]>
Commit | Line | Data |
---|---|---|
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> | |
1da177e4 | 12 | #include <linux/rbtree.h> |
22e2c507 | 13 | #include <linux/ioprio.h> |
7b679138 | 14 | #include <linux/blktrace_api.h> |
1da177e4 LT |
15 | |
16 | /* | |
17 | * tunables | |
18 | */ | |
fe094d98 JA |
19 | /* max queue in one round of service */ |
20 | static const int cfq_quantum = 4; | |
64100099 | 21 | static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
fe094d98 JA |
22 | /* maximum backwards seek, in KiB */ |
23 | static const int cfq_back_max = 16 * 1024; | |
24 | /* penalty of a backwards seek */ | |
25 | static const int cfq_back_penalty = 2; | |
64100099 | 26 | static const int cfq_slice_sync = HZ / 10; |
3b18152c | 27 | static int cfq_slice_async = HZ / 25; |
64100099 | 28 | static const int cfq_slice_async_rq = 2; |
caaa5f9f | 29 | static int cfq_slice_idle = HZ / 125; |
5db5d642 CZ |
30 | static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ |
31 | static const int cfq_hist_divisor = 4; | |
22e2c507 | 32 | |
d9e7620e | 33 | /* |
0871714e | 34 | * offset from end of service tree |
d9e7620e | 35 | */ |
0871714e | 36 | #define CFQ_IDLE_DELAY (HZ / 5) |
d9e7620e JA |
37 | |
38 | /* | |
39 | * below this threshold, we consider thinktime immediate | |
40 | */ | |
41 | #define CFQ_MIN_TT (2) | |
42 | ||
e6c5bc73 JM |
43 | /* |
44 | * Allow merged cfqqs to perform this amount of seeky I/O before | |
45 | * deciding to break the queues up again. | |
46 | */ | |
47 | #define CFQQ_COOP_TOUT (HZ) | |
48 | ||
22e2c507 | 49 | #define CFQ_SLICE_SCALE (5) |
45333d5a | 50 | #define CFQ_HW_QUEUE_MIN (5) |
22e2c507 | 51 | |
fe094d98 JA |
52 | #define RQ_CIC(rq) \ |
53 | ((struct cfq_io_context *) (rq)->elevator_private) | |
7b679138 | 54 | #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2) |
1da177e4 | 55 | |
e18b890b CL |
56 | static struct kmem_cache *cfq_pool; |
57 | static struct kmem_cache *cfq_ioc_pool; | |
1da177e4 | 58 | |
245b2e70 | 59 | static DEFINE_PER_CPU(unsigned long, cfq_ioc_count); |
334e94de | 60 | static struct completion *ioc_gone; |
9a11b4ed | 61 | static DEFINE_SPINLOCK(ioc_gone_lock); |
334e94de | 62 | |
22e2c507 JA |
63 | #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
64 | #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) | |
22e2c507 JA |
65 | #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
66 | ||
206dc69b JA |
67 | #define sample_valid(samples) ((samples) > 80) |
68 | ||
cc09e299 JA |
69 | /* |
70 | * Most of our rbtree usage is for sorting with min extraction, so | |
71 | * if we cache the leftmost node we don't have to walk down the tree | |
72 | * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should | |
73 | * move this into the elevator for the rq sorting as well. | |
74 | */ | |
75 | struct cfq_rb_root { | |
76 | struct rb_root rb; | |
77 | struct rb_node *left; | |
aa6f6a3d | 78 | unsigned count; |
cc09e299 | 79 | }; |
aa6f6a3d | 80 | #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, } |
cc09e299 | 81 | |
6118b70b JA |
82 | /* |
83 | * Per process-grouping structure | |
84 | */ | |
85 | struct cfq_queue { | |
86 | /* reference count */ | |
87 | atomic_t ref; | |
88 | /* various state flags, see below */ | |
89 | unsigned int flags; | |
90 | /* parent cfq_data */ | |
91 | struct cfq_data *cfqd; | |
92 | /* service_tree member */ | |
93 | struct rb_node rb_node; | |
94 | /* service_tree key */ | |
95 | unsigned long rb_key; | |
96 | /* prio tree member */ | |
97 | struct rb_node p_node; | |
98 | /* prio tree root we belong to, if any */ | |
99 | struct rb_root *p_root; | |
100 | /* sorted list of pending requests */ | |
101 | struct rb_root sort_list; | |
102 | /* if fifo isn't expired, next request to serve */ | |
103 | struct request *next_rq; | |
104 | /* requests queued in sort_list */ | |
105 | int queued[2]; | |
106 | /* currently allocated requests */ | |
107 | int allocated[2]; | |
108 | /* fifo list of requests in sort_list */ | |
109 | struct list_head fifo; | |
110 | ||
111 | unsigned long slice_end; | |
112 | long slice_resid; | |
113 | unsigned int slice_dispatch; | |
114 | ||
115 | /* pending metadata requests */ | |
116 | int meta_pending; | |
117 | /* number of requests that are on the dispatch list or inside driver */ | |
118 | int dispatched; | |
119 | ||
120 | /* io prio of this group */ | |
121 | unsigned short ioprio, org_ioprio; | |
122 | unsigned short ioprio_class, org_ioprio_class; | |
123 | ||
b2c18e1e JM |
124 | unsigned int seek_samples; |
125 | u64 seek_total; | |
126 | sector_t seek_mean; | |
127 | sector_t last_request_pos; | |
e6c5bc73 | 128 | unsigned long seeky_start; |
b2c18e1e | 129 | |
6118b70b | 130 | pid_t pid; |
df5fe3e8 | 131 | |
aa6f6a3d | 132 | struct cfq_rb_root *service_tree; |
df5fe3e8 | 133 | struct cfq_queue *new_cfqq; |
6118b70b JA |
134 | }; |
135 | ||
c0324a02 | 136 | /* |
718eee05 | 137 | * First index in the service_trees. |
c0324a02 CZ |
138 | * IDLE is handled separately, so it has negative index |
139 | */ | |
140 | enum wl_prio_t { | |
141 | IDLE_WORKLOAD = -1, | |
142 | BE_WORKLOAD = 0, | |
143 | RT_WORKLOAD = 1 | |
144 | }; | |
145 | ||
718eee05 CZ |
146 | /* |
147 | * Second index in the service_trees. | |
148 | */ | |
149 | enum wl_type_t { | |
150 | ASYNC_WORKLOAD = 0, | |
151 | SYNC_NOIDLE_WORKLOAD = 1, | |
152 | SYNC_WORKLOAD = 2 | |
153 | }; | |
154 | ||
155 | ||
22e2c507 JA |
156 | /* |
157 | * Per block device queue structure | |
158 | */ | |
1da177e4 | 159 | struct cfq_data { |
165125e1 | 160 | struct request_queue *queue; |
22e2c507 JA |
161 | |
162 | /* | |
c0324a02 CZ |
163 | * rr lists of queues with requests, onle rr for each priority class. |
164 | * Counts are embedded in the cfq_rb_root | |
165 | */ | |
718eee05 | 166 | struct cfq_rb_root service_trees[2][3]; |
c0324a02 CZ |
167 | struct cfq_rb_root service_tree_idle; |
168 | /* | |
169 | * The priority currently being served | |
22e2c507 | 170 | */ |
c0324a02 | 171 | enum wl_prio_t serving_prio; |
718eee05 CZ |
172 | enum wl_type_t serving_type; |
173 | unsigned long workload_expires; | |
a36e71f9 JA |
174 | |
175 | /* | |
176 | * Each priority tree is sorted by next_request position. These | |
177 | * trees are used when determining if two or more queues are | |
178 | * interleaving requests (see cfq_close_cooperator). | |
179 | */ | |
180 | struct rb_root prio_trees[CFQ_PRIO_LISTS]; | |
181 | ||
22e2c507 | 182 | unsigned int busy_queues; |
5db5d642 | 183 | unsigned int busy_queues_avg[2]; |
22e2c507 | 184 | |
5ad531db | 185 | int rq_in_driver[2]; |
3ed9a296 | 186 | int sync_flight; |
45333d5a AC |
187 | |
188 | /* | |
189 | * queue-depth detection | |
190 | */ | |
191 | int rq_queued; | |
25776e35 | 192 | int hw_tag; |
45333d5a AC |
193 | int hw_tag_samples; |
194 | int rq_in_driver_peak; | |
1da177e4 | 195 | |
22e2c507 JA |
196 | /* |
197 | * idle window management | |
198 | */ | |
199 | struct timer_list idle_slice_timer; | |
23e018a1 | 200 | struct work_struct unplug_work; |
1da177e4 | 201 | |
22e2c507 JA |
202 | struct cfq_queue *active_queue; |
203 | struct cfq_io_context *active_cic; | |
22e2c507 | 204 | |
c2dea2d1 VT |
205 | /* |
206 | * async queue for each priority case | |
207 | */ | |
208 | struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; | |
209 | struct cfq_queue *async_idle_cfqq; | |
15c31be4 | 210 | |
6d048f53 | 211 | sector_t last_position; |
1da177e4 | 212 | |
1da177e4 LT |
213 | /* |
214 | * tunables, see top of file | |
215 | */ | |
216 | unsigned int cfq_quantum; | |
22e2c507 | 217 | unsigned int cfq_fifo_expire[2]; |
1da177e4 LT |
218 | unsigned int cfq_back_penalty; |
219 | unsigned int cfq_back_max; | |
22e2c507 JA |
220 | unsigned int cfq_slice[2]; |
221 | unsigned int cfq_slice_async_rq; | |
222 | unsigned int cfq_slice_idle; | |
963b72fc | 223 | unsigned int cfq_latency; |
d9ff4187 AV |
224 | |
225 | struct list_head cic_list; | |
1da177e4 | 226 | |
6118b70b JA |
227 | /* |
228 | * Fallback dummy cfqq for extreme OOM conditions | |
229 | */ | |
230 | struct cfq_queue oom_cfqq; | |
365722bb VG |
231 | |
232 | unsigned long last_end_sync_rq; | |
1da177e4 LT |
233 | }; |
234 | ||
c0324a02 | 235 | static struct cfq_rb_root *service_tree_for(enum wl_prio_t prio, |
718eee05 | 236 | enum wl_type_t type, |
c0324a02 CZ |
237 | struct cfq_data *cfqd) |
238 | { | |
239 | if (prio == IDLE_WORKLOAD) | |
240 | return &cfqd->service_tree_idle; | |
241 | ||
718eee05 | 242 | return &cfqd->service_trees[prio][type]; |
c0324a02 CZ |
243 | } |
244 | ||
3b18152c | 245 | enum cfqq_state_flags { |
b0b8d749 JA |
246 | CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
247 | CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ | |
b029195d | 248 | CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
b0b8d749 | 249 | CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
b0b8d749 JA |
250 | CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
251 | CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ | |
252 | CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ | |
44f7c160 | 253 | CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
91fac317 | 254 | CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
b3b6d040 | 255 | CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ |
3b18152c JA |
256 | }; |
257 | ||
258 | #define CFQ_CFQQ_FNS(name) \ | |
259 | static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ | |
260 | { \ | |
fe094d98 | 261 | (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
262 | } \ |
263 | static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ | |
264 | { \ | |
fe094d98 | 265 | (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
3b18152c JA |
266 | } \ |
267 | static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ | |
268 | { \ | |
fe094d98 | 269 | return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
3b18152c JA |
270 | } |
271 | ||
272 | CFQ_CFQQ_FNS(on_rr); | |
273 | CFQ_CFQQ_FNS(wait_request); | |
b029195d | 274 | CFQ_CFQQ_FNS(must_dispatch); |
3b18152c | 275 | CFQ_CFQQ_FNS(must_alloc_slice); |
3b18152c JA |
276 | CFQ_CFQQ_FNS(fifo_expire); |
277 | CFQ_CFQQ_FNS(idle_window); | |
278 | CFQ_CFQQ_FNS(prio_changed); | |
44f7c160 | 279 | CFQ_CFQQ_FNS(slice_new); |
91fac317 | 280 | CFQ_CFQQ_FNS(sync); |
a36e71f9 | 281 | CFQ_CFQQ_FNS(coop); |
3b18152c JA |
282 | #undef CFQ_CFQQ_FNS |
283 | ||
7b679138 JA |
284 | #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
285 | blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) | |
286 | #define cfq_log(cfqd, fmt, args...) \ | |
287 | blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) | |
288 | ||
c0324a02 CZ |
289 | static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) |
290 | { | |
291 | if (cfq_class_idle(cfqq)) | |
292 | return IDLE_WORKLOAD; | |
293 | if (cfq_class_rt(cfqq)) | |
294 | return RT_WORKLOAD; | |
295 | return BE_WORKLOAD; | |
296 | } | |
297 | ||
718eee05 CZ |
298 | |
299 | static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) | |
300 | { | |
301 | if (!cfq_cfqq_sync(cfqq)) | |
302 | return ASYNC_WORKLOAD; | |
303 | if (!cfq_cfqq_idle_window(cfqq)) | |
304 | return SYNC_NOIDLE_WORKLOAD; | |
305 | return SYNC_WORKLOAD; | |
306 | } | |
307 | ||
c0324a02 CZ |
308 | static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd) |
309 | { | |
310 | if (wl == IDLE_WORKLOAD) | |
311 | return cfqd->service_tree_idle.count; | |
312 | ||
718eee05 CZ |
313 | return cfqd->service_trees[wl][ASYNC_WORKLOAD].count |
314 | + cfqd->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count | |
315 | + cfqd->service_trees[wl][SYNC_WORKLOAD].count; | |
c0324a02 CZ |
316 | } |
317 | ||
165125e1 | 318 | static void cfq_dispatch_insert(struct request_queue *, struct request *); |
a6151c3a | 319 | static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, |
fd0928df | 320 | struct io_context *, gfp_t); |
4ac845a2 | 321 | static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *, |
91fac317 VT |
322 | struct io_context *); |
323 | ||
5ad531db JA |
324 | static inline int rq_in_driver(struct cfq_data *cfqd) |
325 | { | |
326 | return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1]; | |
327 | } | |
328 | ||
91fac317 | 329 | static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic, |
a6151c3a | 330 | bool is_sync) |
91fac317 | 331 | { |
a6151c3a | 332 | return cic->cfqq[is_sync]; |
91fac317 VT |
333 | } |
334 | ||
335 | static inline void cic_set_cfqq(struct cfq_io_context *cic, | |
a6151c3a | 336 | struct cfq_queue *cfqq, bool is_sync) |
91fac317 | 337 | { |
a6151c3a | 338 | cic->cfqq[is_sync] = cfqq; |
91fac317 VT |
339 | } |
340 | ||
341 | /* | |
342 | * We regard a request as SYNC, if it's either a read or has the SYNC bit | |
343 | * set (in which case it could also be direct WRITE). | |
344 | */ | |
a6151c3a | 345 | static inline bool cfq_bio_sync(struct bio *bio) |
91fac317 | 346 | { |
a6151c3a | 347 | return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO); |
91fac317 | 348 | } |
1da177e4 | 349 | |
99f95e52 AM |
350 | /* |
351 | * scheduler run of queue, if there are requests pending and no one in the | |
352 | * driver that will restart queueing | |
353 | */ | |
23e018a1 | 354 | static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) |
99f95e52 | 355 | { |
7b679138 JA |
356 | if (cfqd->busy_queues) { |
357 | cfq_log(cfqd, "schedule dispatch"); | |
23e018a1 | 358 | kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
7b679138 | 359 | } |
99f95e52 AM |
360 | } |
361 | ||
165125e1 | 362 | static int cfq_queue_empty(struct request_queue *q) |
99f95e52 AM |
363 | { |
364 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
365 | ||
b4878f24 | 366 | return !cfqd->busy_queues; |
99f95e52 AM |
367 | } |
368 | ||
44f7c160 JA |
369 | /* |
370 | * Scale schedule slice based on io priority. Use the sync time slice only | |
371 | * if a queue is marked sync and has sync io queued. A sync queue with async | |
372 | * io only, should not get full sync slice length. | |
373 | */ | |
a6151c3a | 374 | static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, |
d9e7620e | 375 | unsigned short prio) |
44f7c160 | 376 | { |
d9e7620e | 377 | const int base_slice = cfqd->cfq_slice[sync]; |
44f7c160 | 378 | |
d9e7620e JA |
379 | WARN_ON(prio >= IOPRIO_BE_NR); |
380 | ||
381 | return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); | |
382 | } | |
44f7c160 | 383 | |
d9e7620e JA |
384 | static inline int |
385 | cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
386 | { | |
387 | return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); | |
44f7c160 JA |
388 | } |
389 | ||
5db5d642 CZ |
390 | /* |
391 | * get averaged number of queues of RT/BE priority. | |
392 | * average is updated, with a formula that gives more weight to higher numbers, | |
393 | * to quickly follows sudden increases and decrease slowly | |
394 | */ | |
395 | ||
5869619c JA |
396 | static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt) |
397 | { | |
5db5d642 CZ |
398 | unsigned min_q, max_q; |
399 | unsigned mult = cfq_hist_divisor - 1; | |
400 | unsigned round = cfq_hist_divisor / 2; | |
c0324a02 | 401 | unsigned busy = cfq_busy_queues_wl(rt, cfqd); |
5db5d642 CZ |
402 | |
403 | min_q = min(cfqd->busy_queues_avg[rt], busy); | |
404 | max_q = max(cfqd->busy_queues_avg[rt], busy); | |
405 | cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) / | |
406 | cfq_hist_divisor; | |
407 | return cfqd->busy_queues_avg[rt]; | |
408 | } | |
409 | ||
44f7c160 JA |
410 | static inline void |
411 | cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
412 | { | |
5db5d642 CZ |
413 | unsigned slice = cfq_prio_to_slice(cfqd, cfqq); |
414 | if (cfqd->cfq_latency) { | |
415 | /* interested queues (we consider only the ones with the same | |
416 | * priority class) */ | |
417 | unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq)); | |
418 | unsigned sync_slice = cfqd->cfq_slice[1]; | |
419 | unsigned expect_latency = sync_slice * iq; | |
420 | if (expect_latency > cfq_target_latency) { | |
421 | unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; | |
422 | /* scale low_slice according to IO priority | |
423 | * and sync vs async */ | |
424 | unsigned low_slice = | |
425 | min(slice, base_low_slice * slice / sync_slice); | |
426 | /* the adapted slice value is scaled to fit all iqs | |
427 | * into the target latency */ | |
428 | slice = max(slice * cfq_target_latency / expect_latency, | |
429 | low_slice); | |
430 | } | |
431 | } | |
432 | cfqq->slice_end = jiffies + slice; | |
7b679138 | 433 | cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
44f7c160 JA |
434 | } |
435 | ||
436 | /* | |
437 | * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end | |
438 | * isn't valid until the first request from the dispatch is activated | |
439 | * and the slice time set. | |
440 | */ | |
a6151c3a | 441 | static inline bool cfq_slice_used(struct cfq_queue *cfqq) |
44f7c160 JA |
442 | { |
443 | if (cfq_cfqq_slice_new(cfqq)) | |
444 | return 0; | |
445 | if (time_before(jiffies, cfqq->slice_end)) | |
446 | return 0; | |
447 | ||
448 | return 1; | |
449 | } | |
450 | ||
1da177e4 | 451 | /* |
5e705374 | 452 | * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
1da177e4 | 453 | * We choose the request that is closest to the head right now. Distance |
e8a99053 | 454 | * behind the head is penalized and only allowed to a certain extent. |
1da177e4 | 455 | */ |
5e705374 | 456 | static struct request * |
cf7c25cf | 457 | cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) |
1da177e4 | 458 | { |
cf7c25cf | 459 | sector_t s1, s2, d1 = 0, d2 = 0; |
1da177e4 | 460 | unsigned long back_max; |
e8a99053 AM |
461 | #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
462 | #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ | |
463 | unsigned wrap = 0; /* bit mask: requests behind the disk head? */ | |
1da177e4 | 464 | |
5e705374 JA |
465 | if (rq1 == NULL || rq1 == rq2) |
466 | return rq2; | |
467 | if (rq2 == NULL) | |
468 | return rq1; | |
9c2c38a1 | 469 | |
5e705374 JA |
470 | if (rq_is_sync(rq1) && !rq_is_sync(rq2)) |
471 | return rq1; | |
472 | else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) | |
473 | return rq2; | |
374f84ac JA |
474 | if (rq_is_meta(rq1) && !rq_is_meta(rq2)) |
475 | return rq1; | |
476 | else if (rq_is_meta(rq2) && !rq_is_meta(rq1)) | |
477 | return rq2; | |
1da177e4 | 478 | |
83096ebf TH |
479 | s1 = blk_rq_pos(rq1); |
480 | s2 = blk_rq_pos(rq2); | |
1da177e4 | 481 | |
1da177e4 LT |
482 | /* |
483 | * by definition, 1KiB is 2 sectors | |
484 | */ | |
485 | back_max = cfqd->cfq_back_max * 2; | |
486 | ||
487 | /* | |
488 | * Strict one way elevator _except_ in the case where we allow | |
489 | * short backward seeks which are biased as twice the cost of a | |
490 | * similar forward seek. | |
491 | */ | |
492 | if (s1 >= last) | |
493 | d1 = s1 - last; | |
494 | else if (s1 + back_max >= last) | |
495 | d1 = (last - s1) * cfqd->cfq_back_penalty; | |
496 | else | |
e8a99053 | 497 | wrap |= CFQ_RQ1_WRAP; |
1da177e4 LT |
498 | |
499 | if (s2 >= last) | |
500 | d2 = s2 - last; | |
501 | else if (s2 + back_max >= last) | |
502 | d2 = (last - s2) * cfqd->cfq_back_penalty; | |
503 | else | |
e8a99053 | 504 | wrap |= CFQ_RQ2_WRAP; |
1da177e4 LT |
505 | |
506 | /* Found required data */ | |
e8a99053 AM |
507 | |
508 | /* | |
509 | * By doing switch() on the bit mask "wrap" we avoid having to | |
510 | * check two variables for all permutations: --> faster! | |
511 | */ | |
512 | switch (wrap) { | |
5e705374 | 513 | case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
e8a99053 | 514 | if (d1 < d2) |
5e705374 | 515 | return rq1; |
e8a99053 | 516 | else if (d2 < d1) |
5e705374 | 517 | return rq2; |
e8a99053 AM |
518 | else { |
519 | if (s1 >= s2) | |
5e705374 | 520 | return rq1; |
e8a99053 | 521 | else |
5e705374 | 522 | return rq2; |
e8a99053 | 523 | } |
1da177e4 | 524 | |
e8a99053 | 525 | case CFQ_RQ2_WRAP: |
5e705374 | 526 | return rq1; |
e8a99053 | 527 | case CFQ_RQ1_WRAP: |
5e705374 JA |
528 | return rq2; |
529 | case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ | |
e8a99053 AM |
530 | default: |
531 | /* | |
532 | * Since both rqs are wrapped, | |
533 | * start with the one that's further behind head | |
534 | * (--> only *one* back seek required), | |
535 | * since back seek takes more time than forward. | |
536 | */ | |
537 | if (s1 <= s2) | |
5e705374 | 538 | return rq1; |
1da177e4 | 539 | else |
5e705374 | 540 | return rq2; |
1da177e4 LT |
541 | } |
542 | } | |
543 | ||
498d3aa2 JA |
544 | /* |
545 | * The below is leftmost cache rbtree addon | |
546 | */ | |
0871714e | 547 | static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
cc09e299 JA |
548 | { |
549 | if (!root->left) | |
550 | root->left = rb_first(&root->rb); | |
551 | ||
0871714e JA |
552 | if (root->left) |
553 | return rb_entry(root->left, struct cfq_queue, rb_node); | |
554 | ||
555 | return NULL; | |
cc09e299 JA |
556 | } |
557 | ||
a36e71f9 JA |
558 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
559 | { | |
560 | rb_erase(n, root); | |
561 | RB_CLEAR_NODE(n); | |
562 | } | |
563 | ||
cc09e299 JA |
564 | static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
565 | { | |
566 | if (root->left == n) | |
567 | root->left = NULL; | |
a36e71f9 | 568 | rb_erase_init(n, &root->rb); |
aa6f6a3d | 569 | --root->count; |
cc09e299 JA |
570 | } |
571 | ||
1da177e4 LT |
572 | /* |
573 | * would be nice to take fifo expire time into account as well | |
574 | */ | |
5e705374 JA |
575 | static struct request * |
576 | cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
577 | struct request *last) | |
1da177e4 | 578 | { |
21183b07 JA |
579 | struct rb_node *rbnext = rb_next(&last->rb_node); |
580 | struct rb_node *rbprev = rb_prev(&last->rb_node); | |
5e705374 | 581 | struct request *next = NULL, *prev = NULL; |
1da177e4 | 582 | |
21183b07 | 583 | BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
1da177e4 LT |
584 | |
585 | if (rbprev) | |
5e705374 | 586 | prev = rb_entry_rq(rbprev); |
1da177e4 | 587 | |
21183b07 | 588 | if (rbnext) |
5e705374 | 589 | next = rb_entry_rq(rbnext); |
21183b07 JA |
590 | else { |
591 | rbnext = rb_first(&cfqq->sort_list); | |
592 | if (rbnext && rbnext != &last->rb_node) | |
5e705374 | 593 | next = rb_entry_rq(rbnext); |
21183b07 | 594 | } |
1da177e4 | 595 | |
cf7c25cf | 596 | return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); |
1da177e4 LT |
597 | } |
598 | ||
d9e7620e JA |
599 | static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
600 | struct cfq_queue *cfqq) | |
1da177e4 | 601 | { |
d9e7620e JA |
602 | /* |
603 | * just an approximation, should be ok. | |
604 | */ | |
67e6b49e JA |
605 | return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
606 | cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); | |
d9e7620e JA |
607 | } |
608 | ||
498d3aa2 | 609 | /* |
c0324a02 | 610 | * The cfqd->service_trees holds all pending cfq_queue's that have |
498d3aa2 JA |
611 | * requests waiting to be processed. It is sorted in the order that |
612 | * we will service the queues. | |
613 | */ | |
a36e71f9 | 614 | static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 615 | bool add_front) |
d9e7620e | 616 | { |
0871714e JA |
617 | struct rb_node **p, *parent; |
618 | struct cfq_queue *__cfqq; | |
d9e7620e | 619 | unsigned long rb_key; |
c0324a02 | 620 | struct cfq_rb_root *service_tree; |
498d3aa2 | 621 | int left; |
d9e7620e | 622 | |
718eee05 | 623 | service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd); |
0871714e JA |
624 | if (cfq_class_idle(cfqq)) { |
625 | rb_key = CFQ_IDLE_DELAY; | |
aa6f6a3d | 626 | parent = rb_last(&service_tree->rb); |
0871714e JA |
627 | if (parent && parent != &cfqq->rb_node) { |
628 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
629 | rb_key += __cfqq->rb_key; | |
630 | } else | |
631 | rb_key += jiffies; | |
632 | } else if (!add_front) { | |
b9c8946b JA |
633 | /* |
634 | * Get our rb key offset. Subtract any residual slice | |
635 | * value carried from last service. A negative resid | |
636 | * count indicates slice overrun, and this should position | |
637 | * the next service time further away in the tree. | |
638 | */ | |
edd75ffd | 639 | rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
b9c8946b | 640 | rb_key -= cfqq->slice_resid; |
edd75ffd | 641 | cfqq->slice_resid = 0; |
48e025e6 CZ |
642 | } else { |
643 | rb_key = -HZ; | |
aa6f6a3d | 644 | __cfqq = cfq_rb_first(service_tree); |
48e025e6 CZ |
645 | rb_key += __cfqq ? __cfqq->rb_key : jiffies; |
646 | } | |
1da177e4 | 647 | |
d9e7620e | 648 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
99f9628a | 649 | /* |
d9e7620e | 650 | * same position, nothing more to do |
99f9628a | 651 | */ |
c0324a02 CZ |
652 | if (rb_key == cfqq->rb_key && |
653 | cfqq->service_tree == service_tree) | |
d9e7620e | 654 | return; |
1da177e4 | 655 | |
aa6f6a3d CZ |
656 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
657 | cfqq->service_tree = NULL; | |
1da177e4 | 658 | } |
d9e7620e | 659 | |
498d3aa2 | 660 | left = 1; |
0871714e | 661 | parent = NULL; |
aa6f6a3d CZ |
662 | cfqq->service_tree = service_tree; |
663 | p = &service_tree->rb.rb_node; | |
d9e7620e | 664 | while (*p) { |
67060e37 | 665 | struct rb_node **n; |
cc09e299 | 666 | |
d9e7620e JA |
667 | parent = *p; |
668 | __cfqq = rb_entry(parent, struct cfq_queue, rb_node); | |
669 | ||
0c534e0a | 670 | /* |
c0324a02 | 671 | * sort by key, that represents service time. |
0c534e0a | 672 | */ |
c0324a02 | 673 | if (time_before(rb_key, __cfqq->rb_key)) |
67060e37 | 674 | n = &(*p)->rb_left; |
c0324a02 | 675 | else { |
67060e37 | 676 | n = &(*p)->rb_right; |
cc09e299 | 677 | left = 0; |
c0324a02 | 678 | } |
67060e37 JA |
679 | |
680 | p = n; | |
d9e7620e JA |
681 | } |
682 | ||
cc09e299 | 683 | if (left) |
aa6f6a3d | 684 | service_tree->left = &cfqq->rb_node; |
cc09e299 | 685 | |
d9e7620e JA |
686 | cfqq->rb_key = rb_key; |
687 | rb_link_node(&cfqq->rb_node, parent, p); | |
aa6f6a3d CZ |
688 | rb_insert_color(&cfqq->rb_node, &service_tree->rb); |
689 | service_tree->count++; | |
1da177e4 LT |
690 | } |
691 | ||
a36e71f9 | 692 | static struct cfq_queue * |
f2d1f0ae JA |
693 | cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
694 | sector_t sector, struct rb_node **ret_parent, | |
695 | struct rb_node ***rb_link) | |
a36e71f9 | 696 | { |
a36e71f9 JA |
697 | struct rb_node **p, *parent; |
698 | struct cfq_queue *cfqq = NULL; | |
699 | ||
700 | parent = NULL; | |
701 | p = &root->rb_node; | |
702 | while (*p) { | |
703 | struct rb_node **n; | |
704 | ||
705 | parent = *p; | |
706 | cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
707 | ||
708 | /* | |
709 | * Sort strictly based on sector. Smallest to the left, | |
710 | * largest to the right. | |
711 | */ | |
2e46e8b2 | 712 | if (sector > blk_rq_pos(cfqq->next_rq)) |
a36e71f9 | 713 | n = &(*p)->rb_right; |
2e46e8b2 | 714 | else if (sector < blk_rq_pos(cfqq->next_rq)) |
a36e71f9 JA |
715 | n = &(*p)->rb_left; |
716 | else | |
717 | break; | |
718 | p = n; | |
3ac6c9f8 | 719 | cfqq = NULL; |
a36e71f9 JA |
720 | } |
721 | ||
722 | *ret_parent = parent; | |
723 | if (rb_link) | |
724 | *rb_link = p; | |
3ac6c9f8 | 725 | return cfqq; |
a36e71f9 JA |
726 | } |
727 | ||
728 | static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
729 | { | |
a36e71f9 JA |
730 | struct rb_node **p, *parent; |
731 | struct cfq_queue *__cfqq; | |
732 | ||
f2d1f0ae JA |
733 | if (cfqq->p_root) { |
734 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
735 | cfqq->p_root = NULL; | |
736 | } | |
a36e71f9 JA |
737 | |
738 | if (cfq_class_idle(cfqq)) | |
739 | return; | |
740 | if (!cfqq->next_rq) | |
741 | return; | |
742 | ||
f2d1f0ae | 743 | cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
2e46e8b2 TH |
744 | __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
745 | blk_rq_pos(cfqq->next_rq), &parent, &p); | |
3ac6c9f8 JA |
746 | if (!__cfqq) { |
747 | rb_link_node(&cfqq->p_node, parent, p); | |
f2d1f0ae JA |
748 | rb_insert_color(&cfqq->p_node, cfqq->p_root); |
749 | } else | |
750 | cfqq->p_root = NULL; | |
a36e71f9 JA |
751 | } |
752 | ||
498d3aa2 JA |
753 | /* |
754 | * Update cfqq's position in the service tree. | |
755 | */ | |
edd75ffd | 756 | static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
6d048f53 | 757 | { |
6d048f53 JA |
758 | /* |
759 | * Resorting requires the cfqq to be on the RR list already. | |
760 | */ | |
a36e71f9 | 761 | if (cfq_cfqq_on_rr(cfqq)) { |
edd75ffd | 762 | cfq_service_tree_add(cfqd, cfqq, 0); |
a36e71f9 JA |
763 | cfq_prio_tree_add(cfqd, cfqq); |
764 | } | |
6d048f53 JA |
765 | } |
766 | ||
1da177e4 LT |
767 | /* |
768 | * add to busy list of queues for service, trying to be fair in ordering | |
22e2c507 | 769 | * the pending list according to last request service |
1da177e4 | 770 | */ |
febffd61 | 771 | static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 772 | { |
7b679138 | 773 | cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
3b18152c JA |
774 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
775 | cfq_mark_cfqq_on_rr(cfqq); | |
1da177e4 LT |
776 | cfqd->busy_queues++; |
777 | ||
edd75ffd | 778 | cfq_resort_rr_list(cfqd, cfqq); |
1da177e4 LT |
779 | } |
780 | ||
498d3aa2 JA |
781 | /* |
782 | * Called when the cfqq no longer has requests pending, remove it from | |
783 | * the service tree. | |
784 | */ | |
febffd61 | 785 | static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 786 | { |
7b679138 | 787 | cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
3b18152c JA |
788 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
789 | cfq_clear_cfqq_on_rr(cfqq); | |
1da177e4 | 790 | |
aa6f6a3d CZ |
791 | if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
792 | cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); | |
793 | cfqq->service_tree = NULL; | |
794 | } | |
f2d1f0ae JA |
795 | if (cfqq->p_root) { |
796 | rb_erase(&cfqq->p_node, cfqq->p_root); | |
797 | cfqq->p_root = NULL; | |
798 | } | |
d9e7620e | 799 | |
1da177e4 LT |
800 | BUG_ON(!cfqd->busy_queues); |
801 | cfqd->busy_queues--; | |
802 | } | |
803 | ||
804 | /* | |
805 | * rb tree support functions | |
806 | */ | |
febffd61 | 807 | static void cfq_del_rq_rb(struct request *rq) |
1da177e4 | 808 | { |
5e705374 | 809 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 810 | struct cfq_data *cfqd = cfqq->cfqd; |
5e705374 | 811 | const int sync = rq_is_sync(rq); |
1da177e4 | 812 | |
b4878f24 JA |
813 | BUG_ON(!cfqq->queued[sync]); |
814 | cfqq->queued[sync]--; | |
1da177e4 | 815 | |
5e705374 | 816 | elv_rb_del(&cfqq->sort_list, rq); |
1da177e4 | 817 | |
dd67d051 | 818 | if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
b4878f24 | 819 | cfq_del_cfqq_rr(cfqd, cfqq); |
1da177e4 LT |
820 | } |
821 | ||
5e705374 | 822 | static void cfq_add_rq_rb(struct request *rq) |
1da177e4 | 823 | { |
5e705374 | 824 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 825 | struct cfq_data *cfqd = cfqq->cfqd; |
a36e71f9 | 826 | struct request *__alias, *prev; |
1da177e4 | 827 | |
5380a101 | 828 | cfqq->queued[rq_is_sync(rq)]++; |
1da177e4 LT |
829 | |
830 | /* | |
831 | * looks a little odd, but the first insert might return an alias. | |
832 | * if that happens, put the alias on the dispatch list | |
833 | */ | |
21183b07 | 834 | while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL) |
5e705374 | 835 | cfq_dispatch_insert(cfqd->queue, __alias); |
5fccbf61 JA |
836 | |
837 | if (!cfq_cfqq_on_rr(cfqq)) | |
838 | cfq_add_cfqq_rr(cfqd, cfqq); | |
5044eed4 JA |
839 | |
840 | /* | |
841 | * check if this request is a better next-serve candidate | |
842 | */ | |
a36e71f9 | 843 | prev = cfqq->next_rq; |
cf7c25cf | 844 | cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); |
a36e71f9 JA |
845 | |
846 | /* | |
847 | * adjust priority tree position, if ->next_rq changes | |
848 | */ | |
849 | if (prev != cfqq->next_rq) | |
850 | cfq_prio_tree_add(cfqd, cfqq); | |
851 | ||
5044eed4 | 852 | BUG_ON(!cfqq->next_rq); |
1da177e4 LT |
853 | } |
854 | ||
febffd61 | 855 | static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
1da177e4 | 856 | { |
5380a101 JA |
857 | elv_rb_del(&cfqq->sort_list, rq); |
858 | cfqq->queued[rq_is_sync(rq)]--; | |
5e705374 | 859 | cfq_add_rq_rb(rq); |
1da177e4 LT |
860 | } |
861 | ||
206dc69b JA |
862 | static struct request * |
863 | cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) | |
1da177e4 | 864 | { |
206dc69b | 865 | struct task_struct *tsk = current; |
91fac317 | 866 | struct cfq_io_context *cic; |
206dc69b | 867 | struct cfq_queue *cfqq; |
1da177e4 | 868 | |
4ac845a2 | 869 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
870 | if (!cic) |
871 | return NULL; | |
872 | ||
873 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); | |
89850f7e JA |
874 | if (cfqq) { |
875 | sector_t sector = bio->bi_sector + bio_sectors(bio); | |
876 | ||
21183b07 | 877 | return elv_rb_find(&cfqq->sort_list, sector); |
89850f7e | 878 | } |
1da177e4 | 879 | |
1da177e4 LT |
880 | return NULL; |
881 | } | |
882 | ||
165125e1 | 883 | static void cfq_activate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 884 | { |
22e2c507 | 885 | struct cfq_data *cfqd = q->elevator->elevator_data; |
3b18152c | 886 | |
5ad531db | 887 | cfqd->rq_in_driver[rq_is_sync(rq)]++; |
7b679138 | 888 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
5ad531db | 889 | rq_in_driver(cfqd)); |
25776e35 | 890 | |
5b93629b | 891 | cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
1da177e4 LT |
892 | } |
893 | ||
165125e1 | 894 | static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
1da177e4 | 895 | { |
b4878f24 | 896 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5ad531db | 897 | const int sync = rq_is_sync(rq); |
b4878f24 | 898 | |
5ad531db JA |
899 | WARN_ON(!cfqd->rq_in_driver[sync]); |
900 | cfqd->rq_in_driver[sync]--; | |
7b679138 | 901 | cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
5ad531db | 902 | rq_in_driver(cfqd)); |
1da177e4 LT |
903 | } |
904 | ||
b4878f24 | 905 | static void cfq_remove_request(struct request *rq) |
1da177e4 | 906 | { |
5e705374 | 907 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
21183b07 | 908 | |
5e705374 JA |
909 | if (cfqq->next_rq == rq) |
910 | cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); | |
1da177e4 | 911 | |
b4878f24 | 912 | list_del_init(&rq->queuelist); |
5e705374 | 913 | cfq_del_rq_rb(rq); |
374f84ac | 914 | |
45333d5a | 915 | cfqq->cfqd->rq_queued--; |
374f84ac JA |
916 | if (rq_is_meta(rq)) { |
917 | WARN_ON(!cfqq->meta_pending); | |
918 | cfqq->meta_pending--; | |
919 | } | |
1da177e4 LT |
920 | } |
921 | ||
165125e1 JA |
922 | static int cfq_merge(struct request_queue *q, struct request **req, |
923 | struct bio *bio) | |
1da177e4 LT |
924 | { |
925 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
926 | struct request *__rq; | |
1da177e4 | 927 | |
206dc69b | 928 | __rq = cfq_find_rq_fmerge(cfqd, bio); |
22e2c507 | 929 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
9817064b JA |
930 | *req = __rq; |
931 | return ELEVATOR_FRONT_MERGE; | |
1da177e4 LT |
932 | } |
933 | ||
934 | return ELEVATOR_NO_MERGE; | |
1da177e4 LT |
935 | } |
936 | ||
165125e1 | 937 | static void cfq_merged_request(struct request_queue *q, struct request *req, |
21183b07 | 938 | int type) |
1da177e4 | 939 | { |
21183b07 | 940 | if (type == ELEVATOR_FRONT_MERGE) { |
5e705374 | 941 | struct cfq_queue *cfqq = RQ_CFQQ(req); |
1da177e4 | 942 | |
5e705374 | 943 | cfq_reposition_rq_rb(cfqq, req); |
1da177e4 | 944 | } |
1da177e4 LT |
945 | } |
946 | ||
947 | static void | |
165125e1 | 948 | cfq_merged_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
949 | struct request *next) |
950 | { | |
cf7c25cf | 951 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 JA |
952 | /* |
953 | * reposition in fifo if next is older than rq | |
954 | */ | |
955 | if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && | |
30996f40 | 956 | time_before(rq_fifo_time(next), rq_fifo_time(rq))) { |
22e2c507 | 957 | list_move(&rq->queuelist, &next->queuelist); |
30996f40 JA |
958 | rq_set_fifo_time(rq, rq_fifo_time(next)); |
959 | } | |
22e2c507 | 960 | |
cf7c25cf CZ |
961 | if (cfqq->next_rq == next) |
962 | cfqq->next_rq = rq; | |
b4878f24 | 963 | cfq_remove_request(next); |
22e2c507 JA |
964 | } |
965 | ||
165125e1 | 966 | static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
da775265 JA |
967 | struct bio *bio) |
968 | { | |
969 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
91fac317 | 970 | struct cfq_io_context *cic; |
da775265 | 971 | struct cfq_queue *cfqq; |
da775265 JA |
972 | |
973 | /* | |
ec8acb69 | 974 | * Disallow merge of a sync bio into an async request. |
da775265 | 975 | */ |
91fac317 | 976 | if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
a6151c3a | 977 | return false; |
da775265 JA |
978 | |
979 | /* | |
719d3402 JA |
980 | * Lookup the cfqq that this bio will be queued with. Allow |
981 | * merge only if rq is queued there. | |
da775265 | 982 | */ |
4ac845a2 | 983 | cic = cfq_cic_lookup(cfqd, current->io_context); |
91fac317 | 984 | if (!cic) |
a6151c3a | 985 | return false; |
719d3402 | 986 | |
91fac317 | 987 | cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
a6151c3a | 988 | return cfqq == RQ_CFQQ(rq); |
da775265 JA |
989 | } |
990 | ||
febffd61 JA |
991 | static void __cfq_set_active_queue(struct cfq_data *cfqd, |
992 | struct cfq_queue *cfqq) | |
22e2c507 JA |
993 | { |
994 | if (cfqq) { | |
7b679138 | 995 | cfq_log_cfqq(cfqd, cfqq, "set_active"); |
22e2c507 | 996 | cfqq->slice_end = 0; |
2f5cb738 JA |
997 | cfqq->slice_dispatch = 0; |
998 | ||
2f5cb738 | 999 | cfq_clear_cfqq_wait_request(cfqq); |
b029195d | 1000 | cfq_clear_cfqq_must_dispatch(cfqq); |
3b18152c JA |
1001 | cfq_clear_cfqq_must_alloc_slice(cfqq); |
1002 | cfq_clear_cfqq_fifo_expire(cfqq); | |
44f7c160 | 1003 | cfq_mark_cfqq_slice_new(cfqq); |
2f5cb738 JA |
1004 | |
1005 | del_timer(&cfqd->idle_slice_timer); | |
22e2c507 JA |
1006 | } |
1007 | ||
1008 | cfqd->active_queue = cfqq; | |
1009 | } | |
1010 | ||
7b14e3b5 JA |
1011 | /* |
1012 | * current cfqq expired its slice (or was too idle), select new one | |
1013 | */ | |
1014 | static void | |
1015 | __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
a6151c3a | 1016 | bool timed_out) |
7b14e3b5 | 1017 | { |
7b679138 JA |
1018 | cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
1019 | ||
7b14e3b5 JA |
1020 | if (cfq_cfqq_wait_request(cfqq)) |
1021 | del_timer(&cfqd->idle_slice_timer); | |
1022 | ||
7b14e3b5 JA |
1023 | cfq_clear_cfqq_wait_request(cfqq); |
1024 | ||
1025 | /* | |
6084cdda | 1026 | * store what was left of this slice, if the queue idled/timed out |
7b14e3b5 | 1027 | */ |
7b679138 | 1028 | if (timed_out && !cfq_cfqq_slice_new(cfqq)) { |
c5b680f3 | 1029 | cfqq->slice_resid = cfqq->slice_end - jiffies; |
7b679138 JA |
1030 | cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
1031 | } | |
7b14e3b5 | 1032 | |
edd75ffd | 1033 | cfq_resort_rr_list(cfqd, cfqq); |
7b14e3b5 JA |
1034 | |
1035 | if (cfqq == cfqd->active_queue) | |
1036 | cfqd->active_queue = NULL; | |
1037 | ||
1038 | if (cfqd->active_cic) { | |
1039 | put_io_context(cfqd->active_cic->ioc); | |
1040 | cfqd->active_cic = NULL; | |
1041 | } | |
7b14e3b5 JA |
1042 | } |
1043 | ||
a6151c3a | 1044 | static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) |
7b14e3b5 JA |
1045 | { |
1046 | struct cfq_queue *cfqq = cfqd->active_queue; | |
1047 | ||
1048 | if (cfqq) | |
6084cdda | 1049 | __cfq_slice_expired(cfqd, cfqq, timed_out); |
7b14e3b5 JA |
1050 | } |
1051 | ||
498d3aa2 JA |
1052 | /* |
1053 | * Get next queue for service. Unless we have a queue preemption, | |
1054 | * we'll simply select the first cfqq in the service tree. | |
1055 | */ | |
6d048f53 | 1056 | static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
22e2c507 | 1057 | { |
c0324a02 | 1058 | struct cfq_rb_root *service_tree = |
718eee05 | 1059 | service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd); |
d9e7620e | 1060 | |
c0324a02 CZ |
1061 | if (RB_EMPTY_ROOT(&service_tree->rb)) |
1062 | return NULL; | |
1063 | return cfq_rb_first(service_tree); | |
6d048f53 JA |
1064 | } |
1065 | ||
498d3aa2 JA |
1066 | /* |
1067 | * Get and set a new active queue for service. | |
1068 | */ | |
a36e71f9 JA |
1069 | static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
1070 | struct cfq_queue *cfqq) | |
6d048f53 | 1071 | { |
e00ef799 | 1072 | if (!cfqq) |
a36e71f9 | 1073 | cfqq = cfq_get_next_queue(cfqd); |
6d048f53 | 1074 | |
22e2c507 | 1075 | __cfq_set_active_queue(cfqd, cfqq); |
3b18152c | 1076 | return cfqq; |
22e2c507 JA |
1077 | } |
1078 | ||
d9e7620e JA |
1079 | static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
1080 | struct request *rq) | |
1081 | { | |
83096ebf TH |
1082 | if (blk_rq_pos(rq) >= cfqd->last_position) |
1083 | return blk_rq_pos(rq) - cfqd->last_position; | |
d9e7620e | 1084 | else |
83096ebf | 1085 | return cfqd->last_position - blk_rq_pos(rq); |
d9e7620e JA |
1086 | } |
1087 | ||
b2c18e1e JM |
1088 | #define CFQQ_SEEK_THR 8 * 1024 |
1089 | #define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR) | |
04dc6e71 | 1090 | |
b2c18e1e JM |
1091 | static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
1092 | struct request *rq) | |
6d048f53 | 1093 | { |
b2c18e1e | 1094 | sector_t sdist = cfqq->seek_mean; |
6d048f53 | 1095 | |
b2c18e1e JM |
1096 | if (!sample_valid(cfqq->seek_samples)) |
1097 | sdist = CFQQ_SEEK_THR; | |
6d048f53 | 1098 | |
04dc6e71 | 1099 | return cfq_dist_from_last(cfqd, rq) <= sdist; |
6d048f53 JA |
1100 | } |
1101 | ||
a36e71f9 JA |
1102 | static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
1103 | struct cfq_queue *cur_cfqq) | |
1104 | { | |
f2d1f0ae | 1105 | struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
a36e71f9 JA |
1106 | struct rb_node *parent, *node; |
1107 | struct cfq_queue *__cfqq; | |
1108 | sector_t sector = cfqd->last_position; | |
1109 | ||
1110 | if (RB_EMPTY_ROOT(root)) | |
1111 | return NULL; | |
1112 | ||
1113 | /* | |
1114 | * First, if we find a request starting at the end of the last | |
1115 | * request, choose it. | |
1116 | */ | |
f2d1f0ae | 1117 | __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
a36e71f9 JA |
1118 | if (__cfqq) |
1119 | return __cfqq; | |
1120 | ||
1121 | /* | |
1122 | * If the exact sector wasn't found, the parent of the NULL leaf | |
1123 | * will contain the closest sector. | |
1124 | */ | |
1125 | __cfqq = rb_entry(parent, struct cfq_queue, p_node); | |
b2c18e1e | 1126 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1127 | return __cfqq; |
1128 | ||
2e46e8b2 | 1129 | if (blk_rq_pos(__cfqq->next_rq) < sector) |
a36e71f9 JA |
1130 | node = rb_next(&__cfqq->p_node); |
1131 | else | |
1132 | node = rb_prev(&__cfqq->p_node); | |
1133 | if (!node) | |
1134 | return NULL; | |
1135 | ||
1136 | __cfqq = rb_entry(node, struct cfq_queue, p_node); | |
b2c18e1e | 1137 | if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
a36e71f9 JA |
1138 | return __cfqq; |
1139 | ||
1140 | return NULL; | |
1141 | } | |
1142 | ||
1143 | /* | |
1144 | * cfqd - obvious | |
1145 | * cur_cfqq - passed in so that we don't decide that the current queue is | |
1146 | * closely cooperating with itself. | |
1147 | * | |
1148 | * So, basically we're assuming that that cur_cfqq has dispatched at least | |
1149 | * one request, and that cfqd->last_position reflects a position on the disk | |
1150 | * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid | |
1151 | * assumption. | |
1152 | */ | |
1153 | static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, | |
b3b6d040 | 1154 | struct cfq_queue *cur_cfqq) |
6d048f53 | 1155 | { |
a36e71f9 JA |
1156 | struct cfq_queue *cfqq; |
1157 | ||
e6c5bc73 JM |
1158 | if (!cfq_cfqq_sync(cur_cfqq)) |
1159 | return NULL; | |
1160 | if (CFQQ_SEEKY(cur_cfqq)) | |
1161 | return NULL; | |
1162 | ||
6d048f53 | 1163 | /* |
d9e7620e JA |
1164 | * We should notice if some of the queues are cooperating, eg |
1165 | * working closely on the same area of the disk. In that case, | |
1166 | * we can group them together and don't waste time idling. | |
6d048f53 | 1167 | */ |
a36e71f9 JA |
1168 | cfqq = cfqq_close(cfqd, cur_cfqq); |
1169 | if (!cfqq) | |
1170 | return NULL; | |
1171 | ||
df5fe3e8 JM |
1172 | /* |
1173 | * It only makes sense to merge sync queues. | |
1174 | */ | |
1175 | if (!cfq_cfqq_sync(cfqq)) | |
1176 | return NULL; | |
e6c5bc73 JM |
1177 | if (CFQQ_SEEKY(cfqq)) |
1178 | return NULL; | |
df5fe3e8 | 1179 | |
c0324a02 CZ |
1180 | /* |
1181 | * Do not merge queues of different priority classes | |
1182 | */ | |
1183 | if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) | |
1184 | return NULL; | |
1185 | ||
a36e71f9 | 1186 | return cfqq; |
6d048f53 JA |
1187 | } |
1188 | ||
a6d44e98 CZ |
1189 | /* |
1190 | * Determine whether we should enforce idle window for this queue. | |
1191 | */ | |
1192 | ||
1193 | static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1194 | { | |
1195 | enum wl_prio_t prio = cfqq_prio(cfqq); | |
718eee05 | 1196 | struct cfq_rb_root *service_tree = cfqq->service_tree; |
a6d44e98 CZ |
1197 | |
1198 | /* We never do for idle class queues. */ | |
1199 | if (prio == IDLE_WORKLOAD) | |
1200 | return false; | |
1201 | ||
1202 | /* We do for queues that were marked with idle window flag. */ | |
1203 | if (cfq_cfqq_idle_window(cfqq)) | |
1204 | return true; | |
1205 | ||
1206 | /* | |
1207 | * Otherwise, we do only if they are the last ones | |
1208 | * in their service tree. | |
1209 | */ | |
718eee05 CZ |
1210 | if (!service_tree) |
1211 | service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd); | |
1212 | ||
a6d44e98 CZ |
1213 | if (service_tree->count == 0) |
1214 | return true; | |
1215 | ||
1216 | return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq); | |
1217 | } | |
1218 | ||
6d048f53 | 1219 | static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
22e2c507 | 1220 | { |
1792669c | 1221 | struct cfq_queue *cfqq = cfqd->active_queue; |
206dc69b | 1222 | struct cfq_io_context *cic; |
7b14e3b5 JA |
1223 | unsigned long sl; |
1224 | ||
a68bbddb | 1225 | /* |
f7d7b7a7 JA |
1226 | * SSD device without seek penalty, disable idling. But only do so |
1227 | * for devices that support queuing, otherwise we still have a problem | |
1228 | * with sync vs async workloads. | |
a68bbddb | 1229 | */ |
f7d7b7a7 | 1230 | if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
a68bbddb JA |
1231 | return; |
1232 | ||
dd67d051 | 1233 | WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
6d048f53 | 1234 | WARN_ON(cfq_cfqq_slice_new(cfqq)); |
22e2c507 JA |
1235 | |
1236 | /* | |
1237 | * idle is disabled, either manually or by past process history | |
1238 | */ | |
a6d44e98 | 1239 | if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq)) |
6d048f53 JA |
1240 | return; |
1241 | ||
7b679138 JA |
1242 | /* |
1243 | * still requests with the driver, don't idle | |
1244 | */ | |
5ad531db | 1245 | if (rq_in_driver(cfqd)) |
7b679138 JA |
1246 | return; |
1247 | ||
22e2c507 JA |
1248 | /* |
1249 | * task has exited, don't wait | |
1250 | */ | |
206dc69b | 1251 | cic = cfqd->active_cic; |
66dac98e | 1252 | if (!cic || !atomic_read(&cic->ioc->nr_tasks)) |
6d048f53 JA |
1253 | return; |
1254 | ||
355b659c CZ |
1255 | /* |
1256 | * If our average think time is larger than the remaining time | |
1257 | * slice, then don't idle. This avoids overrunning the allotted | |
1258 | * time slice. | |
1259 | */ | |
1260 | if (sample_valid(cic->ttime_samples) && | |
1261 | (cfqq->slice_end - jiffies < cic->ttime_mean)) | |
1262 | return; | |
1263 | ||
3b18152c | 1264 | cfq_mark_cfqq_wait_request(cfqq); |
22e2c507 | 1265 | |
6d048f53 | 1266 | sl = cfqd->cfq_slice_idle; |
718eee05 CZ |
1267 | /* are we servicing noidle tree, and there are more queues? |
1268 | * non-rotational or NCQ: no idle | |
1269 | * non-NCQ rotational : very small idle, to allow | |
1270 | * fair distribution of slice time for a process doing back-to-back | |
1271 | * seeks. | |
1272 | */ | |
1273 | if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && | |
1274 | service_tree_for(cfqd->serving_prio, SYNC_NOIDLE_WORKLOAD, cfqd) | |
1275 | ->count > 0) { | |
1276 | if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag) | |
1277 | return; | |
d9e7620e | 1278 | sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); |
718eee05 | 1279 | } |
206dc69b | 1280 | |
7b14e3b5 | 1281 | mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
9481ffdc | 1282 | cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); |
1da177e4 LT |
1283 | } |
1284 | ||
498d3aa2 JA |
1285 | /* |
1286 | * Move request from internal lists to the request queue dispatch list. | |
1287 | */ | |
165125e1 | 1288 | static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
1da177e4 | 1289 | { |
3ed9a296 | 1290 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 1291 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 1292 | |
7b679138 JA |
1293 | cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
1294 | ||
06d21886 | 1295 | cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
5380a101 | 1296 | cfq_remove_request(rq); |
6d048f53 | 1297 | cfqq->dispatched++; |
5380a101 | 1298 | elv_dispatch_sort(q, rq); |
3ed9a296 JA |
1299 | |
1300 | if (cfq_cfqq_sync(cfqq)) | |
1301 | cfqd->sync_flight++; | |
1da177e4 LT |
1302 | } |
1303 | ||
1304 | /* | |
1305 | * return expired entry, or NULL to just start from scratch in rbtree | |
1306 | */ | |
febffd61 | 1307 | static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
1da177e4 | 1308 | { |
30996f40 | 1309 | struct request *rq = NULL; |
1da177e4 | 1310 | |
3b18152c | 1311 | if (cfq_cfqq_fifo_expire(cfqq)) |
1da177e4 | 1312 | return NULL; |
cb887411 JA |
1313 | |
1314 | cfq_mark_cfqq_fifo_expire(cfqq); | |
1315 | ||
89850f7e JA |
1316 | if (list_empty(&cfqq->fifo)) |
1317 | return NULL; | |
1da177e4 | 1318 | |
89850f7e | 1319 | rq = rq_entry_fifo(cfqq->fifo.next); |
30996f40 | 1320 | if (time_before(jiffies, rq_fifo_time(rq))) |
7b679138 | 1321 | rq = NULL; |
1da177e4 | 1322 | |
30996f40 | 1323 | cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); |
6d048f53 | 1324 | return rq; |
1da177e4 LT |
1325 | } |
1326 | ||
22e2c507 JA |
1327 | static inline int |
1328 | cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1329 | { | |
1330 | const int base_rq = cfqd->cfq_slice_async_rq; | |
1da177e4 | 1331 | |
22e2c507 | 1332 | WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
1da177e4 | 1333 | |
22e2c507 | 1334 | return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio)); |
1da177e4 LT |
1335 | } |
1336 | ||
df5fe3e8 JM |
1337 | /* |
1338 | * Must be called with the queue_lock held. | |
1339 | */ | |
1340 | static int cfqq_process_refs(struct cfq_queue *cfqq) | |
1341 | { | |
1342 | int process_refs, io_refs; | |
1343 | ||
1344 | io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; | |
1345 | process_refs = atomic_read(&cfqq->ref) - io_refs; | |
1346 | BUG_ON(process_refs < 0); | |
1347 | return process_refs; | |
1348 | } | |
1349 | ||
1350 | static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) | |
1351 | { | |
e6c5bc73 | 1352 | int process_refs, new_process_refs; |
df5fe3e8 JM |
1353 | struct cfq_queue *__cfqq; |
1354 | ||
1355 | /* Avoid a circular list and skip interim queue merges */ | |
1356 | while ((__cfqq = new_cfqq->new_cfqq)) { | |
1357 | if (__cfqq == cfqq) | |
1358 | return; | |
1359 | new_cfqq = __cfqq; | |
1360 | } | |
1361 | ||
1362 | process_refs = cfqq_process_refs(cfqq); | |
1363 | /* | |
1364 | * If the process for the cfqq has gone away, there is no | |
1365 | * sense in merging the queues. | |
1366 | */ | |
1367 | if (process_refs == 0) | |
1368 | return; | |
1369 | ||
e6c5bc73 JM |
1370 | /* |
1371 | * Merge in the direction of the lesser amount of work. | |
1372 | */ | |
1373 | new_process_refs = cfqq_process_refs(new_cfqq); | |
1374 | if (new_process_refs >= process_refs) { | |
1375 | cfqq->new_cfqq = new_cfqq; | |
1376 | atomic_add(process_refs, &new_cfqq->ref); | |
1377 | } else { | |
1378 | new_cfqq->new_cfqq = cfqq; | |
1379 | atomic_add(new_process_refs, &cfqq->ref); | |
1380 | } | |
df5fe3e8 JM |
1381 | } |
1382 | ||
718eee05 CZ |
1383 | static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio, |
1384 | bool prio_changed) | |
1385 | { | |
1386 | struct cfq_queue *queue; | |
1387 | int i; | |
1388 | bool key_valid = false; | |
1389 | unsigned long lowest_key = 0; | |
1390 | enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; | |
1391 | ||
1392 | if (prio_changed) { | |
1393 | /* | |
1394 | * When priorities switched, we prefer starting | |
1395 | * from SYNC_NOIDLE (first choice), or just SYNC | |
1396 | * over ASYNC | |
1397 | */ | |
1398 | if (service_tree_for(prio, cur_best, cfqd)->count) | |
1399 | return cur_best; | |
1400 | cur_best = SYNC_WORKLOAD; | |
1401 | if (service_tree_for(prio, cur_best, cfqd)->count) | |
1402 | return cur_best; | |
1403 | ||
1404 | return ASYNC_WORKLOAD; | |
1405 | } | |
1406 | ||
1407 | for (i = 0; i < 3; ++i) { | |
1408 | /* otherwise, select the one with lowest rb_key */ | |
1409 | queue = cfq_rb_first(service_tree_for(prio, i, cfqd)); | |
1410 | if (queue && | |
1411 | (!key_valid || time_before(queue->rb_key, lowest_key))) { | |
1412 | lowest_key = queue->rb_key; | |
1413 | cur_best = i; | |
1414 | key_valid = true; | |
1415 | } | |
1416 | } | |
1417 | ||
1418 | return cur_best; | |
1419 | } | |
1420 | ||
1421 | static void choose_service_tree(struct cfq_data *cfqd) | |
1422 | { | |
1423 | enum wl_prio_t previous_prio = cfqd->serving_prio; | |
1424 | bool prio_changed; | |
1425 | unsigned slice; | |
1426 | unsigned count; | |
1427 | ||
1428 | /* Choose next priority. RT > BE > IDLE */ | |
1429 | if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd)) | |
1430 | cfqd->serving_prio = RT_WORKLOAD; | |
1431 | else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd)) | |
1432 | cfqd->serving_prio = BE_WORKLOAD; | |
1433 | else { | |
1434 | cfqd->serving_prio = IDLE_WORKLOAD; | |
1435 | cfqd->workload_expires = jiffies + 1; | |
1436 | return; | |
1437 | } | |
1438 | ||
1439 | /* | |
1440 | * For RT and BE, we have to choose also the type | |
1441 | * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload | |
1442 | * expiration time | |
1443 | */ | |
1444 | prio_changed = (cfqd->serving_prio != previous_prio); | |
1445 | count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) | |
1446 | ->count; | |
1447 | ||
1448 | /* | |
1449 | * If priority didn't change, check workload expiration, | |
1450 | * and that we still have other queues ready | |
1451 | */ | |
1452 | if (!prio_changed && count && | |
1453 | !time_after(jiffies, cfqd->workload_expires)) | |
1454 | return; | |
1455 | ||
1456 | /* otherwise select new workload type */ | |
1457 | cfqd->serving_type = | |
1458 | cfq_choose_wl(cfqd, cfqd->serving_prio, prio_changed); | |
1459 | count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) | |
1460 | ->count; | |
1461 | ||
1462 | /* | |
1463 | * the workload slice is computed as a fraction of target latency | |
1464 | * proportional to the number of queues in that workload, over | |
1465 | * all the queues in the same priority class | |
1466 | */ | |
1467 | slice = cfq_target_latency * count / | |
1468 | max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio], | |
1469 | cfq_busy_queues_wl(cfqd->serving_prio, cfqd)); | |
1470 | ||
1471 | if (cfqd->serving_type == ASYNC_WORKLOAD) | |
1472 | /* async workload slice is scaled down according to | |
1473 | * the sync/async slice ratio. */ | |
1474 | slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; | |
1475 | else | |
1476 | /* sync workload slice is at least 2 * cfq_slice_idle */ | |
1477 | slice = max(slice, 2 * cfqd->cfq_slice_idle); | |
1478 | ||
1479 | slice = max_t(unsigned, slice, CFQ_MIN_TT); | |
1480 | cfqd->workload_expires = jiffies + slice; | |
1481 | } | |
1482 | ||
22e2c507 | 1483 | /* |
498d3aa2 JA |
1484 | * Select a queue for service. If we have a current active queue, |
1485 | * check whether to continue servicing it, or retrieve and set a new one. | |
22e2c507 | 1486 | */ |
1b5ed5e1 | 1487 | static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
1da177e4 | 1488 | { |
a36e71f9 | 1489 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
1da177e4 | 1490 | |
22e2c507 JA |
1491 | cfqq = cfqd->active_queue; |
1492 | if (!cfqq) | |
1493 | goto new_queue; | |
1da177e4 | 1494 | |
22e2c507 | 1495 | /* |
6d048f53 | 1496 | * The active queue has run out of time, expire it and select new. |
22e2c507 | 1497 | */ |
b029195d | 1498 | if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) |
3b18152c | 1499 | goto expire; |
1da177e4 | 1500 | |
22e2c507 | 1501 | /* |
6d048f53 JA |
1502 | * The active queue has requests and isn't expired, allow it to |
1503 | * dispatch. | |
22e2c507 | 1504 | */ |
dd67d051 | 1505 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 1506 | goto keep_queue; |
6d048f53 | 1507 | |
a36e71f9 JA |
1508 | /* |
1509 | * If another queue has a request waiting within our mean seek | |
1510 | * distance, let it run. The expire code will check for close | |
1511 | * cooperators and put the close queue at the front of the service | |
df5fe3e8 | 1512 | * tree. If possible, merge the expiring queue with the new cfqq. |
a36e71f9 | 1513 | */ |
b3b6d040 | 1514 | new_cfqq = cfq_close_cooperator(cfqd, cfqq); |
df5fe3e8 JM |
1515 | if (new_cfqq) { |
1516 | if (!cfqq->new_cfqq) | |
1517 | cfq_setup_merge(cfqq, new_cfqq); | |
a36e71f9 | 1518 | goto expire; |
df5fe3e8 | 1519 | } |
a36e71f9 | 1520 | |
6d048f53 JA |
1521 | /* |
1522 | * No requests pending. If the active queue still has requests in | |
1523 | * flight or is idling for a new request, allow either of these | |
1524 | * conditions to happen (or time out) before selecting a new queue. | |
1525 | */ | |
cc197479 | 1526 | if (timer_pending(&cfqd->idle_slice_timer) || |
a6d44e98 | 1527 | (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) { |
caaa5f9f JA |
1528 | cfqq = NULL; |
1529 | goto keep_queue; | |
22e2c507 JA |
1530 | } |
1531 | ||
3b18152c | 1532 | expire: |
6084cdda | 1533 | cfq_slice_expired(cfqd, 0); |
3b18152c | 1534 | new_queue: |
718eee05 CZ |
1535 | /* |
1536 | * Current queue expired. Check if we have to switch to a new | |
1537 | * service tree | |
1538 | */ | |
1539 | if (!new_cfqq) | |
1540 | choose_service_tree(cfqd); | |
1541 | ||
a36e71f9 | 1542 | cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
22e2c507 | 1543 | keep_queue: |
3b18152c | 1544 | return cfqq; |
22e2c507 JA |
1545 | } |
1546 | ||
febffd61 | 1547 | static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
d9e7620e JA |
1548 | { |
1549 | int dispatched = 0; | |
1550 | ||
1551 | while (cfqq->next_rq) { | |
1552 | cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); | |
1553 | dispatched++; | |
1554 | } | |
1555 | ||
1556 | BUG_ON(!list_empty(&cfqq->fifo)); | |
1557 | return dispatched; | |
1558 | } | |
1559 | ||
498d3aa2 JA |
1560 | /* |
1561 | * Drain our current requests. Used for barriers and when switching | |
1562 | * io schedulers on-the-fly. | |
1563 | */ | |
d9e7620e | 1564 | static int cfq_forced_dispatch(struct cfq_data *cfqd) |
1b5ed5e1 | 1565 | { |
0871714e | 1566 | struct cfq_queue *cfqq; |
d9e7620e | 1567 | int dispatched = 0; |
718eee05 | 1568 | int i, j; |
c0324a02 | 1569 | for (i = 0; i < 2; ++i) |
718eee05 CZ |
1570 | for (j = 0; j < 3; ++j) |
1571 | while ((cfqq = cfq_rb_first(&cfqd->service_trees[i][j])) | |
1572 | != NULL) | |
1573 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); | |
1b5ed5e1 | 1574 | |
c0324a02 | 1575 | while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL) |
d9e7620e | 1576 | dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
1b5ed5e1 | 1577 | |
6084cdda | 1578 | cfq_slice_expired(cfqd, 0); |
1b5ed5e1 TH |
1579 | |
1580 | BUG_ON(cfqd->busy_queues); | |
1581 | ||
6923715a | 1582 | cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
1b5ed5e1 TH |
1583 | return dispatched; |
1584 | } | |
1585 | ||
0b182d61 | 1586 | static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
2f5cb738 | 1587 | { |
2f5cb738 | 1588 | unsigned int max_dispatch; |
22e2c507 | 1589 | |
5ad531db JA |
1590 | /* |
1591 | * Drain async requests before we start sync IO | |
1592 | */ | |
a6d44e98 | 1593 | if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) |
0b182d61 | 1594 | return false; |
5ad531db | 1595 | |
2f5cb738 JA |
1596 | /* |
1597 | * If this is an async queue and we have sync IO in flight, let it wait | |
1598 | */ | |
1599 | if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq)) | |
0b182d61 | 1600 | return false; |
2f5cb738 JA |
1601 | |
1602 | max_dispatch = cfqd->cfq_quantum; | |
1603 | if (cfq_class_idle(cfqq)) | |
1604 | max_dispatch = 1; | |
b4878f24 | 1605 | |
2f5cb738 JA |
1606 | /* |
1607 | * Does this cfqq already have too much IO in flight? | |
1608 | */ | |
1609 | if (cfqq->dispatched >= max_dispatch) { | |
1610 | /* | |
1611 | * idle queue must always only have a single IO in flight | |
1612 | */ | |
3ed9a296 | 1613 | if (cfq_class_idle(cfqq)) |
0b182d61 | 1614 | return false; |
3ed9a296 | 1615 | |
2f5cb738 JA |
1616 | /* |
1617 | * We have other queues, don't allow more IO from this one | |
1618 | */ | |
1619 | if (cfqd->busy_queues > 1) | |
0b182d61 | 1620 | return false; |
9ede209e | 1621 | |
365722bb | 1622 | /* |
8e296755 | 1623 | * Sole queue user, allow bigger slice |
365722bb | 1624 | */ |
8e296755 JA |
1625 | max_dispatch *= 4; |
1626 | } | |
1627 | ||
1628 | /* | |
1629 | * Async queues must wait a bit before being allowed dispatch. | |
1630 | * We also ramp up the dispatch depth gradually for async IO, | |
1631 | * based on the last sync IO we serviced | |
1632 | */ | |
963b72fc | 1633 | if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
8e296755 JA |
1634 | unsigned long last_sync = jiffies - cfqd->last_end_sync_rq; |
1635 | unsigned int depth; | |
365722bb | 1636 | |
61f0c1dc | 1637 | depth = last_sync / cfqd->cfq_slice[1]; |
e00c54c3 JA |
1638 | if (!depth && !cfqq->dispatched) |
1639 | depth = 1; | |
8e296755 JA |
1640 | if (depth < max_dispatch) |
1641 | max_dispatch = depth; | |
2f5cb738 | 1642 | } |
3ed9a296 | 1643 | |
0b182d61 JA |
1644 | /* |
1645 | * If we're below the current max, allow a dispatch | |
1646 | */ | |
1647 | return cfqq->dispatched < max_dispatch; | |
1648 | } | |
1649 | ||
1650 | /* | |
1651 | * Dispatch a request from cfqq, moving them to the request queue | |
1652 | * dispatch list. | |
1653 | */ | |
1654 | static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
1655 | { | |
1656 | struct request *rq; | |
1657 | ||
1658 | BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); | |
1659 | ||
1660 | if (!cfq_may_dispatch(cfqd, cfqq)) | |
1661 | return false; | |
1662 | ||
1663 | /* | |
1664 | * follow expired path, else get first next available | |
1665 | */ | |
1666 | rq = cfq_check_fifo(cfqq); | |
1667 | if (!rq) | |
1668 | rq = cfqq->next_rq; | |
1669 | ||
1670 | /* | |
1671 | * insert request into driver dispatch list | |
1672 | */ | |
1673 | cfq_dispatch_insert(cfqd->queue, rq); | |
1674 | ||
1675 | if (!cfqd->active_cic) { | |
1676 | struct cfq_io_context *cic = RQ_CIC(rq); | |
1677 | ||
1678 | atomic_long_inc(&cic->ioc->refcount); | |
1679 | cfqd->active_cic = cic; | |
1680 | } | |
1681 | ||
1682 | return true; | |
1683 | } | |
1684 | ||
1685 | /* | |
1686 | * Find the cfqq that we need to service and move a request from that to the | |
1687 | * dispatch list | |
1688 | */ | |
1689 | static int cfq_dispatch_requests(struct request_queue *q, int force) | |
1690 | { | |
1691 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
1692 | struct cfq_queue *cfqq; | |
1693 | ||
1694 | if (!cfqd->busy_queues) | |
1695 | return 0; | |
1696 | ||
1697 | if (unlikely(force)) | |
1698 | return cfq_forced_dispatch(cfqd); | |
1699 | ||
1700 | cfqq = cfq_select_queue(cfqd); | |
1701 | if (!cfqq) | |
8e296755 JA |
1702 | return 0; |
1703 | ||
2f5cb738 | 1704 | /* |
0b182d61 | 1705 | * Dispatch a request from this cfqq, if it is allowed |
2f5cb738 | 1706 | */ |
0b182d61 JA |
1707 | if (!cfq_dispatch_request(cfqd, cfqq)) |
1708 | return 0; | |
1709 | ||
2f5cb738 | 1710 | cfqq->slice_dispatch++; |
b029195d | 1711 | cfq_clear_cfqq_must_dispatch(cfqq); |
22e2c507 | 1712 | |
2f5cb738 JA |
1713 | /* |
1714 | * expire an async queue immediately if it has used up its slice. idle | |
1715 | * queue always expire after 1 dispatch round. | |
1716 | */ | |
1717 | if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && | |
1718 | cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || | |
1719 | cfq_class_idle(cfqq))) { | |
1720 | cfqq->slice_end = jiffies + 1; | |
1721 | cfq_slice_expired(cfqd, 0); | |
1da177e4 LT |
1722 | } |
1723 | ||
b217a903 | 1724 | cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
2f5cb738 | 1725 | return 1; |
1da177e4 LT |
1726 | } |
1727 | ||
1da177e4 | 1728 | /* |
5e705374 JA |
1729 | * task holds one reference to the queue, dropped when task exits. each rq |
1730 | * in-flight on this queue also holds a reference, dropped when rq is freed. | |
1da177e4 LT |
1731 | * |
1732 | * queue lock must be held here. | |
1733 | */ | |
1734 | static void cfq_put_queue(struct cfq_queue *cfqq) | |
1735 | { | |
22e2c507 JA |
1736 | struct cfq_data *cfqd = cfqq->cfqd; |
1737 | ||
1738 | BUG_ON(atomic_read(&cfqq->ref) <= 0); | |
1da177e4 LT |
1739 | |
1740 | if (!atomic_dec_and_test(&cfqq->ref)) | |
1741 | return; | |
1742 | ||
7b679138 | 1743 | cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
1da177e4 | 1744 | BUG_ON(rb_first(&cfqq->sort_list)); |
22e2c507 | 1745 | BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
3b18152c | 1746 | BUG_ON(cfq_cfqq_on_rr(cfqq)); |
1da177e4 | 1747 | |
28f95cbc | 1748 | if (unlikely(cfqd->active_queue == cfqq)) { |
6084cdda | 1749 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1750 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1751 | } |
22e2c507 | 1752 | |
1da177e4 LT |
1753 | kmem_cache_free(cfq_pool, cfqq); |
1754 | } | |
1755 | ||
d6de8be7 JA |
1756 | /* |
1757 | * Must always be called with the rcu_read_lock() held | |
1758 | */ | |
07416d29 JA |
1759 | static void |
1760 | __call_for_each_cic(struct io_context *ioc, | |
1761 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1762 | { | |
1763 | struct cfq_io_context *cic; | |
1764 | struct hlist_node *n; | |
1765 | ||
1766 | hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) | |
1767 | func(ioc, cic); | |
1768 | } | |
1769 | ||
4ac845a2 | 1770 | /* |
34e6bbf2 | 1771 | * Call func for each cic attached to this ioc. |
4ac845a2 | 1772 | */ |
34e6bbf2 | 1773 | static void |
4ac845a2 JA |
1774 | call_for_each_cic(struct io_context *ioc, |
1775 | void (*func)(struct io_context *, struct cfq_io_context *)) | |
1da177e4 | 1776 | { |
4ac845a2 | 1777 | rcu_read_lock(); |
07416d29 | 1778 | __call_for_each_cic(ioc, func); |
4ac845a2 | 1779 | rcu_read_unlock(); |
34e6bbf2 FC |
1780 | } |
1781 | ||
1782 | static void cfq_cic_free_rcu(struct rcu_head *head) | |
1783 | { | |
1784 | struct cfq_io_context *cic; | |
1785 | ||
1786 | cic = container_of(head, struct cfq_io_context, rcu_head); | |
1787 | ||
1788 | kmem_cache_free(cfq_ioc_pool, cic); | |
245b2e70 | 1789 | elv_ioc_count_dec(cfq_ioc_count); |
34e6bbf2 | 1790 | |
9a11b4ed JA |
1791 | if (ioc_gone) { |
1792 | /* | |
1793 | * CFQ scheduler is exiting, grab exit lock and check | |
1794 | * the pending io context count. If it hits zero, | |
1795 | * complete ioc_gone and set it back to NULL | |
1796 | */ | |
1797 | spin_lock(&ioc_gone_lock); | |
245b2e70 | 1798 | if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) { |
9a11b4ed JA |
1799 | complete(ioc_gone); |
1800 | ioc_gone = NULL; | |
1801 | } | |
1802 | spin_unlock(&ioc_gone_lock); | |
1803 | } | |
34e6bbf2 | 1804 | } |
4ac845a2 | 1805 | |
34e6bbf2 FC |
1806 | static void cfq_cic_free(struct cfq_io_context *cic) |
1807 | { | |
1808 | call_rcu(&cic->rcu_head, cfq_cic_free_rcu); | |
4ac845a2 JA |
1809 | } |
1810 | ||
1811 | static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) | |
1812 | { | |
1813 | unsigned long flags; | |
1814 | ||
1815 | BUG_ON(!cic->dead_key); | |
1816 | ||
1817 | spin_lock_irqsave(&ioc->lock, flags); | |
1818 | radix_tree_delete(&ioc->radix_root, cic->dead_key); | |
ffc4e759 | 1819 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
1820 | spin_unlock_irqrestore(&ioc->lock, flags); |
1821 | ||
34e6bbf2 | 1822 | cfq_cic_free(cic); |
4ac845a2 JA |
1823 | } |
1824 | ||
d6de8be7 JA |
1825 | /* |
1826 | * Must be called with rcu_read_lock() held or preemption otherwise disabled. | |
1827 | * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), | |
1828 | * and ->trim() which is called with the task lock held | |
1829 | */ | |
4ac845a2 JA |
1830 | static void cfq_free_io_context(struct io_context *ioc) |
1831 | { | |
4ac845a2 | 1832 | /* |
34e6bbf2 FC |
1833 | * ioc->refcount is zero here, or we are called from elv_unregister(), |
1834 | * so no more cic's are allowed to be linked into this ioc. So it | |
1835 | * should be ok to iterate over the known list, we will see all cic's | |
1836 | * since no new ones are added. | |
4ac845a2 | 1837 | */ |
07416d29 | 1838 | __call_for_each_cic(ioc, cic_free_func); |
1da177e4 LT |
1839 | } |
1840 | ||
89850f7e | 1841 | static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
1da177e4 | 1842 | { |
df5fe3e8 JM |
1843 | struct cfq_queue *__cfqq, *next; |
1844 | ||
28f95cbc | 1845 | if (unlikely(cfqq == cfqd->active_queue)) { |
6084cdda | 1846 | __cfq_slice_expired(cfqd, cfqq, 0); |
23e018a1 | 1847 | cfq_schedule_dispatch(cfqd); |
28f95cbc | 1848 | } |
22e2c507 | 1849 | |
df5fe3e8 JM |
1850 | /* |
1851 | * If this queue was scheduled to merge with another queue, be | |
1852 | * sure to drop the reference taken on that queue (and others in | |
1853 | * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. | |
1854 | */ | |
1855 | __cfqq = cfqq->new_cfqq; | |
1856 | while (__cfqq) { | |
1857 | if (__cfqq == cfqq) { | |
1858 | WARN(1, "cfqq->new_cfqq loop detected\n"); | |
1859 | break; | |
1860 | } | |
1861 | next = __cfqq->new_cfqq; | |
1862 | cfq_put_queue(__cfqq); | |
1863 | __cfqq = next; | |
1864 | } | |
1865 | ||
89850f7e JA |
1866 | cfq_put_queue(cfqq); |
1867 | } | |
22e2c507 | 1868 | |
89850f7e JA |
1869 | static void __cfq_exit_single_io_context(struct cfq_data *cfqd, |
1870 | struct cfq_io_context *cic) | |
1871 | { | |
4faa3c81 FC |
1872 | struct io_context *ioc = cic->ioc; |
1873 | ||
fc46379d | 1874 | list_del_init(&cic->queue_list); |
4ac845a2 JA |
1875 | |
1876 | /* | |
1877 | * Make sure key == NULL is seen for dead queues | |
1878 | */ | |
fc46379d | 1879 | smp_wmb(); |
4ac845a2 | 1880 | cic->dead_key = (unsigned long) cic->key; |
fc46379d JA |
1881 | cic->key = NULL; |
1882 | ||
4faa3c81 FC |
1883 | if (ioc->ioc_data == cic) |
1884 | rcu_assign_pointer(ioc->ioc_data, NULL); | |
1885 | ||
ff6657c6 JA |
1886 | if (cic->cfqq[BLK_RW_ASYNC]) { |
1887 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); | |
1888 | cic->cfqq[BLK_RW_ASYNC] = NULL; | |
12a05732 AV |
1889 | } |
1890 | ||
ff6657c6 JA |
1891 | if (cic->cfqq[BLK_RW_SYNC]) { |
1892 | cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); | |
1893 | cic->cfqq[BLK_RW_SYNC] = NULL; | |
12a05732 | 1894 | } |
89850f7e JA |
1895 | } |
1896 | ||
4ac845a2 JA |
1897 | static void cfq_exit_single_io_context(struct io_context *ioc, |
1898 | struct cfq_io_context *cic) | |
89850f7e JA |
1899 | { |
1900 | struct cfq_data *cfqd = cic->key; | |
1901 | ||
89850f7e | 1902 | if (cfqd) { |
165125e1 | 1903 | struct request_queue *q = cfqd->queue; |
4ac845a2 | 1904 | unsigned long flags; |
89850f7e | 1905 | |
4ac845a2 | 1906 | spin_lock_irqsave(q->queue_lock, flags); |
62c1fe9d JA |
1907 | |
1908 | /* | |
1909 | * Ensure we get a fresh copy of the ->key to prevent | |
1910 | * race between exiting task and queue | |
1911 | */ | |
1912 | smp_read_barrier_depends(); | |
1913 | if (cic->key) | |
1914 | __cfq_exit_single_io_context(cfqd, cic); | |
1915 | ||
4ac845a2 | 1916 | spin_unlock_irqrestore(q->queue_lock, flags); |
89850f7e | 1917 | } |
1da177e4 LT |
1918 | } |
1919 | ||
498d3aa2 JA |
1920 | /* |
1921 | * The process that ioc belongs to has exited, we need to clean up | |
1922 | * and put the internal structures we have that belongs to that process. | |
1923 | */ | |
e2d74ac0 | 1924 | static void cfq_exit_io_context(struct io_context *ioc) |
1da177e4 | 1925 | { |
4ac845a2 | 1926 | call_for_each_cic(ioc, cfq_exit_single_io_context); |
1da177e4 LT |
1927 | } |
1928 | ||
22e2c507 | 1929 | static struct cfq_io_context * |
8267e268 | 1930 | cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 1931 | { |
b5deef90 | 1932 | struct cfq_io_context *cic; |
1da177e4 | 1933 | |
94f6030c CL |
1934 | cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO, |
1935 | cfqd->queue->node); | |
1da177e4 | 1936 | if (cic) { |
22e2c507 | 1937 | cic->last_end_request = jiffies; |
553698f9 | 1938 | INIT_LIST_HEAD(&cic->queue_list); |
ffc4e759 | 1939 | INIT_HLIST_NODE(&cic->cic_list); |
22e2c507 JA |
1940 | cic->dtor = cfq_free_io_context; |
1941 | cic->exit = cfq_exit_io_context; | |
245b2e70 | 1942 | elv_ioc_count_inc(cfq_ioc_count); |
1da177e4 LT |
1943 | } |
1944 | ||
1945 | return cic; | |
1946 | } | |
1947 | ||
fd0928df | 1948 | static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
22e2c507 JA |
1949 | { |
1950 | struct task_struct *tsk = current; | |
1951 | int ioprio_class; | |
1952 | ||
3b18152c | 1953 | if (!cfq_cfqq_prio_changed(cfqq)) |
22e2c507 JA |
1954 | return; |
1955 | ||
fd0928df | 1956 | ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
22e2c507 | 1957 | switch (ioprio_class) { |
fe094d98 JA |
1958 | default: |
1959 | printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); | |
1960 | case IOPRIO_CLASS_NONE: | |
1961 | /* | |
6d63c275 | 1962 | * no prio set, inherit CPU scheduling settings |
fe094d98 JA |
1963 | */ |
1964 | cfqq->ioprio = task_nice_ioprio(tsk); | |
6d63c275 | 1965 | cfqq->ioprio_class = task_nice_ioclass(tsk); |
fe094d98 JA |
1966 | break; |
1967 | case IOPRIO_CLASS_RT: | |
1968 | cfqq->ioprio = task_ioprio(ioc); | |
1969 | cfqq->ioprio_class = IOPRIO_CLASS_RT; | |
1970 | break; | |
1971 | case IOPRIO_CLASS_BE: | |
1972 | cfqq->ioprio = task_ioprio(ioc); | |
1973 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
1974 | break; | |
1975 | case IOPRIO_CLASS_IDLE: | |
1976 | cfqq->ioprio_class = IOPRIO_CLASS_IDLE; | |
1977 | cfqq->ioprio = 7; | |
1978 | cfq_clear_cfqq_idle_window(cfqq); | |
1979 | break; | |
22e2c507 JA |
1980 | } |
1981 | ||
1982 | /* | |
1983 | * keep track of original prio settings in case we have to temporarily | |
1984 | * elevate the priority of this queue | |
1985 | */ | |
1986 | cfqq->org_ioprio = cfqq->ioprio; | |
1987 | cfqq->org_ioprio_class = cfqq->ioprio_class; | |
3b18152c | 1988 | cfq_clear_cfqq_prio_changed(cfqq); |
22e2c507 JA |
1989 | } |
1990 | ||
febffd61 | 1991 | static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic) |
22e2c507 | 1992 | { |
478a82b0 AV |
1993 | struct cfq_data *cfqd = cic->key; |
1994 | struct cfq_queue *cfqq; | |
c1b707d2 | 1995 | unsigned long flags; |
35e6077c | 1996 | |
caaa5f9f JA |
1997 | if (unlikely(!cfqd)) |
1998 | return; | |
1999 | ||
c1b707d2 | 2000 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
caaa5f9f | 2001 | |
ff6657c6 | 2002 | cfqq = cic->cfqq[BLK_RW_ASYNC]; |
caaa5f9f JA |
2003 | if (cfqq) { |
2004 | struct cfq_queue *new_cfqq; | |
ff6657c6 JA |
2005 | new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc, |
2006 | GFP_ATOMIC); | |
caaa5f9f | 2007 | if (new_cfqq) { |
ff6657c6 | 2008 | cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
caaa5f9f JA |
2009 | cfq_put_queue(cfqq); |
2010 | } | |
22e2c507 | 2011 | } |
caaa5f9f | 2012 | |
ff6657c6 | 2013 | cfqq = cic->cfqq[BLK_RW_SYNC]; |
caaa5f9f JA |
2014 | if (cfqq) |
2015 | cfq_mark_cfqq_prio_changed(cfqq); | |
2016 | ||
c1b707d2 | 2017 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
22e2c507 JA |
2018 | } |
2019 | ||
fc46379d | 2020 | static void cfq_ioc_set_ioprio(struct io_context *ioc) |
22e2c507 | 2021 | { |
4ac845a2 | 2022 | call_for_each_cic(ioc, changed_ioprio); |
fc46379d | 2023 | ioc->ioprio_changed = 0; |
22e2c507 JA |
2024 | } |
2025 | ||
d5036d77 | 2026 | static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
a6151c3a | 2027 | pid_t pid, bool is_sync) |
d5036d77 JA |
2028 | { |
2029 | RB_CLEAR_NODE(&cfqq->rb_node); | |
2030 | RB_CLEAR_NODE(&cfqq->p_node); | |
2031 | INIT_LIST_HEAD(&cfqq->fifo); | |
2032 | ||
2033 | atomic_set(&cfqq->ref, 0); | |
2034 | cfqq->cfqd = cfqd; | |
2035 | ||
2036 | cfq_mark_cfqq_prio_changed(cfqq); | |
2037 | ||
2038 | if (is_sync) { | |
2039 | if (!cfq_class_idle(cfqq)) | |
2040 | cfq_mark_cfqq_idle_window(cfqq); | |
2041 | cfq_mark_cfqq_sync(cfqq); | |
2042 | } | |
2043 | cfqq->pid = pid; | |
2044 | } | |
2045 | ||
22e2c507 | 2046 | static struct cfq_queue * |
a6151c3a | 2047 | cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, |
fd0928df | 2048 | struct io_context *ioc, gfp_t gfp_mask) |
22e2c507 | 2049 | { |
22e2c507 | 2050 | struct cfq_queue *cfqq, *new_cfqq = NULL; |
91fac317 | 2051 | struct cfq_io_context *cic; |
22e2c507 JA |
2052 | |
2053 | retry: | |
4ac845a2 | 2054 | cic = cfq_cic_lookup(cfqd, ioc); |
91fac317 VT |
2055 | /* cic always exists here */ |
2056 | cfqq = cic_to_cfqq(cic, is_sync); | |
22e2c507 | 2057 | |
6118b70b JA |
2058 | /* |
2059 | * Always try a new alloc if we fell back to the OOM cfqq | |
2060 | * originally, since it should just be a temporary situation. | |
2061 | */ | |
2062 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { | |
2063 | cfqq = NULL; | |
22e2c507 JA |
2064 | if (new_cfqq) { |
2065 | cfqq = new_cfqq; | |
2066 | new_cfqq = NULL; | |
2067 | } else if (gfp_mask & __GFP_WAIT) { | |
2068 | spin_unlock_irq(cfqd->queue->queue_lock); | |
94f6030c | 2069 | new_cfqq = kmem_cache_alloc_node(cfq_pool, |
6118b70b | 2070 | gfp_mask | __GFP_ZERO, |
94f6030c | 2071 | cfqd->queue->node); |
22e2c507 | 2072 | spin_lock_irq(cfqd->queue->queue_lock); |
6118b70b JA |
2073 | if (new_cfqq) |
2074 | goto retry; | |
22e2c507 | 2075 | } else { |
94f6030c CL |
2076 | cfqq = kmem_cache_alloc_node(cfq_pool, |
2077 | gfp_mask | __GFP_ZERO, | |
2078 | cfqd->queue->node); | |
22e2c507 JA |
2079 | } |
2080 | ||
6118b70b JA |
2081 | if (cfqq) { |
2082 | cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); | |
2083 | cfq_init_prio_data(cfqq, ioc); | |
2084 | cfq_log_cfqq(cfqd, cfqq, "alloced"); | |
2085 | } else | |
2086 | cfqq = &cfqd->oom_cfqq; | |
22e2c507 JA |
2087 | } |
2088 | ||
2089 | if (new_cfqq) | |
2090 | kmem_cache_free(cfq_pool, new_cfqq); | |
2091 | ||
22e2c507 JA |
2092 | return cfqq; |
2093 | } | |
2094 | ||
c2dea2d1 VT |
2095 | static struct cfq_queue ** |
2096 | cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) | |
2097 | { | |
fe094d98 | 2098 | switch (ioprio_class) { |
c2dea2d1 VT |
2099 | case IOPRIO_CLASS_RT: |
2100 | return &cfqd->async_cfqq[0][ioprio]; | |
2101 | case IOPRIO_CLASS_BE: | |
2102 | return &cfqd->async_cfqq[1][ioprio]; | |
2103 | case IOPRIO_CLASS_IDLE: | |
2104 | return &cfqd->async_idle_cfqq; | |
2105 | default: | |
2106 | BUG(); | |
2107 | } | |
2108 | } | |
2109 | ||
15c31be4 | 2110 | static struct cfq_queue * |
a6151c3a | 2111 | cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, |
15c31be4 JA |
2112 | gfp_t gfp_mask) |
2113 | { | |
fd0928df JA |
2114 | const int ioprio = task_ioprio(ioc); |
2115 | const int ioprio_class = task_ioprio_class(ioc); | |
c2dea2d1 | 2116 | struct cfq_queue **async_cfqq = NULL; |
15c31be4 JA |
2117 | struct cfq_queue *cfqq = NULL; |
2118 | ||
c2dea2d1 VT |
2119 | if (!is_sync) { |
2120 | async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); | |
2121 | cfqq = *async_cfqq; | |
2122 | } | |
2123 | ||
6118b70b | 2124 | if (!cfqq) |
fd0928df | 2125 | cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
15c31be4 JA |
2126 | |
2127 | /* | |
2128 | * pin the queue now that it's allocated, scheduler exit will prune it | |
2129 | */ | |
c2dea2d1 | 2130 | if (!is_sync && !(*async_cfqq)) { |
15c31be4 | 2131 | atomic_inc(&cfqq->ref); |
c2dea2d1 | 2132 | *async_cfqq = cfqq; |
15c31be4 JA |
2133 | } |
2134 | ||
2135 | atomic_inc(&cfqq->ref); | |
2136 | return cfqq; | |
2137 | } | |
2138 | ||
498d3aa2 JA |
2139 | /* |
2140 | * We drop cfq io contexts lazily, so we may find a dead one. | |
2141 | */ | |
dbecf3ab | 2142 | static void |
4ac845a2 JA |
2143 | cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc, |
2144 | struct cfq_io_context *cic) | |
dbecf3ab | 2145 | { |
4ac845a2 JA |
2146 | unsigned long flags; |
2147 | ||
fc46379d | 2148 | WARN_ON(!list_empty(&cic->queue_list)); |
597bc485 | 2149 | |
4ac845a2 JA |
2150 | spin_lock_irqsave(&ioc->lock, flags); |
2151 | ||
4faa3c81 | 2152 | BUG_ON(ioc->ioc_data == cic); |
597bc485 | 2153 | |
4ac845a2 | 2154 | radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd); |
ffc4e759 | 2155 | hlist_del_rcu(&cic->cic_list); |
4ac845a2 JA |
2156 | spin_unlock_irqrestore(&ioc->lock, flags); |
2157 | ||
2158 | cfq_cic_free(cic); | |
dbecf3ab OH |
2159 | } |
2160 | ||
e2d74ac0 | 2161 | static struct cfq_io_context * |
4ac845a2 | 2162 | cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) |
e2d74ac0 | 2163 | { |
e2d74ac0 | 2164 | struct cfq_io_context *cic; |
d6de8be7 | 2165 | unsigned long flags; |
4ac845a2 | 2166 | void *k; |
e2d74ac0 | 2167 | |
91fac317 VT |
2168 | if (unlikely(!ioc)) |
2169 | return NULL; | |
2170 | ||
d6de8be7 JA |
2171 | rcu_read_lock(); |
2172 | ||
597bc485 JA |
2173 | /* |
2174 | * we maintain a last-hit cache, to avoid browsing over the tree | |
2175 | */ | |
4ac845a2 | 2176 | cic = rcu_dereference(ioc->ioc_data); |
d6de8be7 JA |
2177 | if (cic && cic->key == cfqd) { |
2178 | rcu_read_unlock(); | |
597bc485 | 2179 | return cic; |
d6de8be7 | 2180 | } |
597bc485 | 2181 | |
4ac845a2 | 2182 | do { |
4ac845a2 JA |
2183 | cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); |
2184 | rcu_read_unlock(); | |
2185 | if (!cic) | |
2186 | break; | |
be3b0753 OH |
2187 | /* ->key must be copied to avoid race with cfq_exit_queue() */ |
2188 | k = cic->key; | |
2189 | if (unlikely(!k)) { | |
4ac845a2 | 2190 | cfq_drop_dead_cic(cfqd, ioc, cic); |
d6de8be7 | 2191 | rcu_read_lock(); |
4ac845a2 | 2192 | continue; |
dbecf3ab | 2193 | } |
e2d74ac0 | 2194 | |
d6de8be7 | 2195 | spin_lock_irqsave(&ioc->lock, flags); |
4ac845a2 | 2196 | rcu_assign_pointer(ioc->ioc_data, cic); |
d6de8be7 | 2197 | spin_unlock_irqrestore(&ioc->lock, flags); |
4ac845a2 JA |
2198 | break; |
2199 | } while (1); | |
e2d74ac0 | 2200 | |
4ac845a2 | 2201 | return cic; |
e2d74ac0 JA |
2202 | } |
2203 | ||
4ac845a2 JA |
2204 | /* |
2205 | * Add cic into ioc, using cfqd as the search key. This enables us to lookup | |
2206 | * the process specific cfq io context when entered from the block layer. | |
2207 | * Also adds the cic to a per-cfqd list, used when this queue is removed. | |
2208 | */ | |
febffd61 JA |
2209 | static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, |
2210 | struct cfq_io_context *cic, gfp_t gfp_mask) | |
e2d74ac0 | 2211 | { |
0261d688 | 2212 | unsigned long flags; |
4ac845a2 | 2213 | int ret; |
e2d74ac0 | 2214 | |
4ac845a2 JA |
2215 | ret = radix_tree_preload(gfp_mask); |
2216 | if (!ret) { | |
2217 | cic->ioc = ioc; | |
2218 | cic->key = cfqd; | |
e2d74ac0 | 2219 | |
4ac845a2 JA |
2220 | spin_lock_irqsave(&ioc->lock, flags); |
2221 | ret = radix_tree_insert(&ioc->radix_root, | |
2222 | (unsigned long) cfqd, cic); | |
ffc4e759 JA |
2223 | if (!ret) |
2224 | hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list); | |
4ac845a2 | 2225 | spin_unlock_irqrestore(&ioc->lock, flags); |
e2d74ac0 | 2226 | |
4ac845a2 JA |
2227 | radix_tree_preload_end(); |
2228 | ||
2229 | if (!ret) { | |
2230 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); | |
2231 | list_add(&cic->queue_list, &cfqd->cic_list); | |
2232 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2233 | } | |
e2d74ac0 JA |
2234 | } |
2235 | ||
4ac845a2 JA |
2236 | if (ret) |
2237 | printk(KERN_ERR "cfq: cic link failed!\n"); | |
fc46379d | 2238 | |
4ac845a2 | 2239 | return ret; |
e2d74ac0 JA |
2240 | } |
2241 | ||
1da177e4 LT |
2242 | /* |
2243 | * Setup general io context and cfq io context. There can be several cfq | |
2244 | * io contexts per general io context, if this process is doing io to more | |
e2d74ac0 | 2245 | * than one device managed by cfq. |
1da177e4 LT |
2246 | */ |
2247 | static struct cfq_io_context * | |
e2d74ac0 | 2248 | cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) |
1da177e4 | 2249 | { |
22e2c507 | 2250 | struct io_context *ioc = NULL; |
1da177e4 | 2251 | struct cfq_io_context *cic; |
1da177e4 | 2252 | |
22e2c507 | 2253 | might_sleep_if(gfp_mask & __GFP_WAIT); |
1da177e4 | 2254 | |
b5deef90 | 2255 | ioc = get_io_context(gfp_mask, cfqd->queue->node); |
1da177e4 LT |
2256 | if (!ioc) |
2257 | return NULL; | |
2258 | ||
4ac845a2 | 2259 | cic = cfq_cic_lookup(cfqd, ioc); |
e2d74ac0 JA |
2260 | if (cic) |
2261 | goto out; | |
1da177e4 | 2262 | |
e2d74ac0 JA |
2263 | cic = cfq_alloc_io_context(cfqd, gfp_mask); |
2264 | if (cic == NULL) | |
2265 | goto err; | |
1da177e4 | 2266 | |
4ac845a2 JA |
2267 | if (cfq_cic_link(cfqd, ioc, cic, gfp_mask)) |
2268 | goto err_free; | |
2269 | ||
1da177e4 | 2270 | out: |
fc46379d JA |
2271 | smp_read_barrier_depends(); |
2272 | if (unlikely(ioc->ioprio_changed)) | |
2273 | cfq_ioc_set_ioprio(ioc); | |
2274 | ||
1da177e4 | 2275 | return cic; |
4ac845a2 JA |
2276 | err_free: |
2277 | cfq_cic_free(cic); | |
1da177e4 LT |
2278 | err: |
2279 | put_io_context(ioc); | |
2280 | return NULL; | |
2281 | } | |
2282 | ||
22e2c507 JA |
2283 | static void |
2284 | cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) | |
1da177e4 | 2285 | { |
aaf1228d JA |
2286 | unsigned long elapsed = jiffies - cic->last_end_request; |
2287 | unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle); | |
db3b5848 | 2288 | |
22e2c507 JA |
2289 | cic->ttime_samples = (7*cic->ttime_samples + 256) / 8; |
2290 | cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8; | |
2291 | cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples; | |
2292 | } | |
1da177e4 | 2293 | |
206dc69b | 2294 | static void |
b2c18e1e | 2295 | cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
6d048f53 | 2296 | struct request *rq) |
206dc69b JA |
2297 | { |
2298 | sector_t sdist; | |
2299 | u64 total; | |
2300 | ||
b2c18e1e | 2301 | if (!cfqq->last_request_pos) |
4d00aa47 | 2302 | sdist = 0; |
b2c18e1e JM |
2303 | else if (cfqq->last_request_pos < blk_rq_pos(rq)) |
2304 | sdist = blk_rq_pos(rq) - cfqq->last_request_pos; | |
206dc69b | 2305 | else |
b2c18e1e | 2306 | sdist = cfqq->last_request_pos - blk_rq_pos(rq); |
206dc69b JA |
2307 | |
2308 | /* | |
2309 | * Don't allow the seek distance to get too large from the | |
2310 | * odd fragment, pagein, etc | |
2311 | */ | |
b2c18e1e JM |
2312 | if (cfqq->seek_samples <= 60) /* second&third seek */ |
2313 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024); | |
206dc69b | 2314 | else |
b2c18e1e | 2315 | sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64); |
206dc69b | 2316 | |
b2c18e1e JM |
2317 | cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8; |
2318 | cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8; | |
2319 | total = cfqq->seek_total + (cfqq->seek_samples/2); | |
2320 | do_div(total, cfqq->seek_samples); | |
2321 | cfqq->seek_mean = (sector_t)total; | |
e6c5bc73 JM |
2322 | |
2323 | /* | |
2324 | * If this cfqq is shared between multiple processes, check to | |
2325 | * make sure that those processes are still issuing I/Os within | |
2326 | * the mean seek distance. If not, it may be time to break the | |
2327 | * queues apart again. | |
2328 | */ | |
2329 | if (cfq_cfqq_coop(cfqq)) { | |
2330 | if (CFQQ_SEEKY(cfqq) && !cfqq->seeky_start) | |
2331 | cfqq->seeky_start = jiffies; | |
2332 | else if (!CFQQ_SEEKY(cfqq)) | |
2333 | cfqq->seeky_start = 0; | |
2334 | } | |
206dc69b | 2335 | } |
1da177e4 | 2336 | |
22e2c507 JA |
2337 | /* |
2338 | * Disable idle window if the process thinks too long or seeks so much that | |
2339 | * it doesn't matter | |
2340 | */ | |
2341 | static void | |
2342 | cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, | |
2343 | struct cfq_io_context *cic) | |
2344 | { | |
7b679138 | 2345 | int old_idle, enable_idle; |
1be92f2f | 2346 | |
0871714e JA |
2347 | /* |
2348 | * Don't idle for async or idle io prio class | |
2349 | */ | |
2350 | if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) | |
1be92f2f JA |
2351 | return; |
2352 | ||
c265a7f4 | 2353 | enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
1da177e4 | 2354 | |
66dac98e | 2355 | if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || |
718eee05 | 2356 | (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq))) |
22e2c507 JA |
2357 | enable_idle = 0; |
2358 | else if (sample_valid(cic->ttime_samples)) { | |
718eee05 | 2359 | if (cic->ttime_mean > cfqd->cfq_slice_idle) |
22e2c507 JA |
2360 | enable_idle = 0; |
2361 | else | |
2362 | enable_idle = 1; | |
1da177e4 LT |
2363 | } |
2364 | ||
7b679138 JA |
2365 | if (old_idle != enable_idle) { |
2366 | cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); | |
2367 | if (enable_idle) | |
2368 | cfq_mark_cfqq_idle_window(cfqq); | |
2369 | else | |
2370 | cfq_clear_cfqq_idle_window(cfqq); | |
2371 | } | |
22e2c507 | 2372 | } |
1da177e4 | 2373 | |
22e2c507 JA |
2374 | /* |
2375 | * Check if new_cfqq should preempt the currently active queue. Return 0 for | |
2376 | * no or if we aren't sure, a 1 will cause a preempt. | |
2377 | */ | |
a6151c3a | 2378 | static bool |
22e2c507 | 2379 | cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
5e705374 | 2380 | struct request *rq) |
22e2c507 | 2381 | { |
6d048f53 | 2382 | struct cfq_queue *cfqq; |
22e2c507 | 2383 | |
6d048f53 JA |
2384 | cfqq = cfqd->active_queue; |
2385 | if (!cfqq) | |
a6151c3a | 2386 | return false; |
22e2c507 | 2387 | |
6d048f53 | 2388 | if (cfq_slice_used(cfqq)) |
a6151c3a | 2389 | return true; |
6d048f53 JA |
2390 | |
2391 | if (cfq_class_idle(new_cfqq)) | |
a6151c3a | 2392 | return false; |
22e2c507 JA |
2393 | |
2394 | if (cfq_class_idle(cfqq)) | |
a6151c3a | 2395 | return true; |
1e3335de | 2396 | |
718eee05 CZ |
2397 | if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD |
2398 | && new_cfqq->service_tree == cfqq->service_tree) | |
2399 | return true; | |
2400 | ||
374f84ac JA |
2401 | /* |
2402 | * if the new request is sync, but the currently running queue is | |
2403 | * not, let the sync request have priority. | |
2404 | */ | |
5e705374 | 2405 | if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
a6151c3a | 2406 | return true; |
1e3335de | 2407 | |
374f84ac JA |
2408 | /* |
2409 | * So both queues are sync. Let the new request get disk time if | |
2410 | * it's a metadata request and the current queue is doing regular IO. | |
2411 | */ | |
2412 | if (rq_is_meta(rq) && !cfqq->meta_pending) | |
e6ec4fe2 | 2413 | return true; |
22e2c507 | 2414 | |
3a9a3f6c DS |
2415 | /* |
2416 | * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. | |
2417 | */ | |
2418 | if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) | |
a6151c3a | 2419 | return true; |
3a9a3f6c | 2420 | |
1e3335de | 2421 | if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
a6151c3a | 2422 | return false; |
1e3335de JA |
2423 | |
2424 | /* | |
2425 | * if this request is as-good as one we would expect from the | |
2426 | * current cfqq, let it preempt | |
2427 | */ | |
e00ef799 | 2428 | if (cfq_rq_close(cfqd, cfqq, rq)) |
a6151c3a | 2429 | return true; |
1e3335de | 2430 | |
a6151c3a | 2431 | return false; |
22e2c507 JA |
2432 | } |
2433 | ||
2434 | /* | |
2435 | * cfqq preempts the active queue. if we allowed preempt with no slice left, | |
2436 | * let it have half of its nominal slice. | |
2437 | */ | |
2438 | static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) | |
2439 | { | |
7b679138 | 2440 | cfq_log_cfqq(cfqd, cfqq, "preempt"); |
6084cdda | 2441 | cfq_slice_expired(cfqd, 1); |
22e2c507 | 2442 | |
bf572256 JA |
2443 | /* |
2444 | * Put the new queue at the front of the of the current list, | |
2445 | * so we know that it will be selected next. | |
2446 | */ | |
2447 | BUG_ON(!cfq_cfqq_on_rr(cfqq)); | |
edd75ffd JA |
2448 | |
2449 | cfq_service_tree_add(cfqd, cfqq, 1); | |
bf572256 | 2450 | |
44f7c160 JA |
2451 | cfqq->slice_end = 0; |
2452 | cfq_mark_cfqq_slice_new(cfqq); | |
22e2c507 JA |
2453 | } |
2454 | ||
22e2c507 | 2455 | /* |
5e705374 | 2456 | * Called when a new fs request (rq) is added (to cfqq). Check if there's |
22e2c507 JA |
2457 | * something we should do about it |
2458 | */ | |
2459 | static void | |
5e705374 JA |
2460 | cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
2461 | struct request *rq) | |
22e2c507 | 2462 | { |
5e705374 | 2463 | struct cfq_io_context *cic = RQ_CIC(rq); |
12e9fddd | 2464 | |
45333d5a | 2465 | cfqd->rq_queued++; |
374f84ac JA |
2466 | if (rq_is_meta(rq)) |
2467 | cfqq->meta_pending++; | |
2468 | ||
9c2c38a1 | 2469 | cfq_update_io_thinktime(cfqd, cic); |
b2c18e1e | 2470 | cfq_update_io_seektime(cfqd, cfqq, rq); |
9c2c38a1 JA |
2471 | cfq_update_idle_window(cfqd, cfqq, cic); |
2472 | ||
b2c18e1e | 2473 | cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
22e2c507 JA |
2474 | |
2475 | if (cfqq == cfqd->active_queue) { | |
2476 | /* | |
b029195d JA |
2477 | * Remember that we saw a request from this process, but |
2478 | * don't start queuing just yet. Otherwise we risk seeing lots | |
2479 | * of tiny requests, because we disrupt the normal plugging | |
d6ceb25e JA |
2480 | * and merging. If the request is already larger than a single |
2481 | * page, let it rip immediately. For that case we assume that | |
2d870722 JA |
2482 | * merging is already done. Ditto for a busy system that |
2483 | * has other work pending, don't risk delaying until the | |
2484 | * idle timer unplug to continue working. | |
22e2c507 | 2485 | */ |
d6ceb25e | 2486 | if (cfq_cfqq_wait_request(cfqq)) { |
2d870722 JA |
2487 | if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE || |
2488 | cfqd->busy_queues > 1) { | |
d6ceb25e | 2489 | del_timer(&cfqd->idle_slice_timer); |
a7f55792 | 2490 | __blk_run_queue(cfqd->queue); |
d6ceb25e | 2491 | } |
b029195d | 2492 | cfq_mark_cfqq_must_dispatch(cfqq); |
d6ceb25e | 2493 | } |
5e705374 | 2494 | } else if (cfq_should_preempt(cfqd, cfqq, rq)) { |
22e2c507 JA |
2495 | /* |
2496 | * not the active queue - expire current slice if it is | |
2497 | * idle and has expired it's mean thinktime or this new queue | |
3a9a3f6c DS |
2498 | * has some old slice time left and is of higher priority or |
2499 | * this new queue is RT and the current one is BE | |
22e2c507 JA |
2500 | */ |
2501 | cfq_preempt_queue(cfqd, cfqq); | |
a7f55792 | 2502 | __blk_run_queue(cfqd->queue); |
22e2c507 | 2503 | } |
1da177e4 LT |
2504 | } |
2505 | ||
165125e1 | 2506 | static void cfq_insert_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2507 | { |
b4878f24 | 2508 | struct cfq_data *cfqd = q->elevator->elevator_data; |
5e705374 | 2509 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
22e2c507 | 2510 | |
7b679138 | 2511 | cfq_log_cfqq(cfqd, cfqq, "insert_request"); |
fd0928df | 2512 | cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); |
1da177e4 | 2513 | |
30996f40 | 2514 | rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); |
22e2c507 | 2515 | list_add_tail(&rq->queuelist, &cfqq->fifo); |
aa6f6a3d | 2516 | cfq_add_rq_rb(rq); |
22e2c507 | 2517 | |
5e705374 | 2518 | cfq_rq_enqueued(cfqd, cfqq, rq); |
1da177e4 LT |
2519 | } |
2520 | ||
45333d5a AC |
2521 | /* |
2522 | * Update hw_tag based on peak queue depth over 50 samples under | |
2523 | * sufficient load. | |
2524 | */ | |
2525 | static void cfq_update_hw_tag(struct cfq_data *cfqd) | |
2526 | { | |
1a1238a7 SL |
2527 | struct cfq_queue *cfqq = cfqd->active_queue; |
2528 | ||
5ad531db JA |
2529 | if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak) |
2530 | cfqd->rq_in_driver_peak = rq_in_driver(cfqd); | |
45333d5a AC |
2531 | |
2532 | if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN && | |
5ad531db | 2533 | rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN) |
45333d5a AC |
2534 | return; |
2535 | ||
1a1238a7 SL |
2536 | /* |
2537 | * If active queue hasn't enough requests and can idle, cfq might not | |
2538 | * dispatch sufficient requests to hardware. Don't zero hw_tag in this | |
2539 | * case | |
2540 | */ | |
2541 | if (cfqq && cfq_cfqq_idle_window(cfqq) && | |
2542 | cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] < | |
2543 | CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN) | |
2544 | return; | |
2545 | ||
45333d5a AC |
2546 | if (cfqd->hw_tag_samples++ < 50) |
2547 | return; | |
2548 | ||
2549 | if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN) | |
2550 | cfqd->hw_tag = 1; | |
2551 | else | |
2552 | cfqd->hw_tag = 0; | |
2553 | ||
2554 | cfqd->hw_tag_samples = 0; | |
2555 | cfqd->rq_in_driver_peak = 0; | |
2556 | } | |
2557 | ||
165125e1 | 2558 | static void cfq_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 2559 | { |
5e705374 | 2560 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
b4878f24 | 2561 | struct cfq_data *cfqd = cfqq->cfqd; |
5380a101 | 2562 | const int sync = rq_is_sync(rq); |
b4878f24 | 2563 | unsigned long now; |
1da177e4 | 2564 | |
b4878f24 | 2565 | now = jiffies; |
7b679138 | 2566 | cfq_log_cfqq(cfqd, cfqq, "complete"); |
1da177e4 | 2567 | |
45333d5a AC |
2568 | cfq_update_hw_tag(cfqd); |
2569 | ||
5ad531db | 2570 | WARN_ON(!cfqd->rq_in_driver[sync]); |
6d048f53 | 2571 | WARN_ON(!cfqq->dispatched); |
5ad531db | 2572 | cfqd->rq_in_driver[sync]--; |
6d048f53 | 2573 | cfqq->dispatched--; |
1da177e4 | 2574 | |
3ed9a296 JA |
2575 | if (cfq_cfqq_sync(cfqq)) |
2576 | cfqd->sync_flight--; | |
2577 | ||
365722bb | 2578 | if (sync) { |
5e705374 | 2579 | RQ_CIC(rq)->last_end_request = now; |
365722bb VG |
2580 | cfqd->last_end_sync_rq = now; |
2581 | } | |
caaa5f9f JA |
2582 | |
2583 | /* | |
2584 | * If this is the active queue, check if it needs to be expired, | |
2585 | * or if we want to idle in case it has no pending requests. | |
2586 | */ | |
2587 | if (cfqd->active_queue == cfqq) { | |
a36e71f9 JA |
2588 | const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list); |
2589 | ||
44f7c160 JA |
2590 | if (cfq_cfqq_slice_new(cfqq)) { |
2591 | cfq_set_prio_slice(cfqd, cfqq); | |
2592 | cfq_clear_cfqq_slice_new(cfqq); | |
2593 | } | |
a36e71f9 JA |
2594 | /* |
2595 | * If there are no requests waiting in this queue, and | |
2596 | * there are other queues ready to issue requests, AND | |
2597 | * those other queues are issuing requests within our | |
2598 | * mean seek distance, give them a chance to run instead | |
2599 | * of idling. | |
2600 | */ | |
0871714e | 2601 | if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq)) |
6084cdda | 2602 | cfq_slice_expired(cfqd, 1); |
b3b6d040 | 2603 | else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq) && |
a36e71f9 | 2604 | sync && !rq_noidle(rq)) |
6d048f53 | 2605 | cfq_arm_slice_timer(cfqd); |
caaa5f9f | 2606 | } |
6d048f53 | 2607 | |
5ad531db | 2608 | if (!rq_in_driver(cfqd)) |
23e018a1 | 2609 | cfq_schedule_dispatch(cfqd); |
1da177e4 LT |
2610 | } |
2611 | ||
22e2c507 JA |
2612 | /* |
2613 | * we temporarily boost lower priority queues if they are holding fs exclusive | |
2614 | * resources. they are boosted to normal prio (CLASS_BE/4) | |
2615 | */ | |
2616 | static void cfq_prio_boost(struct cfq_queue *cfqq) | |
1da177e4 | 2617 | { |
22e2c507 JA |
2618 | if (has_fs_excl()) { |
2619 | /* | |
2620 | * boost idle prio on transactions that would lock out other | |
2621 | * users of the filesystem | |
2622 | */ | |
2623 | if (cfq_class_idle(cfqq)) | |
2624 | cfqq->ioprio_class = IOPRIO_CLASS_BE; | |
2625 | if (cfqq->ioprio > IOPRIO_NORM) | |
2626 | cfqq->ioprio = IOPRIO_NORM; | |
2627 | } else { | |
2628 | /* | |
dddb7451 | 2629 | * unboost the queue (if needed) |
22e2c507 | 2630 | */ |
dddb7451 CZ |
2631 | cfqq->ioprio_class = cfqq->org_ioprio_class; |
2632 | cfqq->ioprio = cfqq->org_ioprio; | |
22e2c507 | 2633 | } |
22e2c507 | 2634 | } |
1da177e4 | 2635 | |
89850f7e | 2636 | static inline int __cfq_may_queue(struct cfq_queue *cfqq) |
22e2c507 | 2637 | { |
1b379d8d | 2638 | if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) { |
3b18152c | 2639 | cfq_mark_cfqq_must_alloc_slice(cfqq); |
22e2c507 | 2640 | return ELV_MQUEUE_MUST; |
3b18152c | 2641 | } |
1da177e4 | 2642 | |
22e2c507 | 2643 | return ELV_MQUEUE_MAY; |
22e2c507 JA |
2644 | } |
2645 | ||
165125e1 | 2646 | static int cfq_may_queue(struct request_queue *q, int rw) |
22e2c507 JA |
2647 | { |
2648 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2649 | struct task_struct *tsk = current; | |
91fac317 | 2650 | struct cfq_io_context *cic; |
22e2c507 JA |
2651 | struct cfq_queue *cfqq; |
2652 | ||
2653 | /* | |
2654 | * don't force setup of a queue from here, as a call to may_queue | |
2655 | * does not necessarily imply that a request actually will be queued. | |
2656 | * so just lookup a possibly existing queue, or return 'may queue' | |
2657 | * if that fails | |
2658 | */ | |
4ac845a2 | 2659 | cic = cfq_cic_lookup(cfqd, tsk->io_context); |
91fac317 VT |
2660 | if (!cic) |
2661 | return ELV_MQUEUE_MAY; | |
2662 | ||
b0b78f81 | 2663 | cfqq = cic_to_cfqq(cic, rw_is_sync(rw)); |
22e2c507 | 2664 | if (cfqq) { |
fd0928df | 2665 | cfq_init_prio_data(cfqq, cic->ioc); |
22e2c507 JA |
2666 | cfq_prio_boost(cfqq); |
2667 | ||
89850f7e | 2668 | return __cfq_may_queue(cfqq); |
22e2c507 JA |
2669 | } |
2670 | ||
2671 | return ELV_MQUEUE_MAY; | |
1da177e4 LT |
2672 | } |
2673 | ||
1da177e4 LT |
2674 | /* |
2675 | * queue lock held here | |
2676 | */ | |
bb37b94c | 2677 | static void cfq_put_request(struct request *rq) |
1da177e4 | 2678 | { |
5e705374 | 2679 | struct cfq_queue *cfqq = RQ_CFQQ(rq); |
1da177e4 | 2680 | |
5e705374 | 2681 | if (cfqq) { |
22e2c507 | 2682 | const int rw = rq_data_dir(rq); |
1da177e4 | 2683 | |
22e2c507 JA |
2684 | BUG_ON(!cfqq->allocated[rw]); |
2685 | cfqq->allocated[rw]--; | |
1da177e4 | 2686 | |
5e705374 | 2687 | put_io_context(RQ_CIC(rq)->ioc); |
1da177e4 | 2688 | |
1da177e4 | 2689 | rq->elevator_private = NULL; |
5e705374 | 2690 | rq->elevator_private2 = NULL; |
1da177e4 | 2691 | |
1da177e4 LT |
2692 | cfq_put_queue(cfqq); |
2693 | } | |
2694 | } | |
2695 | ||
df5fe3e8 JM |
2696 | static struct cfq_queue * |
2697 | cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic, | |
2698 | struct cfq_queue *cfqq) | |
2699 | { | |
2700 | cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq); | |
2701 | cic_set_cfqq(cic, cfqq->new_cfqq, 1); | |
b3b6d040 | 2702 | cfq_mark_cfqq_coop(cfqq->new_cfqq); |
df5fe3e8 JM |
2703 | cfq_put_queue(cfqq); |
2704 | return cic_to_cfqq(cic, 1); | |
2705 | } | |
2706 | ||
e6c5bc73 JM |
2707 | static int should_split_cfqq(struct cfq_queue *cfqq) |
2708 | { | |
2709 | if (cfqq->seeky_start && | |
2710 | time_after(jiffies, cfqq->seeky_start + CFQQ_COOP_TOUT)) | |
2711 | return 1; | |
2712 | return 0; | |
2713 | } | |
2714 | ||
2715 | /* | |
2716 | * Returns NULL if a new cfqq should be allocated, or the old cfqq if this | |
2717 | * was the last process referring to said cfqq. | |
2718 | */ | |
2719 | static struct cfq_queue * | |
2720 | split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq) | |
2721 | { | |
2722 | if (cfqq_process_refs(cfqq) == 1) { | |
2723 | cfqq->seeky_start = 0; | |
2724 | cfqq->pid = current->pid; | |
2725 | cfq_clear_cfqq_coop(cfqq); | |
2726 | return cfqq; | |
2727 | } | |
2728 | ||
2729 | cic_set_cfqq(cic, NULL, 1); | |
2730 | cfq_put_queue(cfqq); | |
2731 | return NULL; | |
2732 | } | |
1da177e4 | 2733 | /* |
22e2c507 | 2734 | * Allocate cfq data structures associated with this request. |
1da177e4 | 2735 | */ |
22e2c507 | 2736 | static int |
165125e1 | 2737 | cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
2738 | { |
2739 | struct cfq_data *cfqd = q->elevator->elevator_data; | |
2740 | struct cfq_io_context *cic; | |
2741 | const int rw = rq_data_dir(rq); | |
a6151c3a | 2742 | const bool is_sync = rq_is_sync(rq); |
22e2c507 | 2743 | struct cfq_queue *cfqq; |
1da177e4 LT |
2744 | unsigned long flags; |
2745 | ||
2746 | might_sleep_if(gfp_mask & __GFP_WAIT); | |
2747 | ||
e2d74ac0 | 2748 | cic = cfq_get_io_context(cfqd, gfp_mask); |
22e2c507 | 2749 | |
1da177e4 LT |
2750 | spin_lock_irqsave(q->queue_lock, flags); |
2751 | ||
22e2c507 JA |
2752 | if (!cic) |
2753 | goto queue_fail; | |
2754 | ||
e6c5bc73 | 2755 | new_queue: |
91fac317 | 2756 | cfqq = cic_to_cfqq(cic, is_sync); |
32f2e807 | 2757 | if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
fd0928df | 2758 | cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); |
91fac317 | 2759 | cic_set_cfqq(cic, cfqq, is_sync); |
df5fe3e8 | 2760 | } else { |
e6c5bc73 JM |
2761 | /* |
2762 | * If the queue was seeky for too long, break it apart. | |
2763 | */ | |
2764 | if (cfq_cfqq_coop(cfqq) && should_split_cfqq(cfqq)) { | |
2765 | cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq"); | |
2766 | cfqq = split_cfqq(cic, cfqq); | |
2767 | if (!cfqq) | |
2768 | goto new_queue; | |
2769 | } | |
2770 | ||
df5fe3e8 JM |
2771 | /* |
2772 | * Check to see if this queue is scheduled to merge with | |
2773 | * another, closely cooperating queue. The merging of | |
2774 | * queues happens here as it must be done in process context. | |
2775 | * The reference on new_cfqq was taken in merge_cfqqs. | |
2776 | */ | |
2777 | if (cfqq->new_cfqq) | |
2778 | cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq); | |
91fac317 | 2779 | } |
1da177e4 LT |
2780 | |
2781 | cfqq->allocated[rw]++; | |
22e2c507 | 2782 | atomic_inc(&cfqq->ref); |
1da177e4 | 2783 | |
5e705374 | 2784 | spin_unlock_irqrestore(q->queue_lock, flags); |
3b18152c | 2785 | |
5e705374 JA |
2786 | rq->elevator_private = cic; |
2787 | rq->elevator_private2 = cfqq; | |
2788 | return 0; | |
1da177e4 | 2789 | |
22e2c507 JA |
2790 | queue_fail: |
2791 | if (cic) | |
2792 | put_io_context(cic->ioc); | |
89850f7e | 2793 | |
23e018a1 | 2794 | cfq_schedule_dispatch(cfqd); |
1da177e4 | 2795 | spin_unlock_irqrestore(q->queue_lock, flags); |
7b679138 | 2796 | cfq_log(cfqd, "set_request fail"); |
1da177e4 LT |
2797 | return 1; |
2798 | } | |
2799 | ||
65f27f38 | 2800 | static void cfq_kick_queue(struct work_struct *work) |
22e2c507 | 2801 | { |
65f27f38 | 2802 | struct cfq_data *cfqd = |
23e018a1 | 2803 | container_of(work, struct cfq_data, unplug_work); |
165125e1 | 2804 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2805 | |
40bb54d1 | 2806 | spin_lock_irq(q->queue_lock); |
a7f55792 | 2807 | __blk_run_queue(cfqd->queue); |
40bb54d1 | 2808 | spin_unlock_irq(q->queue_lock); |
22e2c507 JA |
2809 | } |
2810 | ||
2811 | /* | |
2812 | * Timer running if the active_queue is currently idling inside its time slice | |
2813 | */ | |
2814 | static void cfq_idle_slice_timer(unsigned long data) | |
2815 | { | |
2816 | struct cfq_data *cfqd = (struct cfq_data *) data; | |
2817 | struct cfq_queue *cfqq; | |
2818 | unsigned long flags; | |
3c6bd2f8 | 2819 | int timed_out = 1; |
22e2c507 | 2820 | |
7b679138 JA |
2821 | cfq_log(cfqd, "idle timer fired"); |
2822 | ||
22e2c507 JA |
2823 | spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
2824 | ||
fe094d98 JA |
2825 | cfqq = cfqd->active_queue; |
2826 | if (cfqq) { | |
3c6bd2f8 JA |
2827 | timed_out = 0; |
2828 | ||
b029195d JA |
2829 | /* |
2830 | * We saw a request before the queue expired, let it through | |
2831 | */ | |
2832 | if (cfq_cfqq_must_dispatch(cfqq)) | |
2833 | goto out_kick; | |
2834 | ||
22e2c507 JA |
2835 | /* |
2836 | * expired | |
2837 | */ | |
44f7c160 | 2838 | if (cfq_slice_used(cfqq)) |
22e2c507 JA |
2839 | goto expire; |
2840 | ||
2841 | /* | |
2842 | * only expire and reinvoke request handler, if there are | |
2843 | * other queues with pending requests | |
2844 | */ | |
caaa5f9f | 2845 | if (!cfqd->busy_queues) |
22e2c507 | 2846 | goto out_cont; |
22e2c507 JA |
2847 | |
2848 | /* | |
2849 | * not expired and it has a request pending, let it dispatch | |
2850 | */ | |
75e50984 | 2851 | if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
22e2c507 | 2852 | goto out_kick; |
22e2c507 JA |
2853 | } |
2854 | expire: | |
6084cdda | 2855 | cfq_slice_expired(cfqd, timed_out); |
22e2c507 | 2856 | out_kick: |
23e018a1 | 2857 | cfq_schedule_dispatch(cfqd); |
22e2c507 JA |
2858 | out_cont: |
2859 | spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); | |
2860 | } | |
2861 | ||
3b18152c JA |
2862 | static void cfq_shutdown_timer_wq(struct cfq_data *cfqd) |
2863 | { | |
2864 | del_timer_sync(&cfqd->idle_slice_timer); | |
23e018a1 | 2865 | cancel_work_sync(&cfqd->unplug_work); |
3b18152c | 2866 | } |
22e2c507 | 2867 | |
c2dea2d1 VT |
2868 | static void cfq_put_async_queues(struct cfq_data *cfqd) |
2869 | { | |
2870 | int i; | |
2871 | ||
2872 | for (i = 0; i < IOPRIO_BE_NR; i++) { | |
2873 | if (cfqd->async_cfqq[0][i]) | |
2874 | cfq_put_queue(cfqd->async_cfqq[0][i]); | |
2875 | if (cfqd->async_cfqq[1][i]) | |
2876 | cfq_put_queue(cfqd->async_cfqq[1][i]); | |
c2dea2d1 | 2877 | } |
2389d1ef ON |
2878 | |
2879 | if (cfqd->async_idle_cfqq) | |
2880 | cfq_put_queue(cfqd->async_idle_cfqq); | |
c2dea2d1 VT |
2881 | } |
2882 | ||
b374d18a | 2883 | static void cfq_exit_queue(struct elevator_queue *e) |
1da177e4 | 2884 | { |
22e2c507 | 2885 | struct cfq_data *cfqd = e->elevator_data; |
165125e1 | 2886 | struct request_queue *q = cfqd->queue; |
22e2c507 | 2887 | |
3b18152c | 2888 | cfq_shutdown_timer_wq(cfqd); |
e2d74ac0 | 2889 | |
d9ff4187 | 2890 | spin_lock_irq(q->queue_lock); |
e2d74ac0 | 2891 | |
d9ff4187 | 2892 | if (cfqd->active_queue) |
6084cdda | 2893 | __cfq_slice_expired(cfqd, cfqd->active_queue, 0); |
e2d74ac0 JA |
2894 | |
2895 | while (!list_empty(&cfqd->cic_list)) { | |
d9ff4187 AV |
2896 | struct cfq_io_context *cic = list_entry(cfqd->cic_list.next, |
2897 | struct cfq_io_context, | |
2898 | queue_list); | |
89850f7e JA |
2899 | |
2900 | __cfq_exit_single_io_context(cfqd, cic); | |
d9ff4187 | 2901 | } |
e2d74ac0 | 2902 | |
c2dea2d1 | 2903 | cfq_put_async_queues(cfqd); |
15c31be4 | 2904 | |
d9ff4187 | 2905 | spin_unlock_irq(q->queue_lock); |
a90d742e AV |
2906 | |
2907 | cfq_shutdown_timer_wq(cfqd); | |
2908 | ||
a90d742e | 2909 | kfree(cfqd); |
1da177e4 LT |
2910 | } |
2911 | ||
165125e1 | 2912 | static void *cfq_init_queue(struct request_queue *q) |
1da177e4 LT |
2913 | { |
2914 | struct cfq_data *cfqd; | |
718eee05 | 2915 | int i, j; |
1da177e4 | 2916 | |
94f6030c | 2917 | cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); |
1da177e4 | 2918 | if (!cfqd) |
bc1c1169 | 2919 | return NULL; |
1da177e4 | 2920 | |
c0324a02 | 2921 | for (i = 0; i < 2; ++i) |
718eee05 CZ |
2922 | for (j = 0; j < 3; ++j) |
2923 | cfqd->service_trees[i][j] = CFQ_RB_ROOT; | |
c0324a02 | 2924 | cfqd->service_tree_idle = CFQ_RB_ROOT; |
26a2ac00 JA |
2925 | |
2926 | /* | |
2927 | * Not strictly needed (since RB_ROOT just clears the node and we | |
2928 | * zeroed cfqd on alloc), but better be safe in case someone decides | |
2929 | * to add magic to the rb code | |
2930 | */ | |
2931 | for (i = 0; i < CFQ_PRIO_LISTS; i++) | |
2932 | cfqd->prio_trees[i] = RB_ROOT; | |
2933 | ||
6118b70b JA |
2934 | /* |
2935 | * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues. | |
2936 | * Grab a permanent reference to it, so that the normal code flow | |
2937 | * will not attempt to free it. | |
2938 | */ | |
2939 | cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0); | |
2940 | atomic_inc(&cfqd->oom_cfqq.ref); | |
2941 | ||
d9ff4187 | 2942 | INIT_LIST_HEAD(&cfqd->cic_list); |
1da177e4 | 2943 | |
1da177e4 | 2944 | cfqd->queue = q; |
1da177e4 | 2945 | |
22e2c507 JA |
2946 | init_timer(&cfqd->idle_slice_timer); |
2947 | cfqd->idle_slice_timer.function = cfq_idle_slice_timer; | |
2948 | cfqd->idle_slice_timer.data = (unsigned long) cfqd; | |
2949 | ||
23e018a1 | 2950 | INIT_WORK(&cfqd->unplug_work, cfq_kick_queue); |
22e2c507 | 2951 | |
1da177e4 | 2952 | cfqd->cfq_quantum = cfq_quantum; |
22e2c507 JA |
2953 | cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0]; |
2954 | cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1]; | |
1da177e4 LT |
2955 | cfqd->cfq_back_max = cfq_back_max; |
2956 | cfqd->cfq_back_penalty = cfq_back_penalty; | |
22e2c507 JA |
2957 | cfqd->cfq_slice[0] = cfq_slice_async; |
2958 | cfqd->cfq_slice[1] = cfq_slice_sync; | |
2959 | cfqd->cfq_slice_async_rq = cfq_slice_async_rq; | |
2960 | cfqd->cfq_slice_idle = cfq_slice_idle; | |
963b72fc | 2961 | cfqd->cfq_latency = 1; |
45333d5a | 2962 | cfqd->hw_tag = 1; |
365722bb | 2963 | cfqd->last_end_sync_rq = jiffies; |
bc1c1169 | 2964 | return cfqd; |
1da177e4 LT |
2965 | } |
2966 | ||
2967 | static void cfq_slab_kill(void) | |
2968 | { | |
d6de8be7 JA |
2969 | /* |
2970 | * Caller already ensured that pending RCU callbacks are completed, | |
2971 | * so we should have no busy allocations at this point. | |
2972 | */ | |
1da177e4 LT |
2973 | if (cfq_pool) |
2974 | kmem_cache_destroy(cfq_pool); | |
2975 | if (cfq_ioc_pool) | |
2976 | kmem_cache_destroy(cfq_ioc_pool); | |
2977 | } | |
2978 | ||
2979 | static int __init cfq_slab_setup(void) | |
2980 | { | |
0a31bd5f | 2981 | cfq_pool = KMEM_CACHE(cfq_queue, 0); |
1da177e4 LT |
2982 | if (!cfq_pool) |
2983 | goto fail; | |
2984 | ||
34e6bbf2 | 2985 | cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0); |
1da177e4 LT |
2986 | if (!cfq_ioc_pool) |
2987 | goto fail; | |
2988 | ||
2989 | return 0; | |
2990 | fail: | |
2991 | cfq_slab_kill(); | |
2992 | return -ENOMEM; | |
2993 | } | |
2994 | ||
1da177e4 LT |
2995 | /* |
2996 | * sysfs parts below --> | |
2997 | */ | |
1da177e4 LT |
2998 | static ssize_t |
2999 | cfq_var_show(unsigned int var, char *page) | |
3000 | { | |
3001 | return sprintf(page, "%d\n", var); | |
3002 | } | |
3003 | ||
3004 | static ssize_t | |
3005 | cfq_var_store(unsigned int *var, const char *page, size_t count) | |
3006 | { | |
3007 | char *p = (char *) page; | |
3008 | ||
3009 | *var = simple_strtoul(p, &p, 10); | |
3010 | return count; | |
3011 | } | |
3012 | ||
1da177e4 | 3013 | #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ |
b374d18a | 3014 | static ssize_t __FUNC(struct elevator_queue *e, char *page) \ |
1da177e4 | 3015 | { \ |
3d1ab40f | 3016 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
3017 | unsigned int __data = __VAR; \ |
3018 | if (__CONV) \ | |
3019 | __data = jiffies_to_msecs(__data); \ | |
3020 | return cfq_var_show(__data, (page)); \ | |
3021 | } | |
3022 | SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); | |
22e2c507 JA |
3023 | SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1); |
3024 | SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1); | |
e572ec7e AV |
3025 | SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0); |
3026 | SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0); | |
22e2c507 JA |
3027 | SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); |
3028 | SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); | |
3029 | SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); | |
3030 | SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); | |
963b72fc | 3031 | SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0); |
1da177e4 LT |
3032 | #undef SHOW_FUNCTION |
3033 | ||
3034 | #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ | |
b374d18a | 3035 | static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ |
1da177e4 | 3036 | { \ |
3d1ab40f | 3037 | struct cfq_data *cfqd = e->elevator_data; \ |
1da177e4 LT |
3038 | unsigned int __data; \ |
3039 | int ret = cfq_var_store(&__data, (page), count); \ | |
3040 | if (__data < (MIN)) \ | |
3041 | __data = (MIN); \ | |
3042 | else if (__data > (MAX)) \ | |
3043 | __data = (MAX); \ | |
3044 | if (__CONV) \ | |
3045 | *(__PTR) = msecs_to_jiffies(__data); \ | |
3046 | else \ | |
3047 | *(__PTR) = __data; \ | |
3048 | return ret; \ | |
3049 | } | |
3050 | STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); | |
fe094d98 JA |
3051 | STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, |
3052 | UINT_MAX, 1); | |
3053 | STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, | |
3054 | UINT_MAX, 1); | |
e572ec7e | 3055 | STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); |
fe094d98 JA |
3056 | STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1, |
3057 | UINT_MAX, 0); | |
22e2c507 JA |
3058 | STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); |
3059 | STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); | |
3060 | STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); | |
fe094d98 JA |
3061 | STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, |
3062 | UINT_MAX, 0); | |
963b72fc | 3063 | STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0); |
1da177e4 LT |
3064 | #undef STORE_FUNCTION |
3065 | ||
e572ec7e AV |
3066 | #define CFQ_ATTR(name) \ |
3067 | __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store) | |
3068 | ||
3069 | static struct elv_fs_entry cfq_attrs[] = { | |
3070 | CFQ_ATTR(quantum), | |
e572ec7e AV |
3071 | CFQ_ATTR(fifo_expire_sync), |
3072 | CFQ_ATTR(fifo_expire_async), | |
3073 | CFQ_ATTR(back_seek_max), | |
3074 | CFQ_ATTR(back_seek_penalty), | |
3075 | CFQ_ATTR(slice_sync), | |
3076 | CFQ_ATTR(slice_async), | |
3077 | CFQ_ATTR(slice_async_rq), | |
3078 | CFQ_ATTR(slice_idle), | |
963b72fc | 3079 | CFQ_ATTR(low_latency), |
e572ec7e | 3080 | __ATTR_NULL |
1da177e4 LT |
3081 | }; |
3082 | ||
1da177e4 LT |
3083 | static struct elevator_type iosched_cfq = { |
3084 | .ops = { | |
3085 | .elevator_merge_fn = cfq_merge, | |
3086 | .elevator_merged_fn = cfq_merged_request, | |
3087 | .elevator_merge_req_fn = cfq_merged_requests, | |
da775265 | 3088 | .elevator_allow_merge_fn = cfq_allow_merge, |
b4878f24 | 3089 | .elevator_dispatch_fn = cfq_dispatch_requests, |
1da177e4 | 3090 | .elevator_add_req_fn = cfq_insert_request, |
b4878f24 | 3091 | .elevator_activate_req_fn = cfq_activate_request, |
1da177e4 LT |
3092 | .elevator_deactivate_req_fn = cfq_deactivate_request, |
3093 | .elevator_queue_empty_fn = cfq_queue_empty, | |
3094 | .elevator_completed_req_fn = cfq_completed_request, | |
21183b07 JA |
3095 | .elevator_former_req_fn = elv_rb_former_request, |
3096 | .elevator_latter_req_fn = elv_rb_latter_request, | |
1da177e4 LT |
3097 | .elevator_set_req_fn = cfq_set_request, |
3098 | .elevator_put_req_fn = cfq_put_request, | |
3099 | .elevator_may_queue_fn = cfq_may_queue, | |
3100 | .elevator_init_fn = cfq_init_queue, | |
3101 | .elevator_exit_fn = cfq_exit_queue, | |
fc46379d | 3102 | .trim = cfq_free_io_context, |
1da177e4 | 3103 | }, |
3d1ab40f | 3104 | .elevator_attrs = cfq_attrs, |
1da177e4 LT |
3105 | .elevator_name = "cfq", |
3106 | .elevator_owner = THIS_MODULE, | |
3107 | }; | |
3108 | ||
3109 | static int __init cfq_init(void) | |
3110 | { | |
22e2c507 JA |
3111 | /* |
3112 | * could be 0 on HZ < 1000 setups | |
3113 | */ | |
3114 | if (!cfq_slice_async) | |
3115 | cfq_slice_async = 1; | |
3116 | if (!cfq_slice_idle) | |
3117 | cfq_slice_idle = 1; | |
3118 | ||
1da177e4 LT |
3119 | if (cfq_slab_setup()) |
3120 | return -ENOMEM; | |
3121 | ||
2fdd82bd | 3122 | elv_register(&iosched_cfq); |
1da177e4 | 3123 | |
2fdd82bd | 3124 | return 0; |
1da177e4 LT |
3125 | } |
3126 | ||
3127 | static void __exit cfq_exit(void) | |
3128 | { | |
6e9a4738 | 3129 | DECLARE_COMPLETION_ONSTACK(all_gone); |
1da177e4 | 3130 | elv_unregister(&iosched_cfq); |
334e94de | 3131 | ioc_gone = &all_gone; |
fba82272 OH |
3132 | /* ioc_gone's update must be visible before reading ioc_count */ |
3133 | smp_wmb(); | |
d6de8be7 JA |
3134 | |
3135 | /* | |
3136 | * this also protects us from entering cfq_slab_kill() with | |
3137 | * pending RCU callbacks | |
3138 | */ | |
245b2e70 | 3139 | if (elv_ioc_count_read(cfq_ioc_count)) |
9a11b4ed | 3140 | wait_for_completion(&all_gone); |
83521d3e | 3141 | cfq_slab_kill(); |
1da177e4 LT |
3142 | } |
3143 | ||
3144 | module_init(cfq_init); | |
3145 | module_exit(cfq_exit); | |
3146 | ||
3147 | MODULE_AUTHOR("Jens Axboe"); | |
3148 | MODULE_LICENSE("GPL"); | |
3149 | MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |