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1/* SPDX-License-Identifier: GPL-2.0
2 *
3 * IO cost model based controller.
4 *
5 * Copyright (C) 2019 Tejun Heo <tj@kernel.org>
6 * Copyright (C) 2019 Andy Newell <newella@fb.com>
7 * Copyright (C) 2019 Facebook
8 *
9 * One challenge of controlling IO resources is the lack of trivially
10 * observable cost metric. This is distinguished from CPU and memory where
11 * wallclock time and the number of bytes can serve as accurate enough
12 * approximations.
13 *
14 * Bandwidth and iops are the most commonly used metrics for IO devices but
15 * depending on the type and specifics of the device, different IO patterns
16 * easily lead to multiple orders of magnitude variations rendering them
17 * useless for the purpose of IO capacity distribution. While on-device
18 * time, with a lot of clutches, could serve as a useful approximation for
19 * non-queued rotational devices, this is no longer viable with modern
20 * devices, even the rotational ones.
21 *
22 * While there is no cost metric we can trivially observe, it isn't a
23 * complete mystery. For example, on a rotational device, seek cost
24 * dominates while a contiguous transfer contributes a smaller amount
25 * proportional to the size. If we can characterize at least the relative
26 * costs of these different types of IOs, it should be possible to
27 * implement a reasonable work-conserving proportional IO resource
28 * distribution.
29 *
30 * 1. IO Cost Model
31 *
32 * IO cost model estimates the cost of an IO given its basic parameters and
33 * history (e.g. the end sector of the last IO). The cost is measured in
34 * device time. If a given IO is estimated to cost 10ms, the device should
35 * be able to process ~100 of those IOs in a second.
36 *
37 * Currently, there's only one builtin cost model - linear. Each IO is
38 * classified as sequential or random and given a base cost accordingly.
39 * On top of that, a size cost proportional to the length of the IO is
40 * added. While simple, this model captures the operational
41 * characteristics of a wide varienty of devices well enough. Default
42 * paramters for several different classes of devices are provided and the
43 * parameters can be configured from userspace via
44 * /sys/fs/cgroup/io.cost.model.
45 *
46 * If needed, tools/cgroup/iocost_coef_gen.py can be used to generate
47 * device-specific coefficients.
48 *
49 * 2. Control Strategy
50 *
51 * The device virtual time (vtime) is used as the primary control metric.
52 * The control strategy is composed of the following three parts.
53 *
54 * 2-1. Vtime Distribution
55 *
56 * When a cgroup becomes active in terms of IOs, its hierarchical share is
57 * calculated. Please consider the following hierarchy where the numbers
58 * inside parentheses denote the configured weights.
59 *
60 * root
61 * / \
62 * A (w:100) B (w:300)
63 * / \
64 * A0 (w:100) A1 (w:100)
65 *
66 * If B is idle and only A0 and A1 are actively issuing IOs, as the two are
67 * of equal weight, each gets 50% share. If then B starts issuing IOs, B
68 * gets 300/(100+300) or 75% share, and A0 and A1 equally splits the rest,
69 * 12.5% each. The distribution mechanism only cares about these flattened
70 * shares. They're called hweights (hierarchical weights) and always add
71 * upto 1 (HWEIGHT_WHOLE).
72 *
73 * A given cgroup's vtime runs slower in inverse proportion to its hweight.
74 * For example, with 12.5% weight, A0's time runs 8 times slower (100/12.5)
75 * against the device vtime - an IO which takes 10ms on the underlying
76 * device is considered to take 80ms on A0.
77 *
78 * This constitutes the basis of IO capacity distribution. Each cgroup's
79 * vtime is running at a rate determined by its hweight. A cgroup tracks
80 * the vtime consumed by past IOs and can issue a new IO iff doing so
81 * wouldn't outrun the current device vtime. Otherwise, the IO is
82 * suspended until the vtime has progressed enough to cover it.
83 *
84 * 2-2. Vrate Adjustment
85 *
86 * It's unrealistic to expect the cost model to be perfect. There are too
87 * many devices and even on the same device the overall performance
88 * fluctuates depending on numerous factors such as IO mixture and device
89 * internal garbage collection. The controller needs to adapt dynamically.
90 *
91 * This is achieved by adjusting the overall IO rate according to how busy
92 * the device is. If the device becomes overloaded, we're sending down too
93 * many IOs and should generally slow down. If there are waiting issuers
94 * but the device isn't saturated, we're issuing too few and should
95 * generally speed up.
96 *
97 * To slow down, we lower the vrate - the rate at which the device vtime
98 * passes compared to the wall clock. For example, if the vtime is running
99 * at the vrate of 75%, all cgroups added up would only be able to issue
100 * 750ms worth of IOs per second, and vice-versa for speeding up.
101 *
102 * Device business is determined using two criteria - rq wait and
103 * completion latencies.
104 *
105 * When a device gets saturated, the on-device and then the request queues
106 * fill up and a bio which is ready to be issued has to wait for a request
107 * to become available. When this delay becomes noticeable, it's a clear
108 * indication that the device is saturated and we lower the vrate. This
109 * saturation signal is fairly conservative as it only triggers when both
110 * hardware and software queues are filled up, and is used as the default
111 * busy signal.
112 *
113 * As devices can have deep queues and be unfair in how the queued commands
114 * are executed, soley depending on rq wait may not result in satisfactory
115 * control quality. For a better control quality, completion latency QoS
116 * parameters can be configured so that the device is considered saturated
117 * if N'th percentile completion latency rises above the set point.
118 *
119 * The completion latency requirements are a function of both the
120 * underlying device characteristics and the desired IO latency quality of
121 * service. There is an inherent trade-off - the tighter the latency QoS,
122 * the higher the bandwidth lossage. Latency QoS is disabled by default
123 * and can be set through /sys/fs/cgroup/io.cost.qos.
124 *
125 * 2-3. Work Conservation
126 *
127 * Imagine two cgroups A and B with equal weights. A is issuing a small IO
128 * periodically while B is sending out enough parallel IOs to saturate the
129 * device on its own. Let's say A's usage amounts to 100ms worth of IO
130 * cost per second, i.e., 10% of the device capacity. The naive
131 * distribution of half and half would lead to 60% utilization of the
132 * device, a significant reduction in the total amount of work done
133 * compared to free-for-all competition. This is too high a cost to pay
134 * for IO control.
135 *
136 * To conserve the total amount of work done, we keep track of how much
137 * each active cgroup is actually using and yield part of its weight if
138 * there are other cgroups which can make use of it. In the above case,
139 * A's weight will be lowered so that it hovers above the actual usage and
140 * B would be able to use the rest.
141 *
142 * As we don't want to penalize a cgroup for donating its weight, the
143 * surplus weight adjustment factors in a margin and has an immediate
144 * snapback mechanism in case the cgroup needs more IO vtime for itself.
145 *
146 * Note that adjusting down surplus weights has the same effects as
147 * accelerating vtime for other cgroups and work conservation can also be
148 * implemented by adjusting vrate dynamically. However, squaring who can
149 * donate and should take back how much requires hweight propagations
150 * anyway making it easier to implement and understand as a separate
151 * mechanism.
152 *
153 * 3. Monitoring
154 *
155 * Instead of debugfs or other clumsy monitoring mechanisms, this
156 * controller uses a drgn based monitoring script -
157 * tools/cgroup/iocost_monitor.py. For details on drgn, please see
158 * https://github.com/osandov/drgn. The ouput looks like the following.
159 *
160 * sdb RUN per=300ms cur_per=234.218:v203.695 busy= +1 vrate= 62.12%
161 * active weight hweight% inflt% dbt delay usages%
162 * test/a * 50/ 50 33.33/ 33.33 27.65 2 0*041 033:033:033
163 * test/b * 100/ 100 66.67/ 66.67 17.56 0 0*000 066:079:077
164 *
165 * - per : Timer period
166 * - cur_per : Internal wall and device vtime clock
167 * - vrate : Device virtual time rate against wall clock
168 * - weight : Surplus-adjusted and configured weights
169 * - hweight : Surplus-adjusted and configured hierarchical weights
170 * - inflt : The percentage of in-flight IO cost at the end of last period
171 * - del_ms : Deferred issuer delay induction level and duration
172 * - usages : Usage history
173 */
174
175#include <linux/kernel.h>
176#include <linux/module.h>
177#include <linux/timer.h>
178#include <linux/time64.h>
179#include <linux/parser.h>
180#include <linux/sched/signal.h>
181#include <linux/blk-cgroup.h>
182#include "blk-rq-qos.h"
183#include "blk-stat.h"
184#include "blk-wbt.h"
185
186#ifdef CONFIG_TRACEPOINTS
187
188/* copied from TRACE_CGROUP_PATH, see cgroup-internal.h */
189#define TRACE_IOCG_PATH_LEN 1024
190static DEFINE_SPINLOCK(trace_iocg_path_lock);
191static char trace_iocg_path[TRACE_IOCG_PATH_LEN];
192
193#define TRACE_IOCG_PATH(type, iocg, ...) \
194 do { \
195 unsigned long flags; \
196 if (trace_iocost_##type##_enabled()) { \
197 spin_lock_irqsave(&trace_iocg_path_lock, flags); \
198 cgroup_path(iocg_to_blkg(iocg)->blkcg->css.cgroup, \
199 trace_iocg_path, TRACE_IOCG_PATH_LEN); \
200 trace_iocost_##type(iocg, trace_iocg_path, \
201 ##__VA_ARGS__); \
202 spin_unlock_irqrestore(&trace_iocg_path_lock, flags); \
203 } \
204 } while (0)
205
206#else /* CONFIG_TRACE_POINTS */
207#define TRACE_IOCG_PATH(type, iocg, ...) do { } while (0)
208#endif /* CONFIG_TRACE_POINTS */
209
210enum {
211 MILLION = 1000000,
212
213 /* timer period is calculated from latency requirements, bound it */
214 MIN_PERIOD = USEC_PER_MSEC,
215 MAX_PERIOD = USEC_PER_SEC,
216
217 /*
218 * A cgroup's vtime can run 50% behind the device vtime, which
219 * serves as its IO credit buffer. Surplus weight adjustment is
220 * immediately canceled if the vtime margin runs below 10%.
221 */
222 MARGIN_PCT = 50,
223 INUSE_MARGIN_PCT = 10,
224
225 /* Have some play in waitq timer operations */
226 WAITQ_TIMER_MARGIN_PCT = 5,
227
228 /*
229 * vtime can wrap well within a reasonable uptime when vrate is
230 * consistently raised. Don't trust recorded cgroup vtime if the
231 * period counter indicates that it's older than 5mins.
232 */
233 VTIME_VALID_DUR = 300 * USEC_PER_SEC,
234
235 /*
236 * Remember the past three non-zero usages and use the max for
237 * surplus calculation. Three slots guarantee that we remember one
238 * full period usage from the last active stretch even after
239 * partial deactivation and re-activation periods. Don't start
240 * giving away weight before collecting two data points to prevent
241 * hweight adjustments based on one partial activation period.
242 */
243 NR_USAGE_SLOTS = 3,
244 MIN_VALID_USAGES = 2,
245
246 /* 1/64k is granular enough and can easily be handled w/ u32 */
247 HWEIGHT_WHOLE = 1 << 16,
248
249 /*
250 * As vtime is used to calculate the cost of each IO, it needs to
251 * be fairly high precision. For example, it should be able to
252 * represent the cost of a single page worth of discard with
253 * suffificient accuracy. At the same time, it should be able to
254 * represent reasonably long enough durations to be useful and
255 * convenient during operation.
256 *
257 * 1s worth of vtime is 2^37. This gives us both sub-nanosecond
258 * granularity and days of wrap-around time even at extreme vrates.
259 */
260 VTIME_PER_SEC_SHIFT = 37,
261 VTIME_PER_SEC = 1LLU << VTIME_PER_SEC_SHIFT,
262 VTIME_PER_USEC = VTIME_PER_SEC / USEC_PER_SEC,
263 VTIME_PER_NSEC = VTIME_PER_SEC / NSEC_PER_SEC,
264
265 /* bound vrate adjustments within two orders of magnitude */
266 VRATE_MIN_PPM = 10000, /* 1% */
267 VRATE_MAX_PPM = 100000000, /* 10000% */
268
269 VRATE_MIN = VTIME_PER_USEC * VRATE_MIN_PPM / MILLION,
270 VRATE_CLAMP_ADJ_PCT = 4,
271
272 /* if IOs end up waiting for requests, issue less */
273 RQ_WAIT_BUSY_PCT = 5,
274
275 /* unbusy hysterisis */
276 UNBUSY_THR_PCT = 75,
277
278 /* don't let cmds which take a very long time pin lagging for too long */
279 MAX_LAGGING_PERIODS = 10,
280
281 /*
282 * If usage% * 1.25 + 2% is lower than hweight% by more than 3%,
283 * donate the surplus.
284 */
285 SURPLUS_SCALE_PCT = 125, /* * 125% */
286 SURPLUS_SCALE_ABS = HWEIGHT_WHOLE / 50, /* + 2% */
287 SURPLUS_MIN_ADJ_DELTA = HWEIGHT_WHOLE / 33, /* 3% */
288
289 /* switch iff the conditions are met for longer than this */
290 AUTOP_CYCLE_NSEC = 10LLU * NSEC_PER_SEC,
291
292 /*
293 * Count IO size in 4k pages. The 12bit shift helps keeping
294 * size-proportional components of cost calculation in closer
295 * numbers of digits to per-IO cost components.
296 */
297 IOC_PAGE_SHIFT = 12,
298 IOC_PAGE_SIZE = 1 << IOC_PAGE_SHIFT,
299 IOC_SECT_TO_PAGE_SHIFT = IOC_PAGE_SHIFT - SECTOR_SHIFT,
300
301 /* if apart further than 16M, consider randio for linear model */
302 LCOEF_RANDIO_PAGES = 4096,
303};
304
305enum ioc_running {
306 IOC_IDLE,
307 IOC_RUNNING,
308 IOC_STOP,
309};
310
311/* io.cost.qos controls including per-dev enable of the whole controller */
312enum {
313 QOS_ENABLE,
314 QOS_CTRL,
315 NR_QOS_CTRL_PARAMS,
316};
317
318/* io.cost.qos params */
319enum {
320 QOS_RPPM,
321 QOS_RLAT,
322 QOS_WPPM,
323 QOS_WLAT,
324 QOS_MIN,
325 QOS_MAX,
326 NR_QOS_PARAMS,
327};
328
329/* io.cost.model controls */
330enum {
331 COST_CTRL,
332 COST_MODEL,
333 NR_COST_CTRL_PARAMS,
334};
335
336/* builtin linear cost model coefficients */
337enum {
338 I_LCOEF_RBPS,
339 I_LCOEF_RSEQIOPS,
340 I_LCOEF_RRANDIOPS,
341 I_LCOEF_WBPS,
342 I_LCOEF_WSEQIOPS,
343 I_LCOEF_WRANDIOPS,
344 NR_I_LCOEFS,
345};
346
347enum {
348 LCOEF_RPAGE,
349 LCOEF_RSEQIO,
350 LCOEF_RRANDIO,
351 LCOEF_WPAGE,
352 LCOEF_WSEQIO,
353 LCOEF_WRANDIO,
354 NR_LCOEFS,
355};
356
357enum {
358 AUTOP_INVALID,
359 AUTOP_HDD,
360 AUTOP_SSD_QD1,
361 AUTOP_SSD_DFL,
362 AUTOP_SSD_FAST,
363};
364
365struct ioc_gq;
366
367struct ioc_params {
368 u32 qos[NR_QOS_PARAMS];
369 u64 i_lcoefs[NR_I_LCOEFS];
370 u64 lcoefs[NR_LCOEFS];
371 u32 too_fast_vrate_pct;
372 u32 too_slow_vrate_pct;
373};
374
375struct ioc_missed {
376 u32 nr_met;
377 u32 nr_missed;
378 u32 last_met;
379 u32 last_missed;
380};
381
382struct ioc_pcpu_stat {
383 struct ioc_missed missed[2];
384
385 u64 rq_wait_ns;
386 u64 last_rq_wait_ns;
387};
388
389/* per device */
390struct ioc {
391 struct rq_qos rqos;
392
393 bool enabled;
394
395 struct ioc_params params;
396 u32 period_us;
397 u32 margin_us;
398 u64 vrate_min;
399 u64 vrate_max;
400
401 spinlock_t lock;
402 struct timer_list timer;
403 struct list_head active_iocgs; /* active cgroups */
404 struct ioc_pcpu_stat __percpu *pcpu_stat;
405
406 enum ioc_running running;
407 atomic64_t vtime_rate;
408
409 seqcount_spinlock_t period_seqcount;
410 u32 period_at; /* wallclock starttime */
411 u64 period_at_vtime; /* vtime starttime */
412
413 atomic64_t cur_period; /* inc'd each period */
414 int busy_level; /* saturation history */
415
416 u64 inuse_margin_vtime;
417 bool weights_updated;
418 atomic_t hweight_gen; /* for lazy hweights */
419
420 u64 autop_too_fast_at;
421 u64 autop_too_slow_at;
422 int autop_idx;
423 bool user_qos_params:1;
424 bool user_cost_model:1;
425};
426
427/* per device-cgroup pair */
428struct ioc_gq {
429 struct blkg_policy_data pd;
430 struct ioc *ioc;
431
432 /*
433 * A iocg can get its weight from two sources - an explicit
434 * per-device-cgroup configuration or the default weight of the
435 * cgroup. `cfg_weight` is the explicit per-device-cgroup
436 * configuration. `weight` is the effective considering both
437 * sources.
438 *
439 * When an idle cgroup becomes active its `active` goes from 0 to
440 * `weight`. `inuse` is the surplus adjusted active weight.
441 * `active` and `inuse` are used to calculate `hweight_active` and
442 * `hweight_inuse`.
443 *
444 * `last_inuse` remembers `inuse` while an iocg is idle to persist
445 * surplus adjustments.
446 */
447 u32 cfg_weight;
448 u32 weight;
449 u32 active;
450 u32 inuse;
451 u32 last_inuse;
452
453 sector_t cursor; /* to detect randio */
454
455 /*
456 * `vtime` is this iocg's vtime cursor which progresses as IOs are
457 * issued. If lagging behind device vtime, the delta represents
458 * the currently available IO budget. If runnning ahead, the
459 * overage.
460 *
461 * `vtime_done` is the same but progressed on completion rather
462 * than issue. The delta behind `vtime` represents the cost of
463 * currently in-flight IOs.
464 *
465 * `last_vtime` is used to remember `vtime` at the end of the last
466 * period to calculate utilization.
467 */
468 atomic64_t vtime;
469 atomic64_t done_vtime;
470 u64 abs_vdebt;
471 u64 last_vtime;
472
473 /*
474 * The period this iocg was last active in. Used for deactivation
475 * and invalidating `vtime`.
476 */
477 atomic64_t active_period;
478 struct list_head active_list;
479
480 /* see __propagate_active_weight() and current_hweight() for details */
481 u64 child_active_sum;
482 u64 child_inuse_sum;
483 int hweight_gen;
484 u32 hweight_active;
485 u32 hweight_inuse;
486 bool has_surplus;
487
488 struct wait_queue_head waitq;
489 struct hrtimer waitq_timer;
490 struct hrtimer delay_timer;
491
492 /* usage is recorded as fractions of HWEIGHT_WHOLE */
493 int usage_idx;
494 u32 usages[NR_USAGE_SLOTS];
495
496 /* this iocg's depth in the hierarchy and ancestors including self */
497 int level;
498 struct ioc_gq *ancestors[];
499};
500
501/* per cgroup */
502struct ioc_cgrp {
503 struct blkcg_policy_data cpd;
504 unsigned int dfl_weight;
505};
506
507struct ioc_now {
508 u64 now_ns;
509 u32 now;
510 u64 vnow;
511 u64 vrate;
512};
513
514struct iocg_wait {
515 struct wait_queue_entry wait;
516 struct bio *bio;
517 u64 abs_cost;
518 bool committed;
519};
520
521struct iocg_wake_ctx {
522 struct ioc_gq *iocg;
523 u32 hw_inuse;
524 s64 vbudget;
525};
526
527static const struct ioc_params autop[] = {
528 [AUTOP_HDD] = {
529 .qos = {
530 [QOS_RLAT] = 250000, /* 250ms */
531 [QOS_WLAT] = 250000,
532 [QOS_MIN] = VRATE_MIN_PPM,
533 [QOS_MAX] = VRATE_MAX_PPM,
534 },
535 .i_lcoefs = {
536 [I_LCOEF_RBPS] = 174019176,
537 [I_LCOEF_RSEQIOPS] = 41708,
538 [I_LCOEF_RRANDIOPS] = 370,
539 [I_LCOEF_WBPS] = 178075866,
540 [I_LCOEF_WSEQIOPS] = 42705,
541 [I_LCOEF_WRANDIOPS] = 378,
542 },
543 },
544 [AUTOP_SSD_QD1] = {
545 .qos = {
546 [QOS_RLAT] = 25000, /* 25ms */
547 [QOS_WLAT] = 25000,
548 [QOS_MIN] = VRATE_MIN_PPM,
549 [QOS_MAX] = VRATE_MAX_PPM,
550 },
551 .i_lcoefs = {
552 [I_LCOEF_RBPS] = 245855193,
553 [I_LCOEF_RSEQIOPS] = 61575,
554 [I_LCOEF_RRANDIOPS] = 6946,
555 [I_LCOEF_WBPS] = 141365009,
556 [I_LCOEF_WSEQIOPS] = 33716,
557 [I_LCOEF_WRANDIOPS] = 26796,
558 },
559 },
560 [AUTOP_SSD_DFL] = {
561 .qos = {
562 [QOS_RLAT] = 25000, /* 25ms */
563 [QOS_WLAT] = 25000,
564 [QOS_MIN] = VRATE_MIN_PPM,
565 [QOS_MAX] = VRATE_MAX_PPM,
566 },
567 .i_lcoefs = {
568 [I_LCOEF_RBPS] = 488636629,
569 [I_LCOEF_RSEQIOPS] = 8932,
570 [I_LCOEF_RRANDIOPS] = 8518,
571 [I_LCOEF_WBPS] = 427891549,
572 [I_LCOEF_WSEQIOPS] = 28755,
573 [I_LCOEF_WRANDIOPS] = 21940,
574 },
575 .too_fast_vrate_pct = 500,
576 },
577 [AUTOP_SSD_FAST] = {
578 .qos = {
579 [QOS_RLAT] = 5000, /* 5ms */
580 [QOS_WLAT] = 5000,
581 [QOS_MIN] = VRATE_MIN_PPM,
582 [QOS_MAX] = VRATE_MAX_PPM,
583 },
584 .i_lcoefs = {
585 [I_LCOEF_RBPS] = 3102524156LLU,
586 [I_LCOEF_RSEQIOPS] = 724816,
587 [I_LCOEF_RRANDIOPS] = 778122,
588 [I_LCOEF_WBPS] = 1742780862LLU,
589 [I_LCOEF_WSEQIOPS] = 425702,
590 [I_LCOEF_WRANDIOPS] = 443193,
591 },
592 .too_slow_vrate_pct = 10,
593 },
594};
595
596/*
597 * vrate adjust percentages indexed by ioc->busy_level. We adjust up on
598 * vtime credit shortage and down on device saturation.
599 */
600static u32 vrate_adj_pct[] =
601 { 0, 0, 0, 0,
602 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
603 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
604 4, 4, 4, 4, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, 16 };
605
606static struct blkcg_policy blkcg_policy_iocost;
607
608/* accessors and helpers */
609static struct ioc *rqos_to_ioc(struct rq_qos *rqos)
610{
611 return container_of(rqos, struct ioc, rqos);
612}
613
614static struct ioc *q_to_ioc(struct request_queue *q)
615{
616 return rqos_to_ioc(rq_qos_id(q, RQ_QOS_COST));
617}
618
619static const char *q_name(struct request_queue *q)
620{
621 if (test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
622 return kobject_name(q->kobj.parent);
623 else
624 return "<unknown>";
625}
626
627static const char __maybe_unused *ioc_name(struct ioc *ioc)
628{
629 return q_name(ioc->rqos.q);
630}
631
632static struct ioc_gq *pd_to_iocg(struct blkg_policy_data *pd)
633{
634 return pd ? container_of(pd, struct ioc_gq, pd) : NULL;
635}
636
637static struct ioc_gq *blkg_to_iocg(struct blkcg_gq *blkg)
638{
639 return pd_to_iocg(blkg_to_pd(blkg, &blkcg_policy_iocost));
640}
641
642static struct blkcg_gq *iocg_to_blkg(struct ioc_gq *iocg)
643{
644 return pd_to_blkg(&iocg->pd);
645}
646
647static struct ioc_cgrp *blkcg_to_iocc(struct blkcg *blkcg)
648{
649 return container_of(blkcg_to_cpd(blkcg, &blkcg_policy_iocost),
650 struct ioc_cgrp, cpd);
651}
652
653/*
654 * Scale @abs_cost to the inverse of @hw_inuse. The lower the hierarchical
655 * weight, the more expensive each IO. Must round up.
656 */
657static u64 abs_cost_to_cost(u64 abs_cost, u32 hw_inuse)
658{
659 return DIV64_U64_ROUND_UP(abs_cost * HWEIGHT_WHOLE, hw_inuse);
660}
661
662/*
663 * The inverse of abs_cost_to_cost(). Must round up.
664 */
665static u64 cost_to_abs_cost(u64 cost, u32 hw_inuse)
666{
667 return DIV64_U64_ROUND_UP(cost * hw_inuse, HWEIGHT_WHOLE);
668}
669
670static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio, u64 cost)
671{
672 bio->bi_iocost_cost = cost;
673 atomic64_add(cost, &iocg->vtime);
674}
675
676#define CREATE_TRACE_POINTS
677#include <trace/events/iocost.h>
678
679/* latency Qos params changed, update period_us and all the dependent params */
680static void ioc_refresh_period_us(struct ioc *ioc)
681{
682 u32 ppm, lat, multi, period_us;
683
684 lockdep_assert_held(&ioc->lock);
685
686 /* pick the higher latency target */
687 if (ioc->params.qos[QOS_RLAT] >= ioc->params.qos[QOS_WLAT]) {
688 ppm = ioc->params.qos[QOS_RPPM];
689 lat = ioc->params.qos[QOS_RLAT];
690 } else {
691 ppm = ioc->params.qos[QOS_WPPM];
692 lat = ioc->params.qos[QOS_WLAT];
693 }
694
695 /*
696 * We want the period to be long enough to contain a healthy number
697 * of IOs while short enough for granular control. Define it as a
698 * multiple of the latency target. Ideally, the multiplier should
699 * be scaled according to the percentile so that it would nominally
700 * contain a certain number of requests. Let's be simpler and
701 * scale it linearly so that it's 2x >= pct(90) and 10x at pct(50).
702 */
703 if (ppm)
704 multi = max_t(u32, (MILLION - ppm) / 50000, 2);
705 else
706 multi = 2;
707 period_us = multi * lat;
708 period_us = clamp_t(u32, period_us, MIN_PERIOD, MAX_PERIOD);
709
710 /* calculate dependent params */
711 ioc->period_us = period_us;
712 ioc->margin_us = period_us * MARGIN_PCT / 100;
713 ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP(
714 period_us * VTIME_PER_USEC * INUSE_MARGIN_PCT, 100);
715}
716
717static int ioc_autop_idx(struct ioc *ioc)
718{
719 int idx = ioc->autop_idx;
720 const struct ioc_params *p = &autop[idx];
721 u32 vrate_pct;
722 u64 now_ns;
723
724 /* rotational? */
725 if (!blk_queue_nonrot(ioc->rqos.q))
726 return AUTOP_HDD;
727
728 /* handle SATA SSDs w/ broken NCQ */
729 if (blk_queue_depth(ioc->rqos.q) == 1)
730 return AUTOP_SSD_QD1;
731
732 /* use one of the normal ssd sets */
733 if (idx < AUTOP_SSD_DFL)
734 return AUTOP_SSD_DFL;
735
736 /* if user is overriding anything, maintain what was there */
737 if (ioc->user_qos_params || ioc->user_cost_model)
738 return idx;
739
740 /* step up/down based on the vrate */
741 vrate_pct = div64_u64(atomic64_read(&ioc->vtime_rate) * 100,
742 VTIME_PER_USEC);
743 now_ns = ktime_get_ns();
744
745 if (p->too_fast_vrate_pct && p->too_fast_vrate_pct <= vrate_pct) {
746 if (!ioc->autop_too_fast_at)
747 ioc->autop_too_fast_at = now_ns;
748 if (now_ns - ioc->autop_too_fast_at >= AUTOP_CYCLE_NSEC)
749 return idx + 1;
750 } else {
751 ioc->autop_too_fast_at = 0;
752 }
753
754 if (p->too_slow_vrate_pct && p->too_slow_vrate_pct >= vrate_pct) {
755 if (!ioc->autop_too_slow_at)
756 ioc->autop_too_slow_at = now_ns;
757 if (now_ns - ioc->autop_too_slow_at >= AUTOP_CYCLE_NSEC)
758 return idx - 1;
759 } else {
760 ioc->autop_too_slow_at = 0;
761 }
762
763 return idx;
764}
765
766/*
767 * Take the followings as input
768 *
769 * @bps maximum sequential throughput
770 * @seqiops maximum sequential 4k iops
771 * @randiops maximum random 4k iops
772 *
773 * and calculate the linear model cost coefficients.
774 *
775 * *@page per-page cost 1s / (@bps / 4096)
776 * *@seqio base cost of a seq IO max((1s / @seqiops) - *@page, 0)
777 * @randiops base cost of a rand IO max((1s / @randiops) - *@page, 0)
778 */
779static void calc_lcoefs(u64 bps, u64 seqiops, u64 randiops,
780 u64 *page, u64 *seqio, u64 *randio)
781{
782 u64 v;
783
784 *page = *seqio = *randio = 0;
785
786 if (bps)
787 *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC,
788 DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE));
789
790 if (seqiops) {
791 v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, seqiops);
792 if (v > *page)
793 *seqio = v - *page;
794 }
795
796 if (randiops) {
797 v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, randiops);
798 if (v > *page)
799 *randio = v - *page;
800 }
801}
802
803static void ioc_refresh_lcoefs(struct ioc *ioc)
804{
805 u64 *u = ioc->params.i_lcoefs;
806 u64 *c = ioc->params.lcoefs;
807
808 calc_lcoefs(u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS],
809 &c[LCOEF_RPAGE], &c[LCOEF_RSEQIO], &c[LCOEF_RRANDIO]);
810 calc_lcoefs(u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS],
811 &c[LCOEF_WPAGE], &c[LCOEF_WSEQIO], &c[LCOEF_WRANDIO]);
812}
813
814static bool ioc_refresh_params(struct ioc *ioc, bool force)
815{
816 const struct ioc_params *p;
817 int idx;
818
819 lockdep_assert_held(&ioc->lock);
820
821 idx = ioc_autop_idx(ioc);
822 p = &autop[idx];
823
824 if (idx == ioc->autop_idx && !force)
825 return false;
826
827 if (idx != ioc->autop_idx)
828 atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC);
829
830 ioc->autop_idx = idx;
831 ioc->autop_too_fast_at = 0;
832 ioc->autop_too_slow_at = 0;
833
834 if (!ioc->user_qos_params)
835 memcpy(ioc->params.qos, p->qos, sizeof(p->qos));
836 if (!ioc->user_cost_model)
837 memcpy(ioc->params.i_lcoefs, p->i_lcoefs, sizeof(p->i_lcoefs));
838
839 ioc_refresh_period_us(ioc);
840 ioc_refresh_lcoefs(ioc);
841
842 ioc->vrate_min = DIV64_U64_ROUND_UP((u64)ioc->params.qos[QOS_MIN] *
843 VTIME_PER_USEC, MILLION);
844 ioc->vrate_max = div64_u64((u64)ioc->params.qos[QOS_MAX] *
845 VTIME_PER_USEC, MILLION);
846
847 return true;
848}
849
850/* take a snapshot of the current [v]time and vrate */
851static void ioc_now(struct ioc *ioc, struct ioc_now *now)
852{
853 unsigned seq;
854
855 now->now_ns = ktime_get();
856 now->now = ktime_to_us(now->now_ns);
857 now->vrate = atomic64_read(&ioc->vtime_rate);
858
859 /*
860 * The current vtime is
861 *
862 * vtime at period start + (wallclock time since the start) * vrate
863 *
864 * As a consistent snapshot of `period_at_vtime` and `period_at` is
865 * needed, they're seqcount protected.
866 */
867 do {
868 seq = read_seqcount_begin(&ioc->period_seqcount);
869 now->vnow = ioc->period_at_vtime +
870 (now->now - ioc->period_at) * now->vrate;
871 } while (read_seqcount_retry(&ioc->period_seqcount, seq));
872}
873
874static void ioc_start_period(struct ioc *ioc, struct ioc_now *now)
875{
876 WARN_ON_ONCE(ioc->running != IOC_RUNNING);
877
878 write_seqcount_begin(&ioc->period_seqcount);
879 ioc->period_at = now->now;
880 ioc->period_at_vtime = now->vnow;
881 write_seqcount_end(&ioc->period_seqcount);
882
883 ioc->timer.expires = jiffies + usecs_to_jiffies(ioc->period_us);
884 add_timer(&ioc->timer);
885}
886
887/*
888 * Update @iocg's `active` and `inuse` to @active and @inuse, update level
889 * weight sums and propagate upwards accordingly.
890 */
891static void __propagate_active_weight(struct ioc_gq *iocg, u32 active, u32 inuse)
892{
893 struct ioc *ioc = iocg->ioc;
894 int lvl;
895
896 lockdep_assert_held(&ioc->lock);
897
898 inuse = min(active, inuse);
899
900 for (lvl = iocg->level - 1; lvl >= 0; lvl--) {
901 struct ioc_gq *parent = iocg->ancestors[lvl];
902 struct ioc_gq *child = iocg->ancestors[lvl + 1];
903 u32 parent_active = 0, parent_inuse = 0;
904
905 /* update the level sums */
906 parent->child_active_sum += (s32)(active - child->active);
907 parent->child_inuse_sum += (s32)(inuse - child->inuse);
908 /* apply the udpates */
909 child->active = active;
910 child->inuse = inuse;
911
912 /*
913 * The delta between inuse and active sums indicates that
914 * that much of weight is being given away. Parent's inuse
915 * and active should reflect the ratio.
916 */
917 if (parent->child_active_sum) {
918 parent_active = parent->weight;
919 parent_inuse = DIV64_U64_ROUND_UP(
920 parent_active * parent->child_inuse_sum,
921 parent->child_active_sum);
922 }
923
924 /* do we need to keep walking up? */
925 if (parent_active == parent->active &&
926 parent_inuse == parent->inuse)
927 break;
928
929 active = parent_active;
930 inuse = parent_inuse;
931 }
932
933 ioc->weights_updated = true;
934}
935
936static void commit_active_weights(struct ioc *ioc)
937{
938 lockdep_assert_held(&ioc->lock);
939
940 if (ioc->weights_updated) {
941 /* paired with rmb in current_hweight(), see there */
942 smp_wmb();
943 atomic_inc(&ioc->hweight_gen);
944 ioc->weights_updated = false;
945 }
946}
947
948static void propagate_active_weight(struct ioc_gq *iocg, u32 active, u32 inuse)
949{
950 __propagate_active_weight(iocg, active, inuse);
951 commit_active_weights(iocg->ioc);
952}
953
954static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep)
955{
956 struct ioc *ioc = iocg->ioc;
957 int lvl;
958 u32 hwa, hwi;
959 int ioc_gen;
960
961 /* hot path - if uptodate, use cached */
962 ioc_gen = atomic_read(&ioc->hweight_gen);
963 if (ioc_gen == iocg->hweight_gen)
964 goto out;
965
966 /*
967 * Paired with wmb in commit_active_weights(). If we saw the
968 * updated hweight_gen, all the weight updates from
969 * __propagate_active_weight() are visible too.
970 *
971 * We can race with weight updates during calculation and get it
972 * wrong. However, hweight_gen would have changed and a future
973 * reader will recalculate and we're guaranteed to discard the
974 * wrong result soon.
975 */
976 smp_rmb();
977
978 hwa = hwi = HWEIGHT_WHOLE;
979 for (lvl = 0; lvl <= iocg->level - 1; lvl++) {
980 struct ioc_gq *parent = iocg->ancestors[lvl];
981 struct ioc_gq *child = iocg->ancestors[lvl + 1];
982 u32 active_sum = READ_ONCE(parent->child_active_sum);
983 u32 inuse_sum = READ_ONCE(parent->child_inuse_sum);
984 u32 active = READ_ONCE(child->active);
985 u32 inuse = READ_ONCE(child->inuse);
986
987 /* we can race with deactivations and either may read as zero */
988 if (!active_sum || !inuse_sum)
989 continue;
990
991 active_sum = max(active, active_sum);
992 hwa = hwa * active / active_sum; /* max 16bits * 10000 */
993
994 inuse_sum = max(inuse, inuse_sum);
995 hwi = hwi * inuse / inuse_sum; /* max 16bits * 10000 */
996 }
997
998 iocg->hweight_active = max_t(u32, hwa, 1);
999 iocg->hweight_inuse = max_t(u32, hwi, 1);
1000 iocg->hweight_gen = ioc_gen;
1001out:
1002 if (hw_activep)
1003 *hw_activep = iocg->hweight_active;
1004 if (hw_inusep)
1005 *hw_inusep = iocg->hweight_inuse;
1006}
1007
1008static void weight_updated(struct ioc_gq *iocg)
1009{
1010 struct ioc *ioc = iocg->ioc;
1011 struct blkcg_gq *blkg = iocg_to_blkg(iocg);
1012 struct ioc_cgrp *iocc = blkcg_to_iocc(blkg->blkcg);
1013 u32 weight;
1014
1015 lockdep_assert_held(&ioc->lock);
1016
1017 weight = iocg->cfg_weight ?: iocc->dfl_weight;
1018 if (weight != iocg->weight && iocg->active)
1019 propagate_active_weight(iocg, weight,
1020 DIV64_U64_ROUND_UP(iocg->inuse * weight, iocg->weight));
1021 iocg->weight = weight;
1022}
1023
1024static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now)
1025{
1026 struct ioc *ioc = iocg->ioc;
1027 u64 last_period, cur_period, max_period_delta;
1028 u64 vtime, vmargin, vmin;
1029 int i;
1030
1031 /*
1032 * If seem to be already active, just update the stamp to tell the
1033 * timer that we're still active. We don't mind occassional races.
1034 */
1035 if (!list_empty(&iocg->active_list)) {
1036 ioc_now(ioc, now);
1037 cur_period = atomic64_read(&ioc->cur_period);
1038 if (atomic64_read(&iocg->active_period) != cur_period)
1039 atomic64_set(&iocg->active_period, cur_period);
1040 return true;
1041 }
1042
1043 /* racy check on internal node IOs, treat as root level IOs */
1044 if (iocg->child_active_sum)
1045 return false;
1046
1047 spin_lock_irq(&ioc->lock);
1048
1049 ioc_now(ioc, now);
1050
1051 /* update period */
1052 cur_period = atomic64_read(&ioc->cur_period);
1053 last_period = atomic64_read(&iocg->active_period);
1054 atomic64_set(&iocg->active_period, cur_period);
1055
1056 /* already activated or breaking leaf-only constraint? */
1057 if (!list_empty(&iocg->active_list))
1058 goto succeed_unlock;
1059 for (i = iocg->level - 1; i > 0; i--)
1060 if (!list_empty(&iocg->ancestors[i]->active_list))
1061 goto fail_unlock;
1062
1063 if (iocg->child_active_sum)
1064 goto fail_unlock;
1065
1066 /*
1067 * vtime may wrap when vrate is raised substantially due to
1068 * underestimated IO costs. Look at the period and ignore its
1069 * vtime if the iocg has been idle for too long. Also, cap the
1070 * budget it can start with to the margin.
1071 */
1072 max_period_delta = DIV64_U64_ROUND_UP(VTIME_VALID_DUR, ioc->period_us);
1073 vtime = atomic64_read(&iocg->vtime);
1074 vmargin = ioc->margin_us * now->vrate;
1075 vmin = now->vnow - vmargin;
1076
1077 if (last_period + max_period_delta < cur_period ||
1078 time_before64(vtime, vmin)) {
1079 atomic64_add(vmin - vtime, &iocg->vtime);
1080 atomic64_add(vmin - vtime, &iocg->done_vtime);
1081 vtime = vmin;
1082 }
1083
1084 /*
1085 * Activate, propagate weight and start period timer if not
1086 * running. Reset hweight_gen to avoid accidental match from
1087 * wrapping.
1088 */
1089 iocg->hweight_gen = atomic_read(&ioc->hweight_gen) - 1;
1090 list_add(&iocg->active_list, &ioc->active_iocgs);
1091 propagate_active_weight(iocg, iocg->weight,
1092 iocg->last_inuse ?: iocg->weight);
1093
1094 TRACE_IOCG_PATH(iocg_activate, iocg, now,
1095 last_period, cur_period, vtime);
1096
1097 iocg->last_vtime = vtime;
1098
1099 if (ioc->running == IOC_IDLE) {
1100 ioc->running = IOC_RUNNING;
1101 ioc_start_period(ioc, now);
1102 }
1103
1104succeed_unlock:
1105 spin_unlock_irq(&ioc->lock);
1106 return true;
1107
1108fail_unlock:
1109 spin_unlock_irq(&ioc->lock);
1110 return false;
1111}
1112
1113static int iocg_wake_fn(struct wait_queue_entry *wq_entry, unsigned mode,
1114 int flags, void *key)
1115{
1116 struct iocg_wait *wait = container_of(wq_entry, struct iocg_wait, wait);
1117 struct iocg_wake_ctx *ctx = (struct iocg_wake_ctx *)key;
1118 u64 cost = abs_cost_to_cost(wait->abs_cost, ctx->hw_inuse);
1119
1120 ctx->vbudget -= cost;
1121
1122 if (ctx->vbudget < 0)
1123 return -1;
1124
1125 iocg_commit_bio(ctx->iocg, wait->bio, cost);
1126
1127 /*
1128 * autoremove_wake_function() removes the wait entry only when it
1129 * actually changed the task state. We want the wait always
1130 * removed. Remove explicitly and use default_wake_function().
1131 */
1132 list_del_init(&wq_entry->entry);
1133 wait->committed = true;
1134
1135 default_wake_function(wq_entry, mode, flags, key);
1136 return 0;
1137}
1138
1139static void iocg_kick_waitq(struct ioc_gq *iocg, struct ioc_now *now)
1140{
1141 struct ioc *ioc = iocg->ioc;
1142 struct iocg_wake_ctx ctx = { .iocg = iocg };
1143 u64 margin_ns = (u64)(ioc->period_us *
1144 WAITQ_TIMER_MARGIN_PCT / 100) * NSEC_PER_USEC;
1145 u64 vdebt, vshortage, expires, oexpires;
1146 s64 vbudget;
1147 u32 hw_inuse;
1148
1149 lockdep_assert_held(&iocg->waitq.lock);
1150
1151 current_hweight(iocg, NULL, &hw_inuse);
1152 vbudget = now->vnow - atomic64_read(&iocg->vtime);
1153
1154 /* pay off debt */
1155 vdebt = abs_cost_to_cost(iocg->abs_vdebt, hw_inuse);
1156 if (vdebt && vbudget > 0) {
1157 u64 delta = min_t(u64, vbudget, vdebt);
1158 u64 abs_delta = min(cost_to_abs_cost(delta, hw_inuse),
1159 iocg->abs_vdebt);
1160
1161 atomic64_add(delta, &iocg->vtime);
1162 atomic64_add(delta, &iocg->done_vtime);
1163 iocg->abs_vdebt -= abs_delta;
1164 }
1165
1166 /*
1167 * Wake up the ones which are due and see how much vtime we'll need
1168 * for the next one.
1169 */
1170 ctx.hw_inuse = hw_inuse;
1171 ctx.vbudget = vbudget - vdebt;
1172 __wake_up_locked_key(&iocg->waitq, TASK_NORMAL, &ctx);
1173 if (!waitqueue_active(&iocg->waitq))
1174 return;
1175 if (WARN_ON_ONCE(ctx.vbudget >= 0))
1176 return;
1177
1178 /* determine next wakeup, add a quarter margin to guarantee chunking */
1179 vshortage = -ctx.vbudget;
1180 expires = now->now_ns +
1181 DIV64_U64_ROUND_UP(vshortage, now->vrate) * NSEC_PER_USEC;
1182 expires += margin_ns / 4;
1183
1184 /* if already active and close enough, don't bother */
1185 oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->waitq_timer));
1186 if (hrtimer_is_queued(&iocg->waitq_timer) &&
1187 abs(oexpires - expires) <= margin_ns / 4)
1188 return;
1189
1190 hrtimer_start_range_ns(&iocg->waitq_timer, ns_to_ktime(expires),
1191 margin_ns / 4, HRTIMER_MODE_ABS);
1192}
1193
1194static enum hrtimer_restart iocg_waitq_timer_fn(struct hrtimer *timer)
1195{
1196 struct ioc_gq *iocg = container_of(timer, struct ioc_gq, waitq_timer);
1197 struct ioc_now now;
1198 unsigned long flags;
1199
1200 ioc_now(iocg->ioc, &now);
1201
1202 spin_lock_irqsave(&iocg->waitq.lock, flags);
1203 iocg_kick_waitq(iocg, &now);
1204 spin_unlock_irqrestore(&iocg->waitq.lock, flags);
1205
1206 return HRTIMER_NORESTART;
1207}
1208
1209static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
1210{
1211 struct ioc *ioc = iocg->ioc;
1212 struct blkcg_gq *blkg = iocg_to_blkg(iocg);
1213 u64 vtime = atomic64_read(&iocg->vtime);
1214 u64 vmargin = ioc->margin_us * now->vrate;
1215 u64 margin_ns = ioc->margin_us * NSEC_PER_USEC;
1216 u64 delta_ns, expires, oexpires;
1217 u32 hw_inuse;
1218
1219 lockdep_assert_held(&iocg->waitq.lock);
1220
1221 /* debt-adjust vtime */
1222 current_hweight(iocg, NULL, &hw_inuse);
1223 vtime += abs_cost_to_cost(iocg->abs_vdebt, hw_inuse);
1224
1225 /*
1226 * Clear or maintain depending on the overage. Non-zero vdebt is what
1227 * guarantees that @iocg is online and future iocg_kick_delay() will
1228 * clear use_delay. Don't leave it on when there's no vdebt.
1229 */
1230 if (!iocg->abs_vdebt || time_before_eq64(vtime, now->vnow)) {
1231 blkcg_clear_delay(blkg);
1232 return false;
1233 }
1234 if (!atomic_read(&blkg->use_delay) &&
1235 time_before_eq64(vtime, now->vnow + vmargin))
1236 return false;
1237
1238 /* use delay */
1239 delta_ns = DIV64_U64_ROUND_UP(vtime - now->vnow,
1240 now->vrate) * NSEC_PER_USEC;
1241 blkcg_set_delay(blkg, delta_ns);
1242 expires = now->now_ns + delta_ns;
1243
1244 /* if already active and close enough, don't bother */
1245 oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->delay_timer));
1246 if (hrtimer_is_queued(&iocg->delay_timer) &&
1247 abs(oexpires - expires) <= margin_ns / 4)
1248 return true;
1249
1250 hrtimer_start_range_ns(&iocg->delay_timer, ns_to_ktime(expires),
1251 margin_ns / 4, HRTIMER_MODE_ABS);
1252 return true;
1253}
1254
1255static enum hrtimer_restart iocg_delay_timer_fn(struct hrtimer *timer)
1256{
1257 struct ioc_gq *iocg = container_of(timer, struct ioc_gq, delay_timer);
1258 struct ioc_now now;
1259 unsigned long flags;
1260
1261 spin_lock_irqsave(&iocg->waitq.lock, flags);
1262 ioc_now(iocg->ioc, &now);
1263 iocg_kick_delay(iocg, &now);
1264 spin_unlock_irqrestore(&iocg->waitq.lock, flags);
1265
1266 return HRTIMER_NORESTART;
1267}
1268
1269static void ioc_lat_stat(struct ioc *ioc, u32 *missed_ppm_ar, u32 *rq_wait_pct_p)
1270{
1271 u32 nr_met[2] = { };
1272 u32 nr_missed[2] = { };
1273 u64 rq_wait_ns = 0;
1274 int cpu, rw;
1275
1276 for_each_online_cpu(cpu) {
1277 struct ioc_pcpu_stat *stat = per_cpu_ptr(ioc->pcpu_stat, cpu);
1278 u64 this_rq_wait_ns;
1279
1280 for (rw = READ; rw <= WRITE; rw++) {
1281 u32 this_met = READ_ONCE(stat->missed[rw].nr_met);
1282 u32 this_missed = READ_ONCE(stat->missed[rw].nr_missed);
1283
1284 nr_met[rw] += this_met - stat->missed[rw].last_met;
1285 nr_missed[rw] += this_missed - stat->missed[rw].last_missed;
1286 stat->missed[rw].last_met = this_met;
1287 stat->missed[rw].last_missed = this_missed;
1288 }
1289
1290 this_rq_wait_ns = READ_ONCE(stat->rq_wait_ns);
1291 rq_wait_ns += this_rq_wait_ns - stat->last_rq_wait_ns;
1292 stat->last_rq_wait_ns = this_rq_wait_ns;
1293 }
1294
1295 for (rw = READ; rw <= WRITE; rw++) {
1296 if (nr_met[rw] + nr_missed[rw])
1297 missed_ppm_ar[rw] =
1298 DIV64_U64_ROUND_UP((u64)nr_missed[rw] * MILLION,
1299 nr_met[rw] + nr_missed[rw]);
1300 else
1301 missed_ppm_ar[rw] = 0;
1302 }
1303
1304 *rq_wait_pct_p = div64_u64(rq_wait_ns * 100,
1305 ioc->period_us * NSEC_PER_USEC);
1306}
1307
1308/* was iocg idle this period? */
1309static bool iocg_is_idle(struct ioc_gq *iocg)
1310{
1311 struct ioc *ioc = iocg->ioc;
1312
1313 /* did something get issued this period? */
1314 if (atomic64_read(&iocg->active_period) ==
1315 atomic64_read(&ioc->cur_period))
1316 return false;
1317
1318 /* is something in flight? */
1319 if (atomic64_read(&iocg->done_vtime) != atomic64_read(&iocg->vtime))
1320 return false;
1321
1322 return true;
1323}
1324
1325/* returns usage with margin added if surplus is large enough */
1326static u32 surplus_adjusted_hweight_inuse(u32 usage, u32 hw_inuse)
1327{
1328 /* add margin */
1329 usage = DIV_ROUND_UP(usage * SURPLUS_SCALE_PCT, 100);
1330 usage += SURPLUS_SCALE_ABS;
1331
1332 /* don't bother if the surplus is too small */
1333 if (usage + SURPLUS_MIN_ADJ_DELTA > hw_inuse)
1334 return 0;
1335
1336 return usage;
1337}
1338
1339static void ioc_timer_fn(struct timer_list *timer)
1340{
1341 struct ioc *ioc = container_of(timer, struct ioc, timer);
1342 struct ioc_gq *iocg, *tiocg;
1343 struct ioc_now now;
1344 int nr_surpluses = 0, nr_shortages = 0, nr_lagging = 0;
1345 u32 ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM];
1346 u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM];
1347 u32 missed_ppm[2], rq_wait_pct;
1348 u64 period_vtime;
1349 int prev_busy_level, i;
1350
1351 /* how were the latencies during the period? */
1352 ioc_lat_stat(ioc, missed_ppm, &rq_wait_pct);
1353
1354 /* take care of active iocgs */
1355 spin_lock_irq(&ioc->lock);
1356
1357 ioc_now(ioc, &now);
1358
1359 period_vtime = now.vnow - ioc->period_at_vtime;
1360 if (WARN_ON_ONCE(!period_vtime)) {
1361 spin_unlock_irq(&ioc->lock);
1362 return;
1363 }
1364
1365 /*
1366 * Waiters determine the sleep durations based on the vrate they
1367 * saw at the time of sleep. If vrate has increased, some waiters
1368 * could be sleeping for too long. Wake up tardy waiters which
1369 * should have woken up in the last period and expire idle iocgs.
1370 */
1371 list_for_each_entry_safe(iocg, tiocg, &ioc->active_iocgs, active_list) {
1372 if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
1373 !iocg_is_idle(iocg))
1374 continue;
1375
1376 spin_lock(&iocg->waitq.lock);
1377
1378 if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt) {
1379 /* might be oversleeping vtime / hweight changes, kick */
1380 iocg_kick_waitq(iocg, &now);
1381 iocg_kick_delay(iocg, &now);
1382 } else if (iocg_is_idle(iocg)) {
1383 /* no waiter and idle, deactivate */
1384 iocg->last_inuse = iocg->inuse;
1385 __propagate_active_weight(iocg, 0, 0);
1386 list_del_init(&iocg->active_list);
1387 }
1388
1389 spin_unlock(&iocg->waitq.lock);
1390 }
1391 commit_active_weights(ioc);
1392
1393 /* calc usages and see whether some weights need to be moved around */
1394 list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
1395 u64 vdone, vtime, vusage, vmargin, vmin;
1396 u32 hw_active, hw_inuse, usage;
1397
1398 /*
1399 * Collect unused and wind vtime closer to vnow to prevent
1400 * iocgs from accumulating a large amount of budget.
1401 */
1402 vdone = atomic64_read(&iocg->done_vtime);
1403 vtime = atomic64_read(&iocg->vtime);
1404 current_hweight(iocg, &hw_active, &hw_inuse);
1405
1406 /*
1407 * Latency QoS detection doesn't account for IOs which are
1408 * in-flight for longer than a period. Detect them by
1409 * comparing vdone against period start. If lagging behind
1410 * IOs from past periods, don't increase vrate.
1411 */
1412 if ((ppm_rthr != MILLION || ppm_wthr != MILLION) &&
1413 !atomic_read(&iocg_to_blkg(iocg)->use_delay) &&
1414 time_after64(vtime, vdone) &&
1415 time_after64(vtime, now.vnow -
1416 MAX_LAGGING_PERIODS * period_vtime) &&
1417 time_before64(vdone, now.vnow - period_vtime))
1418 nr_lagging++;
1419
1420 if (waitqueue_active(&iocg->waitq))
1421 vusage = now.vnow - iocg->last_vtime;
1422 else if (time_before64(iocg->last_vtime, vtime))
1423 vusage = vtime - iocg->last_vtime;
1424 else
1425 vusage = 0;
1426
1427 iocg->last_vtime += vusage;
1428 /*
1429 * Factor in in-flight vtime into vusage to avoid
1430 * high-latency completions appearing as idle. This should
1431 * be done after the above ->last_time adjustment.
1432 */
1433 vusage = max(vusage, vtime - vdone);
1434
1435 /* calculate hweight based usage ratio and record */
1436 if (vusage) {
1437 usage = DIV64_U64_ROUND_UP(vusage * hw_inuse,
1438 period_vtime);
1439 iocg->usage_idx = (iocg->usage_idx + 1) % NR_USAGE_SLOTS;
1440 iocg->usages[iocg->usage_idx] = usage;
1441 } else {
1442 usage = 0;
1443 }
1444
1445 /* see whether there's surplus vtime */
1446 vmargin = ioc->margin_us * now.vrate;
1447 vmin = now.vnow - vmargin;
1448
1449 iocg->has_surplus = false;
1450
1451 if (!waitqueue_active(&iocg->waitq) &&
1452 time_before64(vtime, vmin)) {
1453 u64 delta = vmin - vtime;
1454
1455 /* throw away surplus vtime */
1456 atomic64_add(delta, &iocg->vtime);
1457 atomic64_add(delta, &iocg->done_vtime);
1458 iocg->last_vtime += delta;
1459 /* if usage is sufficiently low, maybe it can donate */
1460 if (surplus_adjusted_hweight_inuse(usage, hw_inuse)) {
1461 iocg->has_surplus = true;
1462 nr_surpluses++;
1463 }
1464 } else if (hw_inuse < hw_active) {
1465 u32 new_hwi, new_inuse;
1466
1467 /* was donating but might need to take back some */
1468 if (waitqueue_active(&iocg->waitq)) {
1469 new_hwi = hw_active;
1470 } else {
1471 new_hwi = max(hw_inuse,
1472 usage * SURPLUS_SCALE_PCT / 100 +
1473 SURPLUS_SCALE_ABS);
1474 }
1475
1476 new_inuse = div64_u64((u64)iocg->inuse * new_hwi,
1477 hw_inuse);
1478 new_inuse = clamp_t(u32, new_inuse, 1, iocg->active);
1479
1480 if (new_inuse > iocg->inuse) {
1481 TRACE_IOCG_PATH(inuse_takeback, iocg, &now,
1482 iocg->inuse, new_inuse,
1483 hw_inuse, new_hwi);
1484 __propagate_active_weight(iocg, iocg->weight,
1485 new_inuse);
1486 }
1487 } else {
1488 /* genuninely out of vtime */
1489 nr_shortages++;
1490 }
1491 }
1492
1493 if (!nr_shortages || !nr_surpluses)
1494 goto skip_surplus_transfers;
1495
1496 /* there are both shortages and surpluses, transfer surpluses */
1497 list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
1498 u32 usage, hw_active, hw_inuse, new_hwi, new_inuse;
1499 int nr_valid = 0;
1500
1501 if (!iocg->has_surplus)
1502 continue;
1503
1504 /* base the decision on max historical usage */
1505 for (i = 0, usage = 0; i < NR_USAGE_SLOTS; i++) {
1506 if (iocg->usages[i]) {
1507 usage = max(usage, iocg->usages[i]);
1508 nr_valid++;
1509 }
1510 }
1511 if (nr_valid < MIN_VALID_USAGES)
1512 continue;
1513
1514 current_hweight(iocg, &hw_active, &hw_inuse);
1515 new_hwi = surplus_adjusted_hweight_inuse(usage, hw_inuse);
1516 if (!new_hwi)
1517 continue;
1518
1519 new_inuse = DIV64_U64_ROUND_UP((u64)iocg->inuse * new_hwi,
1520 hw_inuse);
1521 if (new_inuse < iocg->inuse) {
1522 TRACE_IOCG_PATH(inuse_giveaway, iocg, &now,
1523 iocg->inuse, new_inuse,
1524 hw_inuse, new_hwi);
1525 __propagate_active_weight(iocg, iocg->weight, new_inuse);
1526 }
1527 }
1528skip_surplus_transfers:
1529 commit_active_weights(ioc);
1530
1531 /*
1532 * If q is getting clogged or we're missing too much, we're issuing
1533 * too much IO and should lower vtime rate. If we're not missing
1534 * and experiencing shortages but not surpluses, we're too stingy
1535 * and should increase vtime rate.
1536 */
1537 prev_busy_level = ioc->busy_level;
1538 if (rq_wait_pct > RQ_WAIT_BUSY_PCT ||
1539 missed_ppm[READ] > ppm_rthr ||
1540 missed_ppm[WRITE] > ppm_wthr) {
1541 /* clearly missing QoS targets, slow down vrate */
1542 ioc->busy_level = max(ioc->busy_level, 0);
1543 ioc->busy_level++;
1544 } else if (rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
1545 missed_ppm[READ] <= ppm_rthr * UNBUSY_THR_PCT / 100 &&
1546 missed_ppm[WRITE] <= ppm_wthr * UNBUSY_THR_PCT / 100) {
1547 /* QoS targets are being met with >25% margin */
1548 if (nr_shortages) {
1549 /*
1550 * We're throttling while the device has spare
1551 * capacity. If vrate was being slowed down, stop.
1552 */
1553 ioc->busy_level = min(ioc->busy_level, 0);
1554
1555 /*
1556 * If there are IOs spanning multiple periods, wait
1557 * them out before pushing the device harder. If
1558 * there are surpluses, let redistribution work it
1559 * out first.
1560 */
1561 if (!nr_lagging && !nr_surpluses)
1562 ioc->busy_level--;
1563 } else {
1564 /*
1565 * Nobody is being throttled and the users aren't
1566 * issuing enough IOs to saturate the device. We
1567 * simply don't know how close the device is to
1568 * saturation. Coast.
1569 */
1570 ioc->busy_level = 0;
1571 }
1572 } else {
1573 /* inside the hysterisis margin, we're good */
1574 ioc->busy_level = 0;
1575 }
1576
1577 ioc->busy_level = clamp(ioc->busy_level, -1000, 1000);
1578
1579 if (ioc->busy_level > 0 || (ioc->busy_level < 0 && !nr_lagging)) {
1580 u64 vrate = atomic64_read(&ioc->vtime_rate);
1581 u64 vrate_min = ioc->vrate_min, vrate_max = ioc->vrate_max;
1582
1583 /* rq_wait signal is always reliable, ignore user vrate_min */
1584 if (rq_wait_pct > RQ_WAIT_BUSY_PCT)
1585 vrate_min = VRATE_MIN;
1586
1587 /*
1588 * If vrate is out of bounds, apply clamp gradually as the
1589 * bounds can change abruptly. Otherwise, apply busy_level
1590 * based adjustment.
1591 */
1592 if (vrate < vrate_min) {
1593 vrate = div64_u64(vrate * (100 + VRATE_CLAMP_ADJ_PCT),
1594 100);
1595 vrate = min(vrate, vrate_min);
1596 } else if (vrate > vrate_max) {
1597 vrate = div64_u64(vrate * (100 - VRATE_CLAMP_ADJ_PCT),
1598 100);
1599 vrate = max(vrate, vrate_max);
1600 } else {
1601 int idx = min_t(int, abs(ioc->busy_level),
1602 ARRAY_SIZE(vrate_adj_pct) - 1);
1603 u32 adj_pct = vrate_adj_pct[idx];
1604
1605 if (ioc->busy_level > 0)
1606 adj_pct = 100 - adj_pct;
1607 else
1608 adj_pct = 100 + adj_pct;
1609
1610 vrate = clamp(DIV64_U64_ROUND_UP(vrate * adj_pct, 100),
1611 vrate_min, vrate_max);
1612 }
1613
1614 trace_iocost_ioc_vrate_adj(ioc, vrate, missed_ppm, rq_wait_pct,
1615 nr_lagging, nr_shortages,
1616 nr_surpluses);
1617
1618 atomic64_set(&ioc->vtime_rate, vrate);
1619 ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP(
1620 ioc->period_us * vrate * INUSE_MARGIN_PCT, 100);
1621 } else if (ioc->busy_level != prev_busy_level || nr_lagging) {
1622 trace_iocost_ioc_vrate_adj(ioc, atomic64_read(&ioc->vtime_rate),
1623 missed_ppm, rq_wait_pct, nr_lagging,
1624 nr_shortages, nr_surpluses);
1625 }
1626
1627 ioc_refresh_params(ioc, false);
1628
1629 /*
1630 * This period is done. Move onto the next one. If nothing's
1631 * going on with the device, stop the timer.
1632 */
1633 atomic64_inc(&ioc->cur_period);
1634
1635 if (ioc->running != IOC_STOP) {
1636 if (!list_empty(&ioc->active_iocgs)) {
1637 ioc_start_period(ioc, &now);
1638 } else {
1639 ioc->busy_level = 0;
1640 ioc->running = IOC_IDLE;
1641 }
1642 }
1643
1644 spin_unlock_irq(&ioc->lock);
1645}
1646
1647static void calc_vtime_cost_builtin(struct bio *bio, struct ioc_gq *iocg,
1648 bool is_merge, u64 *costp)
1649{
1650 struct ioc *ioc = iocg->ioc;
1651 u64 coef_seqio, coef_randio, coef_page;
1652 u64 pages = max_t(u64, bio_sectors(bio) >> IOC_SECT_TO_PAGE_SHIFT, 1);
1653 u64 seek_pages = 0;
1654 u64 cost = 0;
1655
1656 switch (bio_op(bio)) {
1657 case REQ_OP_READ:
1658 coef_seqio = ioc->params.lcoefs[LCOEF_RSEQIO];
1659 coef_randio = ioc->params.lcoefs[LCOEF_RRANDIO];
1660 coef_page = ioc->params.lcoefs[LCOEF_RPAGE];
1661 break;
1662 case REQ_OP_WRITE:
1663 coef_seqio = ioc->params.lcoefs[LCOEF_WSEQIO];
1664 coef_randio = ioc->params.lcoefs[LCOEF_WRANDIO];
1665 coef_page = ioc->params.lcoefs[LCOEF_WPAGE];
1666 break;
1667 default:
1668 goto out;
1669 }
1670
1671 if (iocg->cursor) {
1672 seek_pages = abs(bio->bi_iter.bi_sector - iocg->cursor);
1673 seek_pages >>= IOC_SECT_TO_PAGE_SHIFT;
1674 }
1675
1676 if (!is_merge) {
1677 if (seek_pages > LCOEF_RANDIO_PAGES) {
1678 cost += coef_randio;
1679 } else {
1680 cost += coef_seqio;
1681 }
1682 }
1683 cost += pages * coef_page;
1684out:
1685 *costp = cost;
1686}
1687
1688static u64 calc_vtime_cost(struct bio *bio, struct ioc_gq *iocg, bool is_merge)
1689{
1690 u64 cost;
1691
1692 calc_vtime_cost_builtin(bio, iocg, is_merge, &cost);
1693 return cost;
1694}
1695
1696static void calc_size_vtime_cost_builtin(struct request *rq, struct ioc *ioc,
1697 u64 *costp)
1698{
1699 unsigned int pages = blk_rq_stats_sectors(rq) >> IOC_SECT_TO_PAGE_SHIFT;
1700
1701 switch (req_op(rq)) {
1702 case REQ_OP_READ:
1703 *costp = pages * ioc->params.lcoefs[LCOEF_RPAGE];
1704 break;
1705 case REQ_OP_WRITE:
1706 *costp = pages * ioc->params.lcoefs[LCOEF_WPAGE];
1707 break;
1708 default:
1709 *costp = 0;
1710 }
1711}
1712
1713static u64 calc_size_vtime_cost(struct request *rq, struct ioc *ioc)
1714{
1715 u64 cost;
1716
1717 calc_size_vtime_cost_builtin(rq, ioc, &cost);
1718 return cost;
1719}
1720
1721static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
1722{
1723 struct blkcg_gq *blkg = bio->bi_blkg;
1724 struct ioc *ioc = rqos_to_ioc(rqos);
1725 struct ioc_gq *iocg = blkg_to_iocg(blkg);
1726 struct ioc_now now;
1727 struct iocg_wait wait;
1728 u32 hw_active, hw_inuse;
1729 u64 abs_cost, cost, vtime;
1730
1731 /* bypass IOs if disabled or for root cgroup */
1732 if (!ioc->enabled || !iocg->level)
1733 return;
1734
1735 /* always activate so that even 0 cost IOs get protected to some level */
1736 if (!iocg_activate(iocg, &now))
1737 return;
1738
1739 /* calculate the absolute vtime cost */
1740 abs_cost = calc_vtime_cost(bio, iocg, false);
1741 if (!abs_cost)
1742 return;
1743
1744 iocg->cursor = bio_end_sector(bio);
1745
1746 vtime = atomic64_read(&iocg->vtime);
1747 current_hweight(iocg, &hw_active, &hw_inuse);
1748
1749 if (hw_inuse < hw_active &&
1750 time_after_eq64(vtime + ioc->inuse_margin_vtime, now.vnow)) {
1751 TRACE_IOCG_PATH(inuse_reset, iocg, &now,
1752 iocg->inuse, iocg->weight, hw_inuse, hw_active);
1753 spin_lock_irq(&ioc->lock);
1754 propagate_active_weight(iocg, iocg->weight, iocg->weight);
1755 spin_unlock_irq(&ioc->lock);
1756 current_hweight(iocg, &hw_active, &hw_inuse);
1757 }
1758
1759 cost = abs_cost_to_cost(abs_cost, hw_inuse);
1760
1761 /*
1762 * If no one's waiting and within budget, issue right away. The
1763 * tests are racy but the races aren't systemic - we only miss once
1764 * in a while which is fine.
1765 */
1766 if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
1767 time_before_eq64(vtime + cost, now.vnow)) {
1768 iocg_commit_bio(iocg, bio, cost);
1769 return;
1770 }
1771
1772 /*
1773 * We activated above but w/o any synchronization. Deactivation is
1774 * synchronized with waitq.lock and we won't get deactivated as long
1775 * as we're waiting or has debt, so we're good if we're activated
1776 * here. In the unlikely case that we aren't, just issue the IO.
1777 */
1778 spin_lock_irq(&iocg->waitq.lock);
1779
1780 if (unlikely(list_empty(&iocg->active_list))) {
1781 spin_unlock_irq(&iocg->waitq.lock);
1782 iocg_commit_bio(iocg, bio, cost);
1783 return;
1784 }
1785
1786 /*
1787 * We're over budget. If @bio has to be issued regardless, remember
1788 * the abs_cost instead of advancing vtime. iocg_kick_waitq() will pay
1789 * off the debt before waking more IOs.
1790 *
1791 * This way, the debt is continuously paid off each period with the
1792 * actual budget available to the cgroup. If we just wound vtime, we
1793 * would incorrectly use the current hw_inuse for the entire amount
1794 * which, for example, can lead to the cgroup staying blocked for a
1795 * long time even with substantially raised hw_inuse.
1796 *
1797 * An iocg with vdebt should stay online so that the timer can keep
1798 * deducting its vdebt and [de]activate use_delay mechanism
1799 * accordingly. We don't want to race against the timer trying to
1800 * clear them and leave @iocg inactive w/ dangling use_delay heavily
1801 * penalizing the cgroup and its descendants.
1802 */
1803 if (bio_issue_as_root_blkg(bio) || fatal_signal_pending(current)) {
1804 iocg->abs_vdebt += abs_cost;
1805 if (iocg_kick_delay(iocg, &now))
1806 blkcg_schedule_throttle(rqos->q,
1807 (bio->bi_opf & REQ_SWAP) == REQ_SWAP);
1808 spin_unlock_irq(&iocg->waitq.lock);
1809 return;
1810 }
1811
1812 /*
1813 * Append self to the waitq and schedule the wakeup timer if we're
1814 * the first waiter. The timer duration is calculated based on the
1815 * current vrate. vtime and hweight changes can make it too short
1816 * or too long. Each wait entry records the absolute cost it's
1817 * waiting for to allow re-evaluation using a custom wait entry.
1818 *
1819 * If too short, the timer simply reschedules itself. If too long,
1820 * the period timer will notice and trigger wakeups.
1821 *
1822 * All waiters are on iocg->waitq and the wait states are
1823 * synchronized using waitq.lock.
1824 */
1825 init_waitqueue_func_entry(&wait.wait, iocg_wake_fn);
1826 wait.wait.private = current;
1827 wait.bio = bio;
1828 wait.abs_cost = abs_cost;
1829 wait.committed = false; /* will be set true by waker */
1830
1831 __add_wait_queue_entry_tail(&iocg->waitq, &wait.wait);
1832 iocg_kick_waitq(iocg, &now);
1833
1834 spin_unlock_irq(&iocg->waitq.lock);
1835
1836 while (true) {
1837 set_current_state(TASK_UNINTERRUPTIBLE);
1838 if (wait.committed)
1839 break;
1840 io_schedule();
1841 }
1842
1843 /* waker already committed us, proceed */
1844 finish_wait(&iocg->waitq, &wait.wait);
1845}
1846
1847static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
1848 struct bio *bio)
1849{
1850 struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg);
1851 struct ioc *ioc = iocg->ioc;
1852 sector_t bio_end = bio_end_sector(bio);
1853 struct ioc_now now;
1854 u32 hw_inuse;
1855 u64 abs_cost, cost;
1856 unsigned long flags;
1857
1858 /* bypass if disabled or for root cgroup */
1859 if (!ioc->enabled || !iocg->level)
1860 return;
1861
1862 abs_cost = calc_vtime_cost(bio, iocg, true);
1863 if (!abs_cost)
1864 return;
1865
1866 ioc_now(ioc, &now);
1867 current_hweight(iocg, NULL, &hw_inuse);
1868 cost = abs_cost_to_cost(abs_cost, hw_inuse);
1869
1870 /* update cursor if backmerging into the request at the cursor */
1871 if (blk_rq_pos(rq) < bio_end &&
1872 blk_rq_pos(rq) + blk_rq_sectors(rq) == iocg->cursor)
1873 iocg->cursor = bio_end;
1874
1875 /*
1876 * Charge if there's enough vtime budget and the existing request has
1877 * cost assigned.
1878 */
1879 if (rq->bio && rq->bio->bi_iocost_cost &&
1880 time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow)) {
1881 iocg_commit_bio(iocg, bio, cost);
1882 return;
1883 }
1884
1885 /*
1886 * Otherwise, account it as debt if @iocg is online, which it should
1887 * be for the vast majority of cases. See debt handling in
1888 * ioc_rqos_throttle() for details.
1889 */
1890 spin_lock_irqsave(&iocg->waitq.lock, flags);
1891 if (likely(!list_empty(&iocg->active_list))) {
1892 iocg->abs_vdebt += abs_cost;
1893 iocg_kick_delay(iocg, &now);
1894 } else {
1895 iocg_commit_bio(iocg, bio, cost);
1896 }
1897 spin_unlock_irqrestore(&iocg->waitq.lock, flags);
1898}
1899
1900static void ioc_rqos_done_bio(struct rq_qos *rqos, struct bio *bio)
1901{
1902 struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg);
1903
1904 if (iocg && bio->bi_iocost_cost)
1905 atomic64_add(bio->bi_iocost_cost, &iocg->done_vtime);
1906}
1907
1908static void ioc_rqos_done(struct rq_qos *rqos, struct request *rq)
1909{
1910 struct ioc *ioc = rqos_to_ioc(rqos);
1911 u64 on_q_ns, rq_wait_ns, size_nsec;
1912 int pidx, rw;
1913
1914 if (!ioc->enabled || !rq->alloc_time_ns || !rq->start_time_ns)
1915 return;
1916
1917 switch (req_op(rq) & REQ_OP_MASK) {
1918 case REQ_OP_READ:
1919 pidx = QOS_RLAT;
1920 rw = READ;
1921 break;
1922 case REQ_OP_WRITE:
1923 pidx = QOS_WLAT;
1924 rw = WRITE;
1925 break;
1926 default:
1927 return;
1928 }
1929
1930 on_q_ns = ktime_get_ns() - rq->alloc_time_ns;
1931 rq_wait_ns = rq->start_time_ns - rq->alloc_time_ns;
1932 size_nsec = div64_u64(calc_size_vtime_cost(rq, ioc), VTIME_PER_NSEC);
1933
1934 if (on_q_ns <= size_nsec ||
1935 on_q_ns - size_nsec <= ioc->params.qos[pidx] * NSEC_PER_USEC)
1936 this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_met);
1937 else
1938 this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_missed);
1939
1940 this_cpu_add(ioc->pcpu_stat->rq_wait_ns, rq_wait_ns);
1941}
1942
1943static void ioc_rqos_queue_depth_changed(struct rq_qos *rqos)
1944{
1945 struct ioc *ioc = rqos_to_ioc(rqos);
1946
1947 spin_lock_irq(&ioc->lock);
1948 ioc_refresh_params(ioc, false);
1949 spin_unlock_irq(&ioc->lock);
1950}
1951
1952static void ioc_rqos_exit(struct rq_qos *rqos)
1953{
1954 struct ioc *ioc = rqos_to_ioc(rqos);
1955
1956 blkcg_deactivate_policy(rqos->q, &blkcg_policy_iocost);
1957
1958 spin_lock_irq(&ioc->lock);
1959 ioc->running = IOC_STOP;
1960 spin_unlock_irq(&ioc->lock);
1961
1962 del_timer_sync(&ioc->timer);
1963 free_percpu(ioc->pcpu_stat);
1964 kfree(ioc);
1965}
1966
1967static struct rq_qos_ops ioc_rqos_ops = {
1968 .throttle = ioc_rqos_throttle,
1969 .merge = ioc_rqos_merge,
1970 .done_bio = ioc_rqos_done_bio,
1971 .done = ioc_rqos_done,
1972 .queue_depth_changed = ioc_rqos_queue_depth_changed,
1973 .exit = ioc_rqos_exit,
1974};
1975
1976static int blk_iocost_init(struct request_queue *q)
1977{
1978 struct ioc *ioc;
1979 struct rq_qos *rqos;
1980 int ret;
1981
1982 ioc = kzalloc(sizeof(*ioc), GFP_KERNEL);
1983 if (!ioc)
1984 return -ENOMEM;
1985
1986 ioc->pcpu_stat = alloc_percpu(struct ioc_pcpu_stat);
1987 if (!ioc->pcpu_stat) {
1988 kfree(ioc);
1989 return -ENOMEM;
1990 }
1991
1992 rqos = &ioc->rqos;
1993 rqos->id = RQ_QOS_COST;
1994 rqos->ops = &ioc_rqos_ops;
1995 rqos->q = q;
1996
1997 spin_lock_init(&ioc->lock);
1998 timer_setup(&ioc->timer, ioc_timer_fn, 0);
1999 INIT_LIST_HEAD(&ioc->active_iocgs);
2000
2001 ioc->running = IOC_IDLE;
2002 atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC);
2003 seqcount_spinlock_init(&ioc->period_seqcount, &ioc->lock);
2004 ioc->period_at = ktime_to_us(ktime_get());
2005 atomic64_set(&ioc->cur_period, 0);
2006 atomic_set(&ioc->hweight_gen, 0);
2007
2008 spin_lock_irq(&ioc->lock);
2009 ioc->autop_idx = AUTOP_INVALID;
2010 ioc_refresh_params(ioc, true);
2011 spin_unlock_irq(&ioc->lock);
2012
2013 rq_qos_add(q, rqos);
2014 ret = blkcg_activate_policy(q, &blkcg_policy_iocost);
2015 if (ret) {
2016 rq_qos_del(q, rqos);
2017 free_percpu(ioc->pcpu_stat);
2018 kfree(ioc);
2019 return ret;
2020 }
2021 return 0;
2022}
2023
2024static struct blkcg_policy_data *ioc_cpd_alloc(gfp_t gfp)
2025{
2026 struct ioc_cgrp *iocc;
2027
2028 iocc = kzalloc(sizeof(struct ioc_cgrp), gfp);
2029 if (!iocc)
2030 return NULL;
2031
2032 iocc->dfl_weight = CGROUP_WEIGHT_DFL;
2033 return &iocc->cpd;
2034}
2035
2036static void ioc_cpd_free(struct blkcg_policy_data *cpd)
2037{
2038 kfree(container_of(cpd, struct ioc_cgrp, cpd));
2039}
2040
2041static struct blkg_policy_data *ioc_pd_alloc(gfp_t gfp, struct request_queue *q,
2042 struct blkcg *blkcg)
2043{
2044 int levels = blkcg->css.cgroup->level + 1;
2045 struct ioc_gq *iocg;
2046
2047 iocg = kzalloc_node(struct_size(iocg, ancestors, levels), gfp, q->node);
2048 if (!iocg)
2049 return NULL;
2050
2051 return &iocg->pd;
2052}
2053
2054static void ioc_pd_init(struct blkg_policy_data *pd)
2055{
2056 struct ioc_gq *iocg = pd_to_iocg(pd);
2057 struct blkcg_gq *blkg = pd_to_blkg(&iocg->pd);
2058 struct ioc *ioc = q_to_ioc(blkg->q);
2059 struct ioc_now now;
2060 struct blkcg_gq *tblkg;
2061 unsigned long flags;
2062
2063 ioc_now(ioc, &now);
2064
2065 iocg->ioc = ioc;
2066 atomic64_set(&iocg->vtime, now.vnow);
2067 atomic64_set(&iocg->done_vtime, now.vnow);
2068 atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
2069 INIT_LIST_HEAD(&iocg->active_list);
2070 iocg->hweight_active = HWEIGHT_WHOLE;
2071 iocg->hweight_inuse = HWEIGHT_WHOLE;
2072
2073 init_waitqueue_head(&iocg->waitq);
2074 hrtimer_init(&iocg->waitq_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
2075 iocg->waitq_timer.function = iocg_waitq_timer_fn;
2076 hrtimer_init(&iocg->delay_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
2077 iocg->delay_timer.function = iocg_delay_timer_fn;
2078
2079 iocg->level = blkg->blkcg->css.cgroup->level;
2080
2081 for (tblkg = blkg; tblkg; tblkg = tblkg->parent) {
2082 struct ioc_gq *tiocg = blkg_to_iocg(tblkg);
2083 iocg->ancestors[tiocg->level] = tiocg;
2084 }
2085
2086 spin_lock_irqsave(&ioc->lock, flags);
2087 weight_updated(iocg);
2088 spin_unlock_irqrestore(&ioc->lock, flags);
2089}
2090
2091static void ioc_pd_free(struct blkg_policy_data *pd)
2092{
2093 struct ioc_gq *iocg = pd_to_iocg(pd);
2094 struct ioc *ioc = iocg->ioc;
2095 unsigned long flags;
2096
2097 if (ioc) {
2098 spin_lock_irqsave(&ioc->lock, flags);
2099 if (!list_empty(&iocg->active_list)) {
2100 propagate_active_weight(iocg, 0, 0);
2101 list_del_init(&iocg->active_list);
2102 }
2103 spin_unlock_irqrestore(&ioc->lock, flags);
2104
2105 hrtimer_cancel(&iocg->waitq_timer);
2106 hrtimer_cancel(&iocg->delay_timer);
2107 }
2108 kfree(iocg);
2109}
2110
2111static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
2112 int off)
2113{
2114 const char *dname = blkg_dev_name(pd->blkg);
2115 struct ioc_gq *iocg = pd_to_iocg(pd);
2116
2117 if (dname && iocg->cfg_weight)
2118 seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight);
2119 return 0;
2120}
2121
2122
2123static int ioc_weight_show(struct seq_file *sf, void *v)
2124{
2125 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2126 struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
2127
2128 seq_printf(sf, "default %u\n", iocc->dfl_weight);
2129 blkcg_print_blkgs(sf, blkcg, ioc_weight_prfill,
2130 &blkcg_policy_iocost, seq_cft(sf)->private, false);
2131 return 0;
2132}
2133
2134static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
2135 size_t nbytes, loff_t off)
2136{
2137 struct blkcg *blkcg = css_to_blkcg(of_css(of));
2138 struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
2139 struct blkg_conf_ctx ctx;
2140 struct ioc_gq *iocg;
2141 u32 v;
2142 int ret;
2143
2144 if (!strchr(buf, ':')) {
2145 struct blkcg_gq *blkg;
2146
2147 if (!sscanf(buf, "default %u", &v) && !sscanf(buf, "%u", &v))
2148 return -EINVAL;
2149
2150 if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX)
2151 return -EINVAL;
2152
2153 spin_lock(&blkcg->lock);
2154 iocc->dfl_weight = v;
2155 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
2156 struct ioc_gq *iocg = blkg_to_iocg(blkg);
2157
2158 if (iocg) {
2159 spin_lock_irq(&iocg->ioc->lock);
2160 weight_updated(iocg);
2161 spin_unlock_irq(&iocg->ioc->lock);
2162 }
2163 }
2164 spin_unlock(&blkcg->lock);
2165
2166 return nbytes;
2167 }
2168
2169 ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, buf, &ctx);
2170 if (ret)
2171 return ret;
2172
2173 iocg = blkg_to_iocg(ctx.blkg);
2174
2175 if (!strncmp(ctx.body, "default", 7)) {
2176 v = 0;
2177 } else {
2178 if (!sscanf(ctx.body, "%u", &v))
2179 goto einval;
2180 if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX)
2181 goto einval;
2182 }
2183
2184 spin_lock(&iocg->ioc->lock);
2185 iocg->cfg_weight = v;
2186 weight_updated(iocg);
2187 spin_unlock(&iocg->ioc->lock);
2188
2189 blkg_conf_finish(&ctx);
2190 return nbytes;
2191
2192einval:
2193 blkg_conf_finish(&ctx);
2194 return -EINVAL;
2195}
2196
2197static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
2198 int off)
2199{
2200 const char *dname = blkg_dev_name(pd->blkg);
2201 struct ioc *ioc = pd_to_iocg(pd)->ioc;
2202
2203 if (!dname)
2204 return 0;
2205
2206 seq_printf(sf, "%s enable=%d ctrl=%s rpct=%u.%02u rlat=%u wpct=%u.%02u wlat=%u min=%u.%02u max=%u.%02u\n",
2207 dname, ioc->enabled, ioc->user_qos_params ? "user" : "auto",
2208 ioc->params.qos[QOS_RPPM] / 10000,
2209 ioc->params.qos[QOS_RPPM] % 10000 / 100,
2210 ioc->params.qos[QOS_RLAT],
2211 ioc->params.qos[QOS_WPPM] / 10000,
2212 ioc->params.qos[QOS_WPPM] % 10000 / 100,
2213 ioc->params.qos[QOS_WLAT],
2214 ioc->params.qos[QOS_MIN] / 10000,
2215 ioc->params.qos[QOS_MIN] % 10000 / 100,
2216 ioc->params.qos[QOS_MAX] / 10000,
2217 ioc->params.qos[QOS_MAX] % 10000 / 100);
2218 return 0;
2219}
2220
2221static int ioc_qos_show(struct seq_file *sf, void *v)
2222{
2223 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2224
2225 blkcg_print_blkgs(sf, blkcg, ioc_qos_prfill,
2226 &blkcg_policy_iocost, seq_cft(sf)->private, false);
2227 return 0;
2228}
2229
2230static const match_table_t qos_ctrl_tokens = {
2231 { QOS_ENABLE, "enable=%u" },
2232 { QOS_CTRL, "ctrl=%s" },
2233 { NR_QOS_CTRL_PARAMS, NULL },
2234};
2235
2236static const match_table_t qos_tokens = {
2237 { QOS_RPPM, "rpct=%s" },
2238 { QOS_RLAT, "rlat=%u" },
2239 { QOS_WPPM, "wpct=%s" },
2240 { QOS_WLAT, "wlat=%u" },
2241 { QOS_MIN, "min=%s" },
2242 { QOS_MAX, "max=%s" },
2243 { NR_QOS_PARAMS, NULL },
2244};
2245
2246static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
2247 size_t nbytes, loff_t off)
2248{
2249 struct gendisk *disk;
2250 struct ioc *ioc;
2251 u32 qos[NR_QOS_PARAMS];
2252 bool enable, user;
2253 char *p;
2254 int ret;
2255
2256 disk = blkcg_conf_get_disk(&input);
2257 if (IS_ERR(disk))
2258 return PTR_ERR(disk);
2259
2260 ioc = q_to_ioc(disk->queue);
2261 if (!ioc) {
2262 ret = blk_iocost_init(disk->queue);
2263 if (ret)
2264 goto err;
2265 ioc = q_to_ioc(disk->queue);
2266 }
2267
2268 spin_lock_irq(&ioc->lock);
2269 memcpy(qos, ioc->params.qos, sizeof(qos));
2270 enable = ioc->enabled;
2271 user = ioc->user_qos_params;
2272 spin_unlock_irq(&ioc->lock);
2273
2274 while ((p = strsep(&input, " \t\n"))) {
2275 substring_t args[MAX_OPT_ARGS];
2276 char buf[32];
2277 int tok;
2278 s64 v;
2279
2280 if (!*p)
2281 continue;
2282
2283 switch (match_token(p, qos_ctrl_tokens, args)) {
2284 case QOS_ENABLE:
2285 match_u64(&args[0], &v);
2286 enable = v;
2287 continue;
2288 case QOS_CTRL:
2289 match_strlcpy(buf, &args[0], sizeof(buf));
2290 if (!strcmp(buf, "auto"))
2291 user = false;
2292 else if (!strcmp(buf, "user"))
2293 user = true;
2294 else
2295 goto einval;
2296 continue;
2297 }
2298
2299 tok = match_token(p, qos_tokens, args);
2300 switch (tok) {
2301 case QOS_RPPM:
2302 case QOS_WPPM:
2303 if (match_strlcpy(buf, &args[0], sizeof(buf)) >=
2304 sizeof(buf))
2305 goto einval;
2306 if (cgroup_parse_float(buf, 2, &v))
2307 goto einval;
2308 if (v < 0 || v > 10000)
2309 goto einval;
2310 qos[tok] = v * 100;
2311 break;
2312 case QOS_RLAT:
2313 case QOS_WLAT:
2314 if (match_u64(&args[0], &v))
2315 goto einval;
2316 qos[tok] = v;
2317 break;
2318 case QOS_MIN:
2319 case QOS_MAX:
2320 if (match_strlcpy(buf, &args[0], sizeof(buf)) >=
2321 sizeof(buf))
2322 goto einval;
2323 if (cgroup_parse_float(buf, 2, &v))
2324 goto einval;
2325 if (v < 0)
2326 goto einval;
2327 qos[tok] = clamp_t(s64, v * 100,
2328 VRATE_MIN_PPM, VRATE_MAX_PPM);
2329 break;
2330 default:
2331 goto einval;
2332 }
2333 user = true;
2334 }
2335
2336 if (qos[QOS_MIN] > qos[QOS_MAX])
2337 goto einval;
2338
2339 spin_lock_irq(&ioc->lock);
2340
2341 if (enable) {
2342 blk_stat_enable_accounting(ioc->rqos.q);
2343 blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q);
2344 ioc->enabled = true;
2345 } else {
2346 blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q);
2347 ioc->enabled = false;
2348 }
2349
2350 if (user) {
2351 memcpy(ioc->params.qos, qos, sizeof(qos));
2352 ioc->user_qos_params = true;
2353 } else {
2354 ioc->user_qos_params = false;
2355 }
2356
2357 ioc_refresh_params(ioc, true);
2358 spin_unlock_irq(&ioc->lock);
2359
2360 put_disk_and_module(disk);
2361 return nbytes;
2362einval:
2363 ret = -EINVAL;
2364err:
2365 put_disk_and_module(disk);
2366 return ret;
2367}
2368
2369static u64 ioc_cost_model_prfill(struct seq_file *sf,
2370 struct blkg_policy_data *pd, int off)
2371{
2372 const char *dname = blkg_dev_name(pd->blkg);
2373 struct ioc *ioc = pd_to_iocg(pd)->ioc;
2374 u64 *u = ioc->params.i_lcoefs;
2375
2376 if (!dname)
2377 return 0;
2378
2379 seq_printf(sf, "%s ctrl=%s model=linear "
2380 "rbps=%llu rseqiops=%llu rrandiops=%llu "
2381 "wbps=%llu wseqiops=%llu wrandiops=%llu\n",
2382 dname, ioc->user_cost_model ? "user" : "auto",
2383 u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS],
2384 u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS]);
2385 return 0;
2386}
2387
2388static int ioc_cost_model_show(struct seq_file *sf, void *v)
2389{
2390 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2391
2392 blkcg_print_blkgs(sf, blkcg, ioc_cost_model_prfill,
2393 &blkcg_policy_iocost, seq_cft(sf)->private, false);
2394 return 0;
2395}
2396
2397static const match_table_t cost_ctrl_tokens = {
2398 { COST_CTRL, "ctrl=%s" },
2399 { COST_MODEL, "model=%s" },
2400 { NR_COST_CTRL_PARAMS, NULL },
2401};
2402
2403static const match_table_t i_lcoef_tokens = {
2404 { I_LCOEF_RBPS, "rbps=%u" },
2405 { I_LCOEF_RSEQIOPS, "rseqiops=%u" },
2406 { I_LCOEF_RRANDIOPS, "rrandiops=%u" },
2407 { I_LCOEF_WBPS, "wbps=%u" },
2408 { I_LCOEF_WSEQIOPS, "wseqiops=%u" },
2409 { I_LCOEF_WRANDIOPS, "wrandiops=%u" },
2410 { NR_I_LCOEFS, NULL },
2411};
2412
2413static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
2414 size_t nbytes, loff_t off)
2415{
2416 struct gendisk *disk;
2417 struct ioc *ioc;
2418 u64 u[NR_I_LCOEFS];
2419 bool user;
2420 char *p;
2421 int ret;
2422
2423 disk = blkcg_conf_get_disk(&input);
2424 if (IS_ERR(disk))
2425 return PTR_ERR(disk);
2426
2427 ioc = q_to_ioc(disk->queue);
2428 if (!ioc) {
2429 ret = blk_iocost_init(disk->queue);
2430 if (ret)
2431 goto err;
2432 ioc = q_to_ioc(disk->queue);
2433 }
2434
2435 spin_lock_irq(&ioc->lock);
2436 memcpy(u, ioc->params.i_lcoefs, sizeof(u));
2437 user = ioc->user_cost_model;
2438 spin_unlock_irq(&ioc->lock);
2439
2440 while ((p = strsep(&input, " \t\n"))) {
2441 substring_t args[MAX_OPT_ARGS];
2442 char buf[32];
2443 int tok;
2444 u64 v;
2445
2446 if (!*p)
2447 continue;
2448
2449 switch (match_token(p, cost_ctrl_tokens, args)) {
2450 case COST_CTRL:
2451 match_strlcpy(buf, &args[0], sizeof(buf));
2452 if (!strcmp(buf, "auto"))
2453 user = false;
2454 else if (!strcmp(buf, "user"))
2455 user = true;
2456 else
2457 goto einval;
2458 continue;
2459 case COST_MODEL:
2460 match_strlcpy(buf, &args[0], sizeof(buf));
2461 if (strcmp(buf, "linear"))
2462 goto einval;
2463 continue;
2464 }
2465
2466 tok = match_token(p, i_lcoef_tokens, args);
2467 if (tok == NR_I_LCOEFS)
2468 goto einval;
2469 if (match_u64(&args[0], &v))
2470 goto einval;
2471 u[tok] = v;
2472 user = true;
2473 }
2474
2475 spin_lock_irq(&ioc->lock);
2476 if (user) {
2477 memcpy(ioc->params.i_lcoefs, u, sizeof(u));
2478 ioc->user_cost_model = true;
2479 } else {
2480 ioc->user_cost_model = false;
2481 }
2482 ioc_refresh_params(ioc, true);
2483 spin_unlock_irq(&ioc->lock);
2484
2485 put_disk_and_module(disk);
2486 return nbytes;
2487
2488einval:
2489 ret = -EINVAL;
2490err:
2491 put_disk_and_module(disk);
2492 return ret;
2493}
2494
2495static struct cftype ioc_files[] = {
2496 {
2497 .name = "weight",
2498 .flags = CFTYPE_NOT_ON_ROOT,
2499 .seq_show = ioc_weight_show,
2500 .write = ioc_weight_write,
2501 },
2502 {
2503 .name = "cost.qos",
2504 .flags = CFTYPE_ONLY_ON_ROOT,
2505 .seq_show = ioc_qos_show,
2506 .write = ioc_qos_write,
2507 },
2508 {
2509 .name = "cost.model",
2510 .flags = CFTYPE_ONLY_ON_ROOT,
2511 .seq_show = ioc_cost_model_show,
2512 .write = ioc_cost_model_write,
2513 },
2514 {}
2515};
2516
2517static struct blkcg_policy blkcg_policy_iocost = {
2518 .dfl_cftypes = ioc_files,
2519 .cpd_alloc_fn = ioc_cpd_alloc,
2520 .cpd_free_fn = ioc_cpd_free,
2521 .pd_alloc_fn = ioc_pd_alloc,
2522 .pd_init_fn = ioc_pd_init,
2523 .pd_free_fn = ioc_pd_free,
2524};
2525
2526static int __init ioc_init(void)
2527{
2528 return blkcg_policy_register(&blkcg_policy_iocost);
2529}
2530
2531static void __exit ioc_exit(void)
2532{
2533 return blkcg_policy_unregister(&blkcg_policy_iocost);
2534}
2535
2536module_init(ioc_init);
2537module_exit(ioc_exit);