~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/block/bfq-iosched.h

Version: ~ [ linux-5.16 ] ~ [ linux-5.15.13 ] ~ [ linux-5.14.21 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.90 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.170 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.224 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.261 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.296 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.298 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /* SPDX-License-Identifier: GPL-2.0-or-later */
  2 /*
  3  * Header file for the BFQ I/O scheduler: data structures and
  4  * prototypes of interface functions among BFQ components.
  5  */
  6 #ifndef _BFQ_H
  7 #define _BFQ_H
  8 
  9 #include <linux/blktrace_api.h>
 10 #include <linux/hrtimer.h>
 11 #include <linux/blk-cgroup.h>
 12 
 13 #include "blk-cgroup-rwstat.h"
 14 
 15 #define BFQ_IOPRIO_CLASSES      3
 16 #define BFQ_CL_IDLE_TIMEOUT     (HZ/5)
 17 
 18 #define BFQ_MIN_WEIGHT                  1
 19 #define BFQ_MAX_WEIGHT                  1000
 20 #define BFQ_WEIGHT_CONVERSION_COEFF     10
 21 
 22 #define BFQ_DEFAULT_QUEUE_IOPRIO        4
 23 
 24 #define BFQ_WEIGHT_LEGACY_DFL   100
 25 #define BFQ_DEFAULT_GRP_IOPRIO  0
 26 #define BFQ_DEFAULT_GRP_CLASS   IOPRIO_CLASS_BE
 27 
 28 #define MAX_PID_STR_LENGTH 12
 29 
 30 /*
 31  * Soft real-time applications are extremely more latency sensitive
 32  * than interactive ones. Over-raise the weight of the former to
 33  * privilege them against the latter.
 34  */
 35 #define BFQ_SOFTRT_WEIGHT_FACTOR        100
 36 
 37 struct bfq_entity;
 38 
 39 /**
 40  * struct bfq_service_tree - per ioprio_class service tree.
 41  *
 42  * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
 43  * ioprio_class has its own independent scheduler, and so its own
 44  * bfq_service_tree.  All the fields are protected by the queue lock
 45  * of the containing bfqd.
 46  */
 47 struct bfq_service_tree {
 48         /* tree for active entities (i.e., those backlogged) */
 49         struct rb_root active;
 50         /* tree for idle entities (i.e., not backlogged, with V < F_i)*/
 51         struct rb_root idle;
 52 
 53         /* idle entity with minimum F_i */
 54         struct bfq_entity *first_idle;
 55         /* idle entity with maximum F_i */
 56         struct bfq_entity *last_idle;
 57 
 58         /* scheduler virtual time */
 59         u64 vtime;
 60         /* scheduler weight sum; active and idle entities contribute to it */
 61         unsigned long wsum;
 62 };
 63 
 64 /**
 65  * struct bfq_sched_data - multi-class scheduler.
 66  *
 67  * bfq_sched_data is the basic scheduler queue.  It supports three
 68  * ioprio_classes, and can be used either as a toplevel queue or as an
 69  * intermediate queue in a hierarchical setup.
 70  *
 71  * The supported ioprio_classes are the same as in CFQ, in descending
 72  * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
 73  * Requests from higher priority queues are served before all the
 74  * requests from lower priority queues; among requests of the same
 75  * queue requests are served according to B-WF2Q+.
 76  *
 77  * The schedule is implemented by the service trees, plus the field
 78  * @next_in_service, which points to the entity on the active trees
 79  * that will be served next, if 1) no changes in the schedule occurs
 80  * before the current in-service entity is expired, 2) the in-service
 81  * queue becomes idle when it expires, and 3) if the entity pointed by
 82  * in_service_entity is not a queue, then the in-service child entity
 83  * of the entity pointed by in_service_entity becomes idle on
 84  * expiration. This peculiar definition allows for the following
 85  * optimization, not yet exploited: while a given entity is still in
 86  * service, we already know which is the best candidate for next
 87  * service among the other active entities in the same parent
 88  * entity. We can then quickly compare the timestamps of the
 89  * in-service entity with those of such best candidate.
 90  *
 91  * All fields are protected by the lock of the containing bfqd.
 92  */
 93 struct bfq_sched_data {
 94         /* entity in service */
 95         struct bfq_entity *in_service_entity;
 96         /* head-of-line entity (see comments above) */
 97         struct bfq_entity *next_in_service;
 98         /* array of service trees, one per ioprio_class */
 99         struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
100         /* last time CLASS_IDLE was served */
101         unsigned long bfq_class_idle_last_service;
102 
103 };
104 
105 /**
106  * struct bfq_weight_counter - counter of the number of all active queues
107  *                             with a given weight.
108  */
109 struct bfq_weight_counter {
110         unsigned int weight; /* weight of the queues this counter refers to */
111         unsigned int num_active; /* nr of active queues with this weight */
112         /*
113          * Weights tree member (see bfq_data's @queue_weights_tree)
114          */
115         struct rb_node weights_node;
116 };
117 
118 /**
119  * struct bfq_entity - schedulable entity.
120  *
121  * A bfq_entity is used to represent either a bfq_queue (leaf node in the
122  * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
123  * entity belongs to the sched_data of the parent group in the cgroup
124  * hierarchy.  Non-leaf entities have also their own sched_data, stored
125  * in @my_sched_data.
126  *
127  * Each entity stores independently its priority values; this would
128  * allow different weights on different devices, but this
129  * functionality is not exported to userspace by now.  Priorities and
130  * weights are updated lazily, first storing the new values into the
131  * new_* fields, then setting the @prio_changed flag.  As soon as
132  * there is a transition in the entity state that allows the priority
133  * update to take place the effective and the requested priority
134  * values are synchronized.
135  *
136  * Unless cgroups are used, the weight value is calculated from the
137  * ioprio to export the same interface as CFQ.  When dealing with
138  * "well-behaved" queues (i.e., queues that do not spend too much
139  * time to consume their budget and have true sequential behavior, and
140  * when there are no external factors breaking anticipation) the
141  * relative weights at each level of the cgroups hierarchy should be
142  * guaranteed.  All the fields are protected by the queue lock of the
143  * containing bfqd.
144  */
145 struct bfq_entity {
146         /* service_tree member */
147         struct rb_node rb_node;
148 
149         /*
150          * Flag, true if the entity is on a tree (either the active or
151          * the idle one of its service_tree) or is in service.
152          */
153         bool on_st_or_in_serv;
154 
155         /* B-WF2Q+ start and finish timestamps [sectors/weight] */
156         u64 start, finish;
157 
158         /* tree the entity is enqueued into; %NULL if not on a tree */
159         struct rb_root *tree;
160 
161         /*
162          * minimum start time of the (active) subtree rooted at this
163          * entity; used for O(log N) lookups into active trees
164          */
165         u64 min_start;
166 
167         /* amount of service received during the last service slot */
168         int service;
169 
170         /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
171         int budget;
172 
173         /* device weight, if non-zero, it overrides the default weight of
174          * bfq_group_data */
175         int dev_weight;
176         /* weight of the queue */
177         int weight;
178         /* next weight if a change is in progress */
179         int new_weight;
180 
181         /* original weight, used to implement weight boosting */
182         int orig_weight;
183 
184         /* parent entity, for hierarchical scheduling */
185         struct bfq_entity *parent;
186 
187         /*
188          * For non-leaf nodes in the hierarchy, the associated
189          * scheduler queue, %NULL on leaf nodes.
190          */
191         struct bfq_sched_data *my_sched_data;
192         /* the scheduler queue this entity belongs to */
193         struct bfq_sched_data *sched_data;
194 
195         /* flag, set to request a weight, ioprio or ioprio_class change  */
196         int prio_changed;
197 
198         /* flag, set if the entity is counted in groups_with_pending_reqs */
199         bool in_groups_with_pending_reqs;
200 
201         /* last child queue of entity created (for non-leaf entities) */
202         struct bfq_queue *last_bfqq_created;
203 };
204 
205 struct bfq_group;
206 
207 /**
208  * struct bfq_ttime - per process thinktime stats.
209  */
210 struct bfq_ttime {
211         /* completion time of the last request */
212         u64 last_end_request;
213 
214         /* total process thinktime */
215         u64 ttime_total;
216         /* number of thinktime samples */
217         unsigned long ttime_samples;
218         /* average process thinktime */
219         u64 ttime_mean;
220 };
221 
222 /**
223  * struct bfq_queue - leaf schedulable entity.
224  *
225  * A bfq_queue is a leaf request queue; it can be associated with an
226  * io_context or more, if it  is  async or shared  between  cooperating
227  * processes. @cgroup holds a reference to the cgroup, to be sure that it
228  * does not disappear while a bfqq still references it (mostly to avoid
229  * races between request issuing and task migration followed by cgroup
230  * destruction).
231  * All the fields are protected by the queue lock of the containing bfqd.
232  */
233 struct bfq_queue {
234         /* reference counter */
235         int ref;
236         /* counter of references from other queues for delayed stable merge */
237         int stable_ref;
238         /* parent bfq_data */
239         struct bfq_data *bfqd;
240 
241         /* current ioprio and ioprio class */
242         unsigned short ioprio, ioprio_class;
243         /* next ioprio and ioprio class if a change is in progress */
244         unsigned short new_ioprio, new_ioprio_class;
245 
246         /* last total-service-time sample, see bfq_update_inject_limit() */
247         u64 last_serv_time_ns;
248         /* limit for request injection */
249         unsigned int inject_limit;
250         /* last time the inject limit has been decreased, in jiffies */
251         unsigned long decrease_time_jif;
252 
253         /*
254          * Shared bfq_queue if queue is cooperating with one or more
255          * other queues.
256          */
257         struct bfq_queue *new_bfqq;
258         /* request-position tree member (see bfq_group's @rq_pos_tree) */
259         struct rb_node pos_node;
260         /* request-position tree root (see bfq_group's @rq_pos_tree) */
261         struct rb_root *pos_root;
262 
263         /* sorted list of pending requests */
264         struct rb_root sort_list;
265         /* if fifo isn't expired, next request to serve */
266         struct request *next_rq;
267         /* number of sync and async requests queued */
268         int queued[2];
269         /* number of requests currently allocated */
270         int allocated;
271         /* number of pending metadata requests */
272         int meta_pending;
273         /* fifo list of requests in sort_list */
274         struct list_head fifo;
275 
276         /* entity representing this queue in the scheduler */
277         struct bfq_entity entity;
278 
279         /* pointer to the weight counter associated with this entity */
280         struct bfq_weight_counter *weight_counter;
281 
282         /* maximum budget allowed from the feedback mechanism */
283         int max_budget;
284         /* budget expiration (in jiffies) */
285         unsigned long budget_timeout;
286 
287         /* number of requests on the dispatch list or inside driver */
288         int dispatched;
289 
290         /* status flags */
291         unsigned long flags;
292 
293         /* node for active/idle bfqq list inside parent bfqd */
294         struct list_head bfqq_list;
295 
296         /* associated @bfq_ttime struct */
297         struct bfq_ttime ttime;
298 
299         /* when bfqq started to do I/O within the last observation window */
300         u64 io_start_time;
301         /* how long bfqq has remained empty during the last observ. window */
302         u64 tot_idle_time;
303 
304         /* bit vector: a 1 for each seeky requests in history */
305         u32 seek_history;
306 
307         /* node for the device's burst list */
308         struct hlist_node burst_list_node;
309 
310         /* position of the last request enqueued */
311         sector_t last_request_pos;
312 
313         /* Number of consecutive pairs of request completion and
314          * arrival, such that the queue becomes idle after the
315          * completion, but the next request arrives within an idle
316          * time slice; used only if the queue's IO_bound flag has been
317          * cleared.
318          */
319         unsigned int requests_within_timer;
320 
321         /* pid of the process owning the queue, used for logging purposes */
322         pid_t pid;
323 
324         /*
325          * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
326          * if the queue is shared.
327          */
328         struct bfq_io_cq *bic;
329 
330         /* current maximum weight-raising time for this queue */
331         unsigned long wr_cur_max_time;
332         /*
333          * Minimum time instant such that, only if a new request is
334          * enqueued after this time instant in an idle @bfq_queue with
335          * no outstanding requests, then the task associated with the
336          * queue it is deemed as soft real-time (see the comments on
337          * the function bfq_bfqq_softrt_next_start())
338          */
339         unsigned long soft_rt_next_start;
340         /*
341          * Start time of the current weight-raising period if
342          * the @bfq-queue is being weight-raised, otherwise
343          * finish time of the last weight-raising period.
344          */
345         unsigned long last_wr_start_finish;
346         /* factor by which the weight of this queue is multiplied */
347         unsigned int wr_coeff;
348         /*
349          * Time of the last transition of the @bfq_queue from idle to
350          * backlogged.
351          */
352         unsigned long last_idle_bklogged;
353         /*
354          * Cumulative service received from the @bfq_queue since the
355          * last transition from idle to backlogged.
356          */
357         unsigned long service_from_backlogged;
358         /*
359          * Cumulative service received from the @bfq_queue since its
360          * last transition to weight-raised state.
361          */
362         unsigned long service_from_wr;
363 
364         /*
365          * Value of wr start time when switching to soft rt
366          */
367         unsigned long wr_start_at_switch_to_srt;
368 
369         unsigned long split_time; /* time of last split */
370 
371         unsigned long first_IO_time; /* time of first I/O for this queue */
372 
373         unsigned long creation_time; /* when this queue is created */
374 
375         /* max service rate measured so far */
376         u32 max_service_rate;
377 
378         /*
379          * Pointer to the waker queue for this queue, i.e., to the
380          * queue Q such that this queue happens to get new I/O right
381          * after some I/O request of Q is completed. For details, see
382          * the comments on the choice of the queue for injection in
383          * bfq_select_queue().
384          */
385         struct bfq_queue *waker_bfqq;
386         /* pointer to the curr. tentative waker queue, see bfq_check_waker() */
387         struct bfq_queue *tentative_waker_bfqq;
388         /* number of times the same tentative waker has been detected */
389         unsigned int num_waker_detections;
390 
391         /* node for woken_list, see below */
392         struct hlist_node woken_list_node;
393         /*
394          * Head of the list of the woken queues for this queue, i.e.,
395          * of the list of the queues for which this queue is a waker
396          * queue. This list is used to reset the waker_bfqq pointer in
397          * the woken queues when this queue exits.
398          */
399         struct hlist_head woken_list;
400 };
401 
402 /**
403  * struct bfq_io_cq - per (request_queue, io_context) structure.
404  */
405 struct bfq_io_cq {
406         /* associated io_cq structure */
407         struct io_cq icq; /* must be the first member */
408         /* array of two process queues, the sync and the async */
409         struct bfq_queue *bfqq[2];
410         /* per (request_queue, blkcg) ioprio */
411         int ioprio;
412 #ifdef CONFIG_BFQ_GROUP_IOSCHED
413         uint64_t blkcg_serial_nr; /* the current blkcg serial */
414 #endif
415         /*
416          * Snapshot of the has_short_time flag before merging; taken
417          * to remember its value while the queue is merged, so as to
418          * be able to restore it in case of split.
419          */
420         bool saved_has_short_ttime;
421         /*
422          * Same purpose as the previous two fields for the I/O bound
423          * classification of a queue.
424          */
425         bool saved_IO_bound;
426 
427         u64 saved_io_start_time;
428         u64 saved_tot_idle_time;
429 
430         /*
431          * Same purpose as the previous fields for the value of the
432          * field keeping the queue's belonging to a large burst
433          */
434         bool saved_in_large_burst;
435         /*
436          * True if the queue belonged to a burst list before its merge
437          * with another cooperating queue.
438          */
439         bool was_in_burst_list;
440 
441         /*
442          * Save the weight when a merge occurs, to be able
443          * to restore it in case of split. If the weight is not
444          * correctly resumed when the queue is recycled,
445          * then the weight of the recycled queue could differ
446          * from the weight of the original queue.
447          */
448         unsigned int saved_weight;
449 
450         /*
451          * Similar to previous fields: save wr information.
452          */
453         unsigned long saved_wr_coeff;
454         unsigned long saved_last_wr_start_finish;
455         unsigned long saved_service_from_wr;
456         unsigned long saved_wr_start_at_switch_to_srt;
457         unsigned int saved_wr_cur_max_time;
458         struct bfq_ttime saved_ttime;
459 
460         /* Save also injection state */
461         u64 saved_last_serv_time_ns;
462         unsigned int saved_inject_limit;
463         unsigned long saved_decrease_time_jif;
464 
465         /* candidate queue for a stable merge (due to close creation time) */
466         struct bfq_queue *stable_merge_bfqq;
467 
468         bool stably_merged;     /* non splittable if true */
469 };
470 
471 /**
472  * struct bfq_data - per-device data structure.
473  *
474  * All the fields are protected by @lock.
475  */
476 struct bfq_data {
477         /* device request queue */
478         struct request_queue *queue;
479         /* dispatch queue */
480         struct list_head dispatch;
481 
482         /* root bfq_group for the device */
483         struct bfq_group *root_group;
484 
485         /*
486          * rbtree of weight counters of @bfq_queues, sorted by
487          * weight. Used to keep track of whether all @bfq_queues have
488          * the same weight. The tree contains one counter for each
489          * distinct weight associated to some active and not
490          * weight-raised @bfq_queue (see the comments to the functions
491          * bfq_weights_tree_[add|remove] for further details).
492          */
493         struct rb_root_cached queue_weights_tree;
494 
495         /*
496          * Number of groups with at least one descendant process that
497          * has at least one request waiting for completion. Note that
498          * this accounts for also requests already dispatched, but not
499          * yet completed. Therefore this number of groups may differ
500          * (be larger) than the number of active groups, as a group is
501          * considered active only if its corresponding entity has
502          * descendant queues with at least one request queued. This
503          * number is used to decide whether a scenario is symmetric.
504          * For a detailed explanation see comments on the computation
505          * of the variable asymmetric_scenario in the function
506          * bfq_better_to_idle().
507          *
508          * However, it is hard to compute this number exactly, for
509          * groups with multiple descendant processes. Consider a group
510          * that is inactive, i.e., that has no descendant process with
511          * pending I/O inside BFQ queues. Then suppose that
512          * num_groups_with_pending_reqs is still accounting for this
513          * group, because the group has descendant processes with some
514          * I/O request still in flight. num_groups_with_pending_reqs
515          * should be decremented when the in-flight request of the
516          * last descendant process is finally completed (assuming that
517          * nothing else has changed for the group in the meantime, in
518          * terms of composition of the group and active/inactive state of child
519          * groups and processes). To accomplish this, an additional
520          * pending-request counter must be added to entities, and must
521          * be updated correctly. To avoid this additional field and operations,
522          * we resort to the following tradeoff between simplicity and
523          * accuracy: for an inactive group that is still counted in
524          * num_groups_with_pending_reqs, we decrement
525          * num_groups_with_pending_reqs when the first descendant
526          * process of the group remains with no request waiting for
527          * completion.
528          *
529          * Even this simpler decrement strategy requires a little
530          * carefulness: to avoid multiple decrements, we flag a group,
531          * more precisely an entity representing a group, as still
532          * counted in num_groups_with_pending_reqs when it becomes
533          * inactive. Then, when the first descendant queue of the
534          * entity remains with no request waiting for completion,
535          * num_groups_with_pending_reqs is decremented, and this flag
536          * is reset. After this flag is reset for the entity,
537          * num_groups_with_pending_reqs won't be decremented any
538          * longer in case a new descendant queue of the entity remains
539          * with no request waiting for completion.
540          */
541         unsigned int num_groups_with_pending_reqs;
542 
543         /*
544          * Per-class (RT, BE, IDLE) number of bfq_queues containing
545          * requests (including the queue in service, even if it is
546          * idling).
547          */
548         unsigned int busy_queues[3];
549         /* number of weight-raised busy @bfq_queues */
550         int wr_busy_queues;
551         /* number of queued requests */
552         int queued;
553         /* number of requests dispatched and waiting for completion */
554         int rq_in_driver;
555 
556         /* true if the device is non rotational and performs queueing */
557         bool nonrot_with_queueing;
558 
559         /*
560          * Maximum number of requests in driver in the last
561          * @hw_tag_samples completed requests.
562          */
563         int max_rq_in_driver;
564         /* number of samples used to calculate hw_tag */
565         int hw_tag_samples;
566         /* flag set to one if the driver is showing a queueing behavior */
567         int hw_tag;
568 
569         /* number of budgets assigned */
570         int budgets_assigned;
571 
572         /*
573          * Timer set when idling (waiting) for the next request from
574          * the queue in service.
575          */
576         struct hrtimer idle_slice_timer;
577 
578         /* bfq_queue in service */
579         struct bfq_queue *in_service_queue;
580 
581         /* on-disk position of the last served request */
582         sector_t last_position;
583 
584         /* position of the last served request for the in-service queue */
585         sector_t in_serv_last_pos;
586 
587         /* time of last request completion (ns) */
588         u64 last_completion;
589 
590         /* bfqq owning the last completed rq */
591         struct bfq_queue *last_completed_rq_bfqq;
592 
593         /* last bfqq created, among those in the root group */
594         struct bfq_queue *last_bfqq_created;
595 
596         /* time of last transition from empty to non-empty (ns) */
597         u64 last_empty_occupied_ns;
598 
599         /*
600          * Flag set to activate the sampling of the total service time
601          * of a just-arrived first I/O request (see
602          * bfq_update_inject_limit()). This will cause the setting of
603          * waited_rq when the request is finally dispatched.
604          */
605         bool wait_dispatch;
606         /*
607          *  If set, then bfq_update_inject_limit() is invoked when
608          *  waited_rq is eventually completed.
609          */
610         struct request *waited_rq;
611         /*
612          * True if some request has been injected during the last service hole.
613          */
614         bool rqs_injected;
615 
616         /* time of first rq dispatch in current observation interval (ns) */
617         u64 first_dispatch;
618         /* time of last rq dispatch in current observation interval (ns) */
619         u64 last_dispatch;
620 
621         /* beginning of the last budget */
622         ktime_t last_budget_start;
623         /* beginning of the last idle slice */
624         ktime_t last_idling_start;
625         unsigned long last_idling_start_jiffies;
626 
627         /* number of samples in current observation interval */
628         int peak_rate_samples;
629         /* num of samples of seq dispatches in current observation interval */
630         u32 sequential_samples;
631         /* total num of sectors transferred in current observation interval */
632         u64 tot_sectors_dispatched;
633         /* max rq size seen during current observation interval (sectors) */
634         u32 last_rq_max_size;
635         /* time elapsed from first dispatch in current observ. interval (us) */
636         u64 delta_from_first;
637         /*
638          * Current estimate of the device peak rate, measured in
639          * [(sectors/usec) / 2^BFQ_RATE_SHIFT]. The left-shift by
640          * BFQ_RATE_SHIFT is performed to increase precision in
641          * fixed-point calculations.
642          */
643         u32 peak_rate;
644 
645         /* maximum budget allotted to a bfq_queue before rescheduling */
646         int bfq_max_budget;
647 
648         /* list of all the bfq_queues active on the device */
649         struct list_head active_list;
650         /* list of all the bfq_queues idle on the device */
651         struct list_head idle_list;
652 
653         /*
654          * Timeout for async/sync requests; when it fires, requests
655          * are served in fifo order.
656          */
657         u64 bfq_fifo_expire[2];
658         /* weight of backward seeks wrt forward ones */
659         unsigned int bfq_back_penalty;
660         /* maximum allowed backward seek */
661         unsigned int bfq_back_max;
662         /* maximum idling time */
663         u32 bfq_slice_idle;
664 
665         /* user-configured max budget value (0 for auto-tuning) */
666         int bfq_user_max_budget;
667         /*
668          * Timeout for bfq_queues to consume their budget; used to
669          * prevent seeky queues from imposing long latencies to
670          * sequential or quasi-sequential ones (this also implies that
671          * seeky queues cannot receive guarantees in the service
672          * domain; after a timeout they are charged for the time they
673          * have been in service, to preserve fairness among them, but
674          * without service-domain guarantees).
675          */
676         unsigned int bfq_timeout;
677 
678         /*
679          * Force device idling whenever needed to provide accurate
680          * service guarantees, without caring about throughput
681          * issues. CAVEAT: this may even increase latencies, in case
682          * of useless idling for processes that did stop doing I/O.
683          */
684         bool strict_guarantees;
685 
686         /*
687          * Last time at which a queue entered the current burst of
688          * queues being activated shortly after each other; for more
689          * details about this and the following parameters related to
690          * a burst of activations, see the comments on the function
691          * bfq_handle_burst.
692          */
693         unsigned long last_ins_in_burst;
694         /*
695          * Reference time interval used to decide whether a queue has
696          * been activated shortly after @last_ins_in_burst.
697          */
698         unsigned long bfq_burst_interval;
699         /* number of queues in the current burst of queue activations */
700         int burst_size;
701 
702         /* common parent entity for the queues in the burst */
703         struct bfq_entity *burst_parent_entity;
704         /* Maximum burst size above which the current queue-activation
705          * burst is deemed as 'large'.
706          */
707         unsigned long bfq_large_burst_thresh;
708         /* true if a large queue-activation burst is in progress */
709         bool large_burst;
710         /*
711          * Head of the burst list (as for the above fields, more
712          * details in the comments on the function bfq_handle_burst).
713          */
714         struct hlist_head burst_list;
715 
716         /* if set to true, low-latency heuristics are enabled */
717         bool low_latency;
718         /*
719          * Maximum factor by which the weight of a weight-raised queue
720          * is multiplied.
721          */
722         unsigned int bfq_wr_coeff;
723         /* maximum duration of a weight-raising period (jiffies) */
724         unsigned int bfq_wr_max_time;
725 
726         /* Maximum weight-raising duration for soft real-time processes */
727         unsigned int bfq_wr_rt_max_time;
728         /*
729          * Minimum idle period after which weight-raising may be
730          * reactivated for a queue (in jiffies).
731          */
732         unsigned int bfq_wr_min_idle_time;
733         /*
734          * Minimum period between request arrivals after which
735          * weight-raising may be reactivated for an already busy async
736          * queue (in jiffies).
737          */
738         unsigned long bfq_wr_min_inter_arr_async;
739 
740         /* Max service-rate for a soft real-time queue, in sectors/sec */
741         unsigned int bfq_wr_max_softrt_rate;
742         /*
743          * Cached value of the product ref_rate*ref_wr_duration, used
744          * for computing the maximum duration of weight raising
745          * automatically.
746          */
747         u64 rate_dur_prod;
748 
749         /* fallback dummy bfqq for extreme OOM conditions */
750         struct bfq_queue oom_bfqq;
751 
752         spinlock_t lock;
753 
754         /*
755          * bic associated with the task issuing current bio for
756          * merging. This and the next field are used as a support to
757          * be able to perform the bic lookup, needed by bio-merge
758          * functions, before the scheduler lock is taken, and thus
759          * avoid taking the request-queue lock while the scheduler
760          * lock is being held.
761          */
762         struct bfq_io_cq *bio_bic;
763         /* bfqq associated with the task issuing current bio for merging */
764         struct bfq_queue *bio_bfqq;
765 
766         /*
767          * Depth limits used in bfq_limit_depth (see comments on the
768          * function)
769          */
770         unsigned int word_depths[2][2];
771 };
772 
773 enum bfqq_state_flags {
774         BFQQF_just_created = 0, /* queue just allocated */
775         BFQQF_busy,             /* has requests or is in service */
776         BFQQF_wait_request,     /* waiting for a request */
777         BFQQF_non_blocking_wait_rq, /*
778                                      * waiting for a request
779                                      * without idling the device
780                                      */
781         BFQQF_fifo_expire,      /* FIFO checked in this slice */
782         BFQQF_has_short_ttime,  /* queue has a short think time */
783         BFQQF_sync,             /* synchronous queue */
784         BFQQF_IO_bound,         /*
785                                  * bfqq has timed-out at least once
786                                  * having consumed at most 2/10 of
787                                  * its budget
788                                  */
789         BFQQF_in_large_burst,   /*
790                                  * bfqq activated in a large burst,
791                                  * see comments to bfq_handle_burst.
792                                  */
793         BFQQF_softrt_update,    /*
794                                  * may need softrt-next-start
795                                  * update
796                                  */
797         BFQQF_coop,             /* bfqq is shared */
798         BFQQF_split_coop,       /* shared bfqq will be split */
799 };
800 
801 #define BFQ_BFQQ_FNS(name)                                              \
802 void bfq_mark_bfqq_##name(struct bfq_queue *bfqq);                      \
803 void bfq_clear_bfqq_##name(struct bfq_queue *bfqq);                     \
804 int bfq_bfqq_##name(const struct bfq_queue *bfqq);
805 
806 BFQ_BFQQ_FNS(just_created);
807 BFQ_BFQQ_FNS(busy);
808 BFQ_BFQQ_FNS(wait_request);
809 BFQ_BFQQ_FNS(non_blocking_wait_rq);
810 BFQ_BFQQ_FNS(fifo_expire);
811 BFQ_BFQQ_FNS(has_short_ttime);
812 BFQ_BFQQ_FNS(sync);
813 BFQ_BFQQ_FNS(IO_bound);
814 BFQ_BFQQ_FNS(in_large_burst);
815 BFQ_BFQQ_FNS(coop);
816 BFQ_BFQQ_FNS(split_coop);
817 BFQ_BFQQ_FNS(softrt_update);
818 #undef BFQ_BFQQ_FNS
819 
820 /* Expiration reasons. */
821 enum bfqq_expiration {
822         BFQQE_TOO_IDLE = 0,             /*
823                                          * queue has been idling for
824                                          * too long
825                                          */
826         BFQQE_BUDGET_TIMEOUT,   /* budget took too long to be used */
827         BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
828         BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
829         BFQQE_PREEMPTED         /* preemption in progress */
830 };
831 
832 struct bfq_stat {
833         struct percpu_counter           cpu_cnt;
834         atomic64_t                      aux_cnt;
835 };
836 
837 struct bfqg_stats {
838         /* basic stats */
839         struct blkg_rwstat              bytes;
840         struct blkg_rwstat              ios;
841 #ifdef CONFIG_BFQ_CGROUP_DEBUG
842         /* number of ios merged */
843         struct blkg_rwstat              merged;
844         /* total time spent on device in ns, may not be accurate w/ queueing */
845         struct blkg_rwstat              service_time;
846         /* total time spent waiting in scheduler queue in ns */
847         struct blkg_rwstat              wait_time;
848         /* number of IOs queued up */
849         struct blkg_rwstat              queued;
850         /* total disk time and nr sectors dispatched by this group */
851         struct bfq_stat         time;
852         /* sum of number of ios queued across all samples */
853         struct bfq_stat         avg_queue_size_sum;
854         /* count of samples taken for average */
855         struct bfq_stat         avg_queue_size_samples;
856         /* how many times this group has been removed from service tree */
857         struct bfq_stat         dequeue;
858         /* total time spent waiting for it to be assigned a timeslice. */
859         struct bfq_stat         group_wait_time;
860         /* time spent idling for this blkcg_gq */
861         struct bfq_stat         idle_time;
862         /* total time with empty current active q with other requests queued */
863         struct bfq_stat         empty_time;
864         /* fields after this shouldn't be cleared on stat reset */
865         u64                             start_group_wait_time;
866         u64                             start_idle_time;
867         u64                             start_empty_time;
868         uint16_t                        flags;
869 #endif /* CONFIG_BFQ_CGROUP_DEBUG */
870 };
871 
872 #ifdef CONFIG_BFQ_GROUP_IOSCHED
873 
874 /*
875  * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
876  *
877  * @ps: @blkcg_policy_storage that this structure inherits
878  * @weight: weight of the bfq_group
879  */
880 struct bfq_group_data {
881         /* must be the first member */
882         struct blkcg_policy_data pd;
883 
884         unsigned int weight;
885 };
886 
887 /**
888  * struct bfq_group - per (device, cgroup) data structure.
889  * @entity: schedulable entity to insert into the parent group sched_data.
890  * @sched_data: own sched_data, to contain child entities (they may be
891  *              both bfq_queues and bfq_groups).
892  * @bfqd: the bfq_data for the device this group acts upon.
893  * @async_bfqq: array of async queues for all the tasks belonging to
894  *              the group, one queue per ioprio value per ioprio_class,
895  *              except for the idle class that has only one queue.
896  * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
897  * @my_entity: pointer to @entity, %NULL for the toplevel group; used
898  *             to avoid too many special cases during group creation/
899  *             migration.
900  * @stats: stats for this bfqg.
901  * @active_entities: number of active entities belonging to the group;
902  *                   unused for the root group. Used to know whether there
903  *                   are groups with more than one active @bfq_entity
904  *                   (see the comments to the function
905  *                   bfq_bfqq_may_idle()).
906  * @rq_pos_tree: rbtree sorted by next_request position, used when
907  *               determining if two or more queues have interleaving
908  *               requests (see bfq_find_close_cooperator()).
909  *
910  * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
911  * there is a set of bfq_groups, each one collecting the lower-level
912  * entities belonging to the group that are acting on the same device.
913  *
914  * Locking works as follows:
915  *    o @bfqd is protected by the queue lock, RCU is used to access it
916  *      from the readers.
917  *    o All the other fields are protected by the @bfqd queue lock.
918  */
919 struct bfq_group {
920         /* must be the first member */
921         struct blkg_policy_data pd;
922 
923         /* cached path for this blkg (see comments in bfq_bic_update_cgroup) */
924         char blkg_path[128];
925 
926         /* reference counter (see comments in bfq_bic_update_cgroup) */
927         int ref;
928 
929         struct bfq_entity entity;
930         struct bfq_sched_data sched_data;
931 
932         void *bfqd;
933 
934         struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS];
935         struct bfq_queue *async_idle_bfqq;
936 
937         struct bfq_entity *my_entity;
938 
939         int active_entities;
940 
941         struct rb_root rq_pos_tree;
942 
943         struct bfqg_stats stats;
944 };
945 
946 #else
947 struct bfq_group {
948         struct bfq_entity entity;
949         struct bfq_sched_data sched_data;
950 
951         struct bfq_queue *async_bfqq[2][IOPRIO_NR_LEVELS];
952         struct bfq_queue *async_idle_bfqq;
953 
954         struct rb_root rq_pos_tree;
955 };
956 #endif
957 
958 /* --------------- main algorithm interface ----------------- */
959 
960 #define BFQ_SERVICE_TREE_INIT   ((struct bfq_service_tree)              \
961                                 { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
962 
963 extern const int bfq_timeout;
964 
965 struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
966 void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
967 struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
968 void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
969 void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq,
970                           struct rb_root_cached *root);
971 void __bfq_weights_tree_remove(struct bfq_data *bfqd,
972                                struct bfq_queue *bfqq,
973                                struct rb_root_cached *root);
974 void bfq_weights_tree_remove(struct bfq_data *bfqd,
975                              struct bfq_queue *bfqq);
976 void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
977                      bool compensate, enum bfqq_expiration reason);
978 void bfq_put_queue(struct bfq_queue *bfqq);
979 void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
980 void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq);
981 void bfq_schedule_dispatch(struct bfq_data *bfqd);
982 void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
983 
984 /* ------------ end of main algorithm interface -------------- */
985 
986 /* ---------------- cgroups-support interface ---------------- */
987 
988 void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq);
989 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
990                               unsigned int op);
991 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
992 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
993 void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
994                                   u64 io_start_time_ns, unsigned int op);
995 void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
996 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
997 void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
998 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
999 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
1000 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1001                    struct bfq_group *bfqg);
1002 
1003 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
1004 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
1005 void bfq_end_wr_async(struct bfq_data *bfqd);
1006 struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
1007                                      struct blkcg *blkcg);
1008 struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
1009 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
1010 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
1011 void bfqg_and_blkg_put(struct bfq_group *bfqg);
1012 
1013 #ifdef CONFIG_BFQ_GROUP_IOSCHED
1014 extern struct cftype bfq_blkcg_legacy_files[];
1015 extern struct cftype bfq_blkg_files[];
1016 extern struct blkcg_policy blkcg_policy_bfq;
1017 #endif
1018 
1019 /* ------------- end of cgroups-support interface ------------- */
1020 
1021 /* - interface of the internal hierarchical B-WF2Q+ scheduler - */
1022 
1023 #ifdef CONFIG_BFQ_GROUP_IOSCHED
1024 /* both next loops stop at one of the child entities of the root group */
1025 #define for_each_entity(entity) \
1026         for (; entity ; entity = entity->parent)
1027 
1028 /*
1029  * For each iteration, compute parent in advance, so as to be safe if
1030  * entity is deallocated during the iteration. Such a deallocation may
1031  * happen as a consequence of a bfq_put_queue that frees the bfq_queue
1032  * containing entity.
1033  */
1034 #define for_each_entity_safe(entity, parent) \
1035         for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
1036 
1037 #else /* CONFIG_BFQ_GROUP_IOSCHED */
1038 /*
1039  * Next two macros are fake loops when cgroups support is not
1040  * enabled. I fact, in such a case, there is only one level to go up
1041  * (to reach the root group).
1042  */
1043 #define for_each_entity(entity) \
1044         for (; entity ; entity = NULL)
1045 
1046 #define for_each_entity_safe(entity, parent) \
1047         for (parent = NULL; entity ; entity = parent)
1048 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
1049 
1050 struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
1051 struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
1052 unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd);
1053 struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
1054 struct bfq_entity *bfq_entity_of(struct rb_node *node);
1055 unsigned short bfq_ioprio_to_weight(int ioprio);
1056 void bfq_put_idle_entity(struct bfq_service_tree *st,
1057                          struct bfq_entity *entity);
1058 struct bfq_service_tree *
1059 __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
1060                                 struct bfq_entity *entity,
1061                                 bool update_class_too);
1062 void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
1063 void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1064                           unsigned long time_ms);
1065 bool __bfq_deactivate_entity(struct bfq_entity *entity,
1066                              bool ins_into_idle_tree);
1067 bool next_queue_may_preempt(struct bfq_data *bfqd);
1068 struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
1069 bool __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
1070 void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1071                          bool ins_into_idle_tree, bool expiration);
1072 void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1073 void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1074                       bool expiration);
1075 void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1076                        bool expiration);
1077 void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
1078 
1079 /* --------------- end of interface of B-WF2Q+ ---------------- */
1080 
1081 /* Logging facilities. */
1082 static inline void bfq_pid_to_str(int pid, char *str, int len)
1083 {
1084         if (pid != -1)
1085                 snprintf(str, len, "%d", pid);
1086         else
1087                 snprintf(str, len, "SHARED-");
1088 }
1089 
1090 #ifdef CONFIG_BFQ_GROUP_IOSCHED
1091 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
1092 
1093 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)  do {                    \
1094         char pid_str[MAX_PID_STR_LENGTH];       \
1095         if (likely(!blk_trace_note_message_enabled((bfqd)->queue)))     \
1096                 break;                                                  \
1097         bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH);       \
1098         blk_add_cgroup_trace_msg((bfqd)->queue,                         \
1099                         bfqg_to_blkg(bfqq_group(bfqq))->blkcg,          \
1100                         "bfq%s%c " fmt, pid_str,                        \
1101                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args);     \
1102 } while (0)
1103 
1104 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)  do {                    \
1105         blk_add_cgroup_trace_msg((bfqd)->queue,                         \
1106                 bfqg_to_blkg(bfqg)->blkcg, fmt, ##args);                \
1107 } while (0)
1108 
1109 #else /* CONFIG_BFQ_GROUP_IOSCHED */
1110 
1111 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do {     \
1112         char pid_str[MAX_PID_STR_LENGTH];       \
1113         if (likely(!blk_trace_note_message_enabled((bfqd)->queue)))     \
1114                 break;                                                  \
1115         bfq_pid_to_str((bfqq)->pid, pid_str, MAX_PID_STR_LENGTH);       \
1116         blk_add_trace_msg((bfqd)->queue, "bfq%s%c " fmt, pid_str,       \
1117                         bfq_bfqq_sync((bfqq)) ? 'S' : 'A',              \
1118                                 ##args);        \
1119 } while (0)
1120 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)          do {} while (0)
1121 
1122 #endif /* CONFIG_BFQ_GROUP_IOSCHED */
1123 
1124 #define bfq_log(bfqd, fmt, args...) \
1125         blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
1126 
1127 #endif /* _BFQ_H */
1128 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp