1 /* SPDX-License-Identifier: GPL-2.0
3 * IO cost model based controller.
5 * Copyright (C) 2019 Tejun Heo <tj@kernel.org>
6 * Copyright (C) 2019 Andy Newell <newella@fb.com>
7 * Copyright (C) 2019 Facebook
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
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.
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
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.
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.
46 * If needed, tools/cgroup/iocost_coef_gen.py can be used to generate
47 * device-specific coefficients.
51 * The device virtual time (vtime) is used as the primary control metric.
52 * The control strategy is composed of the following three parts.
54 * 2-1. Vtime Distribution
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.
64 * A0 (w:100) A1 (w:100)
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).
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.
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.
84 * 2-2. Vrate Adjustment
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.
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
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.
102 * Device business is determined using two criteria - rq wait and
103 * completion latencies.
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
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.
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.
125 * 2-3. Work Conservation
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
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.
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.
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
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.
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
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
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"
186 #ifdef CONFIG_TRACEPOINTS
188 /* copied from TRACE_CGROUP_PATH, see cgroup-internal.h */
189 #define TRACE_IOCG_PATH_LEN 1024
190 static DEFINE_SPINLOCK(trace_iocg_path_lock);
191 static char trace_iocg_path[TRACE_IOCG_PATH_LEN];
193 #define TRACE_IOCG_PATH(type, iocg, ...) \
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, \
202 spin_unlock_irqrestore(&trace_iocg_path_lock, flags); \
206 #else /* CONFIG_TRACE_POINTS */
207 #define TRACE_IOCG_PATH(type, iocg, ...) do { } while (0)
208 #endif /* CONFIG_TRACE_POINTS */
213 /* timer period is calculated from latency requirements, bound it */
214 MIN_PERIOD = USEC_PER_MSEC,
215 MAX_PERIOD = USEC_PER_SEC,
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%.
223 INUSE_MARGIN_PCT = 10,
225 /* Have some play in waitq timer operations */
226 WAITQ_TIMER_MARGIN_PCT = 5,
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.
233 VTIME_VALID_DUR = 300 * USEC_PER_SEC,
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.
244 MIN_VALID_USAGES = 2,
246 /* 1/64k is granular enough and can easily be handled w/ u32 */
247 HWEIGHT_WHOLE = 1 << 16,
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.
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.
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,
264 /* bound vrate adjustments within two orders of magnitude */
265 VRATE_MIN_PPM = 10000, /* 1% */
266 VRATE_MAX_PPM = 100000000, /* 10000% */
268 VRATE_MIN = VTIME_PER_USEC * VRATE_MIN_PPM / MILLION,
269 VRATE_CLAMP_ADJ_PCT = 4,
271 /* if IOs end up waiting for requests, issue less */
272 RQ_WAIT_BUSY_PCT = 5,
274 /* unbusy hysterisis */
277 /* don't let cmds which take a very long time pin lagging for too long */
278 MAX_LAGGING_PERIODS = 10,
281 * If usage% * 1.25 + 2% is lower than hweight% by more than 3%,
282 * donate the surplus.
284 SURPLUS_SCALE_PCT = 125, /* * 125% */
285 SURPLUS_SCALE_ABS = HWEIGHT_WHOLE / 50, /* + 2% */
286 SURPLUS_MIN_ADJ_DELTA = HWEIGHT_WHOLE / 33, /* 3% */
288 /* switch iff the conditions are met for longer than this */
289 AUTOP_CYCLE_NSEC = 10LLU * NSEC_PER_SEC,
292 * Count IO size in 4k pages. The 12bit shift helps keeping
293 * size-proportional components of cost calculation in closer
294 * numbers of digits to per-IO cost components.
297 IOC_PAGE_SIZE = 1 << IOC_PAGE_SHIFT,
298 IOC_SECT_TO_PAGE_SHIFT = IOC_PAGE_SHIFT - SECTOR_SHIFT,
300 /* if apart further than 16M, consider randio for linear model */
301 LCOEF_RANDIO_PAGES = 4096,
310 /* io.cost.qos controls including per-dev enable of the whole controller */
317 /* io.cost.qos params */
328 /* io.cost.model controls */
335 /* builtin linear cost model coefficients */
367 u32 qos[NR_QOS_PARAMS];
368 u64 i_lcoefs[NR_I_LCOEFS];
369 u64 lcoefs[NR_LCOEFS];
370 u32 too_fast_vrate_pct;
371 u32 too_slow_vrate_pct;
381 struct ioc_pcpu_stat {
382 struct ioc_missed missed[2];
394 struct ioc_params params;
401 struct timer_list timer;
402 struct list_head active_iocgs; /* active cgroups */
403 struct ioc_pcpu_stat __percpu *pcpu_stat;
405 enum ioc_running running;
406 atomic64_t vtime_rate;
408 seqcount_t period_seqcount;
409 u32 period_at; /* wallclock starttime */
410 u64 period_at_vtime; /* vtime starttime */
412 atomic64_t cur_period; /* inc'd each period */
413 int busy_level; /* saturation history */
415 u64 inuse_margin_vtime;
416 bool weights_updated;
417 atomic_t hweight_gen; /* for lazy hweights */
419 u64 autop_too_fast_at;
420 u64 autop_too_slow_at;
422 bool user_qos_params:1;
423 bool user_cost_model:1;
426 /* per device-cgroup pair */
428 struct blkg_policy_data pd;
432 * A iocg can get its weight from two sources - an explicit
433 * per-device-cgroup configuration or the default weight of the
434 * cgroup. `cfg_weight` is the explicit per-device-cgroup
435 * configuration. `weight` is the effective considering both
438 * When an idle cgroup becomes active its `active` goes from 0 to
439 * `weight`. `inuse` is the surplus adjusted active weight.
440 * `active` and `inuse` are used to calculate `hweight_active` and
443 * `last_inuse` remembers `inuse` while an iocg is idle to persist
444 * surplus adjustments.
452 sector_t cursor; /* to detect randio */
455 * `vtime` is this iocg's vtime cursor which progresses as IOs are
456 * issued. If lagging behind device vtime, the delta represents
457 * the currently available IO budget. If runnning ahead, the
460 * `vtime_done` is the same but progressed on completion rather
461 * than issue. The delta behind `vtime` represents the cost of
462 * currently in-flight IOs.
464 * `last_vtime` is used to remember `vtime` at the end of the last
465 * period to calculate utilization.
468 atomic64_t done_vtime;
473 * The period this iocg was last active in. Used for deactivation
474 * and invalidating `vtime`.
476 atomic64_t active_period;
477 struct list_head active_list;
479 /* see __propagate_active_weight() and current_hweight() for details */
480 u64 child_active_sum;
487 struct wait_queue_head waitq;
488 struct hrtimer waitq_timer;
489 struct hrtimer delay_timer;
491 /* usage is recorded as fractions of HWEIGHT_WHOLE */
493 u32 usages[NR_USAGE_SLOTS];
495 /* this iocg's depth in the hierarchy and ancestors including self */
497 struct ioc_gq *ancestors[];
502 struct blkcg_policy_data cpd;
503 unsigned int dfl_weight;
514 struct wait_queue_entry wait;
520 struct iocg_wake_ctx {
526 static const struct ioc_params autop[] = {
529 [QOS_RLAT] = 250000, /* 250ms */
531 [QOS_MIN] = VRATE_MIN_PPM,
532 [QOS_MAX] = VRATE_MAX_PPM,
535 [I_LCOEF_RBPS] = 174019176,
536 [I_LCOEF_RSEQIOPS] = 41708,
537 [I_LCOEF_RRANDIOPS] = 370,
538 [I_LCOEF_WBPS] = 178075866,
539 [I_LCOEF_WSEQIOPS] = 42705,
540 [I_LCOEF_WRANDIOPS] = 378,
545 [QOS_RLAT] = 25000, /* 25ms */
547 [QOS_MIN] = VRATE_MIN_PPM,
548 [QOS_MAX] = VRATE_MAX_PPM,
551 [I_LCOEF_RBPS] = 245855193,
552 [I_LCOEF_RSEQIOPS] = 61575,
553 [I_LCOEF_RRANDIOPS] = 6946,
554 [I_LCOEF_WBPS] = 141365009,
555 [I_LCOEF_WSEQIOPS] = 33716,
556 [I_LCOEF_WRANDIOPS] = 26796,
561 [QOS_RLAT] = 25000, /* 25ms */
563 [QOS_MIN] = VRATE_MIN_PPM,
564 [QOS_MAX] = VRATE_MAX_PPM,
567 [I_LCOEF_RBPS] = 488636629,
568 [I_LCOEF_RSEQIOPS] = 8932,
569 [I_LCOEF_RRANDIOPS] = 8518,
570 [I_LCOEF_WBPS] = 427891549,
571 [I_LCOEF_WSEQIOPS] = 28755,
572 [I_LCOEF_WRANDIOPS] = 21940,
574 .too_fast_vrate_pct = 500,
578 [QOS_RLAT] = 5000, /* 5ms */
580 [QOS_MIN] = VRATE_MIN_PPM,
581 [QOS_MAX] = VRATE_MAX_PPM,
584 [I_LCOEF_RBPS] = 3102524156LLU,
585 [I_LCOEF_RSEQIOPS] = 724816,
586 [I_LCOEF_RRANDIOPS] = 778122,
587 [I_LCOEF_WBPS] = 1742780862LLU,
588 [I_LCOEF_WSEQIOPS] = 425702,
589 [I_LCOEF_WRANDIOPS] = 443193,
591 .too_slow_vrate_pct = 10,
596 * vrate adjust percentages indexed by ioc->busy_level. We adjust up on
597 * vtime credit shortage and down on device saturation.
599 static u32 vrate_adj_pct[] =
601 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
602 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
603 4, 4, 4, 4, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, 16 };
605 static struct blkcg_policy blkcg_policy_iocost;
607 /* accessors and helpers */
608 static struct ioc *rqos_to_ioc(struct rq_qos *rqos)
610 return container_of(rqos, struct ioc, rqos);
613 static struct ioc *q_to_ioc(struct request_queue *q)
615 return rqos_to_ioc(rq_qos_id(q, RQ_QOS_COST));
618 static const char *q_name(struct request_queue *q)
620 if (test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
621 return kobject_name(q->kobj.parent);
626 static const char __maybe_unused *ioc_name(struct ioc *ioc)
628 return q_name(ioc->rqos.q);
631 static struct ioc_gq *pd_to_iocg(struct blkg_policy_data *pd)
633 return pd ? container_of(pd, struct ioc_gq, pd) : NULL;
636 static struct ioc_gq *blkg_to_iocg(struct blkcg_gq *blkg)
638 return pd_to_iocg(blkg_to_pd(blkg, &blkcg_policy_iocost));
641 static struct blkcg_gq *iocg_to_blkg(struct ioc_gq *iocg)
643 return pd_to_blkg(&iocg->pd);
646 static struct ioc_cgrp *blkcg_to_iocc(struct blkcg *blkcg)
648 return container_of(blkcg_to_cpd(blkcg, &blkcg_policy_iocost),
649 struct ioc_cgrp, cpd);
653 * Scale @abs_cost to the inverse of @hw_inuse. The lower the hierarchical
654 * weight, the more expensive each IO. Must round up.
656 static u64 abs_cost_to_cost(u64 abs_cost, u32 hw_inuse)
658 return DIV64_U64_ROUND_UP(abs_cost * HWEIGHT_WHOLE, hw_inuse);
662 * The inverse of abs_cost_to_cost(). Must round up.
664 static u64 cost_to_abs_cost(u64 cost, u32 hw_inuse)
666 return DIV64_U64_ROUND_UP(cost * hw_inuse, HWEIGHT_WHOLE);
669 static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio, u64 cost)
671 bio->bi_iocost_cost = cost;
672 atomic64_add(cost, &iocg->vtime);
675 #define CREATE_TRACE_POINTS
676 #include <trace/events/iocost.h>
678 /* latency Qos params changed, update period_us and all the dependent params */
679 static void ioc_refresh_period_us(struct ioc *ioc)
681 u32 ppm, lat, multi, period_us;
683 lockdep_assert_held(&ioc->lock);
685 /* pick the higher latency target */
686 if (ioc->params.qos[QOS_RLAT] >= ioc->params.qos[QOS_WLAT]) {
687 ppm = ioc->params.qos[QOS_RPPM];
688 lat = ioc->params.qos[QOS_RLAT];
690 ppm = ioc->params.qos[QOS_WPPM];
691 lat = ioc->params.qos[QOS_WLAT];
695 * We want the period to be long enough to contain a healthy number
696 * of IOs while short enough for granular control. Define it as a
697 * multiple of the latency target. Ideally, the multiplier should
698 * be scaled according to the percentile so that it would nominally
699 * contain a certain number of requests. Let's be simpler and
700 * scale it linearly so that it's 2x >= pct(90) and 10x at pct(50).
703 multi = max_t(u32, (MILLION - ppm) / 50000, 2);
706 period_us = multi * lat;
707 period_us = clamp_t(u32, period_us, MIN_PERIOD, MAX_PERIOD);
709 /* calculate dependent params */
710 ioc->period_us = period_us;
711 ioc->margin_us = period_us * MARGIN_PCT / 100;
712 ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP(
713 period_us * VTIME_PER_USEC * INUSE_MARGIN_PCT, 100);
716 static int ioc_autop_idx(struct ioc *ioc)
718 int idx = ioc->autop_idx;
719 const struct ioc_params *p = &autop[idx];
724 if (!blk_queue_nonrot(ioc->rqos.q))
727 /* handle SATA SSDs w/ broken NCQ */
728 if (blk_queue_depth(ioc->rqos.q) == 1)
729 return AUTOP_SSD_QD1;
731 /* use one of the normal ssd sets */
732 if (idx < AUTOP_SSD_DFL)
733 return AUTOP_SSD_DFL;
735 /* if user is overriding anything, maintain what was there */
736 if (ioc->user_qos_params || ioc->user_cost_model)
739 /* step up/down based on the vrate */
740 vrate_pct = div64_u64(atomic64_read(&ioc->vtime_rate) * 100,
742 now_ns = ktime_get_ns();
744 if (p->too_fast_vrate_pct && p->too_fast_vrate_pct <= vrate_pct) {
745 if (!ioc->autop_too_fast_at)
746 ioc->autop_too_fast_at = now_ns;
747 if (now_ns - ioc->autop_too_fast_at >= AUTOP_CYCLE_NSEC)
750 ioc->autop_too_fast_at = 0;
753 if (p->too_slow_vrate_pct && p->too_slow_vrate_pct >= vrate_pct) {
754 if (!ioc->autop_too_slow_at)
755 ioc->autop_too_slow_at = now_ns;
756 if (now_ns - ioc->autop_too_slow_at >= AUTOP_CYCLE_NSEC)
759 ioc->autop_too_slow_at = 0;
766 * Take the followings as input
768 * @bps maximum sequential throughput
769 * @seqiops maximum sequential 4k iops
770 * @randiops maximum random 4k iops
772 * and calculate the linear model cost coefficients.
774 * *@page per-page cost 1s / (@bps / 4096)
775 * *@seqio base cost of a seq IO max((1s / @seqiops) - *@page, 0)
776 * @randiops base cost of a rand IO max((1s / @randiops) - *@page, 0)
778 static void calc_lcoefs(u64 bps, u64 seqiops, u64 randiops,
779 u64 *page, u64 *seqio, u64 *randio)
783 *page = *seqio = *randio = 0;
786 *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC,
787 DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE));
790 v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, seqiops);
796 v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, randiops);
802 static void ioc_refresh_lcoefs(struct ioc *ioc)
804 u64 *u = ioc->params.i_lcoefs;
805 u64 *c = ioc->params.lcoefs;
807 calc_lcoefs(u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS],
808 &c[LCOEF_RPAGE], &c[LCOEF_RSEQIO], &c[LCOEF_RRANDIO]);
809 calc_lcoefs(u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS],
810 &c[LCOEF_WPAGE], &c[LCOEF_WSEQIO], &c[LCOEF_WRANDIO]);
813 static bool ioc_refresh_params(struct ioc *ioc, bool force)
815 const struct ioc_params *p;
818 lockdep_assert_held(&ioc->lock);
820 idx = ioc_autop_idx(ioc);
823 if (idx == ioc->autop_idx && !force)
826 if (idx != ioc->autop_idx)
827 atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC);
829 ioc->autop_idx = idx;
830 ioc->autop_too_fast_at = 0;
831 ioc->autop_too_slow_at = 0;
833 if (!ioc->user_qos_params)
834 memcpy(ioc->params.qos, p->qos, sizeof(p->qos));
835 if (!ioc->user_cost_model)
836 memcpy(ioc->params.i_lcoefs, p->i_lcoefs, sizeof(p->i_lcoefs));
838 ioc_refresh_period_us(ioc);
839 ioc_refresh_lcoefs(ioc);
841 ioc->vrate_min = DIV64_U64_ROUND_UP((u64)ioc->params.qos[QOS_MIN] *
842 VTIME_PER_USEC, MILLION);
843 ioc->vrate_max = div64_u64((u64)ioc->params.qos[QOS_MAX] *
844 VTIME_PER_USEC, MILLION);
849 /* take a snapshot of the current [v]time and vrate */
850 static void ioc_now(struct ioc *ioc, struct ioc_now *now)
854 now->now_ns = ktime_get();
855 now->now = ktime_to_us(now->now_ns);
856 now->vrate = atomic64_read(&ioc->vtime_rate);
859 * The current vtime is
861 * vtime at period start + (wallclock time since the start) * vrate
863 * As a consistent snapshot of `period_at_vtime` and `period_at` is
864 * needed, they're seqcount protected.
867 seq = read_seqcount_begin(&ioc->period_seqcount);
868 now->vnow = ioc->period_at_vtime +
869 (now->now - ioc->period_at) * now->vrate;
870 } while (read_seqcount_retry(&ioc->period_seqcount, seq));
873 static void ioc_start_period(struct ioc *ioc, struct ioc_now *now)
875 lockdep_assert_held(&ioc->lock);
876 WARN_ON_ONCE(ioc->running != IOC_RUNNING);
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);
883 ioc->timer.expires = jiffies + usecs_to_jiffies(ioc->period_us);
884 add_timer(&ioc->timer);
888 * Update @iocg's `active` and `inuse` to @active and @inuse, update level
889 * weight sums and propagate upwards accordingly.
891 static void __propagate_active_weight(struct ioc_gq *iocg, u32 active, u32 inuse)
893 struct ioc *ioc = iocg->ioc;
896 lockdep_assert_held(&ioc->lock);
898 inuse = min(active, inuse);
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;
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;
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.
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);
924 /* do we need to keep walking up? */
925 if (parent_active == parent->active &&
926 parent_inuse == parent->inuse)
929 active = parent_active;
930 inuse = parent_inuse;
933 ioc->weights_updated = true;
936 static void commit_active_weights(struct ioc *ioc)
938 lockdep_assert_held(&ioc->lock);
940 if (ioc->weights_updated) {
941 /* paired with rmb in current_hweight(), see there */
943 atomic_inc(&ioc->hweight_gen);
944 ioc->weights_updated = false;
948 static void propagate_active_weight(struct ioc_gq *iocg, u32 active, u32 inuse)
950 __propagate_active_weight(iocg, active, inuse);
951 commit_active_weights(iocg->ioc);
954 static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep)
956 struct ioc *ioc = iocg->ioc;
961 /* hot path - if uptodate, use cached */
962 ioc_gen = atomic_read(&ioc->hweight_gen);
963 if (ioc_gen == iocg->hweight_gen)
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.
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
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);
987 /* we can race with deactivations and either may read as zero */
988 if (!active_sum || !inuse_sum)
991 active_sum = max(active, active_sum);
992 hwa = hwa * active / active_sum; /* max 16bits * 10000 */
994 inuse_sum = max(inuse, inuse_sum);
995 hwi = hwi * inuse / inuse_sum; /* max 16bits * 10000 */
998 iocg->hweight_active = max_t(u32, hwa, 1);
999 iocg->hweight_inuse = max_t(u32, hwi, 1);
1000 iocg->hweight_gen = ioc_gen;
1003 *hw_activep = iocg->hweight_active;
1005 *hw_inusep = iocg->hweight_inuse;
1008 static void weight_updated(struct ioc_gq *iocg)
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);
1015 lockdep_assert_held(&ioc->lock);
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;
1024 static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now)
1026 struct ioc *ioc = iocg->ioc;
1027 u64 last_period, cur_period, max_period_delta;
1028 u64 vtime, vmargin, vmin;
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.
1035 if (!list_empty(&iocg->active_list)) {
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);
1043 /* racy check on internal node IOs, treat as root level IOs */
1044 if (iocg->child_active_sum)
1047 spin_lock_irq(&ioc->lock);
1052 cur_period = atomic64_read(&ioc->cur_period);
1053 last_period = atomic64_read(&iocg->active_period);
1054 atomic64_set(&iocg->active_period, cur_period);
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))
1063 if (iocg->child_active_sum)
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.
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;
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);
1085 * Activate, propagate weight and start period timer if not
1086 * running. Reset hweight_gen to avoid accidental match from
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);
1094 TRACE_IOCG_PATH(iocg_activate, iocg, now,
1095 last_period, cur_period, vtime);
1097 iocg->last_vtime = vtime;
1099 if (ioc->running == IOC_IDLE) {
1100 ioc->running = IOC_RUNNING;
1101 ioc_start_period(ioc, now);
1105 spin_unlock_irq(&ioc->lock);
1109 spin_unlock_irq(&ioc->lock);
1113 static int iocg_wake_fn(struct wait_queue_entry *wq_entry, unsigned mode,
1114 int flags, void *key)
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);
1120 ctx->vbudget -= cost;
1122 if (ctx->vbudget < 0)
1125 iocg_commit_bio(ctx->iocg, wait->bio, cost);
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().
1132 list_del_init(&wq_entry->entry);
1133 wait->committed = true;
1135 default_wake_function(wq_entry, mode, flags, key);
1139 static void iocg_kick_waitq(struct ioc_gq *iocg, struct ioc_now *now)
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;
1149 lockdep_assert_held(&iocg->waitq.lock);
1151 current_hweight(iocg, NULL, &hw_inuse);
1152 vbudget = now->vnow - atomic64_read(&iocg->vtime);
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),
1161 atomic64_add(delta, &iocg->vtime);
1162 atomic64_add(delta, &iocg->done_vtime);
1163 iocg->abs_vdebt -= abs_delta;
1167 * Wake up the ones which are due and see how much vtime we'll need
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))
1175 if (WARN_ON_ONCE(ctx.vbudget >= 0))
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;
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)
1190 hrtimer_start_range_ns(&iocg->waitq_timer, ns_to_ktime(expires),
1191 margin_ns / 4, HRTIMER_MODE_ABS);
1194 static enum hrtimer_restart iocg_waitq_timer_fn(struct hrtimer *timer)
1196 struct ioc_gq *iocg = container_of(timer, struct ioc_gq, waitq_timer);
1198 unsigned long flags;
1200 ioc_now(iocg->ioc, &now);
1202 spin_lock_irqsave(&iocg->waitq.lock, flags);
1203 iocg_kick_waitq(iocg, &now);
1204 spin_unlock_irqrestore(&iocg->waitq.lock, flags);
1206 return HRTIMER_NORESTART;
1209 static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now, u64 cost)
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 expires, oexpires;
1219 lockdep_assert_held(&iocg->waitq.lock);
1221 /* debt-adjust vtime */
1222 current_hweight(iocg, NULL, &hw_inuse);
1223 vtime += abs_cost_to_cost(iocg->abs_vdebt, hw_inuse);
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.
1230 if (!iocg->abs_vdebt || time_before_eq64(vtime, now->vnow)) {
1231 blkcg_clear_delay(blkg);
1234 if (!atomic_read(&blkg->use_delay) &&
1235 time_before_eq64(vtime, now->vnow + vmargin))
1240 u64 cost_ns = DIV64_U64_ROUND_UP(cost * NSEC_PER_USEC,
1242 blkcg_add_delay(blkg, now->now_ns, cost_ns);
1244 blkcg_use_delay(blkg);
1246 expires = now->now_ns + DIV64_U64_ROUND_UP(vtime - now->vnow,
1247 now->vrate) * NSEC_PER_USEC;
1249 /* if already active and close enough, don't bother */
1250 oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->delay_timer));
1251 if (hrtimer_is_queued(&iocg->delay_timer) &&
1252 abs(oexpires - expires) <= margin_ns / 4)
1255 hrtimer_start_range_ns(&iocg->delay_timer, ns_to_ktime(expires),
1256 margin_ns / 4, HRTIMER_MODE_ABS);
1260 static enum hrtimer_restart iocg_delay_timer_fn(struct hrtimer *timer)
1262 struct ioc_gq *iocg = container_of(timer, struct ioc_gq, delay_timer);
1264 unsigned long flags;
1266 spin_lock_irqsave(&iocg->waitq.lock, flags);
1267 ioc_now(iocg->ioc, &now);
1268 iocg_kick_delay(iocg, &now, 0);
1269 spin_unlock_irqrestore(&iocg->waitq.lock, flags);
1271 return HRTIMER_NORESTART;
1274 static void ioc_lat_stat(struct ioc *ioc, u32 *missed_ppm_ar, u32 *rq_wait_pct_p)
1276 u32 nr_met[2] = { };
1277 u32 nr_missed[2] = { };
1281 for_each_online_cpu(cpu) {
1282 struct ioc_pcpu_stat *stat = per_cpu_ptr(ioc->pcpu_stat, cpu);
1283 u64 this_rq_wait_ns;
1285 for (rw = READ; rw <= WRITE; rw++) {
1286 u32 this_met = READ_ONCE(stat->missed[rw].nr_met);
1287 u32 this_missed = READ_ONCE(stat->missed[rw].nr_missed);
1289 nr_met[rw] += this_met - stat->missed[rw].last_met;
1290 nr_missed[rw] += this_missed - stat->missed[rw].last_missed;
1291 stat->missed[rw].last_met = this_met;
1292 stat->missed[rw].last_missed = this_missed;
1295 this_rq_wait_ns = READ_ONCE(stat->rq_wait_ns);
1296 rq_wait_ns += this_rq_wait_ns - stat->last_rq_wait_ns;
1297 stat->last_rq_wait_ns = this_rq_wait_ns;
1300 for (rw = READ; rw <= WRITE; rw++) {
1301 if (nr_met[rw] + nr_missed[rw])
1303 DIV64_U64_ROUND_UP((u64)nr_missed[rw] * MILLION,
1304 nr_met[rw] + nr_missed[rw]);
1306 missed_ppm_ar[rw] = 0;
1309 *rq_wait_pct_p = div64_u64(rq_wait_ns * 100,
1310 ioc->period_us * NSEC_PER_USEC);
1313 /* was iocg idle this period? */
1314 static bool iocg_is_idle(struct ioc_gq *iocg)
1316 struct ioc *ioc = iocg->ioc;
1318 /* did something get issued this period? */
1319 if (atomic64_read(&iocg->active_period) ==
1320 atomic64_read(&ioc->cur_period))
1323 /* is something in flight? */
1324 if (atomic64_read(&iocg->done_vtime) != atomic64_read(&iocg->vtime))
1330 /* returns usage with margin added if surplus is large enough */
1331 static u32 surplus_adjusted_hweight_inuse(u32 usage, u32 hw_inuse)
1334 usage = DIV_ROUND_UP(usage * SURPLUS_SCALE_PCT, 100);
1335 usage += SURPLUS_SCALE_ABS;
1337 /* don't bother if the surplus is too small */
1338 if (usage + SURPLUS_MIN_ADJ_DELTA > hw_inuse)
1344 static void ioc_timer_fn(struct timer_list *timer)
1346 struct ioc *ioc = container_of(timer, struct ioc, timer);
1347 struct ioc_gq *iocg, *tiocg;
1349 int nr_surpluses = 0, nr_shortages = 0, nr_lagging = 0;
1350 u32 ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM];
1351 u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM];
1352 u32 missed_ppm[2], rq_wait_pct;
1354 int prev_busy_level, i;
1356 /* how were the latencies during the period? */
1357 ioc_lat_stat(ioc, missed_ppm, &rq_wait_pct);
1359 /* take care of active iocgs */
1360 spin_lock_irq(&ioc->lock);
1364 period_vtime = now.vnow - ioc->period_at_vtime;
1365 if (WARN_ON_ONCE(!period_vtime)) {
1366 spin_unlock_irq(&ioc->lock);
1371 * Waiters determine the sleep durations based on the vrate they
1372 * saw at the time of sleep. If vrate has increased, some waiters
1373 * could be sleeping for too long. Wake up tardy waiters which
1374 * should have woken up in the last period and expire idle iocgs.
1376 list_for_each_entry_safe(iocg, tiocg, &ioc->active_iocgs, active_list) {
1377 if (!waitqueue_active(&iocg->waitq) && iocg->abs_vdebt &&
1378 !iocg_is_idle(iocg))
1381 spin_lock(&iocg->waitq.lock);
1383 if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt) {
1384 /* might be oversleeping vtime / hweight changes, kick */
1385 iocg_kick_waitq(iocg, &now);
1386 iocg_kick_delay(iocg, &now, 0);
1387 } else if (iocg_is_idle(iocg)) {
1388 /* no waiter and idle, deactivate */
1389 iocg->last_inuse = iocg->inuse;
1390 __propagate_active_weight(iocg, 0, 0);
1391 list_del_init(&iocg->active_list);
1394 spin_unlock(&iocg->waitq.lock);
1396 commit_active_weights(ioc);
1398 /* calc usages and see whether some weights need to be moved around */
1399 list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
1400 u64 vdone, vtime, vusage, vmargin, vmin;
1401 u32 hw_active, hw_inuse, usage;
1404 * Collect unused and wind vtime closer to vnow to prevent
1405 * iocgs from accumulating a large amount of budget.
1407 vdone = atomic64_read(&iocg->done_vtime);
1408 vtime = atomic64_read(&iocg->vtime);
1409 current_hweight(iocg, &hw_active, &hw_inuse);
1412 * Latency QoS detection doesn't account for IOs which are
1413 * in-flight for longer than a period. Detect them by
1414 * comparing vdone against period start. If lagging behind
1415 * IOs from past periods, don't increase vrate.
1417 if ((ppm_rthr != MILLION || ppm_wthr != MILLION) &&
1418 !atomic_read(&iocg_to_blkg(iocg)->use_delay) &&
1419 time_after64(vtime, vdone) &&
1420 time_after64(vtime, now.vnow -
1421 MAX_LAGGING_PERIODS * period_vtime) &&
1422 time_before64(vdone, now.vnow - period_vtime))
1425 if (waitqueue_active(&iocg->waitq))
1426 vusage = now.vnow - iocg->last_vtime;
1427 else if (time_before64(iocg->last_vtime, vtime))
1428 vusage = vtime - iocg->last_vtime;
1432 iocg->last_vtime += vusage;
1434 * Factor in in-flight vtime into vusage to avoid
1435 * high-latency completions appearing as idle. This should
1436 * be done after the above ->last_time adjustment.
1438 vusage = max(vusage, vtime - vdone);
1440 /* calculate hweight based usage ratio and record */
1442 usage = DIV64_U64_ROUND_UP(vusage * hw_inuse,
1444 iocg->usage_idx = (iocg->usage_idx + 1) % NR_USAGE_SLOTS;
1445 iocg->usages[iocg->usage_idx] = usage;
1450 /* see whether there's surplus vtime */
1451 vmargin = ioc->margin_us * now.vrate;
1452 vmin = now.vnow - vmargin;
1454 iocg->has_surplus = false;
1456 if (!waitqueue_active(&iocg->waitq) &&
1457 time_before64(vtime, vmin)) {
1458 u64 delta = vmin - vtime;
1460 /* throw away surplus vtime */
1461 atomic64_add(delta, &iocg->vtime);
1462 atomic64_add(delta, &iocg->done_vtime);
1463 iocg->last_vtime += delta;
1464 /* if usage is sufficiently low, maybe it can donate */
1465 if (surplus_adjusted_hweight_inuse(usage, hw_inuse)) {
1466 iocg->has_surplus = true;
1469 } else if (hw_inuse < hw_active) {
1470 u32 new_hwi, new_inuse;
1472 /* was donating but might need to take back some */
1473 if (waitqueue_active(&iocg->waitq)) {
1474 new_hwi = hw_active;
1476 new_hwi = max(hw_inuse,
1477 usage * SURPLUS_SCALE_PCT / 100 +
1481 new_inuse = div64_u64((u64)iocg->inuse * new_hwi,
1483 new_inuse = clamp_t(u32, new_inuse, 1, iocg->active);
1485 if (new_inuse > iocg->inuse) {
1486 TRACE_IOCG_PATH(inuse_takeback, iocg, &now,
1487 iocg->inuse, new_inuse,
1489 __propagate_active_weight(iocg, iocg->weight,
1493 /* genuninely out of vtime */
1498 if (!nr_shortages || !nr_surpluses)
1499 goto skip_surplus_transfers;
1501 /* there are both shortages and surpluses, transfer surpluses */
1502 list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
1503 u32 usage, hw_active, hw_inuse, new_hwi, new_inuse;
1506 if (!iocg->has_surplus)
1509 /* base the decision on max historical usage */
1510 for (i = 0, usage = 0; i < NR_USAGE_SLOTS; i++) {
1511 if (iocg->usages[i]) {
1512 usage = max(usage, iocg->usages[i]);
1516 if (nr_valid < MIN_VALID_USAGES)
1519 current_hweight(iocg, &hw_active, &hw_inuse);
1520 new_hwi = surplus_adjusted_hweight_inuse(usage, hw_inuse);
1524 new_inuse = DIV64_U64_ROUND_UP((u64)iocg->inuse * new_hwi,
1526 if (new_inuse < iocg->inuse) {
1527 TRACE_IOCG_PATH(inuse_giveaway, iocg, &now,
1528 iocg->inuse, new_inuse,
1530 __propagate_active_weight(iocg, iocg->weight, new_inuse);
1533 skip_surplus_transfers:
1534 commit_active_weights(ioc);
1537 * If q is getting clogged or we're missing too much, we're issuing
1538 * too much IO and should lower vtime rate. If we're not missing
1539 * and experiencing shortages but not surpluses, we're too stingy
1540 * and should increase vtime rate.
1542 prev_busy_level = ioc->busy_level;
1543 if (rq_wait_pct > RQ_WAIT_BUSY_PCT ||
1544 missed_ppm[READ] > ppm_rthr ||
1545 missed_ppm[WRITE] > ppm_wthr) {
1546 ioc->busy_level = max(ioc->busy_level, 0);
1548 } else if (rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
1549 missed_ppm[READ] <= ppm_rthr * UNBUSY_THR_PCT / 100 &&
1550 missed_ppm[WRITE] <= ppm_wthr * UNBUSY_THR_PCT / 100) {
1551 /* take action iff there is contention */
1552 if (nr_shortages && !nr_lagging) {
1553 ioc->busy_level = min(ioc->busy_level, 0);
1554 /* redistribute surpluses first */
1559 ioc->busy_level = 0;
1562 ioc->busy_level = clamp(ioc->busy_level, -1000, 1000);
1564 if (ioc->busy_level > 0 || (ioc->busy_level < 0 && !nr_lagging)) {
1565 u64 vrate = atomic64_read(&ioc->vtime_rate);
1566 u64 vrate_min = ioc->vrate_min, vrate_max = ioc->vrate_max;
1568 /* rq_wait signal is always reliable, ignore user vrate_min */
1569 if (rq_wait_pct > RQ_WAIT_BUSY_PCT)
1570 vrate_min = VRATE_MIN;
1573 * If vrate is out of bounds, apply clamp gradually as the
1574 * bounds can change abruptly. Otherwise, apply busy_level
1577 if (vrate < vrate_min) {
1578 vrate = div64_u64(vrate * (100 + VRATE_CLAMP_ADJ_PCT),
1580 vrate = min(vrate, vrate_min);
1581 } else if (vrate > vrate_max) {
1582 vrate = div64_u64(vrate * (100 - VRATE_CLAMP_ADJ_PCT),
1584 vrate = max(vrate, vrate_max);
1586 int idx = min_t(int, abs(ioc->busy_level),
1587 ARRAY_SIZE(vrate_adj_pct) - 1);
1588 u32 adj_pct = vrate_adj_pct[idx];
1590 if (ioc->busy_level > 0)
1591 adj_pct = 100 - adj_pct;
1593 adj_pct = 100 + adj_pct;
1595 vrate = clamp(DIV64_U64_ROUND_UP(vrate * adj_pct, 100),
1596 vrate_min, vrate_max);
1599 trace_iocost_ioc_vrate_adj(ioc, vrate, missed_ppm, rq_wait_pct,
1600 nr_lagging, nr_shortages,
1603 atomic64_set(&ioc->vtime_rate, vrate);
1604 ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP(
1605 ioc->period_us * vrate * INUSE_MARGIN_PCT, 100);
1606 } else if (ioc->busy_level != prev_busy_level || nr_lagging) {
1607 trace_iocost_ioc_vrate_adj(ioc, atomic64_read(&ioc->vtime_rate),
1608 missed_ppm, rq_wait_pct, nr_lagging,
1609 nr_shortages, nr_surpluses);
1612 ioc_refresh_params(ioc, false);
1615 * This period is done. Move onto the next one. If nothing's
1616 * going on with the device, stop the timer.
1618 atomic64_inc(&ioc->cur_period);
1620 if (ioc->running != IOC_STOP) {
1621 if (!list_empty(&ioc->active_iocgs)) {
1622 ioc_start_period(ioc, &now);
1624 ioc->busy_level = 0;
1625 ioc->running = IOC_IDLE;
1629 spin_unlock_irq(&ioc->lock);
1632 static void calc_vtime_cost_builtin(struct bio *bio, struct ioc_gq *iocg,
1633 bool is_merge, u64 *costp)
1635 struct ioc *ioc = iocg->ioc;
1636 u64 coef_seqio, coef_randio, coef_page;
1637 u64 pages = max_t(u64, bio_sectors(bio) >> IOC_SECT_TO_PAGE_SHIFT, 1);
1641 switch (bio_op(bio)) {
1643 coef_seqio = ioc->params.lcoefs[LCOEF_RSEQIO];
1644 coef_randio = ioc->params.lcoefs[LCOEF_RRANDIO];
1645 coef_page = ioc->params.lcoefs[LCOEF_RPAGE];
1648 coef_seqio = ioc->params.lcoefs[LCOEF_WSEQIO];
1649 coef_randio = ioc->params.lcoefs[LCOEF_WRANDIO];
1650 coef_page = ioc->params.lcoefs[LCOEF_WPAGE];
1657 seek_pages = abs(bio->bi_iter.bi_sector - iocg->cursor);
1658 seek_pages >>= IOC_SECT_TO_PAGE_SHIFT;
1662 if (seek_pages > LCOEF_RANDIO_PAGES) {
1663 cost += coef_randio;
1668 cost += pages * coef_page;
1673 static u64 calc_vtime_cost(struct bio *bio, struct ioc_gq *iocg, bool is_merge)
1677 calc_vtime_cost_builtin(bio, iocg, is_merge, &cost);
1681 static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
1683 struct blkcg_gq *blkg = bio->bi_blkg;
1684 struct ioc *ioc = rqos_to_ioc(rqos);
1685 struct ioc_gq *iocg = blkg_to_iocg(blkg);
1687 struct iocg_wait wait;
1688 u32 hw_active, hw_inuse;
1689 u64 abs_cost, cost, vtime;
1691 /* bypass IOs if disabled or for root cgroup */
1692 if (!ioc->enabled || !iocg->level)
1695 /* always activate so that even 0 cost IOs get protected to some level */
1696 if (!iocg_activate(iocg, &now))
1699 /* calculate the absolute vtime cost */
1700 abs_cost = calc_vtime_cost(bio, iocg, false);
1704 iocg->cursor = bio_end_sector(bio);
1706 vtime = atomic64_read(&iocg->vtime);
1707 current_hweight(iocg, &hw_active, &hw_inuse);
1709 if (hw_inuse < hw_active &&
1710 time_after_eq64(vtime + ioc->inuse_margin_vtime, now.vnow)) {
1711 TRACE_IOCG_PATH(inuse_reset, iocg, &now,
1712 iocg->inuse, iocg->weight, hw_inuse, hw_active);
1713 spin_lock_irq(&ioc->lock);
1714 propagate_active_weight(iocg, iocg->weight, iocg->weight);
1715 spin_unlock_irq(&ioc->lock);
1716 current_hweight(iocg, &hw_active, &hw_inuse);
1719 cost = abs_cost_to_cost(abs_cost, hw_inuse);
1722 * If no one's waiting and within budget, issue right away. The
1723 * tests are racy but the races aren't systemic - we only miss once
1724 * in a while which is fine.
1726 if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
1727 time_before_eq64(vtime + cost, now.vnow)) {
1728 iocg_commit_bio(iocg, bio, cost);
1733 * We activated above but w/o any synchronization. Deactivation is
1734 * synchronized with waitq.lock and we won't get deactivated as long
1735 * as we're waiting or has debt, so we're good if we're activated
1736 * here. In the unlikely case that we aren't, just issue the IO.
1738 spin_lock_irq(&iocg->waitq.lock);
1740 if (unlikely(list_empty(&iocg->active_list))) {
1741 spin_unlock_irq(&iocg->waitq.lock);
1742 iocg_commit_bio(iocg, bio, cost);
1747 * We're over budget. If @bio has to be issued regardless, remember
1748 * the abs_cost instead of advancing vtime. iocg_kick_waitq() will pay
1749 * off the debt before waking more IOs.
1751 * This way, the debt is continuously paid off each period with the
1752 * actual budget available to the cgroup. If we just wound vtime, we
1753 * would incorrectly use the current hw_inuse for the entire amount
1754 * which, for example, can lead to the cgroup staying blocked for a
1755 * long time even with substantially raised hw_inuse.
1757 * An iocg with vdebt should stay online so that the timer can keep
1758 * deducting its vdebt and [de]activate use_delay mechanism
1759 * accordingly. We don't want to race against the timer trying to
1760 * clear them and leave @iocg inactive w/ dangling use_delay heavily
1761 * penalizing the cgroup and its descendants.
1763 if (bio_issue_as_root_blkg(bio) || fatal_signal_pending(current)) {
1764 iocg->abs_vdebt += abs_cost;
1765 if (iocg_kick_delay(iocg, &now, cost))
1766 blkcg_schedule_throttle(rqos->q,
1767 (bio->bi_opf & REQ_SWAP) == REQ_SWAP);
1768 spin_unlock_irq(&iocg->waitq.lock);
1773 * Append self to the waitq and schedule the wakeup timer if we're
1774 * the first waiter. The timer duration is calculated based on the
1775 * current vrate. vtime and hweight changes can make it too short
1776 * or too long. Each wait entry records the absolute cost it's
1777 * waiting for to allow re-evaluation using a custom wait entry.
1779 * If too short, the timer simply reschedules itself. If too long,
1780 * the period timer will notice and trigger wakeups.
1782 * All waiters are on iocg->waitq and the wait states are
1783 * synchronized using waitq.lock.
1785 init_waitqueue_func_entry(&wait.wait, iocg_wake_fn);
1786 wait.wait.private = current;
1788 wait.abs_cost = abs_cost;
1789 wait.committed = false; /* will be set true by waker */
1791 __add_wait_queue_entry_tail(&iocg->waitq, &wait.wait);
1792 iocg_kick_waitq(iocg, &now);
1794 spin_unlock_irq(&iocg->waitq.lock);
1797 set_current_state(TASK_UNINTERRUPTIBLE);
1803 /* waker already committed us, proceed */
1804 finish_wait(&iocg->waitq, &wait.wait);
1807 static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
1810 struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg);
1811 struct ioc *ioc = iocg->ioc;
1812 sector_t bio_end = bio_end_sector(bio);
1816 unsigned long flags;
1818 /* bypass if disabled or for root cgroup */
1819 if (!ioc->enabled || !iocg->level)
1822 abs_cost = calc_vtime_cost(bio, iocg, true);
1827 current_hweight(iocg, NULL, &hw_inuse);
1828 cost = abs_cost_to_cost(abs_cost, hw_inuse);
1830 /* update cursor if backmerging into the request at the cursor */
1831 if (blk_rq_pos(rq) < bio_end &&
1832 blk_rq_pos(rq) + blk_rq_sectors(rq) == iocg->cursor)
1833 iocg->cursor = bio_end;
1836 * Charge if there's enough vtime budget and the existing request has
1839 if (rq->bio && rq->bio->bi_iocost_cost &&
1840 time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow)) {
1841 iocg_commit_bio(iocg, bio, cost);
1846 * Otherwise, account it as debt if @iocg is online, which it should
1847 * be for the vast majority of cases. See debt handling in
1848 * ioc_rqos_throttle() for details.
1850 spin_lock_irqsave(&iocg->waitq.lock, flags);
1851 if (likely(!list_empty(&iocg->active_list))) {
1852 iocg->abs_vdebt += abs_cost;
1853 iocg_kick_delay(iocg, &now, cost);
1855 iocg_commit_bio(iocg, bio, cost);
1857 spin_unlock_irqrestore(&iocg->waitq.lock, flags);
1860 static void ioc_rqos_done_bio(struct rq_qos *rqos, struct bio *bio)
1862 struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg);
1864 if (iocg && bio->bi_iocost_cost)
1865 atomic64_add(bio->bi_iocost_cost, &iocg->done_vtime);
1868 static void ioc_rqos_done(struct rq_qos *rqos, struct request *rq)
1870 struct ioc *ioc = rqos_to_ioc(rqos);
1871 u64 on_q_ns, rq_wait_ns;
1874 if (!ioc->enabled || !rq->alloc_time_ns || !rq->start_time_ns)
1877 switch (req_op(rq) & REQ_OP_MASK) {
1890 on_q_ns = ktime_get_ns() - rq->alloc_time_ns;
1891 rq_wait_ns = rq->start_time_ns - rq->alloc_time_ns;
1893 if (on_q_ns <= ioc->params.qos[pidx] * NSEC_PER_USEC)
1894 this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_met);
1896 this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_missed);
1898 this_cpu_add(ioc->pcpu_stat->rq_wait_ns, rq_wait_ns);
1901 static void ioc_rqos_queue_depth_changed(struct rq_qos *rqos)
1903 struct ioc *ioc = rqos_to_ioc(rqos);
1905 spin_lock_irq(&ioc->lock);
1906 ioc_refresh_params(ioc, false);
1907 spin_unlock_irq(&ioc->lock);
1910 static void ioc_rqos_exit(struct rq_qos *rqos)
1912 struct ioc *ioc = rqos_to_ioc(rqos);
1914 blkcg_deactivate_policy(rqos->q, &blkcg_policy_iocost);
1916 spin_lock_irq(&ioc->lock);
1917 ioc->running = IOC_STOP;
1918 spin_unlock_irq(&ioc->lock);
1920 del_timer_sync(&ioc->timer);
1921 free_percpu(ioc->pcpu_stat);
1925 static struct rq_qos_ops ioc_rqos_ops = {
1926 .throttle = ioc_rqos_throttle,
1927 .merge = ioc_rqos_merge,
1928 .done_bio = ioc_rqos_done_bio,
1929 .done = ioc_rqos_done,
1930 .queue_depth_changed = ioc_rqos_queue_depth_changed,
1931 .exit = ioc_rqos_exit,
1934 static int blk_iocost_init(struct request_queue *q)
1937 struct rq_qos *rqos;
1940 ioc = kzalloc(sizeof(*ioc), GFP_KERNEL);
1944 ioc->pcpu_stat = alloc_percpu(struct ioc_pcpu_stat);
1945 if (!ioc->pcpu_stat) {
1951 rqos->id = RQ_QOS_COST;
1952 rqos->ops = &ioc_rqos_ops;
1955 spin_lock_init(&ioc->lock);
1956 timer_setup(&ioc->timer, ioc_timer_fn, 0);
1957 INIT_LIST_HEAD(&ioc->active_iocgs);
1959 ioc->running = IOC_IDLE;
1960 atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC);
1961 seqcount_init(&ioc->period_seqcount);
1962 ioc->period_at = ktime_to_us(ktime_get());
1963 atomic64_set(&ioc->cur_period, 0);
1964 atomic_set(&ioc->hweight_gen, 0);
1966 spin_lock_irq(&ioc->lock);
1967 ioc->autop_idx = AUTOP_INVALID;
1968 ioc_refresh_params(ioc, true);
1969 spin_unlock_irq(&ioc->lock);
1971 rq_qos_add(q, rqos);
1972 ret = blkcg_activate_policy(q, &blkcg_policy_iocost);
1974 rq_qos_del(q, rqos);
1975 free_percpu(ioc->pcpu_stat);
1982 static struct blkcg_policy_data *ioc_cpd_alloc(gfp_t gfp)
1984 struct ioc_cgrp *iocc;
1986 iocc = kzalloc(sizeof(struct ioc_cgrp), gfp);
1990 iocc->dfl_weight = CGROUP_WEIGHT_DFL;
1994 static void ioc_cpd_free(struct blkcg_policy_data *cpd)
1996 kfree(container_of(cpd, struct ioc_cgrp, cpd));
1999 static struct blkg_policy_data *ioc_pd_alloc(gfp_t gfp, struct request_queue *q,
2000 struct blkcg *blkcg)
2002 int levels = blkcg->css.cgroup->level + 1;
2003 struct ioc_gq *iocg;
2005 iocg = kzalloc_node(sizeof(*iocg) + levels * sizeof(iocg->ancestors[0]),
2013 static void ioc_pd_init(struct blkg_policy_data *pd)
2015 struct ioc_gq *iocg = pd_to_iocg(pd);
2016 struct blkcg_gq *blkg = pd_to_blkg(&iocg->pd);
2017 struct ioc *ioc = q_to_ioc(blkg->q);
2019 struct blkcg_gq *tblkg;
2020 unsigned long flags;
2025 atomic64_set(&iocg->vtime, now.vnow);
2026 atomic64_set(&iocg->done_vtime, now.vnow);
2027 atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
2028 INIT_LIST_HEAD(&iocg->active_list);
2029 iocg->hweight_active = HWEIGHT_WHOLE;
2030 iocg->hweight_inuse = HWEIGHT_WHOLE;
2032 init_waitqueue_head(&iocg->waitq);
2033 hrtimer_init(&iocg->waitq_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
2034 iocg->waitq_timer.function = iocg_waitq_timer_fn;
2035 hrtimer_init(&iocg->delay_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
2036 iocg->delay_timer.function = iocg_delay_timer_fn;
2038 iocg->level = blkg->blkcg->css.cgroup->level;
2040 for (tblkg = blkg; tblkg; tblkg = tblkg->parent) {
2041 struct ioc_gq *tiocg = blkg_to_iocg(tblkg);
2042 iocg->ancestors[tiocg->level] = tiocg;
2045 spin_lock_irqsave(&ioc->lock, flags);
2046 weight_updated(iocg);
2047 spin_unlock_irqrestore(&ioc->lock, flags);
2050 static void ioc_pd_free(struct blkg_policy_data *pd)
2052 struct ioc_gq *iocg = pd_to_iocg(pd);
2053 struct ioc *ioc = iocg->ioc;
2056 spin_lock(&ioc->lock);
2057 if (!list_empty(&iocg->active_list)) {
2058 propagate_active_weight(iocg, 0, 0);
2059 list_del_init(&iocg->active_list);
2061 spin_unlock(&ioc->lock);
2063 hrtimer_cancel(&iocg->waitq_timer);
2064 hrtimer_cancel(&iocg->delay_timer);
2069 static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
2072 const char *dname = blkg_dev_name(pd->blkg);
2073 struct ioc_gq *iocg = pd_to_iocg(pd);
2075 if (dname && iocg->cfg_weight)
2076 seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight);
2081 static int ioc_weight_show(struct seq_file *sf, void *v)
2083 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2084 struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
2086 seq_printf(sf, "default %u\n", iocc->dfl_weight);
2087 blkcg_print_blkgs(sf, blkcg, ioc_weight_prfill,
2088 &blkcg_policy_iocost, seq_cft(sf)->private, false);
2092 static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
2093 size_t nbytes, loff_t off)
2095 struct blkcg *blkcg = css_to_blkcg(of_css(of));
2096 struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
2097 struct blkg_conf_ctx ctx;
2098 struct ioc_gq *iocg;
2102 if (!strchr(buf, ':')) {
2103 struct blkcg_gq *blkg;
2105 if (!sscanf(buf, "default %u", &v) && !sscanf(buf, "%u", &v))
2108 if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX)
2111 spin_lock(&blkcg->lock);
2112 iocc->dfl_weight = v;
2113 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
2114 struct ioc_gq *iocg = blkg_to_iocg(blkg);
2117 spin_lock_irq(&iocg->ioc->lock);
2118 weight_updated(iocg);
2119 spin_unlock_irq(&iocg->ioc->lock);
2122 spin_unlock(&blkcg->lock);
2127 ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, buf, &ctx);
2131 iocg = blkg_to_iocg(ctx.blkg);
2133 if (!strncmp(ctx.body, "default", 7)) {
2136 if (!sscanf(ctx.body, "%u", &v))
2138 if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX)
2142 spin_lock(&iocg->ioc->lock);
2143 iocg->cfg_weight = v;
2144 weight_updated(iocg);
2145 spin_unlock(&iocg->ioc->lock);
2147 blkg_conf_finish(&ctx);
2151 blkg_conf_finish(&ctx);
2155 static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
2158 const char *dname = blkg_dev_name(pd->blkg);
2159 struct ioc *ioc = pd_to_iocg(pd)->ioc;
2164 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",
2165 dname, ioc->enabled, ioc->user_qos_params ? "user" : "auto",
2166 ioc->params.qos[QOS_RPPM] / 10000,
2167 ioc->params.qos[QOS_RPPM] % 10000 / 100,
2168 ioc->params.qos[QOS_RLAT],
2169 ioc->params.qos[QOS_WPPM] / 10000,
2170 ioc->params.qos[QOS_WPPM] % 10000 / 100,
2171 ioc->params.qos[QOS_WLAT],
2172 ioc->params.qos[QOS_MIN] / 10000,
2173 ioc->params.qos[QOS_MIN] % 10000 / 100,
2174 ioc->params.qos[QOS_MAX] / 10000,
2175 ioc->params.qos[QOS_MAX] % 10000 / 100);
2179 static int ioc_qos_show(struct seq_file *sf, void *v)
2181 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2183 blkcg_print_blkgs(sf, blkcg, ioc_qos_prfill,
2184 &blkcg_policy_iocost, seq_cft(sf)->private, false);
2188 static const match_table_t qos_ctrl_tokens = {
2189 { QOS_ENABLE, "enable=%u" },
2190 { QOS_CTRL, "ctrl=%s" },
2191 { NR_QOS_CTRL_PARAMS, NULL },
2194 static const match_table_t qos_tokens = {
2195 { QOS_RPPM, "rpct=%s" },
2196 { QOS_RLAT, "rlat=%u" },
2197 { QOS_WPPM, "wpct=%s" },
2198 { QOS_WLAT, "wlat=%u" },
2199 { QOS_MIN, "min=%s" },
2200 { QOS_MAX, "max=%s" },
2201 { NR_QOS_PARAMS, NULL },
2204 static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
2205 size_t nbytes, loff_t off)
2207 struct gendisk *disk;
2209 u32 qos[NR_QOS_PARAMS];
2214 disk = blkcg_conf_get_disk(&input);
2216 return PTR_ERR(disk);
2218 ioc = q_to_ioc(disk->queue);
2220 ret = blk_iocost_init(disk->queue);
2223 ioc = q_to_ioc(disk->queue);
2226 spin_lock_irq(&ioc->lock);
2227 memcpy(qos, ioc->params.qos, sizeof(qos));
2228 enable = ioc->enabled;
2229 user = ioc->user_qos_params;
2230 spin_unlock_irq(&ioc->lock);
2232 while ((p = strsep(&input, " \t\n"))) {
2233 substring_t args[MAX_OPT_ARGS];
2241 switch (match_token(p, qos_ctrl_tokens, args)) {
2243 match_u64(&args[0], &v);
2247 match_strlcpy(buf, &args[0], sizeof(buf));
2248 if (!strcmp(buf, "auto"))
2250 else if (!strcmp(buf, "user"))
2257 tok = match_token(p, qos_tokens, args);
2261 if (match_strlcpy(buf, &args[0], sizeof(buf)) >=
2264 if (cgroup_parse_float(buf, 2, &v))
2266 if (v < 0 || v > 10000)
2272 if (match_u64(&args[0], &v))
2278 if (match_strlcpy(buf, &args[0], sizeof(buf)) >=
2281 if (cgroup_parse_float(buf, 2, &v))
2285 qos[tok] = clamp_t(s64, v * 100,
2286 VRATE_MIN_PPM, VRATE_MAX_PPM);
2294 if (qos[QOS_MIN] > qos[QOS_MAX])
2297 spin_lock_irq(&ioc->lock);
2300 blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q);
2301 ioc->enabled = true;
2303 blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q);
2304 ioc->enabled = false;
2308 memcpy(ioc->params.qos, qos, sizeof(qos));
2309 ioc->user_qos_params = true;
2311 ioc->user_qos_params = false;
2314 ioc_refresh_params(ioc, true);
2315 spin_unlock_irq(&ioc->lock);
2317 put_disk_and_module(disk);
2322 put_disk_and_module(disk);
2326 static u64 ioc_cost_model_prfill(struct seq_file *sf,
2327 struct blkg_policy_data *pd, int off)
2329 const char *dname = blkg_dev_name(pd->blkg);
2330 struct ioc *ioc = pd_to_iocg(pd)->ioc;
2331 u64 *u = ioc->params.i_lcoefs;
2336 seq_printf(sf, "%s ctrl=%s model=linear "
2337 "rbps=%llu rseqiops=%llu rrandiops=%llu "
2338 "wbps=%llu wseqiops=%llu wrandiops=%llu\n",
2339 dname, ioc->user_cost_model ? "user" : "auto",
2340 u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS],
2341 u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS]);
2345 static int ioc_cost_model_show(struct seq_file *sf, void *v)
2347 struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2349 blkcg_print_blkgs(sf, blkcg, ioc_cost_model_prfill,
2350 &blkcg_policy_iocost, seq_cft(sf)->private, false);
2354 static const match_table_t cost_ctrl_tokens = {
2355 { COST_CTRL, "ctrl=%s" },
2356 { COST_MODEL, "model=%s" },
2357 { NR_COST_CTRL_PARAMS, NULL },
2360 static const match_table_t i_lcoef_tokens = {
2361 { I_LCOEF_RBPS, "rbps=%u" },
2362 { I_LCOEF_RSEQIOPS, "rseqiops=%u" },
2363 { I_LCOEF_RRANDIOPS, "rrandiops=%u" },
2364 { I_LCOEF_WBPS, "wbps=%u" },
2365 { I_LCOEF_WSEQIOPS, "wseqiops=%u" },
2366 { I_LCOEF_WRANDIOPS, "wrandiops=%u" },
2367 { NR_I_LCOEFS, NULL },
2370 static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input,
2371 size_t nbytes, loff_t off)
2373 struct gendisk *disk;
2380 disk = blkcg_conf_get_disk(&input);
2382 return PTR_ERR(disk);
2384 ioc = q_to_ioc(disk->queue);
2386 ret = blk_iocost_init(disk->queue);
2389 ioc = q_to_ioc(disk->queue);
2392 spin_lock_irq(&ioc->lock);
2393 memcpy(u, ioc->params.i_lcoefs, sizeof(u));
2394 user = ioc->user_cost_model;
2395 spin_unlock_irq(&ioc->lock);
2397 while ((p = strsep(&input, " \t\n"))) {
2398 substring_t args[MAX_OPT_ARGS];
2406 switch (match_token(p, cost_ctrl_tokens, args)) {
2408 match_strlcpy(buf, &args[0], sizeof(buf));
2409 if (!strcmp(buf, "auto"))
2411 else if (!strcmp(buf, "user"))
2417 match_strlcpy(buf, &args[0], sizeof(buf));
2418 if (strcmp(buf, "linear"))
2423 tok = match_token(p, i_lcoef_tokens, args);
2424 if (tok == NR_I_LCOEFS)
2426 if (match_u64(&args[0], &v))
2432 spin_lock_irq(&ioc->lock);
2434 memcpy(ioc->params.i_lcoefs, u, sizeof(u));
2435 ioc->user_cost_model = true;
2437 ioc->user_cost_model = false;
2439 ioc_refresh_params(ioc, true);
2440 spin_unlock_irq(&ioc->lock);
2442 put_disk_and_module(disk);
2448 put_disk_and_module(disk);
2452 static struct cftype ioc_files[] = {
2455 .flags = CFTYPE_NOT_ON_ROOT,
2456 .seq_show = ioc_weight_show,
2457 .write = ioc_weight_write,
2461 .flags = CFTYPE_ONLY_ON_ROOT,
2462 .seq_show = ioc_qos_show,
2463 .write = ioc_qos_write,
2466 .name = "cost.model",
2467 .flags = CFTYPE_ONLY_ON_ROOT,
2468 .seq_show = ioc_cost_model_show,
2469 .write = ioc_cost_model_write,
2474 static struct blkcg_policy blkcg_policy_iocost = {
2475 .dfl_cftypes = ioc_files,
2476 .cpd_alloc_fn = ioc_cpd_alloc,
2477 .cpd_free_fn = ioc_cpd_free,
2478 .pd_alloc_fn = ioc_pd_alloc,
2479 .pd_init_fn = ioc_pd_init,
2480 .pd_free_fn = ioc_pd_free,
2483 static int __init ioc_init(void)
2485 return blkcg_policy_register(&blkcg_policy_iocost);
2488 static void __exit ioc_exit(void)
2490 return blkcg_policy_unregister(&blkcg_policy_iocost);
2493 module_init(ioc_init);
2494 module_exit(ioc_exit);