue structure | |
159 | */ | |
1da177e4 | 160 | struct cfq_data { |
165125e1 | 161 | struct request_queue *queue; |
22e2c507 JA |
162 | |
163 | /* | |
c0324a02 CZ |
164 | * rr lists of queues with requests, onle rr for each priority class. |
165 | * Counts are embedded in the cfq_rb_root | |
166 | */ | |
718eee05 | 167 | struct cfq_rb_root service_trees[2][3]; |
c0324a02 CZ |
168 | struct cfq_rb_root service_tree_idle; |
169 | /* | |
170 | * The priority currently being served | |
22e2c507 | 171 | */ |
c0324a02 | 172 | enum wl_prio_t serving_prio; |
718eee05 CZ |
173 | enum wl_type_t serving_type; |
174 | unsigned long workload_expires; | |
8e550632 | 175 | bool noidle_tree_requires_idle; |
a36e71f9 JA |
176 | |
177 | /* | |
178 | * Each priority tree is sorted by next_request position. These | |
179 | * trees are used when determining if two or more queues are | |
180 | * interleaving requests (see cfq_close_cooperator). | |
181 | */ | |
182 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; | |
183 | ||
22e2c507 | 184 | unsigned int busy_queues; |
5db5d642 | 185 | unsigned int busy_queues_avg[2]; |
22e2c507 | 186 | |
5ad531db | 187 | int rq_in_driver[2]; |
3ed9a296 | 188 | int sync_flight; |
45333d5a AC |
189 | |
190 | /* | |
191 | * queue-depth detection | |
192 | */ | |
193 | int rq_queued; | |
25776e35 | 194 | int hw_tag; |
e459dd08 CZ |
195 | /* |
196 | * hw_tag can be | |
197 | * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) | |
198 | * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) | |
199 | * 0 => no NCQ | |
200 | */ | |
201 | int hw_tag_est_depth; | |
202 | unsigned int hw_tag_samples; | |
1da177e4 | 203 | |
22e2c507 JA |
204 | /* |
205 | * idle window management | |
206 | */ | |
207 | struct timer_list idle_slice_timer; | |
23e018a1 | 208 | struct work_struct unplug_work; |
1da177e4 | 209 | |
22e2c507 JA |
210 | struct cfq_queue *active_queue; |
211 | struct cfq_io_context *active_cic; | |
22e2c507 | 212 | |
c2dea2d1 VT |
213 | /* |
214 | * async queue for each priority case | |
215 | */ | |
216 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; | |
217 | struct cfq_queue *async_idle_cfqq; | |
15c31be4 | 218 | |
6d048f53 | 219 | sector_t last_position; |
1da177e4 | 220 | |
1da177e4 LT |
221 | /* |
222 | * tunables, see top of file | |
223 | */ | |
224 | unsigned int cfq_quantum; | |
22e2c507 | 225 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
226 | unsigned int cfq_back_penalty; |
227 | unsigned int cfq_back_max; | |
22e2c507 JA |
228 | unsigned int cfq_slice[2]; |
229 | unsigned int cfq_slice_async_rq; | |
230 | unsigned int cfq_slice_idle; | |
963b72fc | 231 | unsigned int cfq_latency; |
d9ff4187 AV |
232 | |
233 | struct list_head cic_list; | |
1da177e4 | 234 | |
6118b70b JA |
235 | /* |
236 | * Fallback dummy cfqq for extreme OOM conditions | |
237 | */ | |
238 | struct cfq_queue oom_cfqq; | |
365722bb VG |
239 | |
240 | unsigned long last_end_sync_rq; | |
1da177e4 LT |
241 | }; |
242 | ||
c0324a02 | 243 | static struct cfq_rb_root *service_tree_for(enum wl_prio_t prio, |
718eee05 | 244 | enum wl_type_t type, |
c0324a02 CZ |
245 | struct cfq_data *cfqd) |
246 | { | |
247 | if (prio == IDLE_WORKLOAD) | |
248 | return &cfqd->service_tree_idle; | |
249 | ||
718eee05 | 250 | return &cfqd->service_trees[prio][type]; |
c0324a02 CZ |
251 | } |
252 | ||
3b18152c | 253 | enum cfqq_state_flags { |
b0b8d749 JA |
254 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
255 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
b029195d | 256 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
b0b8d749 | 257 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
b0b8d749 JA |
258 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
259 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
260 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
44f7c160 | 261 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
91fac317 | 262 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
b3b6d040 | 263 | CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ |
76280aff | 264 | CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ |
3b18152c JA |
265 | }; |
266 | ||
267 | #define CFQ_CFQQ_FNS(name) \ | |
268 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
269 | { \ | |
fe094d98 | 270 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
271 | } \ |
272 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
273 | { \ | |
fe094d98 | 274 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
275 | } \ |
276 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
277 | { \ | |
fe094d98 | 278 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
3b18152c JA |
279 | } |
280 | ||
281 | CFQ_CFQQ_FNS(on_rr); | |
282 | CFQ_CFQQ_FNS(wait_request); | |
b029195d | 283 | CFQ_CFQQ_FNS(must_dispatch); |
3b18152c | 284 | CFQ_CFQQ_FNS(must_alloc_slice); |
3b18152c JA |
285 | CFQ_CFQQ_FNS(fifo_expire); |
286 | CFQ_CFQQ_FNS(idle_window); | |
287 | CFQ_CFQQ_FNS(prio_changed); | |
44f7c160 | 288 | CFQ_CFQQ_FNS(slice_new); |
91fac317 | 289 | CFQ_CFQQ_FNS(sync); |
a36e71f9 | 290 | CFQ_CFQQ_FNS(coop); |
76280aff | 291 | CFQ_CFQQ_FNS(deep); |
3b18152c JA |
292 | #undef CFQ_CFQQ_FNS |
293 | ||
7b679138 JA |
294 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
295 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) | |
296 | #define cfq_log(cfqd, fmt, args...) \ | |
297 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) | |
298 | ||
c0324a02 CZ |
299 | static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) |
300 | { | |
301 | if (cfq_class_idle(cfqq)) | |
302 | return IDLE_WORKLOAD; | |
303 | if (cfq_class_rt(cfqq)) | |
304 | return RT_WORKLOAD; | |
305 | return BE_WORKLOAD; | |
306 | } | |
307 | ||
718eee05 CZ |
308 | |
309 | static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) | |
310 | { | |
311 | if (!cfq_cfqq_sync(cfqq)) | |
312 | return ASYNC_WORKLOAD; | |
313 | if (!cfq_cfqq_idle_window(cfqq)) | |
314 | return SYNC_NOIDLE_WORKLOAD; | |
315 | return SYNC_WORKLOAD; | |
316 | } | |
317 | ||
c0324a02 CZ |
318 | static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd) |
319 | { | |
320 | if (wl == IDLE_WORKLOAD) | |
321 | return cfqd->service_tree_idle.count; | |
322 | ||
718eee05 CZ |
323 | return cfqd->service_trees[wl][ASYNC_WORKLOAD].count |
324 | + cfqd->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count | |
325 | + cfqd->service_trees[wl][SYNC_WORKLOAD].count; | |
c0324a02 CZ |
326 | } |
327 | ||
165125e1 | 328 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
a6151c3a | 329 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, |
fd0928df | 330 | struct io_context *, gfp_t); |
4ac845a2 | 331 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
91fac317 VT |
332 | struct io_context *); |
333 | ||
5ad531db JA |
334 | static inline int rq_in_driver(struct cfq_data *cfqd) |
335 | { | |
336 | return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1]; | |
337 | } | |
338 | ||
91fac317 | 339 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, |
a6151c3a | 340 | bool is_sync) |
91fac317 | 341 | { |
a6151c3a | 342 | return cic->cfqq[is_sync]; |
91fac317 VT |
343 | } |
344 | ||
345 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
a6151c3a | 346 | struct cfq_queue *cfqq, bool is_sync) |
91fac317 | 347 | { |
a6151c3a | 348 | cic->cfqq[is_sync] = cfqq; |
91fac317 VT |
349 | } |
350 | ||
351 | /* | |
352 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
353 | * set (in which case it could also be direct WRITE). | |
354 | */ | |
a6151c3a | 355 | static inline bool cfq_bio_sync(struct bio *bio) |
91fac317 | 356 | { |
a6151c3a | 357 | return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO); |
91fac317 | 358 | } |
1da177e4 | 359 | |
99f95e52 AM |
360 | /* |
361 | * scheduler run of queue, if there are requests pending and no one in the | |
362 | * driver that will restart queueing | |
363 | */ | |
23e018a1 | 364 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) |
99f95e52 | 365 | { |
7b679138 JA |
366 | if (cfqd->busy_queues) { |
367 | cfq_log(cfqd, "schedule dispatch"); | |
23e018a1 | 368 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
7b679138 | 369 | } |
99f95e52 AM |
370 | } |
371 | ||
165125e1 | 372 | static int cfq_queue_empty(struct request_queue *q) |
99f95e52 AM |
373 | { |
374 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
375 | ||
b4878f24 | 376 | return !cfqd->busy_queues; |
99f95e52 AM |
377 | } |
378 | ||
44f7c160 JA |
379 | /* |
380 | * Scale schedule slice based on io priority. Use the sync time slice only | |
381 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
382 | * io only, should not get full sync slice length. | |
383 | */ | |
a6151c3a | 384 | static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, |
d9e7620e | 385 | unsigned short prio) |
44f7c160 | 386 | { |
d9e7620e | 387 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 388 | |
d9e7620e JA |
389 | WARN_ON(prio >= IOPRIO_BE_NR); |
390 | ||
391 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
392 | } | |
44f7c160 | 393 | |
d9e7620e JA |
394 | static inline int |
395 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
396 | { | |
397 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
398 | } |
399 | ||
5db5d642 CZ |
400 | /* |
401 | * get averaged number of queues of RT/BE priority. | |
402 | * average is updated, with a formula that gives more weight to higher numbers, | |
403 | * to quickly follows sudden increases and decrease slowly | |
404 | */ | |
405 | ||
5869619c JA |
406 | static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt) |
407 | { | |
5db5d642 CZ |
408 | unsigned min_q, max_q; |
409 | unsigned mult = cfq_hist_divisor - 1; | |
410 | unsigned round = cfq_hist_divisor / 2; | |
c0324a02 | 411 | unsigned busy = cfq_busy_queues_wl(rt, cfqd); |
5db5d642 CZ |
412 | |
413 | min_q = min(cfqd->busy_queues_avg[rt], busy); | |
414 | max_q = max(cfqd->busy_queues_avg[rt], busy); | |
415 | cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) / | |
416 | cfq_hist_divisor; | |
417 | return cfqd->busy_queues_avg[rt]; | |
418 | } | |
419 | ||
44f7c160 JA |
420 | static inline void |
421 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
422 | { | |
5db5d642 CZ |
423 | unsigned slice = cfq_prio_to_slice(cfqd, cfqq); |
424 | if (cfqd->cfq_latency) { | |
425 | /* interested queues (we consider only the ones with the same | |
426 | * priority class) */ | |
427 | unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq)); | |
428 | unsigned sync_slice = cfqd->cfq_slice[1]; | |
429 | unsigned expect_latency = sync_slice * iq; | |
430 | if (expect_latency > cfq_target_latency) { | |
431 | unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; | |
432 | /* scale low_slice according to IO priority | |
433 | * and sync vs async */ | |
434 | unsigned low_slice = | |
435 | min(slice, base_low_slice * slice / sync_slice); | |
436 | /* the adapted slice value is scaled to fit all iqs | |
437 | * into the target latency */ | |
438 | slice = max(slice * cfq_target_latency / expect_latency, | |
439 | low_slice); | |
440 | } | |
441 | } | |
442 | cfqq->slice_end = jiffies + slice; | |
7b679138 | 443 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
44f7c160 JA |
444 | } |
445 | ||
446 | /* | |
447 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
448 | * isn't valid until the first request from the dispatch is activated | |
449 | * and the slice time set. | |
450 | */ | |
a6151c3a | 451 | static inline bool cfq_slice_used(struct cfq_queue *cfqq) |
44f7c160 JA |
452 | { |
453 | if (cfq_cfqq_slice_new(cfqq)) | |
454 | return 0; | |
455 | if (time_before(jiffies, cfqq->slice_end)) | |
456 | return 0; | |
457 | ||
458 | return 1; | |
459 | } | |
460 | ||
1da177e4 | 461 | /* |
5e705374 | 462 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 463 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 464 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 465 | */ |
5e705374 | 466 | static struct request * |
cf7c25cf | 467 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) |
1da177e4 | 468 | { |
cf7c25cf | 469 | sector_t s1, s2, d1 = 0, d2 = 0; |
1da177e4 | 470 | unsigned long back_max; |
e8a99053 AM |
471 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
472 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
473 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 474 | |
5e705374 JA |
475 | if (rq1 == NULL || rq1 == rq2) |
476 | return rq2; | |
477 | if (rq2 == NULL) | |
478 | return rq1; | |
9c2c38a1 | 479 | |
5e705374 JA |
480 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
481 | return rq1; | |
482 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
483 | return rq2; | |
374f84ac JA |
484 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
485 | return rq1; | |
486 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
487 | return rq2; | |
1da177e4 | 488 | |
83096ebf TH |
489 | s1 = blk_rq_pos(rq1); |
490 | s2 = blk_rq_pos(rq2); | |
1da177e4 | 491 | |
1da177e4 LT |
492 | /* |
493 | * by definition, 1KiB is 2 sectors | |
494 | */ | |
495 | back_max = cfqd->cfq_back_max * 2; | |
496 | ||
497 | /* | |
498 | * Strict one way elevator _except_ in the case where we allow | |
499 | * short backward seeks which are biased as twice the cost of a | |
500 | * similar forward seek. | |
501 | */ | |
502 | if (s1 >= last) | |
503 | d1 = s1 - last; | |
504 | else if (s1 + back_max >= last) | |
505 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
506 | else | |
e8a99053 | 507 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
508 | |
509 | if (s2 >= last) | |
510 | d2 = s2 - last; | |
511 | else if (s2 + back_max >= last) | |
512 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
513 | else | |
e8a99053 | 514 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
515 | |
516 | /* Found required data */ | |
e8a99053 AM |
517 | |
518 | /* | |
519 | * By doing switch() on the bit mask "wrap" we avoid having to | |
520 | * check two variables for all permutations: --> faster! | |
521 | */ | |
522 | switch (wrap) { | |
5e705374 | 523 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 524 | if (d1 < d2) |
5e705374 | 525 | return rq1; |
e8a99053 | 526 | else if (d2 < d1) |
5e705374 | 527 | return rq2; |
e8a99053 AM |
528 | else { |
529 | if (s1 >= s2) | |
5e705374 | 530 | return rq1; |
e8a99053 | 531 | else |
5e705374 | 532 | return rq2; |
e8a99053 | 533 | } |
1da177e4 | 534 | |
e8a99053 | 535 | case CFQ_RQ2_WRAP: |
5e705374 | 536 | return rq1; |
e8a99053 | 537 | case CFQ_RQ1_WRAP: |
5e705374 JA |
538 | return rq2; |
539 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
540 | default: |
541 | /* | |
542 | * Since both rqs are wrapped, | |
543 | * start with the one that's further behind head | |
544 | * (--> only *one* back seek required), | |
545 | * since back seek takes more time than forward. | |
546 | */ | |
547 | if (s1 <= s2) | |
5e705374 | 548 | return rq1; |
1da177e4 | 549 | else |
5e705374 | 550 | return rq2; |
1da177e4 LT |
551 | } |
552 | } | |
553 | ||
498d3aa2 JA |
554 | /* |
555 | * The below is leftmost cache rbtree addon | |
556 | */ | |
0871714e | 557 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
cc09e299 JA |
558 | { |
559 | if (!root->left) | |
560 | root->left = rb_first(&root->rb); | |
561 | ||
0871714e JA |
562 | if (root->left) |
563 | return rb_entry(root->left, struct cfq_queue, rb_node); | |
564 | ||
565 | return NULL; | |
cc09e299 JA |
566 | } |
567 | ||
a36e71f9 JA |
568 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
569 | { | |
570 | rb_erase(n, root); | |
571 | RB_CLEAR_NODE(n); | |
572 | } | |
573 | ||
cc09e299 JA |
574 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
575 | { | |
576 | if (root->left == n) | |
577 | root->left = NULL; | |
a36e71f9 | 578 | rb_erase_init(n, &root->rb); |
aa6f6a3d | 579 | --root->count; |
cc09e299 JA |
580 | } |
581 | ||
1da177e4 LT |
582 | /* |
583 | * would be nice to take fifo expire time into account as well | |
584 | */ | |
5e705374 JA |
585 | static struct request * |
586 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
587 | struct request *last) | |
1da177e4 | 588 | { |
21183b07 JA |
589 | struct rb_node *rbnext = rb_next(&last->rb_node); |
590 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 591 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 592 | |
21183b07 | 593 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
594 | |
595 | if (rbprev) | |
5e705374 | 596 | prev = rb_entry_rq(rbprev); |
1da177e4 | 597 | |
21183b07 | 598 | if (rbnext) |
5e705374 | 599 | next = rb_entry_rq(rbnext); |
21183b07 JA |
600 | else { |
601 | rbnext = rb_first(&cfqq->sort_list); | |
602 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 603 | next = rb_entry_rq(rbnext); |
21183b07 | 604 | } |
1da177e4 | 605 | |
cf7c25cf | 606 | return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); |
1da177e4 LT |
607 | } |
608 | ||
d9e7620e JA |
609 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
610 | struct cfq_queue *cfqq) | |
1da177e4 | 611 | { |
3586e917 GJ |
612 | struct cfq_rb_root *service_tree; |
613 | ||
614 | service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd); | |
615 | ||
d9e7620e JA |
616 | /* |
617 | * just an approximation, should be ok. | |
618 | */ | |
3586e917 GJ |
619 | return service_tree->count * (cfq_prio_slice(cfqd, 1, 0) - |
620 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); | |
d9e7620e JA |
621 | } |
622 | ||
498d3aa2 | 623 | /* |
c0324a02 | 624 | * The cfqd->service_trees holds all pending cfq_queue's that have |
498d3aa2 JA |
625 | * requests waiting to be processed. It is sorted in the order that |
626 | * we will service the queues. | |
627 | */ | |
a36e71f9 | 628 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 629 | bool add_front) |
d9e7620e | 630 | { |
0871714e JA |
631 | struct rb_node **p, *parent; |
632 | struct cfq_queue *__cfqq; | |
d9e7620e | 633 | unsigned long rb_key; |
c0324a02 | 634 | struct cfq_rb_root *service_tree; |
498d3aa2 | 635 | int left; |
d9e7620e | 636 | |
718eee05 | 637 | service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd); |
0871714e JA |
638 | if (cfq_class_idle(cfqq)) { |
639 | rb_key = CFQ_IDLE_DELAY; | |
aa6f6a3d | 640 | parent = rb_last(&service_tree->rb); |
0871714e JA |
641 | if (parent && parent != &cfqq->rb_node) { |
642 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
643 | rb_key += __cfqq->rb_key; | |
644 | } else | |
645 | rb_key += jiffies; | |
646 | } else if (!add_front) { | |
b9c8946b JA |
647 | /* |
648 | * Get our rb key offset. Subtract any residual slice | |
649 | * value carried from last service. A negative resid | |
650 | * count indicates slice overrun, and this should position | |
651 | * the next service time further away in the tree. | |
652 | */ | |
edd75ffd | 653 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
b9c8946b | 654 | rb_key -= cfqq->slice_resid; |
edd75ffd | 655 | cfqq->slice_resid = 0; |
48e025e6 CZ |
656 | } else { |
657 | rb_key = -HZ; | |
aa6f6a3d | 658 | __cfqq = cfq_rb_first(service_tree); |
48e025e6 CZ |
659 | rb_key += __cfqq ? __cfqq->rb_key : jiffies; |
660 | } | |
1da177e4 | 661 | |
d9e7620e | 662 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 663 | /* |
d9e7620e | 664 | * same position, nothing more to do |
99f9628a | 665 | */ |
c0324a02 CZ |
666 | if (rb_key == cfqq->rb_key && |
667 | cfqq->service_tree == service_tree) | |
d9e7620e | 668 | return; |
1da177e4 | 669 | |
aa6f6a3d CZ |
670 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
671 | cfqq->service_tree = NULL; | |
1da177e4 | 672 | } |
d9e7620e | 673 | |
498d3aa2 | 674 | left = 1; |
0871714e | 675 | parent = NULL; |
aa6f6a3d CZ |
676 | cfqq->service_tree = service_tree; |
677 | p = &service_tree->rb.rb_node; | |
d9e7620e | 678 | while (*p) { |
67060e37 | 679 | struct rb_node **n; |
cc09e299 | 680 | |
d9e7620e JA |
681 | parent = *p; |
682 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
683 | ||
0c534e0a | 684 | /* |
c0324a02 | 685 | * sort by key, that represents service time. |
0c534e0a | 686 | */ |
c0324a02 | 687 | if (time_before(rb_key, __cfqq->rb_key)) |
67060e37 | 688 | n = &(*p)->rb_left; |
c0324a02 | 689 | else { |
67060e37 | 690 | n = &(*p)->rb_right; |
cc09e299 | 691 | left = 0; |
c0324a02 | 692 | } |
67060e37 JA |
693 | |
694 | p = n; | |
d9e7620e JA |
695 | } |
696 | ||
cc09e299 | 697 | if (left) |
aa6f6a3d | 698 | service_tree->left = &cfqq->rb_node; |
cc09e299 | 699 | |
d9e7620e JA |
700 | cfqq->rb_key = rb_key; |
701 | rb_link_node(&cfqq->rb_node, parent, p); | |
aa6f6a3d CZ |
702 | rb_insert_color(&cfqq->rb_node, &service_tree->rb); |
703 | service_tree->count++; | |
1da177e4 LT |
704 | } |
705 | ||
a36e71f9 | 706 | static struct cfq_queue * |
f2d1f0ae JA |
707 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
708 | sector_t sector, struct rb_node **ret_parent, | |
709 | struct rb_node ***rb_link) | |
a36e71f9 | 710 | { |
a36e71f9 JA |
711 | struct rb_node **p, *parent; |
712 | struct cfq_queue *cfqq = NULL; | |
713 | ||
714 | parent = NULL; | |
715 | p = &root->rb_node; | |
716 | while (*p) { | |
717 | struct rb_node **n; | |
718 | ||
719 | parent = *p; | |
720 | cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
721 | ||
722 | /* | |
723 | * Sort strictly based on sector. Smallest to the left, | |
724 | * largest to the right. | |
725 | */ | |
2e46e8b2 | 726 | if (sector > blk_rq_pos(cfqq->next_rq)) |
a36e71f9 | 727 | n = &(*p)->rb_right; |
2e46e8b2 | 728 | else if (sector < blk_rq_pos(cfqq->next_rq)) |
a36e71f9 JA |
729 | n = &(*p)->rb_left; |
730 | else | |
731 | break; | |
732 | p = n; | |
3ac6c9f8 | 733 | cfqq = NULL; |
a36e71f9 JA |
734 | } |
735 | ||
736 | *ret_parent = parent; | |
737 | if (rb_link) | |
738 | *rb_link = p; | |
3ac6c9f8 | 739 | return cfqq; |
a36e71f9 JA |
740 | } |
741 | ||
742 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
743 | { | |
a36e71f9 JA |
744 | struct rb_node **p, *parent; |
745 | struct cfq_queue *__cfqq; | |
746 | ||
f2d1f0ae JA |
747 | if (cfqq->p_root) { |
748 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
749 | cfqq->p_root = NULL; | |
750 | } | |
a36e71f9 JA |
751 | |
752 | if (cfq_class_idle(cfqq)) | |
753 | return; | |
754 | if (!cfqq->next_rq) | |
755 | return; | |
756 | ||
f2d1f0ae | 757 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
2e46e8b2 TH |
758 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
759 | blk_rq_pos(cfqq->next_rq), &parent, &p); | |
3ac6c9f8 JA |
760 | if (!__cfqq) { |
761 | rb_link_node(&cfqq->p_node, parent, p); | |
f2d1f0ae JA |
762 | rb_insert_color(&cfqq->p_node, cfqq->p_root); |
763 | } else | |
764 | cfqq->p_root = NULL; | |
a36e71f9 JA |
765 | } |
766 | ||
498d3aa2 JA |
767 | /* |
768 | * Update cfqq's position in the service tree. | |
769 | */ | |
edd75ffd | 770 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
6d048f53 | 771 | { |
6d048f53 JA |
772 | /* |
773 | * Resorting requires the cfqq to be on the RR list already. | |
774 | */ | |
a36e71f9 | 775 | if (cfq_cfqq_on_rr(cfqq)) { |
edd75ffd | 776 | cfq_service_tree_add(cfqd, cfqq, 0); |
a36e71f9 JA |
777 | cfq_prio_tree_add(cfqd, cfqq); |
778 | } | |
6d048f53 JA |
779 | } |
780 | ||
1da177e4 LT |
781 | /* |
782 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 783 | * the pending list according to last request service |
1da177e4 | 784 | */ |
febffd61 | 785 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 786 | { |
7b679138 | 787 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
3b18152c JA |
788 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
789 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
790 | cfqd->busy_queues++; |
791 | ||
edd75ffd | 792 | cfq_resort_rr_list(cfqd, cfqq); |
1da177e4 LT |
793 | } |
794 | ||
498d3aa2 JA |
795 | /* |
796 | * Called when the cfqq no longer has requests pending, remove it from | |
797 | * the service tree. | |
798 | */ | |
febffd61 | 799 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 800 | { |
7b679138 | 801 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
3b18152c JA |
802 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
803 | cfq_clear_cfqq_on_rr(cfqq); | |
1da177e4 | 804 | |
aa6f6a3d CZ |
805 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
806 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); | |
807 | cfqq->service_tree = NULL; | |
808 | } | |
f2d1f0ae JA |
809 | if (cfqq->p_root) { |
810 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
811 | cfqq->p_root = NULL; | |
812 | } | |
d9e7620e | 813 | |
1da177e4 LT |
814 | BUG_ON(!cfqd->busy_queues); |
815 | cfqd->busy_queues--; | |
816 | } | |
817 | ||
818 | /* | |
819 | * rb tree support functions | |
820 | */ | |
febffd61 | 821 | static void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 822 | { |
5e705374 | 823 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 824 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 825 | const int sync = rq_is_sync(rq); |
1da177e4 | 826 | |
b4878f24 JA |
827 | BUG_ON(!cfqq->queued[sync]); |
828 | cfqq->queued[sync]--; | |
1da177e4 | 829 | |
5e705374 | 830 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 831 | |
dd67d051 | 832 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 833 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
834 | } |
835 | ||
5e705374 | 836 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 837 | { |
5e705374 | 838 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 839 | struct cfq_data *cfqd = cfqq->cfqd; |
a36e71f9 | 840 | struct request *__alias, *prev; |
1da177e4 | 841 | |
5380a101 | 842 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
843 | |
844 | /* | |
845 | * looks a little odd, but the first insert might return an alias. | |
846 | * if that happens, put the alias on the dispatch list | |
847 | */ | |
21183b07 | 848 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 849 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
850 | |
851 | if (!cfq_cfqq_on_rr(cfqq)) | |
852 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
853 | |
854 | /* | |
855 | * check if this request is a better next-serve candidate | |
856 | */ | |
a36e71f9 | 857 | prev = cfqq->next_rq; |
cf7c25cf | 858 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); |
a36e71f9 JA |
859 | |
860 | /* | |
861 | * adjust priority tree position, if ->next_rq changes | |
862 | */ | |
863 | if (prev != cfqq->next_rq) | |
864 | cfq_prio_tree_add(cfqd, cfqq); | |
865 | ||
5044eed4 | 866 | BUG_ON(!cfqq->next_rq); |
1da177e4 LT |
867 | } |
868 | ||
febffd61 | 869 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 870 | { |
5380a101 JA |
871 | elv_rb_del(&cfqq->sort_list, rq); |
872 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 873 | cfq_add_rq_rb(rq); |
1da177e4 LT |
874 | } |
875 | ||
206dc69b JA |
876 | static struct request * |
877 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 878 | { |
206dc69b | 879 | struct task_struct *tsk = current; |
91fac317 | 880 | struct cfq_io_context *cic; |
206dc69b | 881 | struct cfq_queue *cfqq; |
1da177e4 | 882 | |
4ac845a2 | 883 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
884 | if (!cic) |
885 | return NULL; | |
886 | ||
887 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
89850f7e JA |
888 | if (cfqq) { |
889 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
890 | ||
21183b07 | 891 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 892 | } |
1da177e4 | 893 | |
1da177e4 LT |
894 | return NULL; |
895 | } | |
896 | ||
165125e1 | 897 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 898 | { |
22e2c507 | 899 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 900 | |
5ad531db | 901 | cfqd->rq_in_driver[rq_is_sync(rq)]++; |
7b679138 | 902 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
5ad531db | 903 | rq_in_driver(cfqd)); |
25776e35 | 904 | |
5b93629b | 905 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
1da177e4 LT |
906 | } |
907 | ||
165125e1 | 908 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 909 | { |
b4878f24 | 910 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5ad531db | 911 | const int sync = rq_is_sync(rq); |
b4878f24 | 912 | |
5ad531db JA |
913 | WARN_ON(!cfqd->rq_in_driver[sync]); |
914 | cfqd->rq_in_driver[sync]--; | |
7b679138 | 915 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
5ad531db | 916 | rq_in_driver(cfqd)); |
1da177e4 LT |
917 | } |
918 | ||
b4878f24 | 919 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 920 | { |
5e705374 | 921 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 922 | |
5e705374 JA |
923 | if (cfqq->next_rq == rq) |
924 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 925 | |
b4878f24 | 926 | list_del_init(&rq->queuelist); |
5e705374 | 927 | cfq_del_rq_rb(rq); |
374f84ac | 928 | |
45333d5a | 929 | cfqq->cfqd->rq_queued--; |
374f84ac JA |
930 | if (rq_is_meta(rq)) { |
931 | WARN_ON(!cfqq->meta_pending); | |
932 | cfqq->meta_pending--; | |
933 | } | |
1da177e4 LT |
934 | } |
935 | ||
165125e1 JA |
936 | static int cfq_merge(struct request_queue *q, struct request **req, |
937 | struct bio *bio) | |
1da177e4 LT |
938 | { |
939 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
940 | struct request *__rq; | |
1da177e4 | 941 | |
206dc69b | 942 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 943 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
944 | *req = __rq; |
945 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
946 | } |
947 | ||
948 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
949 | } |
950 | ||
165125e1 | 951 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
21183b07 | 952 | int type) |
1da177e4 | 953 | { |
21183b07 | 954 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 955 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 956 | |
5e705374 | 957 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 958 | } |
1da177e4 LT |
959 | } |
960 | ||
961 | static void | |
165125e1 | 962 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
963 | struct request *next) |
964 | { | |
cf7c25cf | 965 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 JA |
966 | /* |
967 | * reposition in fifo if next is older than rq | |
968 | */ | |
969 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
30996f40 | 970 | time_before(rq_fifo_time(next), rq_fifo_time(rq))) { |
22e2c507 | 971 | list_move(&rq->queuelist, &next->queuelist); |
30996f40 JA |
972 | rq_set_fifo_time(rq, rq_fifo_time(next)); |
973 | } | |
22e2c507 | 974 | |
cf7c25cf CZ |
975 | if (cfqq->next_rq == next) |
976 | cfqq->next_rq = rq; | |
b4878f24 | 977 | cfq_remove_request(next); |
22e2c507 JA |
978 | } |
979 | ||
165125e1 | 980 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
da775265 JA |
981 | struct bio *bio) |
982 | { | |
983 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
91fac317 | 984 | struct cfq_io_context *cic; |
da775265 | 985 | struct cfq_queue *cfqq; |
da775265 JA |
986 | |
987 | /* | |
ec8acb69 | 988 | * Disallow merge of a sync bio into an async request. |
da775265 | 989 | */ |
91fac317 | 990 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
a6151c3a | 991 | return false; |
da775265 JA |
992 | |
993 | /* | |
719d3402 JA |
994 | * Lookup the cfqq that this bio will be queued with. Allow |
995 | * merge only if rq is queued there. | |
da775265 | 996 | */ |
4ac845a2 | 997 | cic = cfq_cic_lookup(cfqd, current->io_context); |
91fac317 | 998 | if (!cic) |
a6151c3a | 999 | return false; |
719d3402 | 1000 | |
91fac317 | 1001 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
a6151c3a | 1002 | return cfqq == RQ_CFQQ(rq); |
da775265 JA |
1003 | } |
1004 | ||
febffd61 JA |
1005 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
1006 | struct cfq_queue *cfqq) | |
22e2c507 JA |
1007 | { |
1008 | if (cfqq) { | |
7b679138 | 1009 | cfq_log_cfqq(cfqd, cfqq, "set_active"); |
22e2c507 | 1010 | cfqq->slice_end = 0; |
2f5cb738 JA |
1011 | cfqq->slice_dispatch = 0; |
1012 | ||
2f5cb738 | 1013 | cfq_clear_cfqq_wait_request(cfqq); |
b029195d | 1014 | cfq_clear_cfqq_must_dispatch(cfqq); |
3b18152c JA |
1015 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
1016 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 1017 | cfq_mark_cfqq_slice_new(cfqq); |
2f5cb738 JA |
1018 | |
1019 | del_timer(&cfqd->idle_slice_timer); | |
22e2c507 JA |
1020 | } |
1021 | ||
1022 | cfqd->active_queue = cfqq; | |
1023 | } | |
1024 | ||
7b14e3b5 JA |
1025 | /* |
1026 | * current cfqq expired its slice (or was too idle), select new one | |
1027 | */ | |
1028 | static void | |
1029 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
a6151c3a | 1030 | bool timed_out) |
7b14e3b5 | 1031 | { |
7b679138 JA |
1032 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
1033 | ||
7b14e3b5 JA |
1034 | if (cfq_cfqq_wait_request(cfqq)) |
1035 | del_timer(&cfqd->idle_slice_timer); | |
1036 | ||
7b14e3b5 JA |
1037 | cfq_clear_cfqq_wait_request(cfqq); |
1038 | ||
1039 | /* | |
6084cdda | 1040 | * store what was left of this slice, if the queue idled/timed out |
7b14e3b5 | 1041 | */ |
7b679138 | 1042 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) { |
c5b680f3 | 1043 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b679138 JA |
1044 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
1045 | } | |
7b14e3b5 | 1046 | |
edd75ffd | 1047 | cfq_resort_rr_list(cfqd, cfqq); |
7b14e3b5 JA |
1048 | |
1049 | if (cfqq == cfqd->active_queue) | |
1050 | cfqd->active_queue = NULL; | |
1051 | ||
1052 | if (cfqd->active_cic) { | |
1053 | put_io_context(cfqd->active_cic->ioc); | |
1054 | cfqd->active_cic = NULL; | |
1055 | } | |
7b14e3b5 JA |
1056 | } |
1057 | ||
a6151c3a | 1058 | static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) |
7b14e3b5 JA |
1059 | { |
1060 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1061 | ||
1062 | if (cfqq) | |
6084cdda | 1063 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
7b14e3b5 JA |
1064 | } |
1065 | ||
498d3aa2 JA |
1066 | /* |
1067 | * Get next queue for service. Unless we have a queue preemption, | |
1068 | * we'll simply select the first cfqq in the service tree. | |
1069 | */ | |
6d048f53 | 1070 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 1071 | { |
c0324a02 | 1072 | struct cfq_rb_root *service_tree = |
718eee05 | 1073 | service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd); |
d9e7620e | 1074 | |
c0324a02 CZ |
1075 | if (RB_EMPTY_ROOT(&service_tree->rb)) |
1076 | return NULL; | |
1077 | return cfq_rb_first(service_tree); | |
6d048f53 JA |
1078 | } |
1079 | ||
498d3aa2 JA |
1080 | /* |
1081 | * Get and set a new active queue for service. | |
1082 | */ | |
a36e71f9 JA |
1083 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
1084 | struct cfq_queue *cfqq) | |
6d048f53 | 1085 | { |
e00ef799 | 1086 | if (!cfqq) |
a36e71f9 | 1087 | cfqq = cfq_get_next_queue(cfqd); |
6d048f53 | 1088 | |
22e2c507 | 1089 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 1090 | return cfqq; |
22e2c507 JA |
1091 | } |
1092 | ||
d9e7620e JA |
1093 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
1094 | struct request *rq) | |
1095 | { | |
83096ebf TH |
1096 | if (blk_rq_pos(rq) >= cfqd->last_position) |
1097 | return blk_rq_pos(rq) - cfqd->last_position; | |
d9e7620e | 1098 | else |
83096ebf | 1099 | return cfqd->last_position - blk_rq_pos(rq); |
d9e7620e JA |
1100 | } |
1101 | ||
b2c18e1e JM |
1102 | #define CFQQ_SEEK_THR 8 * 1024 |
1103 | #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR) | |
04dc6e71 | 1104 | |
b2c18e1e JM |
1105 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1106 | struct request *rq) | |
6d048f53 | 1107 | { |
b2c18e1e | 1108 | sector_t sdist = cfqq->seek_mean; |
6d048f53 | 1109 | |
b2c18e1e JM |
1110 | if (!sample_valid(cfqq->seek_samples)) |
1111 | sdist = CFQQ_SEEK_THR; | |
6d048f53 | 1112 | |
04dc6e71 | 1113 | return cfq_dist_from_last(cfqd, rq) <= sdist; |
6d048f53 JA |
1114 | } |
1115 | ||
a36e71f9 JA |
1116 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
1117 | struct cfq_queue *cur_cfqq) | |
1118 | { | |
f2d1f0ae | 1119 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
a36e71f9 JA |
1120 | struct rb_node *parent, *node; |
1121 | struct cfq_queue *__cfqq; | |
1122 | sector_t sector = cfqd->last_position; | |
1123 | ||
1124 | if (RB_EMPTY_ROOT(root)) | |
1125 | return NULL; | |
1126 | ||
1127 | /* | |
1128 | * First, if we find a request starting at the end of the last | |
1129 | * request, choose it. | |
1130 | */ | |
f2d1f0ae | 1131 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
a36e71f9 JA |
1132 | if (__cfqq) |
1133 | return __cfqq; | |
1134 | ||
1135 | /* | |
1136 | * If the exact sector wasn't found, the parent of the NULL leaf | |
1137 | * will contain the closest sector. | |
1138 | */ | |
1139 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
b2c18e1e | 1140 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1141 | return __cfqq; |
1142 | ||
2e46e8b2 | 1143 | if (blk_rq_pos(__cfqq->next_rq) < sector) |
a36e71f9 JA |
1144 | node = rb_next(&__cfqq->p_node); |
1145 | else | |
1146 | node = rb_prev(&__cfqq->p_node); | |
1147 | if (!node) | |
1148 | return NULL; | |
1149 | ||
1150 | __cfqq = rb_entry(node, struct cfq_queue, p_node); | |
b2c18e1e | 1151 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1152 | return __cfqq; |
1153 | ||
1154 | return NULL; | |
1155 | } | |
1156 | ||
1157 | /* | |
1158 | * cfqd - obvious | |
1159 | * cur_cfqq - passed in so that we don't decide that the current queue is | |
1160 | * closely cooperating with itself. | |
1161 | * | |
1162 | * So, basically we're assuming that that cur_cfqq has dispatched at least | |
1163 | * one request, and that cfqd->last_position reflects a position on the disk | |
1164 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid | |
1165 | * assumption. | |
1166 | */ | |
1167 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, | |
b3b6d040 | 1168 | struct cfq_queue *cur_cfqq) |
6d048f53 | 1169 | { |
a36e71f9 JA |
1170 | struct cfq_queue *cfqq; |
1171 | ||
e6c5bc73 JM |
1172 | if (!cfq_cfqq_sync(cur_cfqq)) |
1173 | return NULL; | |
1174 | if (CFQQ_SEEKY(cur_cfqq)) | |
1175 | return NULL; | |
1176 | ||
6d048f53 | 1177 | /* |
d9e7620e JA |
1178 | * We should notice if some of the queues are cooperating, eg |
1179 | * working closely on the same area of the disk. In that case, | |
1180 | * we can group them together and don't waste time idling. | |
6d048f53 | 1181 | */ |
a36e71f9 JA |
1182 | cfqq = cfqq_close(cfqd, cur_cfqq); |
1183 | if (!cfqq) | |
1184 | return NULL; | |
1185 | ||
df5fe3e8 JM |
1186 | /* |
1187 | * It only makes sense to merge sync queues. | |
1188 | */ | |
1189 | if (!cfq_cfqq_sync(cfqq)) | |
1190 | return NULL; | |
e6c5bc73 JM |
1191 | if (CFQQ_SEEKY(cfqq)) |
1192 | return NULL; | |
df5fe3e8 | 1193 | |
c0324a02 CZ |
1194 | /* |
1195 | * Do not merge queues of different priority classes | |
1196 | */ | |
1197 | if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) | |
1198 | return NULL; | |
1199 | ||
a36e71f9 | 1200 | return cfqq; |
6d048f53 JA |
1201 | } |
1202 | ||
a6d44e98 CZ |
1203 | /* |
1204 | * Determine whether we should enforce idle window for this queue. | |
1205 | */ | |
1206 | ||
1207 | static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1208 | { | |
1209 | enum wl_prio_t prio = cfqq_prio(cfqq); | |
718eee05 | 1210 | struct cfq_rb_root *service_tree = cfqq->service_tree; |
a6d44e98 CZ |
1211 | |
1212 | /* We never do for idle class queues. */ | |
1213 | if (prio == IDLE_WORKLOAD) | |
1214 | return false; | |
1215 | ||
1216 | /* We do for queues that were marked with idle window flag. */ | |
1217 | if (cfq_cfqq_idle_window(cfqq)) | |
1218 | return true; | |
1219 | ||
1220 | /* | |
1221 | * Otherwise, we do only if they are the last ones | |
1222 | * in their service tree. | |
1223 | */ | |
718eee05 CZ |
1224 | if (!service_tree) |
1225 | service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd); | |
1226 | ||
a6d44e98 CZ |
1227 | if (service_tree->count == 0) |
1228 | return true; | |
1229 | ||
1230 | return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq); | |
1231 | } | |
1232 | ||
6d048f53 | 1233 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 1234 | { |
1792669c | 1235 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 1236 | struct cfq_io_context *cic; |
7b14e3b5 JA |
1237 | unsigned long sl; |
1238 | ||
a68bbddb | 1239 | /* |
f7d7b7a7 JA |
1240 | * SSD device without seek penalty, disable idling. But only do so |
1241 | * for devices that support queuing, otherwise we still have a problem | |
1242 | * with sync vs async workloads. | |
a68bbddb | 1243 | */ |
f7d7b7a7 | 1244 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
a68bbddb JA |
1245 | return; |
1246 | ||
dd67d051 | 1247 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 1248 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
1249 | |
1250 | /* | |
1251 | * idle is disabled, either manually or by past process history | |
1252 | */ | |
a6d44e98 | 1253 | if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq)) |
6d048f53 JA |
1254 | return; |
1255 | ||
7b679138 | 1256 | /* |
8e550632 | 1257 | * still active requests from this queue, don't idle |
7b679138 | 1258 | */ |
8e550632 | 1259 | if (cfqq->dispatched) |
7b679138 JA |
1260 | return; |
1261 | ||
22e2c507 JA |
1262 | /* |
1263 | * task has exited, don't wait | |
1264 | */ | |
206dc69b | 1265 | cic = cfqd->active_cic; |
66dac98e | 1266 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
6d048f53 JA |
1267 | return; |
1268 | ||
355b659c CZ |
1269 | /* |
1270 | * If our average think time is larger than the remaining time | |
1271 | * slice, then don't idle. This avoids overrunning the allotted | |
1272 | * time slice. | |
1273 | */ | |
1274 | if (sample_valid(cic->ttime_samples) && | |
1275 | (cfqq->slice_end - jiffies < cic->ttime_mean)) | |
1276 | return; | |
1277 | ||
3b18152c | 1278 | cfq_mark_cfqq_wait_request(cfqq); |
22e2c507 | 1279 | |
6d048f53 | 1280 | sl = cfqd->cfq_slice_idle; |
206dc69b | 1281 | |
7b14e3b5 | 1282 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
9481ffdc | 1283 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); |
1da177e4 LT |
1284 | } |
1285 | ||
498d3aa2 JA |
1286 | /* |
1287 | * Move request from internal lists to the request queue dispatch list. | |
1288 | */ | |
165125e1 | 1289 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
1da177e4 | 1290 | { |
3ed9a296 | 1291 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1292 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 1293 | |
7b679138 JA |
1294 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
1295 | ||
06d21886 | 1296 | cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
5380a101 | 1297 | cfq_remove_request(rq); |
6d048f53 | 1298 | cfqq->dispatched++; |
5380a101 | 1299 | elv_dispatch_sort(q, rq); |
3ed9a296 JA |
1300 | |
1301 | if (cfq_cfqq_sync(cfqq)) | |
1302 | cfqd->sync_flight++; | |
1da177e4 LT |
1303 | } |
1304 | ||
1305 | /* | |
1306 | * return expired entry, or NULL to just start from scratch in rbtree | |
1307 | */ | |
febffd61 | 1308 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 | 1309 | { |
30996f40 | 1310 | struct request *rq = NULL; |
1da177e4 | 1311 | |
3b18152c | 1312 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 1313 | return NULL; |
cb887411 JA |
1314 | |
1315 | cfq_mark_cfqq_fifo_expire(cfqq); | |
1316 | ||
89850f7e JA |
1317 | if (list_empty(&cfqq->fifo)) |
1318 | return NULL; | |
1da177e4 | 1319 | |
89850f7e | 1320 | rq = rq_entry_fifo(cfqq->fifo.next); |
30996f40 | 1321 | if (time_before(jiffies, rq_fifo_time(rq))) |
7b679138 | 1322 | rq = NULL; |
1da177e4 | 1323 | |
30996f40 | 1324 | cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); |
6d048f53 | 1325 | return rq; |
1da177e4 LT |
1326 | } |
1327 | ||
22e2c507 JA |
1328 | static inline int |
1329 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1330 | { | |
1331 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1332 | |
22e2c507 | 1333 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1334 | |
22e2c507 | 1335 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1336 | } |
1337 | ||
df5fe3e8 JM |
1338 | /* |
1339 | * Must be called with the queue_lock held. | |
1340 | */ | |
1341 | static int cfqq_process_refs(struct cfq_queue *cfqq) | |
1342 | { | |
1343 | int process_refs, io_refs; | |
1344 | ||
1345 | io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; | |
1346 | process_refs = atomic_read(&cfqq->ref) - io_refs; | |
1347 | BUG_ON(process_refs < 0); | |
1348 | return process_refs; | |
1349 | } | |
1350 | ||
1351 | static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) | |
1352 | { | |
e6c5bc73 | 1353 | int process_refs, new_process_refs; |
df5fe3e8 JM |
1354 | struct cfq_queue *__cfqq; |
1355 | ||
1356 | /* Avoid a circular list and skip interim queue merges */ | |
1357 | while ((__cfqq = new_cfqq->new_cfqq)) { | |
1358 | if (__cfqq == cfqq) | |
1359 | return; | |
1360 | new_cfqq = __cfqq; | |
1361 | } | |
1362 | ||
1363 | process_refs = cfqq_process_refs(cfqq); | |
1364 | /* | |
1365 | * If the process for the cfqq has gone away, there is no | |
1366 | * sense in merging the queues. | |
1367 | */ | |
1368 | if (process_refs == 0) | |
1369 | return; | |
1370 | ||
e6c5bc73 JM |
1371 | /* |
1372 | * Merge in the direction of the lesser amount of work. | |
1373 | */ | |
1374 | new_process_refs = cfqq_process_refs(new_cfqq); | |
1375 | if (new_process_refs >= process_refs) { | |
1376 | cfqq->new_cfqq = new_cfqq; | |
1377 | atomic_add(process_refs, &new_cfqq->ref); | |
1378 | } else { | |
1379 | new_cfqq->new_cfqq = cfqq; | |
1380 | atomic_add(new_process_refs, &cfqq->ref); | |
1381 | } | |
df5fe3e8 JM |
1382 | } |
1383 | ||
718eee05 CZ |
1384 | static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio, |
1385 | bool prio_changed) | |
1386 | { | |
1387 | struct cfq_queue *queue; | |
1388 | int i; | |
1389 | bool key_valid = false; | |
1390 | unsigned long lowest_key = 0; | |
1391 | enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; | |
1392 | ||
1393 | if (prio_changed) { | |
1394 | /* | |
1395 | * When priorities switched, we prefer starting | |
1396 | * from SYNC_NOIDLE (first choice), or just SYNC | |
1397 | * over ASYNC | |
1398 | */ | |
1399 | if (service_tree_for(prio, cur_best, cfqd)->count) | |
1400 | return cur_best; | |
1401 | cur_best = SYNC_WORKLOAD; | |
1402 | if (service_tree_for(prio, cur_best, cfqd)->count) | |
1403 | return cur_best; | |
1404 | ||
1405 | return ASYNC_WORKLOAD; | |
1406 | } | |
1407 | ||
1408 | for (i = 0; i < 3; ++i) { | |
1409 | /* otherwise, select the one with lowest rb_key */ | |
1410 | queue = cfq_rb_first(service_tree_for(prio, i, cfqd)); | |
1411 | if (queue && | |
1412 | (!key_valid || time_before(queue->rb_key, lowest_key))) { | |
1413 | lowest_key = queue->rb_key; | |
1414 | cur_best = i; | |
1415 | key_valid = true; | |
1416 | } | |
1417 | } | |
1418 | ||
1419 | return cur_best; | |
1420 | } | |
1421 | ||
1422 | static void choose_service_tree(struct cfq_data *cfqd) | |
1423 | { | |
1424 | enum wl_prio_t previous_prio = cfqd->serving_prio; | |
1425 | bool prio_changed; | |
1426 | unsigned slice; | |
1427 | unsigned count; | |
1428 | ||
1429 | /* Choose next priority. RT > BE > IDLE */ | |
1430 | if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd)) | |
1431 | cfqd->serving_prio = RT_WORKLOAD; | |
1432 | else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd)) | |
1433 | cfqd->serving_prio = BE_WORKLOAD; | |
1434 | else { | |
1435 | cfqd->serving_prio = IDLE_WORKLOAD; | |
1436 | cfqd->workload_expires = jiffies + 1; | |
1437 | return; | |
1438 | } | |
1439 | ||
1440 | /* | |
1441 | * For RT and BE, we have to choose also the type | |
1442 | * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload | |
1443 | * expiration time | |
1444 | */ | |
1445 | prio_changed = (cfqd->serving_prio != previous_prio); | |
1446 | count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) | |
1447 | ->count; | |
1448 | ||
1449 | /* | |
1450 | * If priority didn't change, check workload expiration, | |
1451 | * and that we still have other queues ready | |
1452 | */ | |
1453 | if (!prio_changed && count && | |
1454 | !time_after(jiffies, cfqd->workload_expires)) | |
1455 | return; | |
1456 | ||
1457 | /* otherwise select new workload type */ | |
1458 | cfqd->serving_type = | |
1459 | cfq_choose_wl(cfqd, cfqd->serving_prio, prio_changed); | |
1460 | count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) | |
1461 | ->count; | |
1462 | ||
1463 | /* | |
1464 | * the workload slice is computed as a fraction of target latency | |
1465 | * proportional to the number of queues in that workload, over | |
1466 | * all the queues in the same priority class | |
1467 | */ | |
1468 | slice = cfq_target_latency * count / | |
1469 | max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio], | |
1470 | cfq_busy_queues_wl(cfqd->serving_prio, cfqd)); | |
1471 | ||
1472 | if (cfqd->serving_type == ASYNC_WORKLOAD) | |
1473 | /* async workload slice is scaled down according to | |
1474 | * the sync/async slice ratio. */ | |
1475 | slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; | |
1476 | else | |
1477 | /* sync workload slice is at least 2 * cfq_slice_idle */ | |
1478 | slice = max(slice, 2 * cfqd->cfq_slice_idle); | |
1479 | ||
1480 | slice = max_t(unsigned, slice, CFQ_MIN_TT); | |
1481 | cfqd->workload_expires = jiffies + slice; | |
8e550632 | 1482 | cfqd->noidle_tree_requires_idle = false; |
718eee05 CZ |
1483 | } |
1484 | ||
22e2c507 | 1485 | /* |
498d3aa2 JA |
1486 | * Select a queue for service. If we have a current active queue, |
1487 | * check whether to continue servicing it, or retrieve and set a new one. | |
22e2c507 | 1488 | */ |
1b5ed5e1 | 1489 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1490 | { |
a36e71f9 | 1491 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
1da177e4 | 1492 | |
22e2c507 JA |
1493 | cfqq = cfqd->active_queue; |
1494 | if (!cfqq) | |
1495 | goto new_queue; | |
1da177e4 | 1496 | |
22e2c507 | 1497 | /* |
6d048f53 | 1498 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 1499 | */ |
b029195d | 1500 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) |
3b18152c | 1501 | goto expire; |
1da177e4 | 1502 | |
22e2c507 | 1503 | /* |
6d048f53 JA |
1504 | * The active queue has requests and isn't expired, allow it to |
1505 | * dispatch. | |
22e2c507 | 1506 | */ |
dd67d051 | 1507 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 1508 | goto keep_queue; |
6d048f53 | 1509 | |
a36e71f9 JA |
1510 | /* |
1511 | * If another queue has a request waiting within our mean seek | |
1512 | * distance, let it run. The expire code will check for close | |
1513 | * cooperators and put the close queue at the front of the service | |
df5fe3e8 | 1514 | * tree. If possible, merge the expiring queue with the new cfqq. |
a36e71f9 | 1515 | */ |
b3b6d040 | 1516 | new_cfqq = cfq_close_cooperator(cfqd, cfqq); |
df5fe3e8 JM |
1517 | if (new_cfqq) { |
1518 | if (!cfqq->new_cfqq) | |
1519 | cfq_setup_merge(cfqq, new_cfqq); | |
a36e71f9 | 1520 | goto expire; |
df5fe3e8 | 1521 | } |
a36e71f9 | 1522 | |
6d048f53 JA |
1523 | /* |
1524 | * No requests pending. If the active queue still has requests in | |
1525 | * flight or is idling for a new request, allow either of these | |
1526 | * conditions to happen (or time out) before selecting a new queue. | |
1527 | */ | |
cc197479 | 1528 | if (timer_pending(&cfqd->idle_slice_timer) || |
a6d44e98 | 1529 | (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) { |
caaa5f9f JA |
1530 | cfqq = NULL; |
1531 | goto keep_queue; | |
22e2c507 JA |
1532 | } |
1533 | ||
3b18152c | 1534 | expire: |
6084cdda | 1535 | cfq_slice_expired(cfqd, 0); |
3b18152c | 1536 | new_queue: |
718eee05 CZ |
1537 | /* |
1538 | * Current queue expired. Check if we have to switch to a new | |
1539 | * service tree | |
1540 | */ | |
1541 | if (!new_cfqq) | |
1542 | choose_service_tree(cfqd); | |
1543 | ||
a36e71f9 | 1544 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
22e2c507 | 1545 | keep_queue: |
3b18152c | 1546 | return cfqq; |
22e2c507 JA |
1547 | } |
1548 | ||
febffd61 | 1549 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
d9e7620e JA |
1550 | { |
1551 | int dispatched = 0; | |
1552 | ||
1553 | while (cfqq->next_rq) { | |
1554 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1555 | dispatched++; | |
1556 | } | |
1557 | ||
1558 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1559 | return dispatched; | |
1560 | } | |
1561 | ||
498d3aa2 JA |
1562 | /* |
1563 | * Drain our current requests. Used for barriers and when switching | |
1564 | * io schedulers on-the-fly. | |
1565 | */ | |
d9e7620e | 1566 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1567 | { |
0871714e | 1568 | struct cfq_queue *cfqq; |
d9e7620e | 1569 | int dispatched = 0; |
718eee05 | 1570 | int i, j; |
c0324a02 | 1571 | for (i = 0; i < 2; ++i) |
718eee05 CZ |
1572 | for (j = 0; j < 3; ++j) |
1573 | while ((cfqq = cfq_rb_first(&cfqd->service_trees[i][j])) | |
1574 | != NULL) | |
1575 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); | |
1b5ed5e1 | 1576 | |
c0324a02 | 1577 | while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL) |
d9e7620e | 1578 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
1b5ed5e1 | 1579 | |
6084cdda | 1580 | cfq_slice_expired(cfqd, 0); |
1b5ed5e1 TH |
1581 | |
1582 | BUG_ON(cfqd->busy_queues); | |
1583 | ||
6923715a | 1584 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
1b5ed5e1 TH |
1585 | return dispatched; |
1586 | } | |
1587 | ||
0b182d61 | 1588 | static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2f5cb738 | 1589 | { |
2f5cb738 | 1590 | unsigned int max_dispatch; |
22e2c507 | 1591 | |
5ad531db JA |
1592 | /* |
1593 | * Drain async requests before we start sync IO | |
1594 | */ | |
a6d44e98 | 1595 | if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) |
0b182d61 | 1596 | return false; |
5ad531db | 1597 | |
2f5cb738 JA |
1598 | /* |
1599 | * If this is an async queue and we have sync IO in flight, let it wait | |
1600 | */ | |
1601 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) | |
0b182d61 | 1602 | return false; |
2f5cb738 JA |
1603 | |
1604 | max_dispatch = cfqd->cfq_quantum; | |
1605 | if (cfq_class_idle(cfqq)) | |
1606 | max_dispatch = 1; | |
b4878f24 | 1607 | |
2f5cb738 JA |
1608 | /* |
1609 | * Does this cfqq already have too much IO in flight? | |
1610 | */ | |
1611 | if (cfqq->dispatched >= max_dispatch) { | |
1612 | /* | |
1613 | * idle queue must always only have a single IO in flight | |
1614 | */ | |
3ed9a296 | 1615 | if (cfq_class_idle(cfqq)) |
0b182d61 | 1616 | return false; |
3ed9a296 | 1617 | |
2f5cb738 JA |
1618 | /* |
1619 | * We have other queues, don't allow more IO from this one | |
1620 | */ | |
1621 | if (cfqd->busy_queues > 1) | |
0b182d61 | 1622 | return false; |
9ede209e | 1623 | |
365722bb | 1624 | /* |
8e296755 | 1625 | * Sole queue user, allow bigger slice |
365722bb | 1626 | */ |
8e296755 JA |
1627 | max_dispatch *= 4; |
1628 | } | |
1629 | ||
1630 | /* | |
1631 | * Async queues must wait a bit before being allowed dispatch. | |
1632 | * We also ramp up the dispatch depth gradually for async IO, | |
1633 | * based on the last sync IO we serviced | |
1634 | */ | |
963b72fc | 1635 | if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
8e296755 JA |
1636 | unsigned long last_sync = jiffies - cfqd->last_end_sync_rq; |
1637 | unsigned int depth; | |
365722bb | 1638 | |
61f0c1dc | 1639 | depth = last_sync / cfqd->cfq_slice[1]; |
e00c54c3 JA |
1640 | if (!depth && !cfqq->dispatched) |
1641 | depth = 1; | |
8e296755 JA |
1642 | if (depth < max_dispatch) |
1643 | max_dispatch = depth; | |
2f5cb738 | 1644 | } |
3ed9a296 | 1645 | |
0b182d61 JA |
1646 | /* |
1647 | * If we're below the current max, allow a dispatch | |
1648 | */ | |
1649 | return cfqq->dispatched < max_dispatch; | |
1650 | } | |
1651 | ||
1652 | /* | |
1653 | * Dispatch a request from cfqq, moving them to the request queue | |
1654 | * dispatch list. | |
1655 | */ | |
1656 | static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1657 | { | |
1658 | struct request *rq; | |
1659 | ||
1660 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); | |
1661 | ||
1662 | if (!cfq_may_dispatch(cfqd, cfqq)) | |
1663 | return false; | |
1664 | ||
1665 | /* | |
1666 | * follow expired path, else get first next available | |
1667 | */ | |
1668 | rq = cfq_check_fifo(cfqq); | |
1669 | if (!rq) | |
1670 | rq = cfqq->next_rq; | |
1671 | ||
1672 | /* | |
1673 | * insert request into driver dispatch list | |
1674 | */ | |
1675 | cfq_dispatch_insert(cfqd->queue, rq); | |
1676 | ||
1677 | if (!cfqd->active_cic) { | |
1678 | struct cfq_io_context *cic = RQ_CIC(rq); | |
1679 | ||
1680 | atomic_long_inc(&cic->ioc->refcount); | |
1681 | cfqd->active_cic = cic; | |
1682 | } | |
1683 | ||
1684 | return true; | |
1685 | } | |
1686 | ||
1687 | /* | |
1688 | * Find the cfqq that we need to service and move a request from that to the | |
1689 | * dispatch list | |
1690 | */ | |
1691 | static int cfq_dispatch_requests(struct request_queue *q, int force) | |
1692 | { | |
1693 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1694 | struct cfq_queue *cfqq; | |
1695 | ||
1696 | if (!cfqd->busy_queues) | |
1697 | return 0; | |
1698 | ||
1699 | if (unlikely(force)) | |
1700 | return cfq_forced_dispatch(cfqd); | |
1701 | ||
1702 | cfqq = cfq_select_queue(cfqd); | |
1703 | if (!cfqq) | |
8e296755 JA |
1704 | return 0; |
1705 | ||
2f5cb738 | 1706 | /* |
0b182d61 | 1707 | * Dispatch a request from this cfqq, if it is allowed |
2f5cb738 | 1708 | */ |
0b182d61 JA |
1709 | if (!cfq_dispatch_request(cfqd, cfqq)) |
1710 | return 0; | |
1711 | ||
2f5cb738 | 1712 | cfqq->slice_dispatch++; |
b029195d | 1713 | cfq_clear_cfqq_must_dispatch(cfqq); |
22e2c507 | 1714 | |
2f5cb738 JA |
1715 | /* |
1716 | * expire an async queue immediately if it has used up its slice. idle | |
1717 | * queue always expire after 1 dispatch round. | |
1718 | */ | |
1719 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && | |
1720 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1721 | cfq_class_idle(cfqq))) { | |
1722 | cfqq->slice_end = jiffies + 1; | |
1723 | cfq_slice_expired(cfqd, 0); | |
1da177e4 LT |
1724 | } |
1725 | ||
b217a903 | 1726 | cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
2f5cb738 | 1727 | return 1; |
1da177e4 LT |
1728 | } |
1729 | ||
1da177e4 | 1730 | /* |
5e705374 JA |
1731 | * task holds one reference to the queue, dropped when task exits. each rq |
1732 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1733 | * |
1734 | * queue lock must be held here. | |
1735 | */ | |
1736 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1737 | { | |
22e2c507 JA |
1738 | struct cfq_data *cfqd = cfqq->cfqd; |
1739 | ||
1740 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1741 | |
1742 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1743 | return; | |
1744 | ||
7b679138 | 1745 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
1da177e4 | 1746 | BUG_ON(rb_first(&cfqq->sort_list)); |
22e2c507 | 1747 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1748 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1749 | |
28f95cbc | 1750 | if (unlikely(cfqd->active_queue == cfqq)) { |
6084cdda | 1751 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1752 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1753 | } |
22e2c507 | 1754 | |
1da177e4 LT |
1755 | kmem_cache_free(cfq_pool, cfqq); |
1756 | } | |
1757 | ||
d6de8be7 JA |
1758 | /* |
1759 | * Must always be called with the rcu_read_lock() held | |
1760 | */ | |
07416d29 JA |
1761 | static void |
1762 | __call_for_each_cic(struct io_context *ioc, | |
1763 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1764 | { | |
1765 | struct cfq_io_context *cic; | |
1766 | struct hlist_node *n; | |
1767 | ||
1768 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) | |
1769 | func(ioc, cic); | |
1770 | } | |
1771 | ||
4ac845a2 | 1772 | /* |
34e6bbf2 | 1773 | * Call func for each cic attached to this ioc. |
4ac845a2 | 1774 | */ |
34e6bbf2 | 1775 | static void |
4ac845a2 JA |
1776 | call_for_each_cic(struct io_context *ioc, |
1777 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1da177e4 | 1778 | { |
4ac845a2 | 1779 | rcu_read_lock(); |
07416d29 | 1780 | __call_for_each_cic(ioc, func); |
4ac845a2 | 1781 | rcu_read_unlock(); |
34e6bbf2 FC |
1782 | } |
1783 | ||
1784 | static void cfq_cic_free_rcu(struct rcu_head *head) | |
1785 | { | |
1786 | struct cfq_io_context *cic; | |
1787 | ||
1788 | cic = container_of(head, struct cfq_io_context, rcu_head); | |
1789 | ||
1790 | kmem_cache_free(cfq_ioc_pool, cic); | |
245b2e70 | 1791 | elv_ioc_count_dec(cfq_ioc_count); |
34e6bbf2 | 1792 | |
9a11b4ed JA |
1793 | if (ioc_gone) { |
1794 | /* | |
1795 | * CFQ scheduler is exiting, grab exit lock and check | |
1796 | * the pending io context count. If it hits zero, | |
1797 | * complete ioc_gone and set it back to NULL | |
1798 | */ | |
1799 | spin_lock(&ioc_gone_lock); | |
245b2e70 | 1800 | if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { |
9a11b4ed JA |
1801 | complete(ioc_gone); |
1802 | ioc_gone = NULL; | |
1803 | } | |
1804 | spin_unlock(&ioc_gone_lock); | |
1805 | } | |
34e6bbf2 | 1806 | } |
4ac845a2 | 1807 | |
34e6bbf2 FC |
1808 | static void cfq_cic_free(struct cfq_io_context *cic) |
1809 | { | |
1810 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); | |
4ac845a2 JA |
1811 | } |
1812 | ||
1813 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) | |
1814 | { | |
1815 | unsigned long flags; | |
1816 | ||
1817 | BUG_ON(!cic->dead_key); | |
1818 | ||
1819 | spin_lock_irqsave(&ioc->lock, flags); | |
1820 | radix_tree_delete(&ioc->radix_root, cic->dead_key); | |
ffc4e759 | 1821 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
1822 | spin_unlock_irqrestore(&ioc->lock, flags); |
1823 | ||
34e6bbf2 | 1824 | cfq_cic_free(cic); |
4ac845a2 JA |
1825 | } |
1826 | ||
d6de8be7 JA |
1827 | /* |
1828 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. | |
1829 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), | |
1830 | * and ->trim() which is called with the task lock held | |
1831 | */ | |
4ac845a2 JA |
1832 | static void cfq_free_io_context(struct io_context *ioc) |
1833 | { | |
4ac845a2 | 1834 | /* |
34e6bbf2 FC |
1835 | * ioc->refcount is zero here, or we are called from elv_unregister(), |
1836 | * so no more cic's are allowed to be linked into this ioc. So it | |
1837 | * should be ok to iterate over the known list, we will see all cic's | |
1838 | * since no new ones are added. | |
4ac845a2 | 1839 | */ |
07416d29 | 1840 | __call_for_each_cic(ioc, cic_free_func); |
1da177e4 LT |
1841 | } |
1842 | ||
89850f7e | 1843 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1844 | { |
df5fe3e8 JM |
1845 | struct cfq_queue *__cfqq, *next; |
1846 | ||
28f95cbc | 1847 | if (unlikely(cfqq == cfqd->active_queue)) { |
6084cdda | 1848 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1849 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1850 | } |
22e2c507 | 1851 | |
df5fe3e8 JM |
1852 | /* |
1853 | * If this queue was scheduled to merge with another queue, be | |
1854 | * sure to drop the reference taken on that queue (and others in | |
1855 | * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. | |
1856 | */ | |
1857 | __cfqq = cfqq->new_cfqq; | |
1858 | while (__cfqq) { | |
1859 | if (__cfqq == cfqq) { | |
1860 | WARN(1, "cfqq->new_cfqq loop detected\n"); | |
1861 | break; | |
1862 | } | |
1863 | next = __cfqq->new_cfqq; | |
1864 | cfq_put_queue(__cfqq); | |
1865 | __cfqq = next; | |
1866 | } | |
1867 | ||
89850f7e JA |
1868 | cfq_put_queue(cfqq); |
1869 | } | |
22e2c507 | 1870 | |
89850f7e JA |
1871 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1872 | struct cfq_io_context *cic) | |
1873 | { | |
4faa3c81 FC |
1874 | struct io_context *ioc = cic->ioc; |
1875 | ||
fc46379d | 1876 | list_del_init(&cic->queue_list); |
4ac845a2 JA |
1877 | |
1878 | /* | |
1879 | * Make sure key == NULL is seen for dead queues | |
1880 | */ | |
fc46379d | 1881 | smp_wmb(); |
4ac845a2 | 1882 | cic->dead_key = (unsigned long) cic->key; |
fc46379d JA |
1883 | cic->key = NULL; |
1884 | ||
4faa3c81 FC |
1885 | if (ioc->ioc_data == cic) |
1886 | rcu_assign_pointer(ioc->ioc_data, NULL); | |
1887 | ||
ff6657c6 JA |
1888 | if (cic->cfqq[BLK_RW_ASYNC]) { |
1889 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); | |
1890 | cic->cfqq[BLK_RW_ASYNC] = NULL; | |
12a05732 AV |
1891 | } |
1892 | ||
ff6657c6 JA |
1893 | if (cic->cfqq[BLK_RW_SYNC]) { |
1894 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); | |
1895 | cic->cfqq[BLK_RW_SYNC] = NULL; | |
12a05732 | 1896 | } |
89850f7e JA |
1897 | } |
1898 | ||
4ac845a2 JA |
1899 | static void cfq_exit_single_io_context(struct io_context *ioc, |
1900 | struct cfq_io_context *cic) | |
89850f7e JA |
1901 | { |
1902 | struct cfq_data *cfqd = cic->key; | |
1903 | ||
89850f7e | 1904 | if (cfqd) { |
165125e1 | 1905 | struct request_queue *q = cfqd->queue; |
4ac845a2 | 1906 | unsigned long flags; |
89850f7e | 1907 | |
4ac845a2 | 1908 | spin_lock_irqsave(q->queue_lock, flags); |
62c1fe9d JA |
1909 | |
1910 | /* | |
1911 | * Ensure we get a fresh copy of the ->key to prevent | |
1912 | * race between exiting task and queue | |
1913 | */ | |
1914 | smp_read_barrier_depends(); | |
1915 | if (cic->key) | |
1916 | __cfq_exit_single_io_context(cfqd, cic); | |
1917 | ||
4ac845a2 | 1918 | spin_unlock_irqrestore(q->queue_lock, flags); |
89850f7e | 1919 | } |
1da177e4 LT |
1920 | } |
1921 | ||
498d3aa2 JA |
1922 | /* |
1923 | * The process that ioc belongs to has exited, we need to clean up | |
1924 | * and put the internal structures we have that belongs to that process. | |
1925 | */ | |
e2d74ac0 | 1926 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1927 | { |
4ac845a2 | 1928 | call_for_each_cic(ioc, cfq_exit_single_io_context); |
1da177e4 LT |
1929 | } |
1930 | ||
22e2c507 | 1931 | static struct cfq_io_context * |
8267e268 | 1932 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1933 | { |
b5deef90 | 1934 | struct cfq_io_context *cic; |
1da177e4 | 1935 | |
94f6030c CL |
1936 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
1937 | cfqd->queue->node); | |
1da177e4 | 1938 | if (cic) { |
22e2c507 | 1939 | cic->last_end_request = jiffies; |
553698f9 | 1940 | INIT_LIST_HEAD(&cic->queue_list); |
ffc4e759 | 1941 | INIT_HLIST_NODE(&cic->cic_list); |
22e2c507 JA |
1942 | cic->dtor = cfq_free_io_context; |
1943 | cic->exit = cfq_exit_io_context; | |
245b2e70 | 1944 | elv_ioc_count_inc(cfq_ioc_count); |
1da177e4 LT |
1945 | } |
1946 | ||
1947 | return cic; | |
1948 | } | |
1949 | ||
fd0928df | 1950 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
22e2c507 JA |
1951 | { |
1952 | struct task_struct *tsk = current; | |
1953 | int ioprio_class; | |
1954 | ||
3b18152c | 1955 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1956 | return; |
1957 | ||
fd0928df | 1958 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
22e2c507 | 1959 | switch (ioprio_class) { |
fe094d98 JA |
1960 | default: |
1961 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1962 | case IOPRIO_CLASS_NONE: | |
1963 | /* | |
6d63c275 | 1964 | * no prio set, inherit CPU scheduling settings |
fe094d98 JA |
1965 | */ |
1966 | cfqq->ioprio = task_nice_ioprio(tsk); | |
6d63c275 | 1967 | cfqq->ioprio_class = task_nice_ioclass(tsk); |
fe094d98 JA |
1968 | break; |
1969 | case IOPRIO_CLASS_RT: | |
1970 | cfqq->ioprio = task_ioprio(ioc); | |
1971 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1972 | break; | |
1973 | case IOPRIO_CLASS_BE: | |
1974 | cfqq->ioprio = task_ioprio(ioc); | |
1975 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1976 | break; | |
1977 | case IOPRIO_CLASS_IDLE: | |
1978 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1979 | cfqq->ioprio = 7; | |
1980 | cfq_clear_cfqq_idle_window(cfqq); | |
1981 | break; | |
22e2c507 JA |
1982 | } |
1983 | ||
1984 | /* | |
1985 | * keep track of original prio settings in case we have to temporarily | |
1986 | * elevate the priority of this queue | |
1987 | */ | |
1988 | cfqq->org_ioprio = cfqq->ioprio; | |
1989 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 1990 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1991 | } |
1992 | ||
febffd61 | 1993 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
22e2c507 | 1994 | { |
478a82b0 AV |
1995 | struct cfq_data *cfqd = cic->key; |
1996 | struct cfq_queue *cfqq; | |
c1b707d2 | 1997 | unsigned long flags; |
35e6077c | 1998 | |
caaa5f9f JA |
1999 | if (unlikely(!cfqd)) |
2000 | return; | |
2001 | ||
c1b707d2 | 2002 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f | 2003 | |
ff6657c6 | 2004 | cfqq = cic->cfqq[BLK_RW_ASYNC]; |
caaa5f9f JA |
2005 | if (cfqq) { |
2006 | struct cfq_queue *new_cfqq; | |
ff6657c6 JA |
2007 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
2008 | GFP_ATOMIC); | |
caaa5f9f | 2009 | if (new_cfqq) { |
ff6657c6 | 2010 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
caaa5f9f JA |
2011 | cfq_put_queue(cfqq); |
2012 | } | |
22e2c507 | 2013 | } |
caaa5f9f | 2014 | |
ff6657c6 | 2015 | cfqq = cic->cfqq[BLK_RW_SYNC]; |
caaa5f9f JA |
2016 | if (cfqq) |
2017 | cfq_mark_cfqq_prio_changed(cfqq); | |
2018 | ||
c1b707d2 | 2019 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
2020 | } |
2021 | ||
fc46379d | 2022 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 2023 | { |
4ac845a2 | 2024 | call_for_each_cic(ioc, changed_ioprio); |
fc46379d | 2025 | ioc->ioprio_changed = 0; |
22e2c507 JA |
2026 | } |
2027 | ||
d5036d77 | 2028 | static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 2029 | pid_t pid, bool is_sync) |
d5036d77 JA |
2030 | { |
2031 | RB_CLEAR_NODE(&cfqq->rb_node); | |
2032 | RB_CLEAR_NODE(&cfqq->p_node); | |
2033 | INIT_LIST_HEAD(&cfqq->fifo); | |
2034 | ||
2035 | atomic_set(&cfqq->ref, 0); | |
2036 | cfqq->cfqd = cfqd; | |
2037 | ||
2038 | cfq_mark_cfqq_prio_changed(cfqq); | |
2039 | ||
2040 | if (is_sync) { | |
2041 | if (!cfq_class_idle(cfqq)) | |
2042 | cfq_mark_cfqq_idle_window(cfqq); | |
2043 | cfq_mark_cfqq_sync(cfqq); | |
2044 | } | |
2045 | cfqq->pid = pid; | |
2046 | } | |
2047 | ||
22e2c507 | 2048 | static struct cfq_queue * |
a6151c3a | 2049 | cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, |
fd0928df | 2050 | struct io_context *ioc, gfp_t gfp_mask) |
22e2c507 | 2051 | { |
22e2c507 | 2052 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
91fac317 | 2053 | struct cfq_io_context *cic; |
22e2c507 JA |
2054 | |
2055 | retry: | |
4ac845a2 | 2056 | cic = cfq_cic_lookup(cfqd, ioc); |
91fac317 VT |
2057 | /* cic always exists here */ |
2058 | cfqq = cic_to_cfqq(cic, is_sync); | |
22e2c507 | 2059 | |
6118b70b JA |
2060 | /* |
2061 | * Always try a new alloc if we fell back to the OOM cfqq | |
2062 | * originally, since it should just be a temporary situation. | |
2063 | */ | |
2064 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { | |
2065 | cfqq = NULL; | |
22e2c507 JA |
2066 | if (new_cfqq) { |
2067 | cfqq = new_cfqq; | |
2068 | new_cfqq = NULL; | |
2069 | } else if (gfp_mask & __GFP_WAIT) { | |
2070 | spin_unlock_irq(cfqd->queue->queue_lock); | |
94f6030c | 2071 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
6118b70b | 2072 | gfp_mask | __GFP_ZERO, |
94f6030c | 2073 | cfqd->queue->node); |
22e2c507 | 2074 | spin_lock_irq(cfqd->queue->queue_lock); |
6118b70b JA |
2075 | if (new_cfqq) |
2076 | goto retry; | |
22e2c507 | 2077 | } else { |
94f6030c CL |
2078 | cfqq = kmem_cache_alloc_node(cfq_pool, |
2079 | gfp_mask | __GFP_ZERO, | |
2080 | cfqd->queue->node); | |
22e2c507 JA |
2081 | } |
2082 | ||
6118b70b JA |
2083 | if (cfqq) { |
2084 | cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); | |
2085 | cfq_init_prio_data(cfqq, ioc); | |
2086 | cfq_log_cfqq(cfqd, cfqq, "alloced"); | |
2087 | } else | |
2088 | cfqq = &cfqd->oom_cfqq; | |
22e2c507 JA |
2089 | } |
2090 | ||
2091 | if (new_cfqq) | |
2092 | kmem_cache_free(cfq_pool, new_cfqq); | |
2093 | ||
22e2c507 JA |
2094 | return cfqq; |
2095 | } | |
2096 | ||
c2dea2d1 VT |
2097 | static struct cfq_queue ** |
2098 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
2099 | { | |
fe094d98 | 2100 | switch (ioprio_class) { |
c2dea2d1 VT |
2101 | case IOPRIO_CLASS_RT: |
2102 | return &cfqd->async_cfqq[0][ioprio]; | |
2103 | case IOPRIO_CLASS_BE: | |
2104 | return &cfqd->async_cfqq[1][ioprio]; | |
2105 | case IOPRIO_CLASS_IDLE: | |
2106 | return &cfqd->async_idle_cfqq; | |
2107 | default: | |
2108 | BUG(); | |
2109 | } | |
2110 | } | |
2111 | ||
15c31be4 | 2112 | static struct cfq_queue * |
a6151c3a | 2113 | cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, |
15c31be4 JA |
2114 | gfp_t gfp_mask) |
2115 | { | |
fd0928df JA |
2116 | const int ioprio = task_ioprio(ioc); |
2117 | const int ioprio_class = task_ioprio_class(ioc); | |
c2dea2d1 | 2118 | struct cfq_queue **async_cfqq = NULL; |
15c31be4 JA |
2119 | struct cfq_queue *cfqq = NULL; |
2120 | ||
c2dea2d1 VT |
2121 | if (!is_sync) { |
2122 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
2123 | cfqq = *async_cfqq; | |
2124 | } | |
2125 | ||
6118b70b | 2126 | if (!cfqq) |
fd0928df | 2127 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
15c31be4 JA |
2128 | |
2129 | /* | |
2130 | * pin the queue now that it's allocated, scheduler exit will prune it | |
2131 | */ | |
c2dea2d1 | 2132 | if (!is_sync && !(*async_cfqq)) { |
15c31be4 | 2133 | atomic_inc(&cfqq->ref); |
c2dea2d1 | 2134 | *async_cfqq = cfqq; |
15c31be4 JA |
2135 | } |
2136 | ||
2137 | atomic_inc(&cfqq->ref); | |
2138 | return cfqq; | |
2139 | } | |
2140 | ||
498d3aa2 JA |
2141 | /* |
2142 | * We drop cfq io contexts lazily, so we may find a dead one. | |
2143 | */ | |
dbecf3ab | 2144 | static void |
4ac845a2 JA |
2145 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
2146 | struct cfq_io_context *cic) | |
dbecf3ab | 2147 | { |
4ac845a2 JA |
2148 | unsigned long flags; |
2149 | ||
fc46379d | 2150 | WARN_ON(!list_empty(&cic->queue_list)); |
597bc485 | 2151 | |
4ac845a2 JA |
2152 | spin_lock_irqsave(&ioc->lock, flags); |
2153 | ||
4faa3c81 | 2154 | BUG_ON(ioc->ioc_data == cic); |
597bc485 | 2155 | |
4ac845a2 | 2156 | radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
ffc4e759 | 2157 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
2158 | spin_unlock_irqrestore(&ioc->lock, flags); |
2159 | ||
2160 | cfq_cic_free(cic); | |
dbecf3ab OH |
2161 | } |
2162 | ||
e2d74ac0 | 2163 | static struct cfq_io_context * |
4ac845a2 | 2164 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
e2d74ac0 | 2165 | { |
e2d74ac0 | 2166 | struct cfq_io_context *cic; |
d6de8be7 | 2167 | unsigned long flags; |
4ac845a2 | 2168 | void *k; |
e2d74ac0 | 2169 | |
91fac317 VT |
2170 | if (unlikely(!ioc)) |
2171 | return NULL; | |
2172 | ||
d6de8be7 JA |
2173 | rcu_read_lock(); |
2174 | ||
597bc485 JA |
2175 | /* |
2176 | * we maintain a last-hit cache, to avoid browsing over the tree | |
2177 | */ | |
4ac845a2 | 2178 | cic = rcu_dereference(ioc->ioc_data); |
d6de8be7 JA |
2179 | if (cic && cic->key == cfqd) { |
2180 | rcu_read_unlock(); | |
597bc485 | 2181 | return cic; |
d6de8be7 | 2182 | } |
597bc485 | 2183 | |
4ac845a2 | 2184 | do { |
4ac845a2 JA |
2185 | cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); |
2186 | rcu_read_unlock(); | |
2187 | if (!cic) | |
2188 | break; | |
be3b0753 OH |
2189 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
2190 | k = cic->key; | |
2191 | if (unlikely(!k)) { | |
4ac845a2 | 2192 | cfq_drop_dead_cic(cfqd, ioc, cic); |
d6de8be7 | 2193 | rcu_read_lock(); |
4ac845a2 | 2194 | continue; |
dbecf3ab | 2195 | } |
e2d74ac0 | 2196 | |
d6de8be7 | 2197 | spin_lock_irqsave(&ioc->lock, flags); |
4ac845a2 | 2198 | rcu_assign_pointer(ioc->ioc_data, cic); |
d6de8be7 | 2199 | spin_unlock_irqrestore(&ioc->lock, flags); |
4ac845a2 JA |
2200 | break; |
2201 | } while (1); | |
e2d74ac0 | 2202 | |
4ac845a2 | 2203 | return cic; |
e2d74ac0 JA |
2204 | } |
2205 | ||
4ac845a2 JA |
2206 | /* |
2207 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup | |
2208 | * the process specific cfq io context when entered from the block layer. | |
2209 | * Also adds the cic to a per-cfqd list, used when this queue is removed. | |
2210 | */ | |
febffd61 JA |
2211 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
2212 | struct cfq_io_context *cic, gfp_t gfp_mask) | |
e2d74ac0 | 2213 | { |
0261d688 | 2214 | unsigned long flags; |
4ac845a2 | 2215 | int ret; |
e2d74ac0 | 2216 | |
4ac845a2 JA |
2217 | ret = radix_tree_preload(gfp_mask); |
2218 | if (!ret) { | |
2219 | cic->ioc = ioc; | |
2220 | cic->key = cfqd; | |
e2d74ac0 | 2221 | |
4ac845a2 JA |
2222 | spin_lock_irqsave(&ioc->lock, flags); |
2223 | ret = radix_tree_insert(&ioc->radix_root, | |
2224 | (unsigned long) cfqd, cic); | |
ffc4e759 JA |
2225 | if (!ret) |
2226 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); | |
4ac845a2 | 2227 | spin_unlock_irqrestore(&ioc->lock, flags); |
e2d74ac0 | 2228 | |
4ac845a2 JA |
2229 | radix_tree_preload_end(); |
2230 | ||
2231 | if (!ret) { | |
2232 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2233 | list_add(&cic->queue_list, &cfqd->cic_list); | |
2234 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2235 | } | |
e2d74ac0 JA |
2236 | } |
2237 | ||
4ac845a2 JA |
2238 | if (ret) |
2239 | printk(KERN_ERR "cfq: cic link failed!\n"); | |
fc46379d | 2240 | |
4ac845a2 | 2241 | return ret; |
e2d74ac0 JA |
2242 | } |
2243 | ||
1da177e4 LT |
2244 | /* |
2245 | * Setup general io context and cfq io context. There can be several cfq | |
2246 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 2247 | * than one device managed by cfq. |
1da177e4 LT |
2248 | */ |
2249 | static struct cfq_io_context * | |
e2d74ac0 | 2250 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 2251 | { |
22e2c507 | 2252 | struct io_context *ioc = NULL; |
1da177e4 | 2253 | struct cfq_io_context *cic; |
1da177e4 | 2254 | |
22e2c507 | 2255 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 2256 | |
b5deef90 | 2257 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
2258 | if (!ioc) |
2259 | return NULL; | |
2260 | ||
4ac845a2 | 2261 | cic = cfq_cic_lookup(cfqd, ioc); |
e2d74ac0 JA |
2262 | if (cic) |
2263 | goto out; | |
1da177e4 | 2264 | |
e2d74ac0 JA |
2265 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
2266 | if (cic == NULL) | |
2267 | goto err; | |
1da177e4 | 2268 | |
4ac845a2 JA |
2269 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
2270 | goto err_free; | |
2271 | ||
1da177e4 | 2272 | out: |
fc46379d JA |
2273 | smp_read_barrier_depends(); |
2274 | if (unlikely(ioc->ioprio_changed)) | |
2275 | cfq_ioc_set_ioprio(ioc); | |
2276 | ||
1da177e4 | 2277 | return cic; |
4ac845a2 JA |
2278 | err_free: |
2279 | cfq_cic_free(cic); | |
1da177e4 LT |
2280 | err: |
2281 | put_io_context(ioc); | |
2282 | return NULL; | |
2283 | } | |
2284 | ||
22e2c507 JA |
2285 | static void |
2286 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 2287 | { |
aaf1228d JA |
2288 | unsigned long elapsed = jiffies - cic->last_end_request; |
2289 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 2290 | |
22e2c507 JA |
2291 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
2292 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
2293 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
2294 | } | |
1da177e4 | 2295 | |
206dc69b | 2296 | static void |
b2c18e1e | 2297 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
6d048f53 | 2298 | struct request *rq) |
206dc69b JA |
2299 | { |
2300 | sector_t sdist; | |
2301 | u64 total; | |
2302 | ||
b2c18e1e | 2303 | if (!cfqq->last_request_pos) |
4d00aa47 | 2304 | sdist = 0; |
b2c18e1e JM |
2305 | else if (cfqq->last_request_pos < blk_rq_pos(rq)) |
2306 | sdist = blk_rq_pos(rq) - cfqq->last_request_pos; | |
206dc69b | 2307 | else |
b2c18e1e | 2308 | sdist = cfqq->last_request_pos - blk_rq_pos(rq); |
206dc69b JA |
2309 | |
2310 | /* | |
2311 | * Don't allow the seek distance to get too large from the | |
2312 | * odd fragment, pagein, etc | |
2313 | */ | |
b2c18e1e JM |
2314 | if (cfqq->seek_samples <= 60) /* second&third seek */ |
2315 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024); | |
206dc69b | 2316 | else |
b2c18e1e | 2317 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64); |
206dc69b | 2318 | |
b2c18e1e JM |
2319 | cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8; |
2320 | cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8; | |
2321 | total = cfqq->seek_total + (cfqq->seek_samples/2); | |
2322 | do_div(total, cfqq->seek_samples); | |
2323 | cfqq->seek_mean = (sector_t)total; | |
e6c5bc73 JM |
2324 | |
2325 | /* | |
2326 | * If this cfqq is shared between multiple processes, check to | |
2327 | * make sure that those processes are still issuing I/Os within | |
2328 | * the mean seek distance. If not, it may be time to break the | |
2329 | * queues apart again. | |
2330 | */ | |
2331 | if (cfq_cfqq_coop(cfqq)) { | |
2332 | if (CFQQ_SEEKY(cfqq) && !cfqq->seeky_start) | |
2333 | cfqq->seeky_start = jiffies; | |
2334 | else if (!CFQQ_SEEKY(cfqq)) | |
2335 | cfqq->seeky_start = 0; | |
2336 | } | |
206dc69b | 2337 | } |
1da177e4 | 2338 | |
22e2c507 JA |
2339 | /* |
2340 | * Disable idle window if the process thinks too long or seeks so much that | |
2341 | * it doesn't matter | |
2342 | */ | |
2343 | static void | |
2344 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
2345 | struct cfq_io_context *cic) | |
2346 | { | |
7b679138 | 2347 | int old_idle, enable_idle; |
1be92f2f | 2348 | |
0871714e JA |
2349 | /* |
2350 | * Don't idle for async or idle io prio class | |
2351 | */ | |
2352 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) | |
1be92f2f JA |
2353 | return; |
2354 | ||
c265a7f4 | 2355 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 2356 | |
76280aff CZ |
2357 | if (cfqq->queued[0] + cfqq->queued[1] >= 4) |
2358 | cfq_mark_cfqq_deep(cfqq); | |
2359 | ||
66dac98e | 2360 | if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
76280aff CZ |
2361 | (!cfq_cfqq_deep(cfqq) && sample_valid(cfqq->seek_samples) |
2362 | && CFQQ_SEEKY(cfqq))) | |
22e2c507 JA |
2363 | enable_idle = 0; |
2364 | else if (sample_valid(cic->ttime_samples)) { | |
718eee05 | 2365 | if (cic->ttime_mean > cfqd->cfq_slice_idle) |
22e2c507 JA |
2366 | enable_idle = 0; |
2367 | else | |
2368 | enable_idle = 1; | |
1da177e4 LT |
2369 | } |
2370 | ||
7b679138 JA |
2371 | if (old_idle != enable_idle) { |
2372 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); | |
2373 | if (enable_idle) | |
2374 | cfq_mark_cfqq_idle_window(cfqq); | |
2375 | else | |
2376 | cfq_clear_cfqq_idle_window(cfqq); | |
2377 | } | |
22e2c507 | 2378 | } |
1da177e4 | 2379 | |
22e2c507 JA |
2380 | /* |
2381 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
2382 | * no or if we aren't sure, a 1 will cause a preempt. | |
2383 | */ | |
a6151c3a | 2384 | static bool |
22e2c507 | 2385 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
5e705374 | 2386 | struct request *rq) |
22e2c507 | 2387 | { |
6d048f53 | 2388 | struct cfq_queue *cfqq; |
22e2c507 | 2389 | |
6d048f53 JA |
2390 | cfqq = cfqd->active_queue; |
2391 | if (!cfqq) | |
a6151c3a | 2392 | return false; |
22e2c507 | 2393 | |
6d048f53 | 2394 | if (cfq_slice_used(cfqq)) |
a6151c3a | 2395 | return true; |
6d048f53 JA |
2396 | |
2397 | if (cfq_class_idle(new_cfqq)) | |
a6151c3a | 2398 | return false; |
22e2c507 JA |
2399 | |
2400 | if (cfq_class_idle(cfqq)) | |
a6151c3a | 2401 | return true; |
1e3335de | 2402 | |
e4a22919 CZ |
2403 | if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && |
2404 | cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && | |
2405 | new_cfqq->service_tree->count == 1) | |
718eee05 CZ |
2406 | return true; |
2407 | ||
374f84ac JA |
2408 | /* |
2409 | * if the new request is sync, but the currently running queue is | |
2410 | * not, let the sync request have priority. | |
2411 | */ | |
5e705374 | 2412 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
a6151c3a | 2413 | return true; |
1e3335de | 2414 | |
374f84ac JA |
2415 | /* |
2416 | * So both queues are sync. Let the new request get disk time if | |
2417 | * it's a metadata request and the current queue is doing regular IO. | |
2418 | */ | |
2419 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
e6ec4fe2 | 2420 | return true; |
22e2c507 | 2421 | |
3a9a3f6c DS |
2422 | /* |
2423 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. | |
2424 | */ | |
2425 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) | |
a6151c3a | 2426 | return true; |
3a9a3f6c | 2427 | |
1e3335de | 2428 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
a6151c3a | 2429 | return false; |
1e3335de JA |
2430 | |
2431 | /* | |
2432 | * if this request is as-good as one we would expect from the | |
2433 | * current cfqq, let it preempt | |
2434 | */ | |
e00ef799 | 2435 | if (cfq_rq_close(cfqd, cfqq, rq)) |
a6151c3a | 2436 | return true; |
1e3335de | 2437 | |
a6151c3a | 2438 | return false; |
22e2c507 JA |
2439 | } |
2440 | ||
2441 | /* | |
2442 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
2443 | * let it have half of its nominal slice. | |
2444 | */ | |
2445 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2446 | { | |
7b679138 | 2447 | cfq_log_cfqq(cfqd, cfqq, "preempt"); |
6084cdda | 2448 | cfq_slice_expired(cfqd, 1); |
22e2c507 | 2449 | |
bf572256 JA |
2450 | /* |
2451 | * Put the new queue at the front of the of the current list, | |
2452 | * so we know that it will be selected next. | |
2453 | */ | |
2454 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
edd75ffd JA |
2455 | |
2456 | cfq_service_tree_add(cfqd, cfqq, 1); | |
bf572256 | 2457 | |
44f7c160 JA |
2458 | cfqq->slice_end = 0; |
2459 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
2460 | } |
2461 | ||
22e2c507 | 2462 | /* |
5e705374 | 2463 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
2464 | * something we should do about it |
2465 | */ | |
2466 | static void | |
5e705374 JA |
2467 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
2468 | struct request *rq) | |
22e2c507 | 2469 | { |
5e705374 | 2470 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 2471 | |
45333d5a | 2472 | cfqd->rq_queued++; |
374f84ac JA |
2473 | if (rq_is_meta(rq)) |
2474 | cfqq->meta_pending++; | |
2475 | ||
9c2c38a1 | 2476 | cfq_update_io_thinktime(cfqd, cic); |
b2c18e1e | 2477 | cfq_update_io_seektime(cfqd, cfqq, rq); |
9c2c38a1 JA |
2478 | cfq_update_idle_window(cfqd, cfqq, cic); |
2479 | ||
b2c18e1e | 2480 | cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
22e2c507 JA |
2481 | |
2482 | if (cfqq == cfqd->active_queue) { | |
2483 | /* | |
b029195d JA |
2484 | * Remember that we saw a request from this process, but |
2485 | * don't start queuing just yet. Otherwise we risk seeing lots | |
2486 | * of tiny requests, because we disrupt the normal plugging | |
d6ceb25e JA |
2487 | * and merging. If the request is already larger than a single |
2488 | * page, let it rip immediately. For that case we assume that | |
2d870722 JA |
2489 | * merging is already done. Ditto for a busy system that |
2490 | * has other work pending, don't risk delaying until the | |
2491 | * idle timer unplug to continue working. | |
22e2c507 | 2492 | */ |
d6ceb25e | 2493 | if (cfq_cfqq_wait_request(cfqq)) { |
2d870722 JA |
2494 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
2495 | cfqd->busy_queues > 1) { | |
d6ceb25e | 2496 | del_timer(&cfqd->idle_slice_timer); |
a7f55792 | 2497 | __blk_run_queue(cfqd->queue); |
d6ceb25e | 2498 | } |
b029195d | 2499 | cfq_mark_cfqq_must_dispatch(cfqq); |
d6ceb25e | 2500 | } |
5e705374 | 2501 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
2502 | /* |
2503 | * not the active queue - expire current slice if it is | |
2504 | * idle and has expired it's mean thinktime or this new queue | |
3a9a3f6c DS |
2505 | * has some old slice time left and is of higher priority or |
2506 | * this new queue is RT and the current one is BE | |
22e2c507 JA |
2507 | */ |
2508 | cfq_preempt_queue(cfqd, cfqq); | |
a7f55792 | 2509 | __blk_run_queue(cfqd->queue); |
22e2c507 | 2510 | } |
1da177e4 LT |
2511 | } |
2512 | ||
165125e1 | 2513 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2514 | { |
b4878f24 | 2515 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 2516 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 2517 | |
7b679138 | 2518 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
fd0928df | 2519 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
1da177e4 | 2520 | |
30996f40 | 2521 | rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); |
22e2c507 | 2522 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
aa6f6a3d | 2523 | cfq_add_rq_rb(rq); |
22e2c507 | 2524 | |
5e705374 | 2525 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
2526 | } |
2527 | ||
45333d5a AC |
2528 | /* |
2529 | * Update hw_tag based on peak queue depth over 50 samples under | |
2530 | * sufficient load. | |
2531 | */ | |
2532 | static void cfq_update_hw_tag(struct cfq_data *cfqd) | |
2533 | { | |
1a1238a7 SL |
2534 | struct cfq_queue *cfqq = cfqd->active_queue; |
2535 | ||
e459dd08 CZ |
2536 | if (rq_in_driver(cfqd) > cfqd->hw_tag_est_depth) |
2537 | cfqd->hw_tag_est_depth = rq_in_driver(cfqd); | |
2538 | ||
2539 | if (cfqd->hw_tag == 1) | |
2540 | return; | |
45333d5a AC |
2541 | |
2542 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && | |
5ad531db | 2543 | rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN) |
45333d5a AC |
2544 | return; |
2545 | ||
1a1238a7 SL |
2546 | /* |
2547 | * If active queue hasn't enough requests and can idle, cfq might not | |
2548 | * dispatch sufficient requests to hardware. Don't zero hw_tag in this | |
2549 | * case | |
2550 | */ | |
2551 | if (cfqq && cfq_cfqq_idle_window(cfqq) && | |
2552 | cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < | |
2553 | CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN) | |
2554 | return; | |
2555 | ||
45333d5a AC |
2556 | if (cfqd->hw_tag_samples++ < 50) |
2557 | return; | |
2558 | ||
e459dd08 | 2559 | if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN) |
45333d5a AC |
2560 | cfqd->hw_tag = 1; |
2561 | else | |
2562 | cfqd->hw_tag = 0; | |
45333d5a AC |
2563 | } |
2564 | ||
165125e1 | 2565 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2566 | { |
5e705374 | 2567 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 2568 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 2569 | const int sync = rq_is_sync(rq); |
b4878f24 | 2570 | unsigned long now; |
1da177e4 | 2571 | |
b4878f24 | 2572 | now = jiffies; |
7b679138 | 2573 | cfq_log_cfqq(cfqd, cfqq, "complete"); |
1da177e4 | 2574 | |
45333d5a AC |
2575 | cfq_update_hw_tag(cfqd); |
2576 | ||
5ad531db | 2577 | WARN_ON(!cfqd->rq_in_driver[sync]); |
6d048f53 | 2578 | WARN_ON(!cfqq->dispatched); |
5ad531db | 2579 | cfqd->rq_in_driver[sync]--; |
6d048f53 | 2580 | cfqq->dispatched--; |
1da177e4 | 2581 | |
3ed9a296 JA |
2582 | if (cfq_cfqq_sync(cfqq)) |
2583 | cfqd->sync_flight--; | |
2584 | ||
365722bb | 2585 | if (sync) { |
5e705374 | 2586 | RQ_CIC(rq)->last_end_request = now; |
365722bb VG |
2587 | cfqd->last_end_sync_rq = now; |
2588 | } | |
caaa5f9f JA |
2589 | |
2590 | /* | |
2591 | * If this is the active queue, check if it needs to be expired, | |
2592 | * or if we want to idle in case it has no pending requests. | |
2593 | */ | |
2594 | if (cfqd->active_queue == cfqq) { | |
a36e71f9 JA |
2595 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
2596 | ||
44f7c160 JA |
2597 | if (cfq_cfqq_slice_new(cfqq)) { |
2598 | cfq_set_prio_slice(cfqd, cfqq); | |
2599 | cfq_clear_cfqq_slice_new(cfqq); | |
2600 | } | |
a36e71f9 | 2601 | /* |
8e550632 CZ |
2602 | * Idling is not enabled on: |
2603 | * - expired queues | |
2604 | * - idle-priority queues | |
2605 | * - async queues | |
2606 | * - queues with still some requests queued | |
2607 | * - when there is a close cooperator | |
a36e71f9 | 2608 | */ |
0871714e | 2609 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
6084cdda | 2610 | cfq_slice_expired(cfqd, 1); |
8e550632 CZ |
2611 | else if (sync && cfqq_empty && |
2612 | !cfq_close_cooperator(cfqd, cfqq)) { | |
2613 | cfqd->noidle_tree_requires_idle |= !rq_noidle(rq); | |
2614 | /* | |
2615 | * Idling is enabled for SYNC_WORKLOAD. | |
2616 | * SYNC_NOIDLE_WORKLOAD idles at the end of the tree | |
2617 | * only if we processed at least one !rq_noidle request | |
2618 | */ | |
2619 | if (cfqd->serving_type == SYNC_WORKLOAD | |
2620 | || cfqd->noidle_tree_requires_idle) | |
2621 | cfq_arm_slice_timer(cfqd); | |
2622 | } | |
caaa5f9f | 2623 | } |
6d048f53 | 2624 | |
5ad531db | 2625 | if (!rq_in_driver(cfqd)) |
23e018a1 | 2626 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
2627 | } |
2628 | ||
22e2c507 JA |
2629 | /* |
2630 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
2631 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
2632 | */ | |
2633 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 2634 | { |
22e2c507 JA |
2635 | if (has_fs_excl()) { |
2636 | /* | |
2637 | * boost idle prio on transactions that would lock out other | |
2638 | * users of the filesystem | |
2639 | */ | |
2640 | if (cfq_class_idle(cfqq)) | |
2641 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
2642 | if (cfqq->ioprio > IOPRIO_NORM) | |
2643 | cfqq->ioprio = IOPRIO_NORM; | |
2644 | } else { | |
2645 | /* | |
dddb7451 | 2646 | * unboost the queue (if needed) |
22e2c507 | 2647 | */ |
dddb7451 CZ |
2648 | cfqq->ioprio_class = cfqq->org_ioprio_class; |
2649 | cfqq->ioprio = cfqq->org_ioprio; | |
22e2c507 | 2650 | } |
22e2c507 | 2651 | } |
1da177e4 | 2652 | |
89850f7e | 2653 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 2654 | { |
1b379d8d | 2655 | if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 2656 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 2657 | return ELV_MQUEUE_MUST; |
3b18152c | 2658 | } |
1da177e4 | 2659 | |
22e2c507 | 2660 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
2661 | } |
2662 | ||
165125e1 | 2663 | static int cfq_may_queue(struct request_queue *q, int rw) |
22e2c507 JA |
2664 | { |
2665 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2666 | struct task_struct *tsk = current; | |
91fac317 | 2667 | struct cfq_io_context *cic; |
22e2c507 JA |
2668 | struct cfq_queue *cfqq; |
2669 | ||
2670 | /* | |
2671 | * don't force setup of a queue from here, as a call to may_queue | |
2672 | * does not necessarily imply that a request actually will be queued. | |
2673 | * so just lookup a possibly existing queue, or return 'may queue' | |
2674 | * if that fails | |
2675 | */ | |
4ac845a2 | 2676 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
2677 | if (!cic) |
2678 | return ELV_MQUEUE_MAY; | |
2679 | ||
b0b78f81 | 2680 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
22e2c507 | 2681 | if (cfqq) { |
fd0928df | 2682 | cfq_init_prio_data(cfqq, cic->ioc); |
22e2c507 JA |
2683 | cfq_prio_boost(cfqq); |
2684 | ||
89850f7e | 2685 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
2686 | } |
2687 | ||
2688 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
2689 | } |
2690 | ||
1da177e4 LT |
2691 | /* |
2692 | * queue lock held here | |
2693 | */ | |
bb37b94c | 2694 | static void cfq_put_request(struct request *rq) |
1da177e4 | 2695 | { |
5e705374 | 2696 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 2697 | |
5e705374 | 2698 | if (cfqq) { |
22e2c507 | 2699 | const int rw = rq_data_dir(rq); |
1da177e4 | 2700 | |
22e2c507 JA |
2701 | BUG_ON(!cfqq->allocated[rw]); |
2702 | cfqq->allocated[rw]--; | |
1da177e4 | 2703 | |
5e705374 | 2704 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 2705 | |
1da177e4 | 2706 | rq->elevator_private = NULL; |
5e705374 | 2707 | rq->elevator_private2 = NULL; |
1da177e4 | 2708 | |
1da177e4 LT |
2709 | cfq_put_queue(cfqq); |
2710 | } | |
2711 | } | |
2712 | ||
df5fe3e8 JM |
2713 | static struct cfq_queue * |
2714 | cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
2715 | struct cfq_queue *cfqq) | |
2716 | { | |
2717 | cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); | |
2718 | cic_set_cfqq(cic, cfqq->new_cfqq, 1); | |
b3b6d040 | 2719 | cfq_mark_cfqq_coop(cfqq->new_cfqq); |
df5fe3e8 JM |
2720 | cfq_put_queue(cfqq); |
2721 | return cic_to_cfqq(cic, 1); | |
2722 | } | |
2723 | ||
e6c5bc73 JM |
2724 | static int should_split_cfqq(struct cfq_queue *cfqq) |
2725 | { | |
2726 | if (cfqq->seeky_start && | |
2727 | time_after(jiffies, cfqq->seeky_start + CFQQ_COOP_TOUT)) | |
2728 | return 1; | |
2729 | return 0; | |
2730 | } | |
2731 | ||
2732 | /* | |
2733 | * Returns NULL if a new cfqq should be allocated, or the old cfqq if this | |
2734 | * was the last process referring to said cfqq. | |
2735 | */ | |
2736 | static struct cfq_queue * | |
2737 | split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) | |
2738 | { | |
2739 | if (cfqq_process_refs(cfqq) == 1) { | |
2740 | cfqq->seeky_start = 0; | |
2741 | cfqq->pid = current->pid; | |
2742 | cfq_clear_cfqq_coop(cfqq); | |
2743 | return cfqq; | |
2744 | } | |
2745 | ||
2746 | cic_set_cfqq(cic, NULL, 1); | |
2747 | cfq_put_queue(cfqq); | |
2748 | return NULL; | |
2749 | } | |
1da177e4 | 2750 | /* |
22e2c507 | 2751 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2752 | */ |
22e2c507 | 2753 | static int |
165125e1 | 2754 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
2755 | { |
2756 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2757 | struct cfq_io_context *cic; | |
2758 | const int rw = rq_data_dir(rq); | |
a6151c3a | 2759 | const bool is_sync = rq_is_sync(rq); |
22e2c507 | 2760 | struct cfq_queue *cfqq; |
1da177e4 LT |
2761 | unsigned long flags; |
2762 | ||
2763 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2764 | ||
e2d74ac0 | 2765 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2766 | |
1da177e4 LT |
2767 | spin_lock_irqsave(q->queue_lock, flags); |
2768 | ||
22e2c507 JA |
2769 | if (!cic) |
2770 | goto queue_fail; | |
2771 | ||
e6c5bc73 | 2772 | new_queue: |
91fac317 | 2773 | cfqq = cic_to_cfqq(cic, is_sync); |
32f2e807 | 2774 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
fd0928df | 2775 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
91fac317 | 2776 | cic_set_cfqq(cic, cfqq, is_sync); |
df5fe3e8 | 2777 | } else { |
e6c5bc73 JM |
2778 | /* |
2779 | * If the queue was seeky for too long, break it apart. | |
2780 | */ | |
2781 | if (cfq_cfqq_coop(cfqq) && should_split_cfqq(cfqq)) { | |
2782 | cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); | |
2783 | cfqq = split_cfqq(cic, cfqq); | |
2784 | if (!cfqq) | |
2785 | goto new_queue; | |
2786 | } | |
2787 | ||
df5fe3e8 JM |
2788 | /* |
2789 | * Check to see if this queue is scheduled to merge with | |
2790 | * another, closely cooperating queue. The merging of | |
2791 | * queues happens here as it must be done in process context. | |
2792 | * The reference on new_cfqq was taken in merge_cfqqs. | |
2793 | */ | |
2794 | if (cfqq->new_cfqq) | |
2795 | cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); | |
91fac317 | 2796 | } |
1da177e4 LT |
2797 | |
2798 | cfqq->allocated[rw]++; | |
22e2c507 | 2799 | atomic_inc(&cfqq->ref); |
1da177e4 | 2800 | |
5e705374 | 2801 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 2802 | |
5e705374 JA |
2803 | rq->elevator_private = cic; |
2804 | rq->elevator_private2 = cfqq; | |
2805 | return 0; | |
1da177e4 | 2806 | |
22e2c507 JA |
2807 | queue_fail: |
2808 | if (cic) | |
2809 | put_io_context(cic->ioc); | |
89850f7e | 2810 | |
23e018a1 | 2811 | cfq_schedule_dispatch(cfqd); |
1da177e4 | 2812 | spin_unlock_irqrestore(q->queue_lock, flags); |
7b679138 | 2813 | cfq_log(cfqd, "set_request fail"); |
1da177e4 LT |
2814 | return 1; |
2815 | } | |
2816 | ||
65f27f38 | 2817 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 2818 | { |
65f27f38 | 2819 | struct cfq_data *cfqd = |
23e018a1 | 2820 | container_of(work, struct cfq_data, unplug_work); |
165125e1 | 2821 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2822 | |
40bb54d1 | 2823 | spin_lock_irq(q->queue_lock); |
a7f55792 | 2824 | __blk_run_queue(cfqd->queue); |
40bb54d1 | 2825 | spin_unlock_irq(q->queue_lock); |
22e2c507 JA |
2826 | } |
2827 | ||
2828 | /* | |
2829 | * Timer running if the active_queue is currently idling inside its time slice | |
2830 | */ | |
2831 | static void cfq_idle_slice_timer(unsigned long data) | |
2832 | { | |
2833 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2834 | struct cfq_queue *cfqq; | |
2835 | unsigned long flags; | |
3c6bd2f8 | 2836 | int timed_out = 1; |
22e2c507 | 2837 | |
7b679138 JA |
2838 | cfq_log(cfqd, "idle timer fired"); |
2839 | ||
22e2c507 JA |
2840 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
2841 | ||
fe094d98 JA |
2842 | cfqq = cfqd->active_queue; |
2843 | if (cfqq) { | |
3c6bd2f8 JA |
2844 | timed_out = 0; |
2845 | ||
b029195d JA |
2846 | /* |
2847 | * We saw a request before the queue expired, let it through | |
2848 | */ | |
2849 | if (cfq_cfqq_must_dispatch(cfqq)) | |
2850 | goto out_kick; | |
2851 | ||
22e2c507 JA |
2852 | /* |
2853 | * expired | |
2854 | */ | |
44f7c160 | 2855 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
2856 | goto expire; |
2857 | ||
2858 | /* | |
2859 | * only expire and reinvoke request handler, if there are | |
2860 | * other queues with pending requests | |
2861 | */ | |
caaa5f9f | 2862 | if (!cfqd->busy_queues) |
22e2c507 | 2863 | goto out_cont; |
22e2c507 JA |
2864 | |
2865 | /* | |
2866 | * not expired and it has a request pending, let it dispatch | |
2867 | */ | |
75e50984 | 2868 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 2869 | goto out_kick; |
76280aff CZ |
2870 | |
2871 | /* | |
2872 | * Queue depth flag is reset only when the idle didn't succeed | |
2873 | */ | |
2874 | cfq_clear_cfqq_deep(cfqq); | |
22e2c507 JA |
2875 | } |
2876 | expire: | |
6084cdda | 2877 | cfq_slice_expired(cfqd, timed_out); |
22e2c507 | 2878 | out_kick: |
23e018a1 | 2879 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2880 | out_cont: |
2881 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2882 | } | |
2883 | ||
3b18152c JA |
2884 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2885 | { | |
2886 | del_timer_sync(&cfqd->idle_slice_timer); | |
23e018a1 | 2887 | cancel_work_sync(&cfqd->unplug_work); |
3b18152c | 2888 | } |
22e2c507 | 2889 | |
c2dea2d1 VT |
2890 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
2891 | { | |
2892 | int i; | |
2893 | ||
2894 | for (i = 0; i < IOPRIO_BE_NR; i++) { | |
2895 | if (cfqd->async_cfqq[0][i]) | |
2896 | cfq_put_queue(cfqd->async_cfqq[0][i]); | |
2897 | if (cfqd->async_cfqq[1][i]) | |
2898 | cfq_put_queue(cfqd->async_cfqq[1][i]); | |
c2dea2d1 | 2899 | } |
2389d1ef ON |
2900 | |
2901 | if (cfqd->async_idle_cfqq) | |
2902 | cfq_put_queue(cfqd->async_idle_cfqq); | |
c2dea2d1 VT |
2903 | } |
2904 | ||
b374d18a | 2905 | static void cfq_exit_queue(struct elevator_queue *e) |
1da177e4 | 2906 | { |
22e2c507 | 2907 | struct cfq_data *cfqd = e->elevator_data; |
165125e1 | 2908 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2909 | |
3b18152c | 2910 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2911 | |
d9ff4187 | 2912 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2913 | |
d9ff4187 | 2914 | if (cfqd->active_queue) |
6084cdda | 2915 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
e2d74ac0 JA |
2916 | |
2917 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2918 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2919 | struct cfq_io_context, | |
2920 | queue_list); | |
89850f7e JA |
2921 | |
2922 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 2923 | } |
e2d74ac0 | 2924 | |
c2dea2d1 | 2925 | cfq_put_async_queues(cfqd); |
15c31be4 | 2926 | |
d9ff4187 | 2927 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
2928 | |
2929 | cfq_shutdown_timer_wq(cfqd); | |
2930 | ||
a90d742e | 2931 | kfree(cfqd); |
1da177e4 LT |
2932 | } |
2933 | ||
165125e1 | 2934 | static void *cfq_init_queue(struct request_queue *q) |
1da177e4 LT |
2935 | { |
2936 | struct cfq_data *cfqd; | |
718eee05 | 2937 | int i, j; |
1da177e4 | 2938 | |
94f6030c | 2939 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
1da177e4 | 2940 | if (!cfqd) |
bc1c1169 | 2941 | return NULL; |
1da177e4 | 2942 | |
c0324a02 | 2943 | for (i = 0; i < 2; ++i) |
718eee05 CZ |
2944 | for (j = 0; j < 3; ++j) |
2945 | cfqd->service_trees[i][j] = CFQ_RB_ROOT; | |
c0324a02 | 2946 | cfqd->service_tree_idle = CFQ_RB_ROOT; |
26a2ac00 JA |
2947 | |
2948 | /* | |
2949 | * Not strictly needed (since RB_ROOT just clears the node and we | |
2950 | * zeroed cfqd on alloc), but better be safe in case someone decides | |
2951 | * to add magic to the rb code | |
2952 | */ | |
2953 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2954 | cfqd->prio_trees[i] = RB_ROOT; | |
2955 | ||
6118b70b JA |
2956 | /* |
2957 | * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. | |
2958 | * Grab a permanent reference to it, so that the normal code flow | |
2959 | * will not attempt to free it. | |
2960 | */ | |
2961 | cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); | |
2962 | atomic_inc(&cfqd->oom_cfqq.ref); | |
2963 | ||
d9ff4187 | 2964 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 2965 | |
1da177e4 | 2966 | cfqd->queue = q; |
1da177e4 | 2967 | |
22e2c507 JA |
2968 | init_timer(&cfqd->idle_slice_timer); |
2969 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2970 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2971 | ||
23e018a1 | 2972 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 2973 | |
1da177e4 | 2974 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
2975 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2976 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2977 | cfqd->cfq_back_max = cfq_back_max; |
2978 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2979 | cfqd->cfq_slice[0] = cfq_slice_async; |
2980 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2981 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2982 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
963b72fc | 2983 | cfqd->cfq_latency = 1; |
e459dd08 | 2984 | cfqd->hw_tag = -1; |
365722bb | 2985 | cfqd->last_end_sync_rq = jiffies; |
bc1c1169 | 2986 | return cfqd; |
1da177e4 LT |
2987 | } |
2988 | ||
2989 | static void cfq_slab_kill(void) | |
2990 | { | |
d6de8be7 JA |
2991 | /* |
2992 | * Caller already ensured that pending RCU callbacks are completed, | |
2993 | * so we should have no busy allocations at this point. | |
2994 | */ | |
1da177e4 LT |
2995 | if (cfq_pool) |
2996 | kmem_cache_destroy(cfq_pool); | |
2997 | if (cfq_ioc_pool) | |
2998 | kmem_cache_destroy(cfq_ioc_pool); | |
2999 | } | |
3000 | ||
3001 | static int __init cfq_slab_setup(void) | |
3002 | { | |
0a31bd5f | 3003 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
1da177e4 LT |
3004 | if (!cfq_pool) |
3005 | goto fail; | |
3006 | ||
34e6bbf2 | 3007 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
1da177e4 LT |
3008 | if (!cfq_ioc_pool) |
3009 | goto fail; | |
3010 | ||
3011 | return 0; | |
3012 | fail: | |
3013 | cfq_slab_kill(); | |
3014 | return -ENOMEM; | |
3015 | } | |
3016 | ||
1da177e4 LT |
3017 | /* |
3018 | * sysfs parts below --> | |
3019 | */ | |
1da177e4 LT |
3020 | static ssize_t |
3021 | cfq_var_show(unsigned int var, char *page) | |
3022 | { | |
3023 | return sprintf(page, "%d\n", var); | |
3024 | } | |
3025 | ||
3026 | static ssize_t | |
3027 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
3028 | { | |
3029 | char *p = (char *) page; | |
3030 | ||
3031 | *var = simple_strtoul(p, &p, 10); | |
3032 | return count; | |
3033 | } | |
3034 | ||
1da177e4 | 3035 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
b374d18a | 3036 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
1da177e4 | 3037 | { \ |
3d1ab40f | 3038 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
3039 | unsigned int __data = __VAR; \ |
3040 | if (__CONV) \ | |
3041 | __data = jiffies_to_msecs(__data); \ | |
3042 | return cfq_var_show(__data, (page)); \ | |
3043 | } | |
3044 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
3045 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
3046 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
3047 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
3048 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
3049 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
3050 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
3051 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
3052 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
963b72fc | 3053 | SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); |
1da177e4 LT |
3054 | #undef SHOW_FUNCTION |
3055 | ||
3056 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
b374d18a | 3057 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
1da177e4 | 3058 | { \ |
3d1ab40f | 3059 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
3060 | unsigned int __data; \ |
3061 | int ret = cfq_var_store(&__data, (page), count); \ | |
3062 | if (__data < (MIN)) \ | |
3063 | __data = (MIN); \ | |
3064 | else if (__data > (MAX)) \ | |
3065 | __data = (MAX); \ | |
3066 | if (__CONV) \ | |
3067 | *(__PTR) = msecs_to_jiffies(__data); \ | |
3068 | else \ | |
3069 | *(__PTR) = __data; \ | |
3070 | return ret; \ | |
3071 | } | |
3072 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
fe094d98 JA |
3073 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
3074 | UINT_MAX, 1); | |
3075 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, | |
3076 | UINT_MAX, 1); | |
e572ec7e | 3077 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
fe094d98 JA |
3078 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
3079 | UINT_MAX, 0); | |
22e2c507 JA |
3080 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
3081 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
3082 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
fe094d98 JA |
3083 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
3084 | UINT_MAX, 0); | |
963b72fc | 3085 | STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); |
1da177e4 LT |
3086 | #undef STORE_FUNCTION |
3087 | ||
e572ec7e AV |
3088 | #define CFQ_ATTR(name) \ |
3089 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
3090 | ||
3091 | static struct elv_fs_entry cfq_attrs[] = { | |
3092 | CFQ_ATTR(quantum), | |
e572ec7e AV |
3093 | CFQ_ATTR(fifo_expire_sync), |
3094 | CFQ_ATTR(fifo_expire_async), | |
3095 | CFQ_ATTR(back_seek_max), | |
3096 | CFQ_ATTR(back_seek_penalty), | |
3097 | CFQ_ATTR(slice_sync), | |
3098 | CFQ_ATTR(slice_async), | |
3099 | CFQ_ATTR(slice_async_rq), | |
3100 | CFQ_ATTR(slice_idle), | |
963b72fc | 3101 | CFQ_ATTR(low_latency), |
e572ec7e | 3102 | __ATTR_NULL |
1da177e4 LT |
3103 | }; |
3104 | ||
1da177e4 LT |
3105 | static struct elevator_type iosched_cfq = { |
3106 | .ops = { | |
3107 | .elevator_merge_fn = cfq_merge, | |
3108 | .elevator_merged_fn = cfq_merged_request, | |
3109 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 3110 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 3111 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 3112 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 3113 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
3114 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
3115 | .elevator_queue_empty_fn = cfq_queue_empty, | |
3116 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
3117 | .elevator_former_req_fn = elv_rb_former_request, |
3118 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
3119 | .elevator_set_req_fn = cfq_set_request, |
3120 | .elevator_put_req_fn = cfq_put_request, | |
3121 | .elevator_may_queue_fn = cfq_may_queue, | |
3122 | .elevator_init_fn = cfq_init_queue, | |
3123 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 3124 | .trim = cfq_free_io_context, |
1da177e4 | 3125 | }, |
3d1ab40f | 3126 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
3127 | .elevator_name = "cfq", |
3128 | .elevator_owner = THIS_MODULE, | |
3129 | }; | |
3130 | ||
3131 | static int __init cfq_init(void) | |
3132 | { | |
22e2c507 JA |
3133 | /* |
3134 | * could be 0 on HZ < 1000 setups | |
3135 | */ | |
3136 | if (!cfq_slice_async) | |
3137 | cfq_slice_async = 1; | |
3138 | if (!cfq_slice_idle) | |
3139 | cfq_slice_idle = 1; | |
3140 | ||
1da177e4 LT |
3141 | if (cfq_slab_setup()) |
3142 | return -ENOMEM; | |
3143 | ||
2fdd82bd | 3144 | elv_register(&iosched_cfq); |
1da177e4 | 3145 | |
2fdd82bd | 3146 | return 0; |
1da177e4 LT |
3147 | } |
3148 | ||
3149 | static void __exit cfq_exit(void) | |
3150 | { | |
6e9a4738 | 3151 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 3152 | elv_unregister(&iosched_cfq); |
334e94de | 3153 | ioc_gone = &all_gone; |
fba82272 OH |
3154 | /* ioc_gone's update must be visible before reading ioc_count */ |
3155 | smp_wmb(); | |
d6de8be7 JA |
3156 | |
3157 | /* | |
3158 | * this also protects us from entering cfq_slab_kill() with | |
3159 | * pending RCU callbacks | |
3160 | */ | |
245b2e70 | 3161 | if (elv_ioc_count_read(cfq_ioc_count)) |
9a11b4ed | 3162 | wait_for_completion(&all_gone); |
83521d3e | 3163 | cfq_slab_kill(); |
1da177e4 LT |
3164 | } |
3165 | ||
3166 | module_init(cfq_init); | |
3167 | module_exit(cfq_exit); | |
3168 | ||
3169 | MODULE_AUTHOR("Jens Axboe"); | |
3170 | MODULE_LICENSE("GPL"); | |
3171 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |