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ea25da48 PV |
1 | /* |
2 | * Header file for the BFQ I/O scheduler: data structures and | |
3 | * prototypes of interface functions among BFQ components. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU General Public License as | |
7 | * published by the Free Software Foundation; either version 2 of the | |
8 | * License, or (at your option) any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * General Public License for more details. | |
14 | */ | |
15 | #ifndef _BFQ_H | |
16 | #define _BFQ_H | |
17 | ||
18 | #include <linux/blktrace_api.h> | |
19 | #include <linux/hrtimer.h> | |
20 | #include <linux/blk-cgroup.h> | |
21 | ||
22 | #define BFQ_IOPRIO_CLASSES 3 | |
23 | #define BFQ_CL_IDLE_TIMEOUT (HZ/5) | |
24 | ||
25 | #define BFQ_MIN_WEIGHT 1 | |
26 | #define BFQ_MAX_WEIGHT 1000 | |
27 | #define BFQ_WEIGHT_CONVERSION_COEFF 10 | |
28 | ||
29 | #define BFQ_DEFAULT_QUEUE_IOPRIO 4 | |
30 | ||
31 | #define BFQ_WEIGHT_LEGACY_DFL 100 | |
32 | #define BFQ_DEFAULT_GRP_IOPRIO 0 | |
33 | #define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE | |
34 | ||
35 | /* | |
36 | * Soft real-time applications are extremely more latency sensitive | |
37 | * than interactive ones. Over-raise the weight of the former to | |
38 | * privilege them against the latter. | |
39 | */ | |
40 | #define BFQ_SOFTRT_WEIGHT_FACTOR 100 | |
41 | ||
42 | struct bfq_entity; | |
43 | ||
44 | /** | |
45 | * struct bfq_service_tree - per ioprio_class service tree. | |
46 | * | |
47 | * Each service tree represents a B-WF2Q+ scheduler on its own. Each | |
48 | * ioprio_class has its own independent scheduler, and so its own | |
49 | * bfq_service_tree. All the fields are protected by the queue lock | |
50 | * of the containing bfqd. | |
51 | */ | |
52 | struct bfq_service_tree { | |
53 | /* tree for active entities (i.e., those backlogged) */ | |
54 | struct rb_root active; | |
38c91407 | 55 | /* tree for idle entities (i.e., not backlogged, with V < F_i)*/ |
ea25da48 PV |
56 | struct rb_root idle; |
57 | ||
58 | /* idle entity with minimum F_i */ | |
59 | struct bfq_entity *first_idle; | |
60 | /* idle entity with maximum F_i */ | |
61 | struct bfq_entity *last_idle; | |
62 | ||
63 | /* scheduler virtual time */ | |
64 | u64 vtime; | |
65 | /* scheduler weight sum; active and idle entities contribute to it */ | |
66 | unsigned long wsum; | |
67 | }; | |
68 | ||
69 | /** | |
70 | * struct bfq_sched_data - multi-class scheduler. | |
71 | * | |
72 | * bfq_sched_data is the basic scheduler queue. It supports three | |
73 | * ioprio_classes, and can be used either as a toplevel queue or as an | |
46d556e6 | 74 | * intermediate queue in a hierarchical setup. |
ea25da48 PV |
75 | * |
76 | * The supported ioprio_classes are the same as in CFQ, in descending | |
77 | * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. | |
78 | * Requests from higher priority queues are served before all the | |
79 | * requests from lower priority queues; among requests of the same | |
80 | * queue requests are served according to B-WF2Q+. | |
46d556e6 PV |
81 | * |
82 | * The schedule is implemented by the service trees, plus the field | |
83 | * @next_in_service, which points to the entity on the active trees | |
84 | * that will be served next, if 1) no changes in the schedule occurs | |
85 | * before the current in-service entity is expired, 2) the in-service | |
86 | * queue becomes idle when it expires, and 3) if the entity pointed by | |
87 | * in_service_entity is not a queue, then the in-service child entity | |
88 | * of the entity pointed by in_service_entity becomes idle on | |
89 | * expiration. This peculiar definition allows for the following | |
90 | * optimization, not yet exploited: while a given entity is still in | |
91 | * service, we already know which is the best candidate for next | |
92 | * service among the other active entitities in the same parent | |
93 | * entity. We can then quickly compare the timestamps of the | |
94 | * in-service entity with those of such best candidate. | |
95 | * | |
96 | * All fields are protected by the lock of the containing bfqd. | |
ea25da48 PV |
97 | */ |
98 | struct bfq_sched_data { | |
99 | /* entity in service */ | |
100 | struct bfq_entity *in_service_entity; | |
101 | /* head-of-line entity (see comments above) */ | |
102 | struct bfq_entity *next_in_service; | |
103 | /* array of service trees, one per ioprio_class */ | |
104 | struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; | |
105 | /* last time CLASS_IDLE was served */ | |
106 | unsigned long bfq_class_idle_last_service; | |
107 | ||
108 | }; | |
109 | ||
110 | /** | |
2d29c9f8 | 111 | * struct bfq_weight_counter - counter of the number of all active queues |
ea25da48 PV |
112 | * with a given weight. |
113 | */ | |
114 | struct bfq_weight_counter { | |
2d29c9f8 FM |
115 | unsigned int weight; /* weight of the queues this counter refers to */ |
116 | unsigned int num_active; /* nr of active queues with this weight */ | |
ea25da48 | 117 | /* |
2d29c9f8 | 118 | * Weights tree member (see bfq_data's @queue_weights_tree) |
ea25da48 PV |
119 | */ |
120 | struct rb_node weights_node; | |
121 | }; | |
122 | ||
123 | /** | |
124 | * struct bfq_entity - schedulable entity. | |
125 | * | |
126 | * A bfq_entity is used to represent either a bfq_queue (leaf node in the | |
127 | * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each | |
128 | * entity belongs to the sched_data of the parent group in the cgroup | |
129 | * hierarchy. Non-leaf entities have also their own sched_data, stored | |
130 | * in @my_sched_data. | |
131 | * | |
132 | * Each entity stores independently its priority values; this would | |
133 | * allow different weights on different devices, but this | |
134 | * functionality is not exported to userspace by now. Priorities and | |
135 | * weights are updated lazily, first storing the new values into the | |
136 | * new_* fields, then setting the @prio_changed flag. As soon as | |
137 | * there is a transition in the entity state that allows the priority | |
138 | * update to take place the effective and the requested priority | |
139 | * values are synchronized. | |
140 | * | |
141 | * Unless cgroups are used, the weight value is calculated from the | |
142 | * ioprio to export the same interface as CFQ. When dealing with | |
143 | * ``well-behaved'' queues (i.e., queues that do not spend too much | |
144 | * time to consume their budget and have true sequential behavior, and | |
145 | * when there are no external factors breaking anticipation) the | |
146 | * relative weights at each level of the cgroups hierarchy should be | |
147 | * guaranteed. All the fields are protected by the queue lock of the | |
148 | * containing bfqd. | |
149 | */ | |
150 | struct bfq_entity { | |
151 | /* service_tree member */ | |
152 | struct rb_node rb_node; | |
ea25da48 PV |
153 | |
154 | /* | |
155 | * Flag, true if the entity is on a tree (either the active or | |
156 | * the idle one of its service_tree) or is in service. | |
157 | */ | |
158 | bool on_st; | |
159 | ||
160 | /* B-WF2Q+ start and finish timestamps [sectors/weight] */ | |
161 | u64 start, finish; | |
162 | ||
163 | /* tree the entity is enqueued into; %NULL if not on a tree */ | |
164 | struct rb_root *tree; | |
165 | ||
166 | /* | |
167 | * minimum start time of the (active) subtree rooted at this | |
168 | * entity; used for O(log N) lookups into active trees | |
169 | */ | |
170 | u64 min_start; | |
171 | ||
172 | /* amount of service received during the last service slot */ | |
173 | int service; | |
174 | ||
175 | /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ | |
176 | int budget; | |
177 | ||
178 | /* weight of the queue */ | |
179 | int weight; | |
180 | /* next weight if a change is in progress */ | |
181 | int new_weight; | |
182 | ||
183 | /* original weight, used to implement weight boosting */ | |
184 | int orig_weight; | |
185 | ||
186 | /* parent entity, for hierarchical scheduling */ | |
187 | struct bfq_entity *parent; | |
188 | ||
189 | /* | |
190 | * For non-leaf nodes in the hierarchy, the associated | |
191 | * scheduler queue, %NULL on leaf nodes. | |
192 | */ | |
193 | struct bfq_sched_data *my_sched_data; | |
194 | /* the scheduler queue this entity belongs to */ | |
195 | struct bfq_sched_data *sched_data; | |
196 | ||
197 | /* flag, set to request a weight, ioprio or ioprio_class change */ | |
198 | int prio_changed; | |
199 | }; | |
200 | ||
201 | struct bfq_group; | |
202 | ||
203 | /** | |
204 | * struct bfq_ttime - per process thinktime stats. | |
205 | */ | |
206 | struct bfq_ttime { | |
207 | /* completion time of the last request */ | |
208 | u64 last_end_request; | |
209 | ||
210 | /* total process thinktime */ | |
211 | u64 ttime_total; | |
212 | /* number of thinktime samples */ | |
213 | unsigned long ttime_samples; | |
214 | /* average process thinktime */ | |
215 | u64 ttime_mean; | |
216 | }; | |
217 | ||
218 | /** | |
219 | * struct bfq_queue - leaf schedulable entity. | |
220 | * | |
221 | * A bfq_queue is a leaf request queue; it can be associated with an | |
222 | * io_context or more, if it is async or shared between cooperating | |
223 | * processes. @cgroup holds a reference to the cgroup, to be sure that it | |
224 | * does not disappear while a bfqq still references it (mostly to avoid | |
225 | * races between request issuing and task migration followed by cgroup | |
226 | * destruction). | |
227 | * All the fields are protected by the queue lock of the containing bfqd. | |
228 | */ | |
229 | struct bfq_queue { | |
230 | /* reference counter */ | |
231 | int ref; | |
232 | /* parent bfq_data */ | |
233 | struct bfq_data *bfqd; | |
234 | ||
235 | /* current ioprio and ioprio class */ | |
236 | unsigned short ioprio, ioprio_class; | |
237 | /* next ioprio and ioprio class if a change is in progress */ | |
238 | unsigned short new_ioprio, new_ioprio_class; | |
239 | ||
240 | /* | |
241 | * Shared bfq_queue if queue is cooperating with one or more | |
242 | * other queues. | |
243 | */ | |
244 | struct bfq_queue *new_bfqq; | |
245 | /* request-position tree member (see bfq_group's @rq_pos_tree) */ | |
246 | struct rb_node pos_node; | |
247 | /* request-position tree root (see bfq_group's @rq_pos_tree) */ | |
248 | struct rb_root *pos_root; | |
249 | ||
250 | /* sorted list of pending requests */ | |
251 | struct rb_root sort_list; | |
252 | /* if fifo isn't expired, next request to serve */ | |
253 | struct request *next_rq; | |
254 | /* number of sync and async requests queued */ | |
255 | int queued[2]; | |
256 | /* number of requests currently allocated */ | |
257 | int allocated; | |
258 | /* number of pending metadata requests */ | |
259 | int meta_pending; | |
260 | /* fifo list of requests in sort_list */ | |
261 | struct list_head fifo; | |
262 | ||
263 | /* entity representing this queue in the scheduler */ | |
264 | struct bfq_entity entity; | |
265 | ||
2d29c9f8 FM |
266 | /* pointer to the weight counter associated with this entity */ |
267 | struct bfq_weight_counter *weight_counter; | |
268 | ||
ea25da48 PV |
269 | /* maximum budget allowed from the feedback mechanism */ |
270 | int max_budget; | |
271 | /* budget expiration (in jiffies) */ | |
272 | unsigned long budget_timeout; | |
273 | ||
274 | /* number of requests on the dispatch list or inside driver */ | |
275 | int dispatched; | |
276 | ||
277 | /* status flags */ | |
278 | unsigned long flags; | |
279 | ||
280 | /* node for active/idle bfqq list inside parent bfqd */ | |
281 | struct list_head bfqq_list; | |
282 | ||
283 | /* associated @bfq_ttime struct */ | |
284 | struct bfq_ttime ttime; | |
285 | ||
286 | /* bit vector: a 1 for each seeky requests in history */ | |
287 | u32 seek_history; | |
288 | ||
289 | /* node for the device's burst list */ | |
290 | struct hlist_node burst_list_node; | |
291 | ||
292 | /* position of the last request enqueued */ | |
293 | sector_t last_request_pos; | |
294 | ||
295 | /* Number of consecutive pairs of request completion and | |
296 | * arrival, such that the queue becomes idle after the | |
297 | * completion, but the next request arrives within an idle | |
298 | * time slice; used only if the queue's IO_bound flag has been | |
299 | * cleared. | |
300 | */ | |
301 | unsigned int requests_within_timer; | |
302 | ||
303 | /* pid of the process owning the queue, used for logging purposes */ | |
304 | pid_t pid; | |
305 | ||
306 | /* | |
307 | * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL | |
308 | * if the queue is shared. | |
309 | */ | |
310 | struct bfq_io_cq *bic; | |
311 | ||
312 | /* current maximum weight-raising time for this queue */ | |
313 | unsigned long wr_cur_max_time; | |
314 | /* | |
315 | * Minimum time instant such that, only if a new request is | |
316 | * enqueued after this time instant in an idle @bfq_queue with | |
317 | * no outstanding requests, then the task associated with the | |
318 | * queue it is deemed as soft real-time (see the comments on | |
319 | * the function bfq_bfqq_softrt_next_start()) | |
320 | */ | |
321 | unsigned long soft_rt_next_start; | |
322 | /* | |
323 | * Start time of the current weight-raising period if | |
324 | * the @bfq-queue is being weight-raised, otherwise | |
325 | * finish time of the last weight-raising period. | |
326 | */ | |
327 | unsigned long last_wr_start_finish; | |
328 | /* factor by which the weight of this queue is multiplied */ | |
329 | unsigned int wr_coeff; | |
330 | /* | |
331 | * Time of the last transition of the @bfq_queue from idle to | |
332 | * backlogged. | |
333 | */ | |
334 | unsigned long last_idle_bklogged; | |
335 | /* | |
336 | * Cumulative service received from the @bfq_queue since the | |
337 | * last transition from idle to backlogged. | |
338 | */ | |
339 | unsigned long service_from_backlogged; | |
8a8747dc PV |
340 | /* |
341 | * Cumulative service received from the @bfq_queue since its | |
342 | * last transition to weight-raised state. | |
343 | */ | |
344 | unsigned long service_from_wr; | |
ea25da48 PV |
345 | |
346 | /* | |
347 | * Value of wr start time when switching to soft rt | |
348 | */ | |
349 | unsigned long wr_start_at_switch_to_srt; | |
350 | ||
351 | unsigned long split_time; /* time of last split */ | |
7b8fa3b9 PV |
352 | |
353 | unsigned long first_IO_time; /* time of first I/O for this queue */ | |
d0edc247 PV |
354 | |
355 | /* max service rate measured so far */ | |
356 | u32 max_service_rate; | |
357 | /* | |
358 | * Ratio between the service received by bfqq while it is in | |
359 | * service, and the cumulative service (of requests of other | |
360 | * queues) that may be injected while bfqq is empty but still | |
361 | * in service. To increase precision, the coefficient is | |
362 | * measured in tenths of unit. Here are some example of (1) | |
363 | * ratios, (2) resulting percentages of service injected | |
364 | * w.r.t. to the total service dispatched while bfqq is in | |
365 | * service, and (3) corresponding values of the coefficient: | |
366 | * 1 (50%) -> 10 | |
367 | * 2 (33%) -> 20 | |
368 | * 10 (9%) -> 100 | |
369 | * 9.9 (9%) -> 99 | |
370 | * 1.5 (40%) -> 15 | |
371 | * 0.5 (66%) -> 5 | |
372 | * 0.1 (90%) -> 1 | |
373 | * | |
374 | * So, if the coefficient is lower than 10, then | |
375 | * injected service is more than bfqq service. | |
376 | */ | |
377 | unsigned int inject_coeff; | |
378 | /* amount of service injected in current service slot */ | |
379 | unsigned int injected_service; | |
ea25da48 PV |
380 | }; |
381 | ||
382 | /** | |
383 | * struct bfq_io_cq - per (request_queue, io_context) structure. | |
384 | */ | |
385 | struct bfq_io_cq { | |
386 | /* associated io_cq structure */ | |
387 | struct io_cq icq; /* must be the first member */ | |
388 | /* array of two process queues, the sync and the async */ | |
389 | struct bfq_queue *bfqq[2]; | |
390 | /* per (request_queue, blkcg) ioprio */ | |
391 | int ioprio; | |
392 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
393 | uint64_t blkcg_serial_nr; /* the current blkcg serial */ | |
394 | #endif | |
395 | /* | |
d5be3fef PV |
396 | * Snapshot of the has_short_time flag before merging; taken |
397 | * to remember its value while the queue is merged, so as to | |
398 | * be able to restore it in case of split. | |
ea25da48 | 399 | */ |
d5be3fef | 400 | bool saved_has_short_ttime; |
ea25da48 PV |
401 | /* |
402 | * Same purpose as the previous two fields for the I/O bound | |
403 | * classification of a queue. | |
404 | */ | |
405 | bool saved_IO_bound; | |
406 | ||
407 | /* | |
408 | * Same purpose as the previous fields for the value of the | |
409 | * field keeping the queue's belonging to a large burst | |
410 | */ | |
411 | bool saved_in_large_burst; | |
412 | /* | |
413 | * True if the queue belonged to a burst list before its merge | |
414 | * with another cooperating queue. | |
415 | */ | |
416 | bool was_in_burst_list; | |
417 | ||
418 | /* | |
419 | * Similar to previous fields: save wr information. | |
420 | */ | |
421 | unsigned long saved_wr_coeff; | |
422 | unsigned long saved_last_wr_start_finish; | |
423 | unsigned long saved_wr_start_at_switch_to_srt; | |
424 | unsigned int saved_wr_cur_max_time; | |
425 | struct bfq_ttime saved_ttime; | |
426 | }; | |
427 | ||
ea25da48 PV |
428 | /** |
429 | * struct bfq_data - per-device data structure. | |
430 | * | |
431 | * All the fields are protected by @lock. | |
432 | */ | |
433 | struct bfq_data { | |
434 | /* device request queue */ | |
435 | struct request_queue *queue; | |
436 | /* dispatch queue */ | |
437 | struct list_head dispatch; | |
438 | ||
439 | /* root bfq_group for the device */ | |
440 | struct bfq_group *root_group; | |
441 | ||
442 | /* | |
443 | * rbtree of weight counters of @bfq_queues, sorted by | |
444 | * weight. Used to keep track of whether all @bfq_queues have | |
445 | * the same weight. The tree contains one counter for each | |
446 | * distinct weight associated to some active and not | |
447 | * weight-raised @bfq_queue (see the comments to the functions | |
448 | * bfq_weights_tree_[add|remove] for further details). | |
449 | */ | |
450 | struct rb_root queue_weights_tree; | |
451 | /* | |
2d29c9f8 | 452 | * number of groups with requests still waiting for completion |
ea25da48 | 453 | */ |
2d29c9f8 | 454 | unsigned int num_active_groups; |
ea25da48 PV |
455 | |
456 | /* | |
457 | * Number of bfq_queues containing requests (including the | |
458 | * queue in service, even if it is idling). | |
459 | */ | |
460 | int busy_queues; | |
461 | /* number of weight-raised busy @bfq_queues */ | |
462 | int wr_busy_queues; | |
463 | /* number of queued requests */ | |
464 | int queued; | |
465 | /* number of requests dispatched and waiting for completion */ | |
466 | int rq_in_driver; | |
467 | ||
468 | /* | |
469 | * Maximum number of requests in driver in the last | |
470 | * @hw_tag_samples completed requests. | |
471 | */ | |
472 | int max_rq_in_driver; | |
473 | /* number of samples used to calculate hw_tag */ | |
474 | int hw_tag_samples; | |
475 | /* flag set to one if the driver is showing a queueing behavior */ | |
476 | int hw_tag; | |
477 | ||
478 | /* number of budgets assigned */ | |
479 | int budgets_assigned; | |
480 | ||
481 | /* | |
482 | * Timer set when idling (waiting) for the next request from | |
483 | * the queue in service. | |
484 | */ | |
485 | struct hrtimer idle_slice_timer; | |
486 | ||
487 | /* bfq_queue in service */ | |
488 | struct bfq_queue *in_service_queue; | |
489 | ||
490 | /* on-disk position of the last served request */ | |
491 | sector_t last_position; | |
492 | ||
493 | /* time of last request completion (ns) */ | |
494 | u64 last_completion; | |
495 | ||
496 | /* time of first rq dispatch in current observation interval (ns) */ | |
497 | u64 first_dispatch; | |
498 | /* time of last rq dispatch in current observation interval (ns) */ | |
499 | u64 last_dispatch; | |
500 | ||
501 | /* beginning of the last budget */ | |
502 | ktime_t last_budget_start; | |
503 | /* beginning of the last idle slice */ | |
504 | ktime_t last_idling_start; | |
505 | ||
506 | /* number of samples in current observation interval */ | |
507 | int peak_rate_samples; | |
508 | /* num of samples of seq dispatches in current observation interval */ | |
509 | u32 sequential_samples; | |
510 | /* total num of sectors transferred in current observation interval */ | |
511 | u64 tot_sectors_dispatched; | |
512 | /* max rq size seen during current observation interval (sectors) */ | |
513 | u32 last_rq_max_size; | |
514 | /* time elapsed from first dispatch in current observ. interval (us) */ | |
515 | u64 delta_from_first; | |
516 | /* | |
517 | * Current estimate of the device peak rate, measured in | |
bc56e2ca | 518 | * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by |
ea25da48 PV |
519 | * BFQ_RATE_SHIFT is performed to increase precision in |
520 | * fixed-point calculations. | |
521 | */ | |
522 | u32 peak_rate; | |
523 | ||
524 | /* maximum budget allotted to a bfq_queue before rescheduling */ | |
525 | int bfq_max_budget; | |
526 | ||
527 | /* list of all the bfq_queues active on the device */ | |
528 | struct list_head active_list; | |
529 | /* list of all the bfq_queues idle on the device */ | |
530 | struct list_head idle_list; | |
531 | ||
532 | /* | |
533 | * Timeout for async/sync requests; when it fires, requests | |
534 | * are served in fifo order. | |
535 | */ | |
536 | u64 bfq_fifo_expire[2]; | |
537 | /* weight of backward seeks wrt forward ones */ | |
538 | unsigned int bfq_back_penalty; | |
539 | /* maximum allowed backward seek */ | |
540 | unsigned int bfq_back_max; | |
541 | /* maximum idling time */ | |
542 | u32 bfq_slice_idle; | |
543 | ||
544 | /* user-configured max budget value (0 for auto-tuning) */ | |
545 | int bfq_user_max_budget; | |
546 | /* | |
547 | * Timeout for bfq_queues to consume their budget; used to | |
548 | * prevent seeky queues from imposing long latencies to | |
549 | * sequential or quasi-sequential ones (this also implies that | |
550 | * seeky queues cannot receive guarantees in the service | |
551 | * domain; after a timeout they are charged for the time they | |
552 | * have been in service, to preserve fairness among them, but | |
553 | * without service-domain guarantees). | |
554 | */ | |
555 | unsigned int bfq_timeout; | |
556 | ||
557 | /* | |
558 | * Number of consecutive requests that must be issued within | |
559 | * the idle time slice to set again idling to a queue which | |
560 | * was marked as non-I/O-bound (see the definition of the | |
561 | * IO_bound flag for further details). | |
562 | */ | |
563 | unsigned int bfq_requests_within_timer; | |
564 | ||
565 | /* | |
566 | * Force device idling whenever needed to provide accurate | |
567 | * service guarantees, without caring about throughput | |
568 | * issues. CAVEAT: this may even increase latencies, in case | |
569 | * of useless idling for processes that did stop doing I/O. | |
570 | */ | |
571 | bool strict_guarantees; | |
572 | ||
573 | /* | |
574 | * Last time at which a queue entered the current burst of | |
575 | * queues being activated shortly after each other; for more | |
576 | * details about this and the following parameters related to | |
577 | * a burst of activations, see the comments on the function | |
578 | * bfq_handle_burst. | |
579 | */ | |
580 | unsigned long last_ins_in_burst; | |
581 | /* | |
582 | * Reference time interval used to decide whether a queue has | |
583 | * been activated shortly after @last_ins_in_burst. | |
584 | */ | |
585 | unsigned long bfq_burst_interval; | |
586 | /* number of queues in the current burst of queue activations */ | |
587 | int burst_size; | |
588 | ||
589 | /* common parent entity for the queues in the burst */ | |
590 | struct bfq_entity *burst_parent_entity; | |
591 | /* Maximum burst size above which the current queue-activation | |
592 | * burst is deemed as 'large'. | |
593 | */ | |
594 | unsigned long bfq_large_burst_thresh; | |
595 | /* true if a large queue-activation burst is in progress */ | |
596 | bool large_burst; | |
597 | /* | |
598 | * Head of the burst list (as for the above fields, more | |
599 | * details in the comments on the function bfq_handle_burst). | |
600 | */ | |
601 | struct hlist_head burst_list; | |
602 | ||
603 | /* if set to true, low-latency heuristics are enabled */ | |
604 | bool low_latency; | |
605 | /* | |
606 | * Maximum factor by which the weight of a weight-raised queue | |
607 | * is multiplied. | |
608 | */ | |
609 | unsigned int bfq_wr_coeff; | |
610 | /* maximum duration of a weight-raising period (jiffies) */ | |
611 | unsigned int bfq_wr_max_time; | |
612 | ||
613 | /* Maximum weight-raising duration for soft real-time processes */ | |
614 | unsigned int bfq_wr_rt_max_time; | |
615 | /* | |
616 | * Minimum idle period after which weight-raising may be | |
617 | * reactivated for a queue (in jiffies). | |
618 | */ | |
619 | unsigned int bfq_wr_min_idle_time; | |
620 | /* | |
621 | * Minimum period between request arrivals after which | |
622 | * weight-raising may be reactivated for an already busy async | |
623 | * queue (in jiffies). | |
624 | */ | |
625 | unsigned long bfq_wr_min_inter_arr_async; | |
626 | ||
627 | /* Max service-rate for a soft real-time queue, in sectors/sec */ | |
628 | unsigned int bfq_wr_max_softrt_rate; | |
629 | /* | |
e24f1c24 PV |
630 | * Cached value of the product ref_rate*ref_wr_duration, used |
631 | * for computing the maximum duration of weight raising | |
632 | * automatically. | |
ea25da48 | 633 | */ |
e24f1c24 | 634 | u64 rate_dur_prod; |
ea25da48 PV |
635 | |
636 | /* fallback dummy bfqq for extreme OOM conditions */ | |
637 | struct bfq_queue oom_bfqq; | |
638 | ||
639 | spinlock_t lock; | |
640 | ||
641 | /* | |
642 | * bic associated with the task issuing current bio for | |
643 | * merging. This and the next field are used as a support to | |
644 | * be able to perform the bic lookup, needed by bio-merge | |
645 | * functions, before the scheduler lock is taken, and thus | |
646 | * avoid taking the request-queue lock while the scheduler | |
647 | * lock is being held. | |
648 | */ | |
649 | struct bfq_io_cq *bio_bic; | |
650 | /* bfqq associated with the task issuing current bio for merging */ | |
651 | struct bfq_queue *bio_bfqq; | |
a52a69ea | 652 | |
a52a69ea PV |
653 | /* |
654 | * Depth limits used in bfq_limit_depth (see comments on the | |
655 | * function) | |
656 | */ | |
657 | unsigned int word_depths[2][2]; | |
ea25da48 PV |
658 | }; |
659 | ||
660 | enum bfqq_state_flags { | |
661 | BFQQF_just_created = 0, /* queue just allocated */ | |
662 | BFQQF_busy, /* has requests or is in service */ | |
663 | BFQQF_wait_request, /* waiting for a request */ | |
664 | BFQQF_non_blocking_wait_rq, /* | |
665 | * waiting for a request | |
666 | * without idling the device | |
667 | */ | |
668 | BFQQF_fifo_expire, /* FIFO checked in this slice */ | |
d5be3fef | 669 | BFQQF_has_short_ttime, /* queue has a short think time */ |
ea25da48 PV |
670 | BFQQF_sync, /* synchronous queue */ |
671 | BFQQF_IO_bound, /* | |
672 | * bfqq has timed-out at least once | |
673 | * having consumed at most 2/10 of | |
674 | * its budget | |
675 | */ | |
676 | BFQQF_in_large_burst, /* | |
677 | * bfqq activated in a large burst, | |
678 | * see comments to bfq_handle_burst. | |
679 | */ | |
680 | BFQQF_softrt_update, /* | |
681 | * may need softrt-next-start | |
682 | * update | |
683 | */ | |
684 | BFQQF_coop, /* bfqq is shared */ | |
685 | BFQQF_split_coop /* shared bfqq will be split */ | |
686 | }; | |
687 | ||
688 | #define BFQ_BFQQ_FNS(name) \ | |
689 | void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \ | |
690 | void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \ | |
691 | int bfq_bfqq_##name(const struct bfq_queue *bfqq); | |
692 | ||
693 | BFQ_BFQQ_FNS(just_created); | |
694 | BFQ_BFQQ_FNS(busy); | |
695 | BFQ_BFQQ_FNS(wait_request); | |
696 | BFQ_BFQQ_FNS(non_blocking_wait_rq); | |
697 | BFQ_BFQQ_FNS(fifo_expire); | |
d5be3fef | 698 | BFQ_BFQQ_FNS(has_short_ttime); |
ea25da48 PV |
699 | BFQ_BFQQ_FNS(sync); |
700 | BFQ_BFQQ_FNS(IO_bound); | |
701 | BFQ_BFQQ_FNS(in_large_burst); | |
702 | BFQ_BFQQ_FNS(coop); | |
703 | BFQ_BFQQ_FNS(split_coop); | |
704 | BFQ_BFQQ_FNS(softrt_update); | |
705 | #undef BFQ_BFQQ_FNS | |
706 | ||
707 | /* Expiration reasons. */ | |
708 | enum bfqq_expiration { | |
709 | BFQQE_TOO_IDLE = 0, /* | |
710 | * queue has been idling for | |
711 | * too long | |
712 | */ | |
713 | BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */ | |
714 | BFQQE_BUDGET_EXHAUSTED, /* budget consumed */ | |
715 | BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */ | |
716 | BFQQE_PREEMPTED /* preemption in progress */ | |
717 | }; | |
718 | ||
719 | struct bfqg_stats { | |
a33801e8 | 720 | #if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP) |
ea25da48 PV |
721 | /* number of ios merged */ |
722 | struct blkg_rwstat merged; | |
723 | /* total time spent on device in ns, may not be accurate w/ queueing */ | |
724 | struct blkg_rwstat service_time; | |
725 | /* total time spent waiting in scheduler queue in ns */ | |
726 | struct blkg_rwstat wait_time; | |
727 | /* number of IOs queued up */ | |
728 | struct blkg_rwstat queued; | |
729 | /* total disk time and nr sectors dispatched by this group */ | |
730 | struct blkg_stat time; | |
731 | /* sum of number of ios queued across all samples */ | |
732 | struct blkg_stat avg_queue_size_sum; | |
733 | /* count of samples taken for average */ | |
734 | struct blkg_stat avg_queue_size_samples; | |
735 | /* how many times this group has been removed from service tree */ | |
736 | struct blkg_stat dequeue; | |
737 | /* total time spent waiting for it to be assigned a timeslice. */ | |
738 | struct blkg_stat group_wait_time; | |
739 | /* time spent idling for this blkcg_gq */ | |
740 | struct blkg_stat idle_time; | |
741 | /* total time with empty current active q with other requests queued */ | |
742 | struct blkg_stat empty_time; | |
743 | /* fields after this shouldn't be cleared on stat reset */ | |
84c7afce OS |
744 | u64 start_group_wait_time; |
745 | u64 start_idle_time; | |
746 | u64 start_empty_time; | |
ea25da48 | 747 | uint16_t flags; |
a33801e8 | 748 | #endif /* CONFIG_BFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */ |
ea25da48 PV |
749 | }; |
750 | ||
751 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
752 | ||
753 | /* | |
754 | * struct bfq_group_data - per-blkcg storage for the blkio subsystem. | |
755 | * | |
756 | * @ps: @blkcg_policy_storage that this structure inherits | |
757 | * @weight: weight of the bfq_group | |
758 | */ | |
759 | struct bfq_group_data { | |
760 | /* must be the first member */ | |
761 | struct blkcg_policy_data pd; | |
762 | ||
763 | unsigned int weight; | |
764 | }; | |
765 | ||
766 | /** | |
767 | * struct bfq_group - per (device, cgroup) data structure. | |
768 | * @entity: schedulable entity to insert into the parent group sched_data. | |
769 | * @sched_data: own sched_data, to contain child entities (they may be | |
770 | * both bfq_queues and bfq_groups). | |
771 | * @bfqd: the bfq_data for the device this group acts upon. | |
772 | * @async_bfqq: array of async queues for all the tasks belonging to | |
773 | * the group, one queue per ioprio value per ioprio_class, | |
774 | * except for the idle class that has only one queue. | |
775 | * @async_idle_bfqq: async queue for the idle class (ioprio is ignored). | |
776 | * @my_entity: pointer to @entity, %NULL for the toplevel group; used | |
777 | * to avoid too many special cases during group creation/ | |
778 | * migration. | |
779 | * @stats: stats for this bfqg. | |
780 | * @active_entities: number of active entities belonging to the group; | |
781 | * unused for the root group. Used to know whether there | |
782 | * are groups with more than one active @bfq_entity | |
783 | * (see the comments to the function | |
784 | * bfq_bfqq_may_idle()). | |
785 | * @rq_pos_tree: rbtree sorted by next_request position, used when | |
786 | * determining if two or more queues have interleaving | |
787 | * requests (see bfq_find_close_cooperator()). | |
788 | * | |
789 | * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup | |
790 | * there is a set of bfq_groups, each one collecting the lower-level | |
791 | * entities belonging to the group that are acting on the same device. | |
792 | * | |
793 | * Locking works as follows: | |
794 | * o @bfqd is protected by the queue lock, RCU is used to access it | |
795 | * from the readers. | |
796 | * o All the other fields are protected by the @bfqd queue lock. | |
797 | */ | |
798 | struct bfq_group { | |
799 | /* must be the first member */ | |
800 | struct blkg_policy_data pd; | |
801 | ||
8f9bebc3 PV |
802 | /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */ |
803 | char blkg_path[128]; | |
804 | ||
805 | /* reference counter (see comments in bfq_bic_update_cgroup) */ | |
806 | int ref; | |
807 | ||
ea25da48 PV |
808 | struct bfq_entity entity; |
809 | struct bfq_sched_data sched_data; | |
810 | ||
811 | void *bfqd; | |
812 | ||
813 | struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; | |
814 | struct bfq_queue *async_idle_bfqq; | |
815 | ||
816 | struct bfq_entity *my_entity; | |
817 | ||
818 | int active_entities; | |
819 | ||
820 | struct rb_root rq_pos_tree; | |
821 | ||
822 | struct bfqg_stats stats; | |
823 | }; | |
824 | ||
825 | #else | |
826 | struct bfq_group { | |
827 | struct bfq_sched_data sched_data; | |
828 | ||
829 | struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; | |
830 | struct bfq_queue *async_idle_bfqq; | |
831 | ||
832 | struct rb_root rq_pos_tree; | |
833 | }; | |
834 | #endif | |
835 | ||
836 | struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); | |
837 | ||
838 | /* --------------- main algorithm interface ----------------- */ | |
839 | ||
840 | #define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ | |
841 | { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) | |
842 | ||
843 | extern const int bfq_timeout; | |
844 | ||
845 | struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync); | |
846 | void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync); | |
847 | struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic); | |
ea25da48 | 848 | void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq); |
2d29c9f8 | 849 | void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq, |
ea25da48 | 850 | struct rb_root *root); |
0471559c | 851 | void __bfq_weights_tree_remove(struct bfq_data *bfqd, |
2d29c9f8 | 852 | struct bfq_queue *bfqq, |
0471559c PV |
853 | struct rb_root *root); |
854 | void bfq_weights_tree_remove(struct bfq_data *bfqd, | |
855 | struct bfq_queue *bfqq); | |
ea25da48 PV |
856 | void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq, |
857 | bool compensate, enum bfqq_expiration reason); | |
858 | void bfq_put_queue(struct bfq_queue *bfqq); | |
859 | void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); | |
860 | void bfq_schedule_dispatch(struct bfq_data *bfqd); | |
861 | void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); | |
862 | ||
863 | /* ------------ end of main algorithm interface -------------- */ | |
864 | ||
865 | /* ---------------- cgroups-support interface ---------------- */ | |
866 | ||
ea25da48 PV |
867 | void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, |
868 | unsigned int op); | |
869 | void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op); | |
870 | void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op); | |
84c7afce OS |
871 | void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns, |
872 | u64 io_start_time_ns, unsigned int op); | |
ea25da48 PV |
873 | void bfqg_stats_update_dequeue(struct bfq_group *bfqg); |
874 | void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); | |
875 | void bfqg_stats_update_idle_time(struct bfq_group *bfqg); | |
876 | void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg); | |
877 | void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg); | |
878 | void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
879 | struct bfq_group *bfqg); | |
880 | ||
881 | void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg); | |
882 | void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio); | |
883 | void bfq_end_wr_async(struct bfq_data *bfqd); | |
884 | struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, | |
885 | struct blkcg *blkcg); | |
886 | struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); | |
887 | struct bfq_group *bfqq_group(struct bfq_queue *bfqq); | |
888 | struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node); | |
8f9bebc3 | 889 | void bfqg_and_blkg_put(struct bfq_group *bfqg); |
ea25da48 PV |
890 | |
891 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
659b3394 JA |
892 | extern struct cftype bfq_blkcg_legacy_files[]; |
893 | extern struct cftype bfq_blkg_files[]; | |
ea25da48 PV |
894 | extern struct blkcg_policy blkcg_policy_bfq; |
895 | #endif | |
896 | ||
897 | /* ------------- end of cgroups-support interface ------------- */ | |
898 | ||
899 | /* - interface of the internal hierarchical B-WF2Q+ scheduler - */ | |
900 | ||
901 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
902 | /* both next loops stop at one of the child entities of the root group */ | |
903 | #define for_each_entity(entity) \ | |
904 | for (; entity ; entity = entity->parent) | |
905 | ||
906 | /* | |
907 | * For each iteration, compute parent in advance, so as to be safe if | |
908 | * entity is deallocated during the iteration. Such a deallocation may | |
909 | * happen as a consequence of a bfq_put_queue that frees the bfq_queue | |
910 | * containing entity. | |
911 | */ | |
912 | #define for_each_entity_safe(entity, parent) \ | |
913 | for (; entity && ({ parent = entity->parent; 1; }); entity = parent) | |
914 | ||
915 | #else /* CONFIG_BFQ_GROUP_IOSCHED */ | |
916 | /* | |
917 | * Next two macros are fake loops when cgroups support is not | |
918 | * enabled. I fact, in such a case, there is only one level to go up | |
919 | * (to reach the root group). | |
920 | */ | |
921 | #define for_each_entity(entity) \ | |
922 | for (; entity ; entity = NULL) | |
923 | ||
924 | #define for_each_entity_safe(entity, parent) \ | |
925 | for (parent = NULL; entity ; entity = parent) | |
926 | #endif /* CONFIG_BFQ_GROUP_IOSCHED */ | |
927 | ||
928 | struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq); | |
929 | struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); | |
930 | struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity); | |
931 | struct bfq_entity *bfq_entity_of(struct rb_node *node); | |
932 | unsigned short bfq_ioprio_to_weight(int ioprio); | |
933 | void bfq_put_idle_entity(struct bfq_service_tree *st, | |
934 | struct bfq_entity *entity); | |
935 | struct bfq_service_tree * | |
936 | __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, | |
431b17f9 PV |
937 | struct bfq_entity *entity, |
938 | bool update_class_too); | |
ea25da48 PV |
939 | void bfq_bfqq_served(struct bfq_queue *bfqq, int served); |
940 | void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
941 | unsigned long time_ms); | |
942 | bool __bfq_deactivate_entity(struct bfq_entity *entity, | |
943 | bool ins_into_idle_tree); | |
944 | bool next_queue_may_preempt(struct bfq_data *bfqd); | |
945 | struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd); | |
946 | void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd); | |
947 | void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, | |
948 | bool ins_into_idle_tree, bool expiration); | |
949 | void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); | |
80294c3b PV |
950 | void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, |
951 | bool expiration); | |
ea25da48 PV |
952 | void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, |
953 | bool expiration); | |
954 | void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq); | |
955 | ||
956 | /* --------------- end of interface of B-WF2Q+ ---------------- */ | |
957 | ||
958 | /* Logging facilities. */ | |
959 | #ifdef CONFIG_BFQ_GROUP_IOSCHED | |
960 | struct bfq_group *bfqq_group(struct bfq_queue *bfqq); | |
961 | ||
962 | #define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ | |
35fe6d76 SL |
963 | blk_add_cgroup_trace_msg((bfqd)->queue, \ |
964 | bfqg_to_blkg(bfqq_group(bfqq))->blkcg, \ | |
965 | "bfq%d%c " fmt, (bfqq)->pid, \ | |
966 | bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args); \ | |
ea25da48 PV |
967 | } while (0) |
968 | ||
35fe6d76 SL |
969 | #define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ |
970 | blk_add_cgroup_trace_msg((bfqd)->queue, \ | |
971 | bfqg_to_blkg(bfqg)->blkcg, fmt, ##args); \ | |
972 | } while (0) | |
ea25da48 PV |
973 | |
974 | #else /* CONFIG_BFQ_GROUP_IOSCHED */ | |
975 | ||
976 | #define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ | |
977 | blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \ | |
978 | bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ | |
979 | ##args) | |
980 | #define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) | |
981 | ||
982 | #endif /* CONFIG_BFQ_GROUP_IOSCHED */ | |
983 | ||
984 | #define bfq_log(bfqd, fmt, args...) \ | |
985 | blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) | |
986 | ||
987 | #endif /* _BFQ_H */ |