| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Tejun Heo | 13389 | 91.99% | 54 | 48.21% |
| Baolin Wang | 500 | 3.44% | 6 | 5.36% |
| yu kuai | 175 | 1.20% | 6 | 5.36% |
| Chengming Zhou | 156 | 1.07% | 4 | 3.57% |
| Christoph Hellwig | 96 | 0.66% | 13 | 11.61% |
| Breno Leitão | 46 | 0.32% | 1 | 0.89% |
| Li Nan | 44 | 0.30% | 4 | 3.57% |
| Jiufei (Joyce) Xue | 23 | 0.16% | 1 | 0.89% |
| Josef Bacik | 23 | 0.16% | 2 | 1.79% |
| Jinke Han | 19 | 0.13% | 1 | 0.89% |
| Jens Axboe | 18 | 0.12% | 4 | 3.57% |
| Rik Van Riel | 16 | 0.11% | 1 | 0.89% |
| KeMeng Shi | 14 | 0.10% | 5 | 4.46% |
| Ahmed S. Darwish | 7 | 0.05% | 1 | 0.89% |
| Ming Lei | 7 | 0.05% | 2 | 1.79% |
| Pavel Begunkov | 5 | 0.03% | 1 | 0.89% |
| Jiri Slaby (SUSE) | 4 | 0.03% | 1 | 0.89% |
| Arnd Bergmann | 4 | 0.03% | 1 | 0.89% |
| Gustavo A. R. Silva | 4 | 0.03% | 1 | 0.89% |
| Wolfgang Bumiller | 2 | 0.01% | 1 | 0.89% |
| Dan Carpenter | 2 | 0.01% | 1 | 0.89% |
| Steven Rostedt | 1 | 0.01% | 1 | 0.89% |
| Total | 14555 | 112 |
/* SPDX-License-Identifier: GPL-2.0 * * IO cost model based controller. * * Copyright (C) 2019 Tejun Heo <tj@kernel.org> * Copyright (C) 2019 Andy Newell <newella@fb.com> * Copyright (C) 2019 Facebook * * One challenge of controlling IO resources is the lack of trivially * observable cost metric. This is distinguished from CPU and memory where * wallclock time and the number of bytes can serve as accurate enough * approximations. * * Bandwidth and iops are the most commonly used metrics for IO devices but * depending on the type and specifics of the device, different IO patterns * easily lead to multiple orders of magnitude variations rendering them * useless for the purpose of IO capacity distribution. While on-device * time, with a lot of clutches, could serve as a useful approximation for * non-queued rotational devices, this is no longer viable with modern * devices, even the rotational ones. * * While there is no cost metric we can trivially observe, it isn't a * complete mystery. For example, on a rotational device, seek cost * dominates while a contiguous transfer contributes a smaller amount * proportional to the size. If we can characterize at least the relative * costs of these different types of IOs, it should be possible to * implement a reasonable work-conserving proportional IO resource * distribution. * * 1. IO Cost Model * * IO cost model estimates the cost of an IO given its basic parameters and * history (e.g. the end sector of the last IO). The cost is measured in * device time. If a given IO is estimated to cost 10ms, the device should * be able to process ~100 of those IOs in a second. * * Currently, there's only one builtin cost model - linear. Each IO is * classified as sequential or random and given a base cost accordingly. * On top of that, a size cost proportional to the length of the IO is * added. While simple, this model captures the operational * characteristics of a wide varienty of devices well enough. Default * parameters for several different classes of devices are provided and the * parameters can be configured from userspace via * /sys/fs/cgroup/io.cost.model. * * If needed, tools/cgroup/iocost_coef_gen.py can be used to generate * device-specific coefficients. * * 2. Control Strategy * * The device virtual time (vtime) is used as the primary control metric. * The control strategy is composed of the following three parts. * * 2-1. Vtime Distribution * * When a cgroup becomes active in terms of IOs, its hierarchical share is * calculated. Please consider the following hierarchy where the numbers * inside parentheses denote the configured weights. * * root * / \ * A (w:100) B (w:300) * / \ * A0 (w:100) A1 (w:100) * * If B is idle and only A0 and A1 are actively issuing IOs, as the two are * of equal weight, each gets 50% share. If then B starts issuing IOs, B * gets 300/(100+300) or 75% share, and A0 and A1 equally splits the rest, * 12.5% each. The distribution mechanism only cares about these flattened * shares. They're called hweights (hierarchical weights) and always add * upto 1 (WEIGHT_ONE). * * A given cgroup's vtime runs slower in inverse proportion to its hweight. * For example, with 12.5% weight, A0's time runs 8 times slower (100/12.5) * against the device vtime - an IO which takes 10ms on the underlying * device is considered to take 80ms on A0. * * This constitutes the basis of IO capacity distribution. Each cgroup's * vtime is running at a rate determined by its hweight. A cgroup tracks * the vtime consumed by past IOs and can issue a new IO if doing so * wouldn't outrun the current device vtime. Otherwise, the IO is * suspended until the vtime has progressed enough to cover it. * * 2-2. Vrate Adjustment * * It's unrealistic to expect the cost model to be perfect. There are too * many devices and even on the same device the overall performance * fluctuates depending on numerous factors such as IO mixture and device * internal garbage collection. The controller needs to adapt dynamically. * * This is achieved by adjusting the overall IO rate according to how busy * the device is. If the device becomes overloaded, we're sending down too * many IOs and should generally slow down. If there are waiting issuers * but the device isn't saturated, we're issuing too few and should * generally speed up. * * To slow down, we lower the vrate - the rate at which the device vtime * passes compared to the wall clock. For example, if the vtime is running * at the vrate of 75%, all cgroups added up would only be able to issue * 750ms worth of IOs per second, and vice-versa for speeding up. * * Device business is determined using two criteria - rq wait and * completion latencies. * * When a device gets saturated, the on-device and then the request queues * fill up and a bio which is ready to be issued has to wait for a request * to become available. When this delay becomes noticeable, it's a clear * indication that the device is saturated and we lower the vrate. This * saturation signal is fairly conservative as it only triggers when both * hardware and software queues are filled up, and is used as the default * busy signal. * * As devices can have deep queues and be unfair in how the queued commands * are executed, solely depending on rq wait may not result in satisfactory * control quality. For a better control quality, completion latency QoS * parameters can be configured so that the device is considered saturated * if N'th percentile completion latency rises above the set point. * * The completion latency requirements are a function of both the * underlying device characteristics and the desired IO latency quality of * service. There is an inherent trade-off - the tighter the latency QoS, * the higher the bandwidth lossage. Latency QoS is disabled by default * and can be set through /sys/fs/cgroup/io.cost.qos. * * 2-3. Work Conservation * * Imagine two cgroups A and B with equal weights. A is issuing a small IO * periodically while B is sending out enough parallel IOs to saturate the * device on its own. Let's say A's usage amounts to 100ms worth of IO * cost per second, i.e., 10% of the device capacity. The naive * distribution of half and half would lead to 60% utilization of the * device, a significant reduction in the total amount of work done * compared to free-for-all competition. This is too high a cost to pay * for IO control. * * To conserve the total amount of work done, we keep track of how much * each active cgroup is actually using and yield part of its weight if * there are other cgroups which can make use of it. In the above case, * A's weight will be lowered so that it hovers above the actual usage and * B would be able to use the rest. * * As we don't want to penalize a cgroup for donating its weight, the * surplus weight adjustment factors in a margin and has an immediate * snapback mechanism in case the cgroup needs more IO vtime for itself. * * Note that adjusting down surplus weights has the same effects as * accelerating vtime for other cgroups and work conservation can also be * implemented by adjusting vrate dynamically. However, squaring who can * donate and should take back how much requires hweight propagations * anyway making it easier to implement and understand as a separate * mechanism. * * 3. Monitoring * * Instead of debugfs or other clumsy monitoring mechanisms, this * controller uses a drgn based monitoring script - * tools/cgroup/iocost_monitor.py. For details on drgn, please see * https://github.com/osandov/drgn. The output looks like the following. * * sdb RUN per=300ms cur_per=234.218:v203.695 busy= +1 vrate= 62.12% * active weight hweight% inflt% dbt delay usages% * test/a * 50/ 50 33.33/ 33.33 27.65 2 0*041 033:033:033 * test/b * 100/ 100 66.67/ 66.67 17.56 0 0*000 066:079:077 * * - per : Timer period * - cur_per : Internal wall and device vtime clock * - vrate : Device virtual time rate against wall clock * - weight : Surplus-adjusted and configured weights * - hweight : Surplus-adjusted and configured hierarchical weights * - inflt : The percentage of in-flight IO cost at the end of last period * - del_ms : Deferred issuer delay induction level and duration * - usages : Usage history */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/timer.h> #include <linux/time64.h> #include <linux/parser.h> #include <linux/sched/signal.h> #include <asm/local.h> #include <asm/local64.h> #include "blk-rq-qos.h" #include "blk-stat.h" #include "blk-wbt.h" #include "blk-cgroup.h" #ifdef CONFIG_TRACEPOINTS /* copied from TRACE_CGROUP_PATH, see cgroup-internal.h */ #define TRACE_IOCG_PATH_LEN 1024 static DEFINE_SPINLOCK(trace_iocg_path_lock); static char trace_iocg_path[TRACE_IOCG_PATH_LEN]; #define TRACE_IOCG_PATH(type, iocg, ...) \ do { \ unsigned long flags; \ if (trace_iocost_##type##_enabled()) { \ spin_lock_irqsave(&trace_iocg_path_lock, flags); \ cgroup_path(iocg_to_blkg(iocg)->blkcg->css.cgroup, \ trace_iocg_path, TRACE_IOCG_PATH_LEN); \ trace_iocost_##type(iocg, trace_iocg_path, \ ##__VA_ARGS__); \ spin_unlock_irqrestore(&trace_iocg_path_lock, flags); \ } \ } while (0) #else /* CONFIG_TRACE_POINTS */ #define TRACE_IOCG_PATH(type, iocg, ...) do { } while (0) #endif /* CONFIG_TRACE_POINTS */ enum { MILLION = 1000000, /* timer period is calculated from latency requirements, bound it */ MIN_PERIOD = USEC_PER_MSEC, MAX_PERIOD = USEC_PER_SEC, /* * iocg->vtime is targeted at 50% behind the device vtime, which * serves as its IO credit buffer. Surplus weight adjustment is * immediately canceled if the vtime margin runs below 10%. */ MARGIN_MIN_PCT = 10, MARGIN_LOW_PCT = 20, MARGIN_TARGET_PCT = 50, INUSE_ADJ_STEP_PCT = 25, /* Have some play in timer operations */ TIMER_SLACK_PCT = 1, /* 1/64k is granular enough and can easily be handled w/ u32 */ WEIGHT_ONE = 1 << 16, }; enum { /* * As vtime is used to calculate the cost of each IO, it needs to * be fairly high precision. For example, it should be able to * represent the cost of a single page worth of discard with * suffificient accuracy. At the same time, it should be able to * represent reasonably long enough durations to be useful and * convenient during operation. * * 1s worth of vtime is 2^37. This gives us both sub-nanosecond * granularity and days of wrap-around time even at extreme vrates. */ VTIME_PER_SEC_SHIFT = 37, VTIME_PER_SEC = 1LLU << VTIME_PER_SEC_SHIFT, VTIME_PER_USEC = VTIME_PER_SEC / USEC_PER_SEC, VTIME_PER_NSEC = VTIME_PER_SEC / NSEC_PER_SEC, /* bound vrate adjustments within two orders of magnitude */ VRATE_MIN_PPM = 10000, /* 1% */ VRATE_MAX_PPM = 100000000, /* 10000% */ VRATE_MIN = VTIME_PER_USEC * VRATE_MIN_PPM / MILLION, VRATE_CLAMP_ADJ_PCT = 4, /* switch iff the conditions are met for longer than this */ AUTOP_CYCLE_NSEC = 10LLU * NSEC_PER_SEC, }; enum { /* if IOs end up waiting for requests, issue less */ RQ_WAIT_BUSY_PCT = 5, /* unbusy hysterisis */ UNBUSY_THR_PCT = 75, /* * The effect of delay is indirect and non-linear and a huge amount of * future debt can accumulate abruptly while unthrottled. Linearly scale * up delay as debt is going up and then let it decay exponentially. * This gives us quick ramp ups while delay is accumulating and long * tails which can help reducing the frequency of debt explosions on * unthrottle. The parameters are experimentally determined. * * The delay mechanism provides adequate protection and behavior in many * cases. However, this is far from ideal and falls shorts on both * fronts. The debtors are often throttled too harshly costing a * significant level of fairness and possibly total work while the * protection against their impacts on the system can be choppy and * unreliable. * * The shortcoming primarily stems from the fact that, unlike for page * cache, the kernel doesn't have well-defined back-pressure propagation * mechanism and policies for anonymous memory. Fully addressing this * issue will likely require substantial improvements in the area. */ MIN_DELAY_THR_PCT = 500, MAX_DELAY_THR_PCT = 25000, MIN_DELAY = 250, MAX_DELAY = 250 * USEC_PER_MSEC, /* halve debts if avg usage over 100ms is under 50% */ DFGV_USAGE_PCT = 50, DFGV_PERIOD = 100 * USEC_PER_MSEC, /* don't let cmds which take a very long time pin lagging for too long */ MAX_LAGGING_PERIODS = 10, /* * Count IO size in 4k pages. The 12bit shift helps keeping * size-proportional components of cost calculation in closer * numbers of digits to per-IO cost components. */ IOC_PAGE_SHIFT = 12, IOC_PAGE_SIZE = 1 << IOC_PAGE_SHIFT, IOC_SECT_TO_PAGE_SHIFT = IOC_PAGE_SHIFT - SECTOR_SHIFT, /* if apart further than 16M, consider randio for linear model */ LCOEF_RANDIO_PAGES = 4096, }; enum ioc_running { IOC_IDLE, IOC_RUNNING, IOC_STOP, }; /* io.cost.qos controls including per-dev enable of the whole controller */ enum { QOS_ENABLE, QOS_CTRL, NR_QOS_CTRL_PARAMS, }; /* io.cost.qos params */ enum { QOS_RPPM, QOS_RLAT, QOS_WPPM, QOS_WLAT, QOS_MIN, QOS_MAX, NR_QOS_PARAMS, }; /* io.cost.model controls */ enum { COST_CTRL, COST_MODEL, NR_COST_CTRL_PARAMS, }; /* builtin linear cost model coefficients */ enum { I_LCOEF_RBPS, I_LCOEF_RSEQIOPS, I_LCOEF_RRANDIOPS, I_LCOEF_WBPS, I_LCOEF_WSEQIOPS, I_LCOEF_WRANDIOPS, NR_I_LCOEFS, }; enum { LCOEF_RPAGE, LCOEF_RSEQIO, LCOEF_RRANDIO, LCOEF_WPAGE, LCOEF_WSEQIO, LCOEF_WRANDIO, NR_LCOEFS, }; enum { AUTOP_INVALID, AUTOP_HDD, AUTOP_SSD_QD1, AUTOP_SSD_DFL, AUTOP_SSD_FAST, }; struct ioc_params { u32 qos[NR_QOS_PARAMS]; u64 i_lcoefs[NR_I_LCOEFS]; u64 lcoefs[NR_LCOEFS]; u32 too_fast_vrate_pct; u32 too_slow_vrate_pct; }; struct ioc_margins { s64 min; s64 low; s64 target; }; struct ioc_missed { local_t nr_met; local_t nr_missed; u32 last_met; u32 last_missed; }; struct ioc_pcpu_stat { struct ioc_missed missed[2]; local64_t rq_wait_ns; u64 last_rq_wait_ns; }; /* per device */ struct ioc { struct rq_qos rqos; bool enabled; struct ioc_params params; struct ioc_margins margins; u32 period_us; u32 timer_slack_ns; u64 vrate_min; u64 vrate_max; spinlock_t lock; struct timer_list timer; struct list_head active_iocgs; /* active cgroups */ struct ioc_pcpu_stat __percpu *pcpu_stat; enum ioc_running running; atomic64_t vtime_rate; u64 vtime_base_rate; s64 vtime_err; seqcount_spinlock_t period_seqcount; u64 period_at; /* wallclock starttime */ u64 period_at_vtime; /* vtime starttime */ atomic64_t cur_period; /* inc'd each period */ int busy_level; /* saturation history */ bool weights_updated; atomic_t hweight_gen; /* for lazy hweights */ /* debt forgivness */ u64 dfgv_period_at; u64 dfgv_period_rem; u64 dfgv_usage_us_sum; u64 autop_too_fast_at; u64 autop_too_slow_at; int autop_idx; bool user_qos_params:1; bool user_cost_model:1; }; struct iocg_pcpu_stat { local64_t abs_vusage; }; struct iocg_stat { u64 usage_us; u64 wait_us; u64 indebt_us; u64 indelay_us; }; /* per device-cgroup pair */ struct ioc_gq { struct blkg_policy_data pd; struct ioc *ioc; /* * A iocg can get its weight from two sources - an explicit * per-device-cgroup configuration or the default weight of the * cgroup. `cfg_weight` is the explicit per-device-cgroup * configuration. `weight` is the effective considering both * sources. * * When an idle cgroup becomes active its `active` goes from 0 to * `weight`. `inuse` is the surplus adjusted active weight. * `active` and `inuse` are used to calculate `hweight_active` and * `hweight_inuse`. * * `last_inuse` remembers `inuse` while an iocg is idle to persist * surplus adjustments. * * `inuse` may be adjusted dynamically during period. `saved_*` are used * to determine and track adjustments. */ u32 cfg_weight; u32 weight; u32 active; u32 inuse; u32 last_inuse; s64 saved_margin; sector_t cursor; /* to detect randio */ /* * `vtime` is this iocg's vtime cursor which progresses as IOs are * issued. If lagging behind device vtime, the delta represents * the currently available IO budget. If running ahead, the * overage. * * `vtime_done` is the same but progressed on completion rather * than issue. The delta behind `vtime` represents the cost of * currently in-flight IOs. */ atomic64_t vtime; atomic64_t done_vtime; u64 abs_vdebt; /* current delay in effect and when it started */ u64 delay; u64 delay_at; /* * The period this iocg was last active in. Used for deactivation * and invalidating `vtime`. */ atomic64_t active_period; struct list_head active_list; /* see __propagate_weights() and current_hweight() for details */ u64 child_active_sum; u64 child_inuse_sum; u64 child_adjusted_sum; int hweight_gen; u32 hweight_active; u32 hweight_inuse; u32 hweight_donating; u32 hweight_after_donation; struct list_head walk_list; struct list_head surplus_list; struct wait_queue_head waitq; struct hrtimer waitq_timer; /* timestamp at the latest activation */ u64 activated_at; /* statistics */ struct iocg_pcpu_stat __percpu *pcpu_stat; struct iocg_stat stat; struct iocg_stat last_stat; u64 last_stat_abs_vusage; u64 usage_delta_us; u64 wait_since; u64 indebt_since; u64 indelay_since; /* this iocg's depth in the hierarchy and ancestors including self */ int level; struct ioc_gq *ancestors[]; }; /* per cgroup */ struct ioc_cgrp { struct blkcg_policy_data cpd; unsigned int dfl_weight; }; struct ioc_now { u64 now_ns; u64 now; u64 vnow; }; struct iocg_wait { struct wait_queue_entry wait; struct bio *bio; u64 abs_cost; bool committed; }; struct iocg_wake_ctx { struct ioc_gq *iocg; u32 hw_inuse; s64 vbudget; }; static const struct ioc_params autop[] = { [AUTOP_HDD] = { .qos = { [QOS_RLAT] = 250000, /* 250ms */ [QOS_WLAT] = 250000, [QOS_MIN] = VRATE_MIN_PPM, [QOS_MAX] = VRATE_MAX_PPM, }, .i_lcoefs = { [I_LCOEF_RBPS] = 174019176, [I_LCOEF_RSEQIOPS] = 41708, [I_LCOEF_RRANDIOPS] = 370, [I_LCOEF_WBPS] = 178075866, [I_LCOEF_WSEQIOPS] = 42705, [I_LCOEF_WRANDIOPS] = 378, }, }, [AUTOP_SSD_QD1] = { .qos = { [QOS_RLAT] = 25000, /* 25ms */ [QOS_WLAT] = 25000, [QOS_MIN] = VRATE_MIN_PPM, [QOS_MAX] = VRATE_MAX_PPM, }, .i_lcoefs = { [I_LCOEF_RBPS] = 245855193, [I_LCOEF_RSEQIOPS] = 61575, [I_LCOEF_RRANDIOPS] = 6946, [I_LCOEF_WBPS] = 141365009, [I_LCOEF_WSEQIOPS] = 33716, [I_LCOEF_WRANDIOPS] = 26796, }, }, [AUTOP_SSD_DFL] = { .qos = { [QOS_RLAT] = 25000, /* 25ms */ [QOS_WLAT] = 25000, [QOS_MIN] = VRATE_MIN_PPM, [QOS_MAX] = VRATE_MAX_PPM, }, .i_lcoefs = { [I_LCOEF_RBPS] = 488636629, [I_LCOEF_RSEQIOPS] = 8932, [I_LCOEF_RRANDIOPS] = 8518, [I_LCOEF_WBPS] = 427891549, [I_LCOEF_WSEQIOPS] = 28755, [I_LCOEF_WRANDIOPS] = 21940, }, .too_fast_vrate_pct = 500, }, [AUTOP_SSD_FAST] = { .qos = { [QOS_RLAT] = 5000, /* 5ms */ [QOS_WLAT] = 5000, [QOS_MIN] = VRATE_MIN_PPM, [QOS_MAX] = VRATE_MAX_PPM, }, .i_lcoefs = { [I_LCOEF_RBPS] = 3102524156LLU, [I_LCOEF_RSEQIOPS] = 724816, [I_LCOEF_RRANDIOPS] = 778122, [I_LCOEF_WBPS] = 1742780862LLU, [I_LCOEF_WSEQIOPS] = 425702, [I_LCOEF_WRANDIOPS] = 443193, }, .too_slow_vrate_pct = 10, }, }; /* * vrate adjust percentages indexed by ioc->busy_level. We adjust up on * vtime credit shortage and down on device saturation. */ static u32 vrate_adj_pct[] = { 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 4, 4, 4, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, 16 }; static struct blkcg_policy blkcg_policy_iocost; /* accessors and helpers */ static struct ioc *rqos_to_ioc(struct rq_qos *rqos) { return container_of(rqos, struct ioc, rqos); } static struct ioc *q_to_ioc(struct request_queue *q) { return rqos_to_ioc(rq_qos_id(q, RQ_QOS_COST)); } static const char __maybe_unused *ioc_name(struct ioc *ioc) { struct gendisk *disk = ioc->rqos.disk; if (!disk) return "<unknown>"; return disk->disk_name; } static struct ioc_gq *pd_to_iocg(struct blkg_policy_data *pd) { return pd ? container_of(pd, struct ioc_gq, pd) : NULL; } static struct ioc_gq *blkg_to_iocg(struct blkcg_gq *blkg) { return pd_to_iocg(blkg_to_pd(blkg, &blkcg_policy_iocost)); } static struct blkcg_gq *iocg_to_blkg(struct ioc_gq *iocg) { return pd_to_blkg(&iocg->pd); } static struct ioc_cgrp *blkcg_to_iocc(struct blkcg *blkcg) { return container_of(blkcg_to_cpd(blkcg, &blkcg_policy_iocost), struct ioc_cgrp, cpd); } /* * Scale @abs_cost to the inverse of @hw_inuse. The lower the hierarchical * weight, the more expensive each IO. Must round up. */ static u64 abs_cost_to_cost(u64 abs_cost, u32 hw_inuse) { return DIV64_U64_ROUND_UP(abs_cost * WEIGHT_ONE, hw_inuse); } /* * The inverse of abs_cost_to_cost(). Must round up. */ static u64 cost_to_abs_cost(u64 cost, u32 hw_inuse) { return DIV64_U64_ROUND_UP(cost * hw_inuse, WEIGHT_ONE); } static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio, u64 abs_cost, u64 cost) { struct iocg_pcpu_stat *gcs; bio->bi_iocost_cost = cost; atomic64_add(cost, &iocg->vtime); gcs = get_cpu_ptr(iocg->pcpu_stat); local64_add(abs_cost, &gcs->abs_vusage); put_cpu_ptr(gcs); } static void iocg_lock(struct ioc_gq *iocg, bool lock_ioc, unsigned long *flags) { if (lock_ioc) { spin_lock_irqsave(&iocg->ioc->lock, *flags); spin_lock(&iocg->waitq.lock); } else { spin_lock_irqsave(&iocg->waitq.lock, *flags); } } static void iocg_unlock(struct ioc_gq *iocg, bool unlock_ioc, unsigned long *flags) { if (unlock_ioc) { spin_unlock(&iocg->waitq.lock); spin_unlock_irqrestore(&iocg->ioc->lock, *flags); } else { spin_unlock_irqrestore(&iocg->waitq.lock, *flags); } } #define CREATE_TRACE_POINTS #include <trace/events/iocost.h> static void ioc_refresh_margins(struct ioc *ioc) { struct ioc_margins *margins = &ioc->margins; u32 period_us = ioc->period_us; u64 vrate = ioc->vtime_base_rate; margins->min = (period_us * MARGIN_MIN_PCT / 100) * vrate; margins->low = (period_us * MARGIN_LOW_PCT / 100) * vrate; margins->target = (period_us * MARGIN_TARGET_PCT / 100) * vrate; } /* latency Qos params changed, update period_us and all the dependent params */ static void ioc_refresh_period_us(struct ioc *ioc) { u32 ppm, lat, multi, period_us; lockdep_assert_held(&ioc->lock); /* pick the higher latency target */ if (ioc->params.qos[QOS_RLAT] >= ioc->params.qos[QOS_WLAT]) { ppm = ioc->params.qos[QOS_RPPM]; lat = ioc->params.qos[QOS_RLAT]; } else { ppm = ioc->params.qos[QOS_WPPM]; lat = ioc->params.qos[QOS_WLAT]; } /* * We want the period to be long enough to contain a healthy number * of IOs while short enough for granular control. Define it as a * multiple of the latency target. Ideally, the multiplier should * be scaled according to the percentile so that it would nominally * contain a certain number of requests. Let's be simpler and * scale it linearly so that it's 2x >= pct(90) and 10x at pct(50). */ if (ppm) multi = max_t(u32, (MILLION - ppm) / 50000, 2); else multi = 2; period_us = multi * lat; period_us = clamp_t(u32, period_us, MIN_PERIOD, MAX_PERIOD); /* calculate dependent params */ ioc->period_us = period_us; ioc->timer_slack_ns = div64_u64( (u64)period_us * NSEC_PER_USEC * TIMER_SLACK_PCT, 100); ioc_refresh_margins(ioc); } /* * ioc->rqos.disk isn't initialized when this function is called from * the init path. */ static int ioc_autop_idx(struct ioc *ioc, struct gendisk *disk) { int idx = ioc->autop_idx; const struct ioc_params *p = &autop[idx]; u32 vrate_pct; u64 now_ns; /* rotational? */ if (!blk_queue_nonrot(disk->queue)) return AUTOP_HDD; /* handle SATA SSDs w/ broken NCQ */ if (blk_queue_depth(disk->queue) == 1) return AUTOP_SSD_QD1; /* use one of the normal ssd sets */ if (idx < AUTOP_SSD_DFL) return AUTOP_SSD_DFL; /* if user is overriding anything, maintain what was there */ if (ioc->user_qos_params || ioc->user_cost_model) return idx; /* step up/down based on the vrate */ vrate_pct = div64_u64(ioc->vtime_base_rate * 100, VTIME_PER_USEC); now_ns = blk_time_get_ns(); if (p->too_fast_vrate_pct && p->too_fast_vrate_pct <= vrate_pct) { if (!ioc->autop_too_fast_at) ioc->autop_too_fast_at = now_ns; if (now_ns - ioc->autop_too_fast_at >= AUTOP_CYCLE_NSEC) return idx + 1; } else { ioc->autop_too_fast_at = 0; } if (p->too_slow_vrate_pct && p->too_slow_vrate_pct >= vrate_pct) { if (!ioc->autop_too_slow_at) ioc->autop_too_slow_at = now_ns; if (now_ns - ioc->autop_too_slow_at >= AUTOP_CYCLE_NSEC) return idx - 1; } else { ioc->autop_too_slow_at = 0; } return idx; } /* * Take the followings as input * * @bps maximum sequential throughput * @seqiops maximum sequential 4k iops * @randiops maximum random 4k iops * * and calculate the linear model cost coefficients. * * *@page per-page cost 1s / (@bps / 4096) * *@seqio base cost of a seq IO max((1s / @seqiops) - *@page, 0) * @randiops base cost of a rand IO max((1s / @randiops) - *@page, 0) */ static void calc_lcoefs(u64 bps, u64 seqiops, u64 randiops, u64 *page, u64 *seqio, u64 *randio) { u64 v; *page = *seqio = *randio = 0; if (bps) { u64 bps_pages = DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE); if (bps_pages) *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC, bps_pages); else *page = 1; } if (seqiops) { v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, seqiops); if (v > *page) *seqio = v - *page; } if (randiops) { v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, randiops); if (v > *page) *randio = v - *page; } } static void ioc_refresh_lcoefs(struct ioc *ioc) { u64 *u = ioc->params.i_lcoefs; u64 *c = ioc->params.lcoefs; calc_lcoefs(u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS], &c[LCOEF_RPAGE], &c[LCOEF_RSEQIO], &c[LCOEF_RRANDIO]); calc_lcoefs(u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS], &c[LCOEF_WPAGE], &c[LCOEF_WSEQIO], &c[LCOEF_WRANDIO]); } /* * struct gendisk is required as an argument because ioc->rqos.disk * is not properly initialized when called from the init path. */ static bool ioc_refresh_params_disk(struct ioc *ioc, bool force, struct gendisk *disk) { const struct ioc_params *p; int idx; lockdep_assert_held(&ioc->lock); idx = ioc_autop_idx(ioc, disk); p = &autop[idx]; if (idx == ioc->autop_idx && !force) return false; if (idx != ioc->autop_idx) { atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC); ioc->vtime_base_rate = VTIME_PER_USEC; } ioc->autop_idx = idx; ioc->autop_too_fast_at = 0; ioc->autop_too_slow_at = 0; if (!ioc->user_qos_params) memcpy(ioc->params.qos, p->qos, sizeof(p->qos)); if (!ioc->user_cost_model) memcpy(ioc->params.i_lcoefs, p->i_lcoefs, sizeof(p->i_lcoefs)); ioc_refresh_period_us(ioc); ioc_refresh_lcoefs(ioc); ioc->vrate_min = DIV64_U64_ROUND_UP((u64)ioc->params.qos[QOS_MIN] * VTIME_PER_USEC, MILLION); ioc->vrate_max = DIV64_U64_ROUND_UP((u64)ioc->params.qos[QOS_MAX] * VTIME_PER_USEC, MILLION); return true; } static bool ioc_refresh_params(struct ioc *ioc, bool force) { return ioc_refresh_params_disk(ioc, force, ioc->rqos.disk); } /* * When an iocg accumulates too much vtime or gets deactivated, we throw away * some vtime, which lowers the overall device utilization. As the exact amount * which is being thrown away is known, we can compensate by accelerating the * vrate accordingly so that the extra vtime generated in the current period * matches what got lost. */ static void ioc_refresh_vrate(struct ioc *ioc, struct ioc_now *now) { s64 pleft = ioc->period_at + ioc->period_us - now->now; s64 vperiod = ioc->period_us * ioc->vtime_base_rate; s64 vcomp, vcomp_min, vcomp_max; lockdep_assert_held(&ioc->lock); /* we need some time left in this period */ if (pleft <= 0) goto done; /* * Calculate how much vrate should be adjusted to offset the error. * Limit the amount of adjustment and deduct the adjusted amount from * the error. */ vcomp = -div64_s64(ioc->vtime_err, pleft); vcomp_min = -(ioc->vtime_base_rate >> 1); vcomp_max = ioc->vtime_base_rate; vcomp = clamp(vcomp, vcomp_min, vcomp_max); ioc->vtime_err += vcomp * pleft; atomic64_set(&ioc->vtime_rate, ioc->vtime_base_rate + vcomp); done: /* bound how much error can accumulate */ ioc->vtime_err = clamp(ioc->vtime_err, -vperiod, vperiod); } static void ioc_adjust_base_vrate(struct ioc *ioc, u32 rq_wait_pct, int nr_lagging, int nr_shortages, int prev_busy_level, u32 *missed_ppm) { u64 vrate = ioc->vtime_base_rate; u64 vrate_min = ioc->vrate_min, vrate_max = ioc->vrate_max; if (!ioc->busy_level || (ioc->busy_level < 0 && nr_lagging)) { if (ioc->busy_level != prev_busy_level || nr_lagging) trace_iocost_ioc_vrate_adj(ioc, vrate, missed_ppm, rq_wait_pct, nr_lagging, nr_shortages); return; } /* * If vrate is out of bounds, apply clamp gradually as the * bounds can change abruptly. Otherwise, apply busy_level * based adjustment. */ if (vrate < vrate_min) { vrate = div64_u64(vrate * (100 + VRATE_CLAMP_ADJ_PCT), 100); vrate = min(vrate, vrate_min); } else if (vrate > vrate_max) { vrate = div64_u64(vrate * (100 - VRATE_CLAMP_ADJ_PCT), 100); vrate = max(vrate, vrate_max); } else { int idx = min_t(int, abs(ioc->busy_level), ARRAY_SIZE(vrate_adj_pct) - 1); u32 adj_pct = vrate_adj_pct[idx]; if (ioc->busy_level > 0) adj_pct = 100 - adj_pct; else adj_pct = 100 + adj_pct; vrate = clamp(DIV64_U64_ROUND_UP(vrate * adj_pct, 100), vrate_min, vrate_max); } trace_iocost_ioc_vrate_adj(ioc, vrate, missed_ppm, rq_wait_pct, nr_lagging, nr_shortages); ioc->vtime_base_rate = vrate; ioc_refresh_margins(ioc); } /* take a snapshot of the current [v]time and vrate */ static void ioc_now(struct ioc *ioc, struct ioc_now *now) { unsigned seq; u64 vrate; now->now_ns = blk_time_get_ns(); now->now = ktime_to_us(now->now_ns); vrate = atomic64_read(&ioc->vtime_rate); /* * The current vtime is * * vtime at period start + (wallclock time since the start) * vrate * * As a consistent snapshot of `period_at_vtime` and `period_at` is * needed, they're seqcount protected. */ do { seq = read_seqcount_begin(&ioc->period_seqcount); now->vnow = ioc->period_at_vtime + (now->now - ioc->period_at) * vrate; } while (read_seqcount_retry(&ioc->period_seqcount, seq)); } static void ioc_start_period(struct ioc *ioc, struct ioc_now *now) { WARN_ON_ONCE(ioc->running != IOC_RUNNING); write_seqcount_begin(&ioc->period_seqcount); ioc->period_at = now->now; ioc->period_at_vtime = now->vnow; write_seqcount_end(&ioc->period_seqcount); ioc->timer.expires = jiffies + usecs_to_jiffies(ioc->period_us); add_timer(&ioc->timer); } /* * Update @iocg's `active` and `inuse` to @active and @inuse, update level * weight sums and propagate upwards accordingly. If @save, the current margin * is saved to be used as reference for later inuse in-period adjustments. */ static void __propagate_weights(struct ioc_gq *iocg, u32 active, u32 inuse, bool save, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; int lvl; lockdep_assert_held(&ioc->lock); /* * For an active leaf node, its inuse shouldn't be zero or exceed * @active. An active internal node's inuse is solely determined by the * inuse to active ratio of its children regardless of @inuse. */ if (list_empty(&iocg->active_list) && iocg->child_active_sum) { inuse = DIV64_U64_ROUND_UP(active * iocg->child_inuse_sum, iocg->child_active_sum); } else { inuse = clamp_t(u32, inuse, 1, active); } iocg->last_inuse = iocg->inuse; if (save) iocg->saved_margin = now->vnow - atomic64_read(&iocg->vtime); if (active == iocg->active && inuse == iocg->inuse) return; for (lvl = iocg->level - 1; lvl >= 0; lvl--) { struct ioc_gq *parent = iocg->ancestors[lvl]; struct ioc_gq *child = iocg->ancestors[lvl + 1]; u32 parent_active = 0, parent_inuse = 0; /* update the level sums */ parent->child_active_sum += (s32)(active - child->active); parent->child_inuse_sum += (s32)(inuse - child->inuse); /* apply the updates */ child->active = active; child->inuse = inuse; /* * The delta between inuse and active sums indicates that * much of weight is being given away. Parent's inuse * and active should reflect the ratio. */ if (parent->child_active_sum) { parent_active = parent->weight; parent_inuse = DIV64_U64_ROUND_UP( parent_active * parent->child_inuse_sum, parent->child_active_sum); } /* do we need to keep walking up? */ if (parent_active == parent->active && parent_inuse == parent->inuse) break; active = parent_active; inuse = parent_inuse; } ioc->weights_updated = true; } static void commit_weights(struct ioc *ioc) { lockdep_assert_held(&ioc->lock); if (ioc->weights_updated) { /* paired with rmb in current_hweight(), see there */ smp_wmb(); atomic_inc(&ioc->hweight_gen); ioc->weights_updated = false; } } static void propagate_weights(struct ioc_gq *iocg, u32 active, u32 inuse, bool save, struct ioc_now *now) { __propagate_weights(iocg, active, inuse, save, now); commit_weights(iocg->ioc); } static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep) { struct ioc *ioc = iocg->ioc; int lvl; u32 hwa, hwi; int ioc_gen; /* hot path - if uptodate, use cached */ ioc_gen = atomic_read(&ioc->hweight_gen); if (ioc_gen == iocg->hweight_gen) goto out; /* * Paired with wmb in commit_weights(). If we saw the updated * hweight_gen, all the weight updates from __propagate_weights() are * visible too. * * We can race with weight updates during calculation and get it * wrong. However, hweight_gen would have changed and a future * reader will recalculate and we're guaranteed to discard the * wrong result soon. */ smp_rmb(); hwa = hwi = WEIGHT_ONE; for (lvl = 0; lvl <= iocg->level - 1; lvl++) { struct ioc_gq *parent = iocg->ancestors[lvl]; struct ioc_gq *child = iocg->ancestors[lvl + 1]; u64 active_sum = READ_ONCE(parent->child_active_sum); u64 inuse_sum = READ_ONCE(parent->child_inuse_sum); u32 active = READ_ONCE(child->active); u32 inuse = READ_ONCE(child->inuse); /* we can race with deactivations and either may read as zero */ if (!active_sum || !inuse_sum) continue; active_sum = max_t(u64, active, active_sum); hwa = div64_u64((u64)hwa * active, active_sum); inuse_sum = max_t(u64, inuse, inuse_sum); hwi = div64_u64((u64)hwi * inuse, inuse_sum); } iocg->hweight_active = max_t(u32, hwa, 1); iocg->hweight_inuse = max_t(u32, hwi, 1); iocg->hweight_gen = ioc_gen; out: if (hw_activep) *hw_activep = iocg->hweight_active; if (hw_inusep) *hw_inusep = iocg->hweight_inuse; } /* * Calculate the hweight_inuse @iocg would get with max @inuse assuming all the * other weights stay unchanged. */ static u32 current_hweight_max(struct ioc_gq *iocg) { u32 hwm = WEIGHT_ONE; u32 inuse = iocg->active; u64 child_inuse_sum; int lvl; lockdep_assert_held(&iocg->ioc->lock); for (lvl = iocg->level - 1; lvl >= 0; lvl--) { struct ioc_gq *parent = iocg->ancestors[lvl]; struct ioc_gq *child = iocg->ancestors[lvl + 1]; child_inuse_sum = parent->child_inuse_sum + inuse - child->inuse; hwm = div64_u64((u64)hwm * inuse, child_inuse_sum); inuse = DIV64_U64_ROUND_UP(parent->active * child_inuse_sum, parent->child_active_sum); } return max_t(u32, hwm, 1); } static void weight_updated(struct ioc_gq *iocg, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; struct blkcg_gq *blkg = iocg_to_blkg(iocg); struct ioc_cgrp *iocc = blkcg_to_iocc(blkg->blkcg); u32 weight; lockdep_assert_held(&ioc->lock); weight = iocg->cfg_weight ?: iocc->dfl_weight; if (weight != iocg->weight && iocg->active) propagate_weights(iocg, weight, iocg->inuse, true, now); iocg->weight = weight; } static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; u64 __maybe_unused last_period, cur_period; u64 vtime, vtarget; int i; /* * If seem to be already active, just update the stamp to tell the * timer that we're still active. We don't mind occassional races. */ if (!list_empty(&iocg->active_list)) { ioc_now(ioc, now); cur_period = atomic64_read(&ioc->cur_period); if (atomic64_read(&iocg->active_period) != cur_period) atomic64_set(&iocg->active_period, cur_period); return true; } /* racy check on internal node IOs, treat as root level IOs */ if (iocg->child_active_sum) return false; spin_lock_irq(&ioc->lock); ioc_now(ioc, now); /* update period */ cur_period = atomic64_read(&ioc->cur_period); last_period = atomic64_read(&iocg->active_period); atomic64_set(&iocg->active_period, cur_period); /* already activated or breaking leaf-only constraint? */ if (!list_empty(&iocg->active_list)) goto succeed_unlock; for (i = iocg->level - 1; i > 0; i--) if (!list_empty(&iocg->ancestors[i]->active_list)) goto fail_unlock; if (iocg->child_active_sum) goto fail_unlock; /* * Always start with the target budget. On deactivation, we throw away * anything above it. */ vtarget = now->vnow - ioc->margins.target; vtime = atomic64_read(&iocg->vtime); atomic64_add(vtarget - vtime, &iocg->vtime); atomic64_add(vtarget - vtime, &iocg->done_vtime); vtime = vtarget; /* * Activate, propagate weight and start period timer if not * running. Reset hweight_gen to avoid accidental match from * wrapping. */ iocg->hweight_gen = atomic_read(&ioc->hweight_gen) - 1; list_add(&iocg->active_list, &ioc->active_iocgs); propagate_weights(iocg, iocg->weight, iocg->last_inuse ?: iocg->weight, true, now); TRACE_IOCG_PATH(iocg_activate, iocg, now, last_period, cur_period, vtime); iocg->activated_at = now->now; if (ioc->running == IOC_IDLE) { ioc->running = IOC_RUNNING; ioc->dfgv_period_at = now->now; ioc->dfgv_period_rem = 0; ioc_start_period(ioc, now); } succeed_unlock: spin_unlock_irq(&ioc->lock); return true; fail_unlock: spin_unlock_irq(&ioc->lock); return false; } static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; struct blkcg_gq *blkg = iocg_to_blkg(iocg); u64 tdelta, delay, new_delay, shift; s64 vover, vover_pct; u32 hwa; lockdep_assert_held(&iocg->waitq.lock); /* * If the delay is set by another CPU, we may be in the past. No need to * change anything if so. This avoids decay calculation underflow. */ if (time_before64(now->now, iocg->delay_at)) return false; /* calculate the current delay in effect - 1/2 every second */ tdelta = now->now - iocg->delay_at; shift = div64_u64(tdelta, USEC_PER_SEC); if (iocg->delay && shift < BITS_PER_LONG) delay = iocg->delay >> shift; else delay = 0; /* calculate the new delay from the debt amount */ current_hweight(iocg, &hwa, NULL); vover = atomic64_read(&iocg->vtime) + abs_cost_to_cost(iocg->abs_vdebt, hwa) - now->vnow; vover_pct = div64_s64(100 * vover, ioc->period_us * ioc->vtime_base_rate); if (vover_pct <= MIN_DELAY_THR_PCT) new_delay = 0; else if (vover_pct >= MAX_DELAY_THR_PCT) new_delay = MAX_DELAY; else new_delay = MIN_DELAY + div_u64((MAX_DELAY - MIN_DELAY) * (vover_pct - MIN_DELAY_THR_PCT), MAX_DELAY_THR_PCT - MIN_DELAY_THR_PCT); /* pick the higher one and apply */ if (new_delay > delay) { iocg->delay = new_delay; iocg->delay_at = now->now; delay = new_delay; } if (delay >= MIN_DELAY) { if (!iocg->indelay_since) iocg->indelay_since = now->now; blkcg_set_delay(blkg, delay * NSEC_PER_USEC); return true; } else { if (iocg->indelay_since) { iocg->stat.indelay_us += now->now - iocg->indelay_since; iocg->indelay_since = 0; } iocg->delay = 0; blkcg_clear_delay(blkg); return false; } } static void iocg_incur_debt(struct ioc_gq *iocg, u64 abs_cost, struct ioc_now *now) { struct iocg_pcpu_stat *gcs; lockdep_assert_held(&iocg->ioc->lock); lockdep_assert_held(&iocg->waitq.lock); WARN_ON_ONCE(list_empty(&iocg->active_list)); /* * Once in debt, debt handling owns inuse. @iocg stays at the minimum * inuse donating all of it share to others until its debt is paid off. */ if (!iocg->abs_vdebt && abs_cost) { iocg->indebt_since = now->now; propagate_weights(iocg, iocg->active, 0, false, now); } iocg->abs_vdebt += abs_cost; gcs = get_cpu_ptr(iocg->pcpu_stat); local64_add(abs_cost, &gcs->abs_vusage); put_cpu_ptr(gcs); } static void iocg_pay_debt(struct ioc_gq *iocg, u64 abs_vpay, struct ioc_now *now) { lockdep_assert_held(&iocg->ioc->lock); lockdep_assert_held(&iocg->waitq.lock); /* * make sure that nobody messed with @iocg. Check iocg->pd.online * to avoid warn when removing blkcg or disk. */ WARN_ON_ONCE(list_empty(&iocg->active_list) && iocg->pd.online); WARN_ON_ONCE(iocg->inuse > 1); iocg->abs_vdebt -= min(abs_vpay, iocg->abs_vdebt); /* if debt is paid in full, restore inuse */ if (!iocg->abs_vdebt) { iocg->stat.indebt_us += now->now - iocg->indebt_since; iocg->indebt_since = 0; propagate_weights(iocg, iocg->active, iocg->last_inuse, false, now); } } static int iocg_wake_fn(struct wait_queue_entry *wq_entry, unsigned mode, int flags, void *key) { struct iocg_wait *wait = container_of(wq_entry, struct iocg_wait, wait); struct iocg_wake_ctx *ctx = key; u64 cost = abs_cost_to_cost(wait->abs_cost, ctx->hw_inuse); ctx->vbudget -= cost; if (ctx->vbudget < 0) return -1; iocg_commit_bio(ctx->iocg, wait->bio, wait->abs_cost, cost); wait->committed = true; /* * autoremove_wake_function() removes the wait entry only when it * actually changed the task state. We want the wait always removed. * Remove explicitly and use default_wake_function(). Note that the * order of operations is important as finish_wait() tests whether * @wq_entry is removed without grabbing the lock. */ default_wake_function(wq_entry, mode, flags, key); list_del_init_careful(&wq_entry->entry); return 0; } /* * Calculate the accumulated budget, pay debt if @pay_debt and wake up waiters * accordingly. When @pay_debt is %true, the caller must be holding ioc->lock in * addition to iocg->waitq.lock. */ static void iocg_kick_waitq(struct ioc_gq *iocg, bool pay_debt, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; struct iocg_wake_ctx ctx = { .iocg = iocg }; u64 vshortage, expires, oexpires; s64 vbudget; u32 hwa; lockdep_assert_held(&iocg->waitq.lock); current_hweight(iocg, &hwa, NULL); vbudget = now->vnow - atomic64_read(&iocg->vtime); /* pay off debt */ if (pay_debt && iocg->abs_vdebt && vbudget > 0) { u64 abs_vbudget = cost_to_abs_cost(vbudget, hwa); u64 abs_vpay = min_t(u64, abs_vbudget, iocg->abs_vdebt); u64 vpay = abs_cost_to_cost(abs_vpay, hwa); lockdep_assert_held(&ioc->lock); atomic64_add(vpay, &iocg->vtime); atomic64_add(vpay, &iocg->done_vtime); iocg_pay_debt(iocg, abs_vpay, now); vbudget -= vpay; } if (iocg->abs_vdebt || iocg->delay) iocg_kick_delay(iocg, now); /* * Debt can still be outstanding if we haven't paid all yet or the * caller raced and called without @pay_debt. Shouldn't wake up waiters * under debt. Make sure @vbudget reflects the outstanding amount and is * not positive. */ if (iocg->abs_vdebt) { s64 vdebt = abs_cost_to_cost(iocg->abs_vdebt, hwa); vbudget = min_t(s64, 0, vbudget - vdebt); } /* * Wake up the ones which are due and see how much vtime we'll need for * the next one. As paying off debt restores hw_inuse, it must be read * after the above debt payment. */ ctx.vbudget = vbudget; current_hweight(iocg, NULL, &ctx.hw_inuse); __wake_up_locked_key(&iocg->waitq, TASK_NORMAL, &ctx); if (!waitqueue_active(&iocg->waitq)) { if (iocg->wait_since) { iocg->stat.wait_us += now->now - iocg->wait_since; iocg->wait_since = 0; } return; } if (!iocg->wait_since) iocg->wait_since = now->now; if (WARN_ON_ONCE(ctx.vbudget >= 0)) return; /* determine next wakeup, add a timer margin to guarantee chunking */ vshortage = -ctx.vbudget; expires = now->now_ns + DIV64_U64_ROUND_UP(vshortage, ioc->vtime_base_rate) * NSEC_PER_USEC; expires += ioc->timer_slack_ns; /* if already active and close enough, don't bother */ oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->waitq_timer)); if (hrtimer_is_queued(&iocg->waitq_timer) && abs(oexpires - expires) <= ioc->timer_slack_ns) return; hrtimer_start_range_ns(&iocg->waitq_timer, ns_to_ktime(expires), ioc->timer_slack_ns, HRTIMER_MODE_ABS); } static enum hrtimer_restart iocg_waitq_timer_fn(struct hrtimer *timer) { struct ioc_gq *iocg = container_of(timer, struct ioc_gq, waitq_timer); bool pay_debt = READ_ONCE(iocg->abs_vdebt); struct ioc_now now; unsigned long flags; ioc_now(iocg->ioc, &now); iocg_lock(iocg, pay_debt, &flags); iocg_kick_waitq(iocg, pay_debt, &now); iocg_unlock(iocg, pay_debt, &flags); return HRTIMER_NORESTART; } static void ioc_lat_stat(struct ioc *ioc, u32 *missed_ppm_ar, u32 *rq_wait_pct_p) { u32 nr_met[2] = { }; u32 nr_missed[2] = { }; u64 rq_wait_ns = 0; int cpu, rw; for_each_online_cpu(cpu) { struct ioc_pcpu_stat *stat = per_cpu_ptr(ioc->pcpu_stat, cpu); u64 this_rq_wait_ns; for (rw = READ; rw <= WRITE; rw++) { u32 this_met = local_read(&stat->missed[rw].nr_met); u32 this_missed = local_read(&stat->missed[rw].nr_missed); nr_met[rw] += this_met - stat->missed[rw].last_met; nr_missed[rw] += this_missed - stat->missed[rw].last_missed; stat->missed[rw].last_met = this_met; stat->missed[rw].last_missed = this_missed; } this_rq_wait_ns = local64_read(&stat->rq_wait_ns); rq_wait_ns += this_rq_wait_ns - stat->last_rq_wait_ns; stat->last_rq_wait_ns = this_rq_wait_ns; } for (rw = READ; rw <= WRITE; rw++) { if (nr_met[rw] + nr_missed[rw]) missed_ppm_ar[rw] = DIV64_U64_ROUND_UP((u64)nr_missed[rw] * MILLION, nr_met[rw] + nr_missed[rw]); else missed_ppm_ar[rw] = 0; } *rq_wait_pct_p = div64_u64(rq_wait_ns * 100, ioc->period_us * NSEC_PER_USEC); } /* was iocg idle this period? */ static bool iocg_is_idle(struct ioc_gq *iocg) { struct ioc *ioc = iocg->ioc; /* did something get issued this period? */ if (atomic64_read(&iocg->active_period) == atomic64_read(&ioc->cur_period)) return false; /* is something in flight? */ if (atomic64_read(&iocg->done_vtime) != atomic64_read(&iocg->vtime)) return false; return true; } /* * Call this function on the target leaf @iocg's to build pre-order traversal * list of all the ancestors in @inner_walk. The inner nodes are linked through * ->walk_list and the caller is responsible for dissolving the list after use. */ static void iocg_build_inner_walk(struct ioc_gq *iocg, struct list_head *inner_walk) { int lvl; WARN_ON_ONCE(!list_empty(&iocg->walk_list)); /* find the first ancestor which hasn't been visited yet */ for (lvl = iocg->level - 1; lvl >= 0; lvl--) { if (!list_empty(&iocg->ancestors[lvl]->walk_list)) break; } /* walk down and visit the inner nodes to get pre-order traversal */ while (++lvl <= iocg->level - 1) { struct ioc_gq *inner = iocg->ancestors[lvl]; /* record traversal order */ list_add_tail(&inner->walk_list, inner_walk); } } /* propagate the deltas to the parent */ static void iocg_flush_stat_upward(struct ioc_gq *iocg) { if (iocg->level > 0) { struct iocg_stat *parent_stat = &iocg->ancestors[iocg->level - 1]->stat; parent_stat->usage_us += iocg->stat.usage_us - iocg->last_stat.usage_us; parent_stat->wait_us += iocg->stat.wait_us - iocg->last_stat.wait_us; parent_stat->indebt_us += iocg->stat.indebt_us - iocg->last_stat.indebt_us; parent_stat->indelay_us += iocg->stat.indelay_us - iocg->last_stat.indelay_us; } iocg->last_stat = iocg->stat; } /* collect per-cpu counters and propagate the deltas to the parent */ static void iocg_flush_stat_leaf(struct ioc_gq *iocg, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; u64 abs_vusage = 0; u64 vusage_delta; int cpu; lockdep_assert_held(&iocg->ioc->lock); /* collect per-cpu counters */ for_each_possible_cpu(cpu) { abs_vusage += local64_read( per_cpu_ptr(&iocg->pcpu_stat->abs_vusage, cpu)); } vusage_delta = abs_vusage - iocg->last_stat_abs_vusage; iocg->last_stat_abs_vusage = abs_vusage; iocg->usage_delta_us = div64_u64(vusage_delta, ioc->vtime_base_rate); iocg->stat.usage_us += iocg->usage_delta_us; iocg_flush_stat_upward(iocg); } /* get stat counters ready for reading on all active iocgs */ static void iocg_flush_stat(struct list_head *target_iocgs, struct ioc_now *now) { LIST_HEAD(inner_walk); struct ioc_gq *iocg, *tiocg; /* flush leaves and build inner node walk list */ list_for_each_entry(iocg, target_iocgs, active_list) { iocg_flush_stat_leaf(iocg, now); iocg_build_inner_walk(iocg, &inner_walk); } /* keep flushing upwards by walking the inner list backwards */ list_for_each_entry_safe_reverse(iocg, tiocg, &inner_walk, walk_list) { iocg_flush_stat_upward(iocg); list_del_init(&iocg->walk_list); } } /* * Determine what @iocg's hweight_inuse should be after donating unused * capacity. @hwm is the upper bound and used to signal no donation. This * function also throws away @iocg's excess budget. */ static u32 hweight_after_donation(struct ioc_gq *iocg, u32 old_hwi, u32 hwm, u32 usage, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; u64 vtime = atomic64_read(&iocg->vtime); s64 excess, delta, target, new_hwi; /* debt handling owns inuse for debtors */ if (iocg->abs_vdebt) return 1; /* see whether minimum margin requirement is met */ if (waitqueue_active(&iocg->waitq) || time_after64(vtime, now->vnow - ioc->margins.min)) return hwm; /* throw away excess above target */ excess = now->vnow - vtime - ioc->margins.target; if (excess > 0) { atomic64_add(excess, &iocg->vtime); atomic64_add(excess, &iocg->done_vtime); vtime += excess; ioc->vtime_err -= div64_u64(excess * old_hwi, WEIGHT_ONE); } /* * Let's say the distance between iocg's and device's vtimes as a * fraction of period duration is delta. Assuming that the iocg will * consume the usage determined above, we want to determine new_hwi so * that delta equals MARGIN_TARGET at the end of the next period. * * We need to execute usage worth of IOs while spending the sum of the * new budget (1 - MARGIN_TARGET) and the leftover from the last period * (delta): * * usage = (1 - MARGIN_TARGET + delta) * new_hwi * * Therefore, the new_hwi is: * * new_hwi = usage / (1 - MARGIN_TARGET + delta) */ delta = div64_s64(WEIGHT_ONE * (now->vnow - vtime), now->vnow - ioc->period_at_vtime); target = WEIGHT_ONE * MARGIN_TARGET_PCT / 100; new_hwi = div64_s64(WEIGHT_ONE * usage, WEIGHT_ONE - target + delta); return clamp_t(s64, new_hwi, 1, hwm); } /* * For work-conservation, an iocg which isn't using all of its share should * donate the leftover to other iocgs. There are two ways to achieve this - 1. * bumping up vrate accordingly 2. lowering the donating iocg's inuse weight. * * #1 is mathematically simpler but has the drawback of requiring synchronous * global hweight_inuse updates when idle iocg's get activated or inuse weights * change due to donation snapbacks as it has the possibility of grossly * overshooting what's allowed by the model and vrate. * * #2 is inherently safe with local operations. The donating iocg can easily * snap back to higher weights when needed without worrying about impacts on * other nodes as the impacts will be inherently correct. This also makes idle * iocg activations safe. The only effect activations have is decreasing * hweight_inuse of others, the right solution to which is for those iocgs to * snap back to higher weights. * * So, we go with #2. The challenge is calculating how each donating iocg's * inuse should be adjusted to achieve the target donation amounts. This is done * using Andy's method described in the following pdf. * * https://drive.google.com/file/d/1PsJwxPFtjUnwOY1QJ5AeICCcsL7BM3bo * * Given the weights and target after-donation hweight_inuse values, Andy's * method determines how the proportional distribution should look like at each * sibling level to maintain the relative relationship between all non-donating * pairs. To roughly summarize, it divides the tree into donating and * non-donating parts, calculates global donation rate which is used to * determine the target hweight_inuse for each node, and then derives per-level * proportions. * * The following pdf shows that global distribution calculated this way can be * achieved by scaling inuse weights of donating leaves and propagating the * adjustments upwards proportionally. * * https://drive.google.com/file/d/1vONz1-fzVO7oY5DXXsLjSxEtYYQbOvsE * * Combining the above two, we can determine how each leaf iocg's inuse should * be adjusted to achieve the target donation. * * https://drive.google.com/file/d/1WcrltBOSPN0qXVdBgnKm4mdp9FhuEFQN * * The inline comments use symbols from the last pdf. * * b is the sum of the absolute budgets in the subtree. 1 for the root node. * f is the sum of the absolute budgets of non-donating nodes in the subtree. * t is the sum of the absolute budgets of donating nodes in the subtree. * w is the weight of the node. w = w_f + w_t * w_f is the non-donating portion of w. w_f = w * f / b * w_b is the donating portion of w. w_t = w * t / b * s is the sum of all sibling weights. s = Sum(w) for siblings * s_f and s_t are the non-donating and donating portions of s. * * Subscript p denotes the parent's counterpart and ' the adjusted value - e.g. * w_pt is the donating portion of the parent's weight and w'_pt the same value * after adjustments. Subscript r denotes the root node's values. */ static void transfer_surpluses(struct list_head *surpluses, struct ioc_now *now) { LIST_HEAD(over_hwa); LIST_HEAD(inner_walk); struct ioc_gq *iocg, *tiocg, *root_iocg; u32 after_sum, over_sum, over_target, gamma; /* * It's pretty unlikely but possible for the total sum of * hweight_after_donation's to be higher than WEIGHT_ONE, which will * confuse the following calculations. If such condition is detected, * scale down everyone over its full share equally to keep the sum below * WEIGHT_ONE. */ after_sum = 0; over_sum = 0; list_for_each_entry(iocg, surpluses, surplus_list) { u32 hwa; current_hweight(iocg, &hwa, NULL); after_sum += iocg->hweight_after_donation; if (iocg->hweight_after_donation > hwa) { over_sum += iocg->hweight_after_donation; list_add(&iocg->walk_list, &over_hwa); } } if (after_sum >= WEIGHT_ONE) { /* * The delta should be deducted from the over_sum, calculate * target over_sum value. */ u32 over_delta = after_sum - (WEIGHT_ONE - 1); WARN_ON_ONCE(over_sum <= over_delta); over_target = over_sum - over_delta; } else { over_target = 0; } list_for_each_entry_safe(iocg, tiocg, &over_hwa, walk_list) { if (over_target) iocg->hweight_after_donation = div_u64((u64)iocg->hweight_after_donation * over_target, over_sum); list_del_init(&iocg->walk_list); } /* * Build pre-order inner node walk list and prepare for donation * adjustment calculations. */ list_for_each_entry(iocg, surpluses, surplus_list) { iocg_build_inner_walk(iocg, &inner_walk); } root_iocg = list_first_entry(&inner_walk, struct ioc_gq, walk_list); WARN_ON_ONCE(root_iocg->level > 0); list_for_each_entry(iocg, &inner_walk, walk_list) { iocg->child_adjusted_sum = 0; iocg->hweight_donating = 0; iocg->hweight_after_donation = 0; } /* * Propagate the donating budget (b_t) and after donation budget (b'_t) * up the hierarchy. */ list_for_each_entry(iocg, surpluses, surplus_list) { struct ioc_gq *parent = iocg->ancestors[iocg->level - 1]; parent->hweight_donating += iocg->hweight_donating; parent->hweight_after_donation += iocg->hweight_after_donation; } list_for_each_entry_reverse(iocg, &inner_walk, walk_list) { if (iocg->level > 0) { struct ioc_gq *parent = iocg->ancestors[iocg->level - 1]; parent->hweight_donating += iocg->hweight_donating; parent->hweight_after_donation += iocg->hweight_after_donation; } } /* * Calculate inner hwa's (b) and make sure the donation values are * within the accepted ranges as we're doing low res calculations with * roundups. */ list_for_each_entry(iocg, &inner_walk, walk_list) { if (iocg->level) { struct ioc_gq *parent = iocg->ancestors[iocg->level - 1]; iocg->hweight_active = DIV64_U64_ROUND_UP( (u64)parent->hweight_active * iocg->active, parent->child_active_sum); } iocg->hweight_donating = min(iocg->hweight_donating, iocg->hweight_active); iocg->hweight_after_donation = min(iocg->hweight_after_donation, iocg->hweight_donating - 1); if (WARN_ON_ONCE(iocg->hweight_active <= 1 || iocg->hweight_donating <= 1 || iocg->hweight_after_donation == 0)) { pr_warn("iocg: invalid donation weights in "); pr_cont_cgroup_path(iocg_to_blkg(iocg)->blkcg->css.cgroup); pr_cont(": active=%u donating=%u after=%u\n", iocg->hweight_active, iocg->hweight_donating, iocg->hweight_after_donation); } } /* * Calculate the global donation rate (gamma) - the rate to adjust * non-donating budgets by. * * No need to use 64bit multiplication here as the first operand is * guaranteed to be smaller than WEIGHT_ONE (1<<16). * * We know that there are beneficiary nodes and the sum of the donating * hweights can't be whole; however, due to the round-ups during hweight * calculations, root_iocg->hweight_donating might still end up equal to * or greater than whole. Limit the range when calculating the divider. * * gamma = (1 - t_r') / (1 - t_r) */ gamma = DIV_ROUND_UP( (WEIGHT_ONE - root_iocg->hweight_after_donation) * WEIGHT_ONE, WEIGHT_ONE - min_t(u32, root_iocg->hweight_donating, WEIGHT_ONE - 1)); /* * Calculate adjusted hwi, child_adjusted_sum and inuse for the inner * nodes. */ list_for_each_entry(iocg, &inner_walk, walk_list) { struct ioc_gq *parent; u32 inuse, wpt, wptp; u64 st, sf; if (iocg->level == 0) { /* adjusted weight sum for 1st level: s' = s * b_pf / b'_pf */ iocg->child_adjusted_sum = DIV64_U64_ROUND_UP( iocg->child_active_sum * (WEIGHT_ONE - iocg->hweight_donating), WEIGHT_ONE - iocg->hweight_after_donation); continue; } parent = iocg->ancestors[iocg->level - 1]; /* b' = gamma * b_f + b_t' */ iocg->hweight_inuse = DIV64_U64_ROUND_UP( (u64)gamma * (iocg->hweight_active - iocg->hweight_donating), WEIGHT_ONE) + iocg->hweight_after_donation; /* w' = s' * b' / b'_p */ inuse = DIV64_U64_ROUND_UP( (u64)parent->child_adjusted_sum * iocg->hweight_inuse, parent->hweight_inuse); /* adjusted weight sum for children: s' = s_f + s_t * w'_pt / w_pt */ st = DIV64_U64_ROUND_UP( iocg->child_active_sum * iocg->hweight_donating, iocg->hweight_active); sf = iocg->child_active_sum - st; wpt = DIV64_U64_ROUND_UP( (u64)iocg->active * iocg->hweight_donating, iocg->hweight_active); wptp = DIV64_U64_ROUND_UP( (u64)inuse * iocg->hweight_after_donation, iocg->hweight_inuse); iocg->child_adjusted_sum = sf + DIV64_U64_ROUND_UP(st * wptp, wpt); } /* * All inner nodes now have ->hweight_inuse and ->child_adjusted_sum and * we can finally determine leaf adjustments. */ list_for_each_entry(iocg, surpluses, surplus_list) { struct ioc_gq *parent = iocg->ancestors[iocg->level - 1]; u32 inuse; /* * In-debt iocgs participated in the donation calculation with * the minimum target hweight_inuse. Configuring inuse * accordingly would work fine but debt handling expects * @iocg->inuse stay at the minimum and we don't wanna * interfere. */ if (iocg->abs_vdebt) { WARN_ON_ONCE(iocg->inuse > 1); continue; } /* w' = s' * b' / b'_p, note that b' == b'_t for donating leaves */ inuse = DIV64_U64_ROUND_UP( parent->child_adjusted_sum * iocg->hweight_after_donation, parent->hweight_inuse); TRACE_IOCG_PATH(inuse_transfer, iocg, now, iocg->inuse, inuse, iocg->hweight_inuse, iocg->hweight_after_donation); __propagate_weights(iocg, iocg->active, inuse, true, now); } /* walk list should be dissolved after use */ list_for_each_entry_safe(iocg, tiocg, &inner_walk, walk_list) list_del_init(&iocg->walk_list); } /* * A low weight iocg can amass a large amount of debt, for example, when * anonymous memory gets reclaimed aggressively. If the system has a lot of * memory paired with a slow IO device, the debt can span multiple seconds or * more. If there are no other subsequent IO issuers, the in-debt iocg may end * up blocked paying its debt while the IO device is idle. * * The following protects against such cases. If the device has been * sufficiently idle for a while, the debts are halved and delays are * recalculated. */ static void ioc_forgive_debts(struct ioc *ioc, u64 usage_us_sum, int nr_debtors, struct ioc_now *now) { struct ioc_gq *iocg; u64 dur, usage_pct, nr_cycles; /* if no debtor, reset the cycle */ if (!nr_debtors) { ioc->dfgv_period_at = now->now; ioc->dfgv_period_rem = 0; ioc->dfgv_usage_us_sum = 0; return; } /* * Debtors can pass through a lot of writes choking the device and we * don't want to be forgiving debts while the device is struggling from * write bursts. If we're missing latency targets, consider the device * fully utilized. */ if (ioc->busy_level > 0) usage_us_sum = max_t(u64, usage_us_sum, ioc->period_us); ioc->dfgv_usage_us_sum += usage_us_sum; if (time_before64(now->now, ioc->dfgv_period_at + DFGV_PERIOD)) return; /* * At least DFGV_PERIOD has passed since the last period. Calculate the * average usage and reset the period counters. */ dur = now->now - ioc->dfgv_period_at; usage_pct = div64_u64(100 * ioc->dfgv_usage_us_sum, dur); ioc->dfgv_period_at = now->now; ioc->dfgv_usage_us_sum = 0; /* if was too busy, reset everything */ if (usage_pct > DFGV_USAGE_PCT) { ioc->dfgv_period_rem = 0; return; } /* * Usage is lower than threshold. Let's forgive some debts. Debt * forgiveness runs off of the usual ioc timer but its period usually * doesn't match ioc's. Compensate the difference by performing the * reduction as many times as would fit in the duration since the last * run and carrying over the left-over duration in @ioc->dfgv_period_rem * - if ioc period is 75% of DFGV_PERIOD, one out of three consecutive * reductions is doubled. */ nr_cycles = dur + ioc->dfgv_period_rem; ioc->dfgv_period_rem = do_div(nr_cycles, DFGV_PERIOD); list_for_each_entry(iocg, &ioc->active_iocgs, active_list) { u64 __maybe_unused old_debt, __maybe_unused old_delay; if (!iocg->abs_vdebt && !iocg->delay) continue; spin_lock(&iocg->waitq.lock); old_debt = iocg->abs_vdebt; old_delay = iocg->delay; if (iocg->abs_vdebt) iocg->abs_vdebt = iocg->abs_vdebt >> nr_cycles ?: 1; if (iocg->delay) iocg->delay = iocg->delay >> nr_cycles ?: 1; iocg_kick_waitq(iocg, true, now); TRACE_IOCG_PATH(iocg_forgive_debt, iocg, now, usage_pct, old_debt, iocg->abs_vdebt, old_delay, iocg->delay); spin_unlock(&iocg->waitq.lock); } } /* * Check the active iocgs' state to avoid oversleeping and deactive * idle iocgs. * * Since waiters determine the sleep durations based on the vrate * they saw at the time of sleep, if vrate has increased, some * waiters could be sleeping for too long. Wake up tardy waiters * which should have woken up in the last period and expire idle * iocgs. */ static int ioc_check_iocgs(struct ioc *ioc, struct ioc_now *now) { int nr_debtors = 0; struct ioc_gq *iocg, *tiocg; list_for_each_entry_safe(iocg, tiocg, &ioc->active_iocgs, active_list) { if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt && !iocg->delay && !iocg_is_idle(iocg)) continue; spin_lock(&iocg->waitq.lock); /* flush wait and indebt stat deltas */ if (iocg->wait_since) { iocg->stat.wait_us += now->now - iocg->wait_since; iocg->wait_since = now->now; } if (iocg->indebt_since) { iocg->stat.indebt_us += now->now - iocg->indebt_since; iocg->indebt_since = now->now; } if (iocg->indelay_since) { iocg->stat.indelay_us += now->now - iocg->indelay_since; iocg->indelay_since = now->now; } if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt || iocg->delay) { /* might be oversleeping vtime / hweight changes, kick */ iocg_kick_waitq(iocg, true, now); if (iocg->abs_vdebt || iocg->delay) nr_debtors++; } else if (iocg_is_idle(iocg)) { /* no waiter and idle, deactivate */ u64 vtime = atomic64_read(&iocg->vtime); s64 excess; /* * @iocg has been inactive for a full duration and will * have a high budget. Account anything above target as * error and throw away. On reactivation, it'll start * with the target budget. */ excess = now->vnow - vtime - ioc->margins.target; if (excess > 0) { u32 old_hwi; current_hweight(iocg, NULL, &old_hwi); ioc->vtime_err -= div64_u64(excess * old_hwi, WEIGHT_ONE); } TRACE_IOCG_PATH(iocg_idle, iocg, now, atomic64_read(&iocg->active_period), atomic64_read(&ioc->cur_period), vtime); __propagate_weights(iocg, 0, 0, false, now); list_del_init(&iocg->active_list); } spin_unlock(&iocg->waitq.lock); } commit_weights(ioc); return nr_debtors; } static void ioc_timer_fn(struct timer_list *timer) { struct ioc *ioc = container_of(timer, struct ioc, timer); struct ioc_gq *iocg, *tiocg; struct ioc_now now; LIST_HEAD(surpluses); int nr_debtors, nr_shortages = 0, nr_lagging = 0; u64 usage_us_sum = 0; u32 ppm_rthr; u32 ppm_wthr; u32 missed_ppm[2], rq_wait_pct; u64 period_vtime; int prev_busy_level; /* how were the latencies during the period? */ ioc_lat_stat(ioc, missed_ppm, &rq_wait_pct); /* take care of active iocgs */ spin_lock_irq(&ioc->lock); ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM]; ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM]; ioc_now(ioc, &now); period_vtime = now.vnow - ioc->period_at_vtime; if (WARN_ON_ONCE(!period_vtime)) { spin_unlock_irq(&ioc->lock); return; } nr_debtors = ioc_check_iocgs(ioc, &now); /* * Wait and indebt stat are flushed above and the donation calculation * below needs updated usage stat. Let's bring stat up-to-date. */ iocg_flush_stat(&ioc->active_iocgs, &now); /* calc usage and see whether some weights need to be moved around */ list_for_each_entry(iocg, &ioc->active_iocgs, active_list) { u64 vdone, vtime, usage_us; u32 hw_active, hw_inuse; /* * Collect unused and wind vtime closer to vnow to prevent * iocgs from accumulating a large amount of budget. */ vdone = atomic64_read(&iocg->done_vtime); vtime = atomic64_read(&iocg->vtime); current_hweight(iocg, &hw_active, &hw_inuse); /* * Latency QoS detection doesn't account for IOs which are * in-flight for longer than a period. Detect them by * comparing vdone against period start. If lagging behind * IOs from past periods, don't increase vrate. */ if ((ppm_rthr != MILLION || ppm_wthr != MILLION) && !atomic_read(&iocg_to_blkg(iocg)->use_delay) && time_after64(vtime, vdone) && time_after64(vtime, now.vnow - MAX_LAGGING_PERIODS * period_vtime) && time_before64(vdone, now.vnow - period_vtime)) nr_lagging++; /* * Determine absolute usage factoring in in-flight IOs to avoid * high-latency completions appearing as idle. */ usage_us = iocg->usage_delta_us; usage_us_sum += usage_us; /* see whether there's surplus vtime */ WARN_ON_ONCE(!list_empty(&iocg->surplus_list)); if (hw_inuse < hw_active || (!waitqueue_active(&iocg->waitq) && time_before64(vtime, now.vnow - ioc->margins.low))) { u32 hwa, old_hwi, hwm, new_hwi, usage; u64 usage_dur; if (vdone != vtime) { u64 inflight_us = DIV64_U64_ROUND_UP( cost_to_abs_cost(vtime - vdone, hw_inuse), ioc->vtime_base_rate); usage_us = max(usage_us, inflight_us); } /* convert to hweight based usage ratio */ if (time_after64(iocg->activated_at, ioc->period_at)) usage_dur = max_t(u64, now.now - iocg->activated_at, 1); else usage_dur = max_t(u64, now.now - ioc->period_at, 1); usage = clamp_t(u32, DIV64_U64_ROUND_UP(usage_us * WEIGHT_ONE, usage_dur), 1, WEIGHT_ONE); /* * Already donating or accumulated enough to start. * Determine the donation amount. */ current_hweight(iocg, &hwa, &old_hwi); hwm = current_hweight_max(iocg); new_hwi = hweight_after_donation(iocg, old_hwi, hwm, usage, &now); /* * Donation calculation assumes hweight_after_donation * to be positive, a condition that a donor w/ hwa < 2 * can't meet. Don't bother with donation if hwa is * below 2. It's not gonna make a meaningful difference * anyway. */ if (new_hwi < hwm && hwa >= 2) { iocg->hweight_donating = hwa; iocg->hweight_after_donation = new_hwi; list_add(&iocg->surplus_list, &surpluses); } else if (!iocg->abs_vdebt) { /* * @iocg doesn't have enough to donate. Reset * its inuse to active. * * Don't reset debtors as their inuse's are * owned by debt handling. This shouldn't affect * donation calculuation in any meaningful way * as @iocg doesn't have a meaningful amount of * share anyway. */ TRACE_IOCG_PATH(inuse_shortage, iocg, &now, iocg->inuse, iocg->active, iocg->hweight_inuse, new_hwi); __propagate_weights(iocg, iocg->active, iocg->active, true, &now); nr_shortages++; } } else { /* genuinely short on vtime */ nr_shortages++; } } if (!list_empty(&surpluses) && nr_shortages) transfer_surpluses(&surpluses, &now); commit_weights(ioc); /* surplus list should be dissolved after use */ list_for_each_entry_safe(iocg, tiocg, &surpluses, surplus_list) list_del_init(&iocg->surplus_list); /* * If q is getting clogged or we're missing too much, we're issuing * too much IO and should lower vtime rate. If we're not missing * and experiencing shortages but not surpluses, we're too stingy * and should increase vtime rate. */ prev_busy_level = ioc->busy_level; if (rq_wait_pct > RQ_WAIT_BUSY_PCT || missed_ppm[READ] > ppm_rthr || missed_ppm[WRITE] > ppm_wthr) { /* clearly missing QoS targets, slow down vrate */ ioc->busy_level = max(ioc->busy_level, 0); ioc->busy_level++; } else if (rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 && missed_ppm[READ] <= ppm_rthr * UNBUSY_THR_PCT / 100 && missed_ppm[WRITE] <= ppm_wthr * UNBUSY_THR_PCT / 100) { /* QoS targets are being met with >25% margin */ if (nr_shortages) { /* * We're throttling while the device has spare * capacity. If vrate was being slowed down, stop. */ ioc->busy_level = min(ioc->busy_level, 0); /* * If there are IOs spanning multiple periods, wait * them out before pushing the device harder. */ if (!nr_lagging) ioc->busy_level--; } else { /* * Nobody is being throttled and the users aren't * issuing enough IOs to saturate the device. We * simply don't know how close the device is to * saturation. Coast. */ ioc->busy_level = 0; } } else { /* inside the hysterisis margin, we're good */ ioc->busy_level = 0; } ioc->busy_level = clamp(ioc->busy_level, -1000, 1000); ioc_adjust_base_vrate(ioc, rq_wait_pct, nr_lagging, nr_shortages, prev_busy_level, missed_ppm); ioc_refresh_params(ioc, false); ioc_forgive_debts(ioc, usage_us_sum, nr_debtors, &now); /* * This period is done. Move onto the next one. If nothing's * going on with the device, stop the timer. */ atomic64_inc(&ioc->cur_period); if (ioc->running != IOC_STOP) { if (!list_empty(&ioc->active_iocgs)) { ioc_start_period(ioc, &now); } else { ioc->busy_level = 0; ioc->vtime_err = 0; ioc->running = IOC_IDLE; } ioc_refresh_vrate(ioc, &now); } spin_unlock_irq(&ioc->lock); } static u64 adjust_inuse_and_calc_cost(struct ioc_gq *iocg, u64 vtime, u64 abs_cost, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; struct ioc_margins *margins = &ioc->margins; u32 __maybe_unused old_inuse = iocg->inuse, __maybe_unused old_hwi; u32 hwi, adj_step; s64 margin; u64 cost, new_inuse; unsigned long flags; current_hweight(iocg, NULL, &hwi); old_hwi = hwi; cost = abs_cost_to_cost(abs_cost, hwi); margin = now->vnow - vtime - cost; /* debt handling owns inuse for debtors */ if (iocg->abs_vdebt) return cost; /* * We only increase inuse during period and do so if the margin has * deteriorated since the previous adjustment. */ if (margin >= iocg->saved_margin || margin >= margins->low || iocg->inuse == iocg->active) return cost; spin_lock_irqsave(&ioc->lock, flags); /* we own inuse only when @iocg is in the normal active state */ if (iocg->abs_vdebt || list_empty(&iocg->active_list)) { spin_unlock_irqrestore(&ioc->lock, flags); return cost; } /* * Bump up inuse till @abs_cost fits in the existing budget. * adj_step must be determined after acquiring ioc->lock - we might * have raced and lost to another thread for activation and could * be reading 0 iocg->active before ioc->lock which will lead to * infinite loop. */ new_inuse = iocg->inuse; adj_step = DIV_ROUND_UP(iocg->active * INUSE_ADJ_STEP_PCT, 100); do { new_inuse = new_inuse + adj_step; propagate_weights(iocg, iocg->active, new_inuse, true, now); current_hweight(iocg, NULL, &hwi); cost = abs_cost_to_cost(abs_cost, hwi); } while (time_after64(vtime + cost, now->vnow) && iocg->inuse != iocg->active); spin_unlock_irqrestore(&ioc->lock, flags); TRACE_IOCG_PATH(inuse_adjust, iocg, now, old_inuse, iocg->inuse, old_hwi, hwi); return cost; } static void calc_vtime_cost_builtin(struct bio *bio, struct ioc_gq *iocg, bool is_merge, u64 *costp) { struct ioc *ioc = iocg->ioc; u64 coef_seqio, coef_randio, coef_page; u64 pages = max_t(u64, bio_sectors(bio) >> IOC_SECT_TO_PAGE_SHIFT, 1); u64 seek_pages = 0; u64 cost = 0; /* Can't calculate cost for empty bio */ if (!bio->bi_iter.bi_size) goto out; switch (bio_op(bio)) { case REQ_OP_READ: coef_seqio = ioc->params.lcoefs[LCOEF_RSEQIO]; coef_randio = ioc->params.lcoefs[LCOEF_RRANDIO]; coef_page = ioc->params.lcoefs[LCOEF_RPAGE]; break; case REQ_OP_WRITE: coef_seqio = ioc->params.lcoefs[LCOEF_WSEQIO]; coef_randio = ioc->params.lcoefs[LCOEF_WRANDIO]; coef_page = ioc->params.lcoefs[LCOEF_WPAGE]; break; default: goto out; } if (iocg->cursor) { seek_pages = abs(bio->bi_iter.bi_sector - iocg->cursor); seek_pages >>= IOC_SECT_TO_PAGE_SHIFT; } if (!is_merge) { if (seek_pages > LCOEF_RANDIO_PAGES) { cost += coef_randio; } else { cost += coef_seqio; } } cost += pages * coef_page; out: *costp = cost; } static u64 calc_vtime_cost(struct bio *bio, struct ioc_gq *iocg, bool is_merge) { u64 cost; calc_vtime_cost_builtin(bio, iocg, is_merge, &cost); return cost; } static void calc_size_vtime_cost_builtin(struct request *rq, struct ioc *ioc, u64 *costp) { unsigned int pages = blk_rq_stats_sectors(rq) >> IOC_SECT_TO_PAGE_SHIFT; switch (req_op(rq)) { case REQ_OP_READ: *costp = pages * ioc->params.lcoefs[LCOEF_RPAGE]; break; case REQ_OP_WRITE: *costp = pages * ioc->params.lcoefs[LCOEF_WPAGE]; break; default: *costp = 0; } } static u64 calc_size_vtime_cost(struct request *rq, struct ioc *ioc) { u64 cost; calc_size_vtime_cost_builtin(rq, ioc, &cost); return cost; } static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio) { struct blkcg_gq *blkg = bio->bi_blkg; struct ioc *ioc = rqos_to_ioc(rqos); struct ioc_gq *iocg = blkg_to_iocg(blkg); struct ioc_now now; struct iocg_wait wait; u64 abs_cost, cost, vtime; bool use_debt, ioc_locked; unsigned long flags; /* bypass IOs if disabled, still initializing, or for root cgroup */ if (!ioc->enabled || !iocg || !iocg->level) return; /* calculate the absolute vtime cost */ abs_cost = calc_vtime_cost(bio, iocg, false); if (!abs_cost) return; if (!iocg_activate(iocg, &now)) return; iocg->cursor = bio_end_sector(bio); vtime = atomic64_read(&iocg->vtime); cost = adjust_inuse_and_calc_cost(iocg, vtime, abs_cost, &now); /* * If no one's waiting and within budget, issue right away. The * tests are racy but the races aren't systemic - we only miss once * in a while which is fine. */ if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt && time_before_eq64(vtime + cost, now.vnow)) { iocg_commit_bio(iocg, bio, abs_cost, cost); return; } /* * We're over budget. This can be handled in two ways. IOs which may * cause priority inversions are punted to @ioc->aux_iocg and charged as * debt. Otherwise, the issuer is blocked on @iocg->waitq. Debt handling * requires @ioc->lock, waitq handling @iocg->waitq.lock. Determine * whether debt handling is needed and acquire locks accordingly. */ use_debt = bio_issue_as_root_blkg(bio) || fatal_signal_pending(current); ioc_locked = use_debt || READ_ONCE(iocg->abs_vdebt); retry_lock: iocg_lock(iocg, ioc_locked, &flags); /* * @iocg must stay activated for debt and waitq handling. Deactivation * is synchronized against both ioc->lock and waitq.lock and we won't * get deactivated as long as we're waiting or has debt, so we're good * if we're activated here. In the unlikely cases that we aren't, just * issue the IO. */ if (unlikely(list_empty(&iocg->active_list))) { iocg_unlock(iocg, ioc_locked, &flags); iocg_commit_bio(iocg, bio, abs_cost, cost); return; } /* * We're over budget. If @bio has to be issued regardless, remember * the abs_cost instead of advancing vtime. iocg_kick_waitq() will pay * off the debt before waking more IOs. * * This way, the debt is continuously paid off each period with the * actual budget available to the cgroup. If we just wound vtime, we * would incorrectly use the current hw_inuse for the entire amount * which, for example, can lead to the cgroup staying blocked for a * long time even with substantially raised hw_inuse. * * An iocg with vdebt should stay online so that the timer can keep * deducting its vdebt and [de]activate use_delay mechanism * accordingly. We don't want to race against the timer trying to * clear them and leave @iocg inactive w/ dangling use_delay heavily * penalizing the cgroup and its descendants. */ if (use_debt) { iocg_incur_debt(iocg, abs_cost, &now); if (iocg_kick_delay(iocg, &now)) blkcg_schedule_throttle(rqos->disk, (bio->bi_opf & REQ_SWAP) == REQ_SWAP); iocg_unlock(iocg, ioc_locked, &flags); return; } /* guarantee that iocgs w/ waiters have maximum inuse */ if (!iocg->abs_vdebt && iocg->inuse != iocg->active) { if (!ioc_locked) { iocg_unlock(iocg, false, &flags); ioc_locked = true; goto retry_lock; } propagate_weights(iocg, iocg->active, iocg->active, true, &now); } /* * Append self to the waitq and schedule the wakeup timer if we're * the first waiter. The timer duration is calculated based on the * current vrate. vtime and hweight changes can make it too short * or too long. Each wait entry records the absolute cost it's * waiting for to allow re-evaluation using a custom wait entry. * * If too short, the timer simply reschedules itself. If too long, * the period timer will notice and trigger wakeups. * * All waiters are on iocg->waitq and the wait states are * synchronized using waitq.lock. */ init_waitqueue_func_entry(&wait.wait, iocg_wake_fn); wait.wait.private = current; wait.bio = bio; wait.abs_cost = abs_cost; wait.committed = false; /* will be set true by waker */ __add_wait_queue_entry_tail(&iocg->waitq, &wait.wait); iocg_kick_waitq(iocg, ioc_locked, &now); iocg_unlock(iocg, ioc_locked, &flags); while (true) { set_current_state(TASK_UNINTERRUPTIBLE); if (wait.committed) break; io_schedule(); } /* waker already committed us, proceed */ finish_wait(&iocg->waitq, &wait.wait); } static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq, struct bio *bio) { struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg); struct ioc *ioc = rqos_to_ioc(rqos); sector_t bio_end = bio_end_sector(bio); struct ioc_now now; u64 vtime, abs_cost, cost; unsigned long flags; /* bypass if disabled, still initializing, or for root cgroup */ if (!ioc->enabled || !iocg || !iocg->level) return; abs_cost = calc_vtime_cost(bio, iocg, true); if (!abs_cost) return; ioc_now(ioc, &now); vtime = atomic64_read(&iocg->vtime); cost = adjust_inuse_and_calc_cost(iocg, vtime, abs_cost, &now); /* update cursor if backmerging into the request at the cursor */ if (blk_rq_pos(rq) < bio_end && blk_rq_pos(rq) + blk_rq_sectors(rq) == iocg->cursor) iocg->cursor = bio_end; /* * Charge if there's enough vtime budget and the existing request has * cost assigned. */ if (rq->bio && rq->bio->bi_iocost_cost && time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow)) { iocg_commit_bio(iocg, bio, abs_cost, cost); return; } /* * Otherwise, account it as debt if @iocg is online, which it should * be for the vast majority of cases. See debt handling in * ioc_rqos_throttle() for details. */ spin_lock_irqsave(&ioc->lock, flags); spin_lock(&iocg->waitq.lock); if (likely(!list_empty(&iocg->active_list))) { iocg_incur_debt(iocg, abs_cost, &now); if (iocg_kick_delay(iocg, &now)) blkcg_schedule_throttle(rqos->disk, (bio->bi_opf & REQ_SWAP) == REQ_SWAP); } else { iocg_commit_bio(iocg, bio, abs_cost, cost); } spin_unlock(&iocg->waitq.lock); spin_unlock_irqrestore(&ioc->lock, flags); } static void ioc_rqos_done_bio(struct rq_qos *rqos, struct bio *bio) { struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg); if (iocg && bio->bi_iocost_cost) atomic64_add(bio->bi_iocost_cost, &iocg->done_vtime); } static void ioc_rqos_done(struct rq_qos *rqos, struct request *rq) { struct ioc *ioc = rqos_to_ioc(rqos); struct ioc_pcpu_stat *ccs; u64 on_q_ns, rq_wait_ns, size_nsec; int pidx, rw; if (!ioc->enabled || !rq->alloc_time_ns || !rq->start_time_ns) return; switch (req_op(rq)) { case REQ_OP_READ: pidx = QOS_RLAT; rw = READ; break; case REQ_OP_WRITE: pidx = QOS_WLAT; rw = WRITE; break; default: return; } on_q_ns = blk_time_get_ns() - rq->alloc_time_ns; rq_wait_ns = rq->start_time_ns - rq->alloc_time_ns; size_nsec = div64_u64(calc_size_vtime_cost(rq, ioc), VTIME_PER_NSEC); ccs = get_cpu_ptr(ioc->pcpu_stat); if (on_q_ns <= size_nsec || on_q_ns - size_nsec <= ioc->params.qos[pidx] * NSEC_PER_USEC) local_inc(&ccs->missed[rw].nr_met); else local_inc(&ccs->missed[rw].nr_missed); local64_add(rq_wait_ns, &ccs->rq_wait_ns); put_cpu_ptr(ccs); } static void ioc_rqos_queue_depth_changed(struct rq_qos *rqos) { struct ioc *ioc = rqos_to_ioc(rqos); spin_lock_irq(&ioc->lock); ioc_refresh_params(ioc, false); spin_unlock_irq(&ioc->lock); } static void ioc_rqos_exit(struct rq_qos *rqos) { struct ioc *ioc = rqos_to_ioc(rqos); blkcg_deactivate_policy(rqos->disk, &blkcg_policy_iocost); spin_lock_irq(&ioc->lock); ioc->running = IOC_STOP; spin_unlock_irq(&ioc->lock); timer_shutdown_sync(&ioc->timer); free_percpu(ioc->pcpu_stat); kfree(ioc); } static const struct rq_qos_ops ioc_rqos_ops = { .throttle = ioc_rqos_throttle, .merge = ioc_rqos_merge, .done_bio = ioc_rqos_done_bio, .done = ioc_rqos_done, .queue_depth_changed = ioc_rqos_queue_depth_changed, .exit = ioc_rqos_exit, }; static int blk_iocost_init(struct gendisk *disk) { struct ioc *ioc; int i, cpu, ret; ioc = kzalloc(sizeof(*ioc), GFP_KERNEL); if (!ioc) return -ENOMEM; ioc->pcpu_stat = alloc_percpu(struct ioc_pcpu_stat); if (!ioc->pcpu_stat) { kfree(ioc); return -ENOMEM; } for_each_possible_cpu(cpu) { struct ioc_pcpu_stat *ccs = per_cpu_ptr(ioc->pcpu_stat, cpu); for (i = 0; i < ARRAY_SIZE(ccs->missed); i++) { local_set(&ccs->missed[i].nr_met, 0); local_set(&ccs->missed[i].nr_missed, 0); } local64_set(&ccs->rq_wait_ns, 0); } spin_lock_init(&ioc->lock); timer_setup(&ioc->timer, ioc_timer_fn, 0); INIT_LIST_HEAD(&ioc->active_iocgs); ioc->running = IOC_IDLE; ioc->vtime_base_rate = VTIME_PER_USEC; atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC); seqcount_spinlock_init(&ioc->period_seqcount, &ioc->lock); ioc->period_at = ktime_to_us(blk_time_get()); atomic64_set(&ioc->cur_period, 0); atomic_set(&ioc->hweight_gen, 0); spin_lock_irq(&ioc->lock); ioc->autop_idx = AUTOP_INVALID; ioc_refresh_params_disk(ioc, true, disk); spin_unlock_irq(&ioc->lock); /* * rqos must be added before activation to allow ioc_pd_init() to * lookup the ioc from q. This means that the rqos methods may get * called before policy activation completion, can't assume that the * target bio has an iocg associated and need to test for NULL iocg. */ ret = rq_qos_add(&ioc->rqos, disk, RQ_QOS_COST, &ioc_rqos_ops); if (ret) goto err_free_ioc; ret = blkcg_activate_policy(disk, &blkcg_policy_iocost); if (ret) goto err_del_qos; return 0; err_del_qos: rq_qos_del(&ioc->rqos); err_free_ioc: free_percpu(ioc->pcpu_stat); kfree(ioc); return ret; } static struct blkcg_policy_data *ioc_cpd_alloc(gfp_t gfp) { struct ioc_cgrp *iocc; iocc = kzalloc(sizeof(struct ioc_cgrp), gfp); if (!iocc) return NULL; iocc->dfl_weight = CGROUP_WEIGHT_DFL * WEIGHT_ONE; return &iocc->cpd; } static void ioc_cpd_free(struct blkcg_policy_data *cpd) { kfree(container_of(cpd, struct ioc_cgrp, cpd)); } static struct blkg_policy_data *ioc_pd_alloc(struct gendisk *disk, struct blkcg *blkcg, gfp_t gfp) { int levels = blkcg->css.cgroup->level + 1; struct ioc_gq *iocg; iocg = kzalloc_node(struct_size(iocg, ancestors, levels), gfp, disk->node_id); if (!iocg) return NULL; iocg->pcpu_stat = alloc_percpu_gfp(struct iocg_pcpu_stat, gfp); if (!iocg->pcpu_stat) { kfree(iocg); return NULL; } return &iocg->pd; } static void ioc_pd_init(struct blkg_policy_data *pd) { struct ioc_gq *iocg = pd_to_iocg(pd); struct blkcg_gq *blkg = pd_to_blkg(&iocg->pd); struct ioc *ioc = q_to_ioc(blkg->q); struct ioc_now now; struct blkcg_gq *tblkg; unsigned long flags; ioc_now(ioc, &now); iocg->ioc = ioc; atomic64_set(&iocg->vtime, now.vnow); atomic64_set(&iocg->done_vtime, now.vnow); atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period)); INIT_LIST_HEAD(&iocg->active_list); INIT_LIST_HEAD(&iocg->walk_list); INIT_LIST_HEAD(&iocg->surplus_list); iocg->hweight_active = WEIGHT_ONE; iocg->hweight_inuse = WEIGHT_ONE; init_waitqueue_head(&iocg->waitq); hrtimer_init(&iocg->waitq_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); iocg->waitq_timer.function = iocg_waitq_timer_fn; iocg->level = blkg->blkcg->css.cgroup->level; for (tblkg = blkg; tblkg; tblkg = tblkg->parent) { struct ioc_gq *tiocg = blkg_to_iocg(tblkg); iocg->ancestors[tiocg->level] = tiocg; } spin_lock_irqsave(&ioc->lock, flags); weight_updated(iocg, &now); spin_unlock_irqrestore(&ioc->lock, flags); } static void ioc_pd_free(struct blkg_policy_data *pd) { struct ioc_gq *iocg = pd_to_iocg(pd); struct ioc *ioc = iocg->ioc; unsigned long flags; if (ioc) { spin_lock_irqsave(&ioc->lock, flags); if (!list_empty(&iocg->active_list)) { struct ioc_now now; ioc_now(ioc, &now); propagate_weights(iocg, 0, 0, false, &now); list_del_init(&iocg->active_list); } WARN_ON_ONCE(!list_empty(&iocg->walk_list)); WARN_ON_ONCE(!list_empty(&iocg->surplus_list)); spin_unlock_irqrestore(&ioc->lock, flags); hrtimer_cancel(&iocg->waitq_timer); } free_percpu(iocg->pcpu_stat); kfree(iocg); } static void ioc_pd_stat(struct blkg_policy_data *pd, struct seq_file *s) { struct ioc_gq *iocg = pd_to_iocg(pd); struct ioc *ioc = iocg->ioc; if (!ioc->enabled) return; if (iocg->level == 0) { unsigned vp10k = DIV64_U64_ROUND_CLOSEST( ioc->vtime_base_rate * 10000, VTIME_PER_USEC); seq_printf(s, " cost.vrate=%u.%02u", vp10k / 100, vp10k % 100); } seq_printf(s, " cost.usage=%llu", iocg->last_stat.usage_us); if (blkcg_debug_stats) seq_printf(s, " cost.wait=%llu cost.indebt=%llu cost.indelay=%llu", iocg->last_stat.wait_us, iocg->last_stat.indebt_us, iocg->last_stat.indelay_us); } static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd, int off) { const char *dname = blkg_dev_name(pd->blkg); struct ioc_gq *iocg = pd_to_iocg(pd); if (dname && iocg->cfg_weight) seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight / WEIGHT_ONE); return 0; } static int ioc_weight_show(struct seq_file *sf, void *v) { struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg); seq_printf(sf, "default %u\n", iocc->dfl_weight / WEIGHT_ONE); blkcg_print_blkgs(sf, blkcg, ioc_weight_prfill, &blkcg_policy_iocost, seq_cft(sf)->private, false); return 0; } static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct blkcg *blkcg = css_to_blkcg(of_css(of)); struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg); struct blkg_conf_ctx ctx; struct ioc_now now; struct ioc_gq *iocg; u32 v; int ret; if (!strchr(buf, ':')) { struct blkcg_gq *blkg; if (!sscanf(buf, "default %u", &v) && !sscanf(buf, "%u", &v)) return -EINVAL; if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX) return -EINVAL; spin_lock_irq(&blkcg->lock); iocc->dfl_weight = v * WEIGHT_ONE; hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { struct ioc_gq *iocg = blkg_to_iocg(blkg); if (iocg) { spin_lock(&iocg->ioc->lock); ioc_now(iocg->ioc, &now); weight_updated(iocg, &now); spin_unlock(&iocg->ioc->lock); } } spin_unlock_irq(&blkcg->lock); return nbytes; } blkg_conf_init(&ctx, buf); ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, &ctx); if (ret) goto err; iocg = blkg_to_iocg(ctx.blkg); if (!strncmp(ctx.body, "default", 7)) { v = 0; } else { if (!sscanf(ctx.body, "%u", &v)) goto einval; if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX) goto einval; } spin_lock(&iocg->ioc->lock); iocg->cfg_weight = v * WEIGHT_ONE; ioc_now(iocg->ioc, &now); weight_updated(iocg, &now); spin_unlock(&iocg->ioc->lock); blkg_conf_exit(&ctx); return nbytes; einval: ret = -EINVAL; err: blkg_conf_exit(&ctx); return ret; } static u64 ioc_qos_prfill(struct seq_file *sf, struct blkg_policy_data *pd, int off) { const char *dname = blkg_dev_name(pd->blkg); struct ioc *ioc = pd_to_iocg(pd)->ioc; if (!dname) return 0; spin_lock_irq(&ioc->lock); 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", dname, ioc->enabled, ioc->user_qos_params ? "user" : "auto", ioc->params.qos[QOS_RPPM] / 10000, ioc->params.qos[QOS_RPPM] % 10000 / 100, ioc->params.qos[QOS_RLAT], ioc->params.qos[QOS_WPPM] / 10000, ioc->params.qos[QOS_WPPM] % 10000 / 100, ioc->params.qos[QOS_WLAT], ioc->params.qos[QOS_MIN] / 10000, ioc->params.qos[QOS_MIN] % 10000 / 100, ioc->params.qos[QOS_MAX] / 10000, ioc->params.qos[QOS_MAX] % 10000 / 100); spin_unlock_irq(&ioc->lock); return 0; } static int ioc_qos_show(struct seq_file *sf, void *v) { struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); blkcg_print_blkgs(sf, blkcg, ioc_qos_prfill, &blkcg_policy_iocost, seq_cft(sf)->private, false); return 0; } static const match_table_t qos_ctrl_tokens = { { QOS_ENABLE, "enable=%u" }, { QOS_CTRL, "ctrl=%s" }, { NR_QOS_CTRL_PARAMS, NULL }, }; static const match_table_t qos_tokens = { { QOS_RPPM, "rpct=%s" }, { QOS_RLAT, "rlat=%u" }, { QOS_WPPM, "wpct=%s" }, { QOS_WLAT, "wlat=%u" }, { QOS_MIN, "min=%s" }, { QOS_MAX, "max=%s" }, { NR_QOS_PARAMS, NULL }, }; static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, size_t nbytes, loff_t off) { struct blkg_conf_ctx ctx; struct gendisk *disk; struct ioc *ioc; u32 qos[NR_QOS_PARAMS]; bool enable, user; char *body, *p; int ret; blkg_conf_init(&ctx, input); ret = blkg_conf_open_bdev(&ctx); if (ret) goto err; body = ctx.body; disk = ctx.bdev->bd_disk; if (!queue_is_mq(disk->queue)) { ret = -EOPNOTSUPP; goto err; } ioc = q_to_ioc(disk->queue); if (!ioc) { ret = blk_iocost_init(disk); if (ret) goto err; ioc = q_to_ioc(disk->queue); } blk_mq_freeze_queue(disk->queue); blk_mq_quiesce_queue(disk->queue); spin_lock_irq(&ioc->lock); memcpy(qos, ioc->params.qos, sizeof(qos)); enable = ioc->enabled; user = ioc->user_qos_params; while ((p = strsep(&body, " \t\n"))) { substring_t args[MAX_OPT_ARGS]; char buf[32]; int tok; s64 v; if (!*p) continue; switch (match_token(p, qos_ctrl_tokens, args)) { case QOS_ENABLE: if (match_u64(&args[0], &v)) goto einval; enable = v; continue; case QOS_CTRL: match_strlcpy(buf, &args[0], sizeof(buf)); if (!strcmp(buf, "auto")) user = false; else if (!strcmp(buf, "user")) user = true; else goto einval; continue; } tok = match_token(p, qos_tokens, args); switch (tok) { case QOS_RPPM: case QOS_WPPM: if (match_strlcpy(buf, &args[0], sizeof(buf)) >= sizeof(buf)) goto einval; if (cgroup_parse_float(buf, 2, &v)) goto einval; if (v < 0 || v > 10000) goto einval; qos[tok] = v * 100; break; case QOS_RLAT: case QOS_WLAT: if (match_u64(&args[0], &v)) goto einval; qos[tok] = v; break; case QOS_MIN: case QOS_MAX: if (match_strlcpy(buf, &args[0], sizeof(buf)) >= sizeof(buf)) goto einval; if (cgroup_parse_float(buf, 2, &v)) goto einval; if (v < 0) goto einval; qos[tok] = clamp_t(s64, v * 100, VRATE_MIN_PPM, VRATE_MAX_PPM); break; default: goto einval; } user = true; } if (qos[QOS_MIN] > qos[QOS_MAX]) goto einval; if (enable && !ioc->enabled) { blk_stat_enable_accounting(disk->queue); blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue); ioc->enabled = true; } else if (!enable && ioc->enabled) { blk_stat_disable_accounting(disk->queue); blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue); ioc->enabled = false; } if (user) { memcpy(ioc->params.qos, qos, sizeof(qos)); ioc->user_qos_params = true; } else { ioc->user_qos_params = false; } ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); if (enable) wbt_disable_default(disk); else wbt_enable_default(disk); blk_mq_unquiesce_queue(disk->queue); blk_mq_unfreeze_queue(disk->queue); blkg_conf_exit(&ctx); return nbytes; einval: spin_unlock_irq(&ioc->lock); blk_mq_unquiesce_queue(disk->queue); blk_mq_unfreeze_queue(disk->queue); ret = -EINVAL; err: blkg_conf_exit(&ctx); return ret; } static u64 ioc_cost_model_prfill(struct seq_file *sf, struct blkg_policy_data *pd, int off) { const char *dname = blkg_dev_name(pd->blkg); struct ioc *ioc = pd_to_iocg(pd)->ioc; u64 *u = ioc->params.i_lcoefs; if (!dname) return 0; spin_lock_irq(&ioc->lock); seq_printf(sf, "%s ctrl=%s model=linear " "rbps=%llu rseqiops=%llu rrandiops=%llu " "wbps=%llu wseqiops=%llu wrandiops=%llu\n", dname, ioc->user_cost_model ? "user" : "auto", u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS], u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS]); spin_unlock_irq(&ioc->lock); return 0; } static int ioc_cost_model_show(struct seq_file *sf, void *v) { struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); blkcg_print_blkgs(sf, blkcg, ioc_cost_model_prfill, &blkcg_policy_iocost, seq_cft(sf)->private, false); return 0; } static const match_table_t cost_ctrl_tokens = { { COST_CTRL, "ctrl=%s" }, { COST_MODEL, "model=%s" }, { NR_COST_CTRL_PARAMS, NULL }, }; static const match_table_t i_lcoef_tokens = { { I_LCOEF_RBPS, "rbps=%u" }, { I_LCOEF_RSEQIOPS, "rseqiops=%u" }, { I_LCOEF_RRANDIOPS, "rrandiops=%u" }, { I_LCOEF_WBPS, "wbps=%u" }, { I_LCOEF_WSEQIOPS, "wseqiops=%u" }, { I_LCOEF_WRANDIOPS, "wrandiops=%u" }, { NR_I_LCOEFS, NULL }, }; static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, size_t nbytes, loff_t off) { struct blkg_conf_ctx ctx; struct request_queue *q; struct ioc *ioc; u64 u[NR_I_LCOEFS]; bool user; char *body, *p; int ret; blkg_conf_init(&ctx, input); ret = blkg_conf_open_bdev(&ctx); if (ret) goto err; body = ctx.body; q = bdev_get_queue(ctx.bdev); if (!queue_is_mq(q)) { ret = -EOPNOTSUPP; goto err; } ioc = q_to_ioc(q); if (!ioc) { ret = blk_iocost_init(ctx.bdev->bd_disk); if (ret) goto err; ioc = q_to_ioc(q); } blk_mq_freeze_queue(q); blk_mq_quiesce_queue(q); spin_lock_irq(&ioc->lock); memcpy(u, ioc->params.i_lcoefs, sizeof(u)); user = ioc->user_cost_model; while ((p = strsep(&body, " \t\n"))) { substring_t args[MAX_OPT_ARGS]; char buf[32]; int tok; u64 v; if (!*p) continue; switch (match_token(p, cost_ctrl_tokens, args)) { case COST_CTRL: match_strlcpy(buf, &args[0], sizeof(buf)); if (!strcmp(buf, "auto")) user = false; else if (!strcmp(buf, "user")) user = true; else goto einval; continue; case COST_MODEL: match_strlcpy(buf, &args[0], sizeof(buf)); if (strcmp(buf, "linear")) goto einval; continue; } tok = match_token(p, i_lcoef_tokens, args); if (tok == NR_I_LCOEFS) goto einval; if (match_u64(&args[0], &v)) goto einval; u[tok] = v; user = true; } if (user) { memcpy(ioc->params.i_lcoefs, u, sizeof(u)); ioc->user_cost_model = true; } else { ioc->user_cost_model = false; } ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); blk_mq_unquiesce_queue(q); blk_mq_unfreeze_queue(q); blkg_conf_exit(&ctx); return nbytes; einval: spin_unlock_irq(&ioc->lock); blk_mq_unquiesce_queue(q); blk_mq_unfreeze_queue(q); ret = -EINVAL; err: blkg_conf_exit(&ctx); return ret; } static struct cftype ioc_files[] = { { .name = "weight", .flags = CFTYPE_NOT_ON_ROOT, .seq_show = ioc_weight_show, .write = ioc_weight_write, }, { .name = "cost.qos", .flags = CFTYPE_ONLY_ON_ROOT, .seq_show = ioc_qos_show, .write = ioc_qos_write, }, { .name = "cost.model", .flags = CFTYPE_ONLY_ON_ROOT, .seq_show = ioc_cost_model_show, .write = ioc_cost_model_write, }, {} }; static struct blkcg_policy blkcg_policy_iocost = { .dfl_cftypes = ioc_files, .cpd_alloc_fn = ioc_cpd_alloc, .cpd_free_fn = ioc_cpd_free, .pd_alloc_fn = ioc_pd_alloc, .pd_init_fn = ioc_pd_init, .pd_free_fn = ioc_pd_free, .pd_stat_fn = ioc_pd_stat, }; static int __init ioc_init(void) { return blkcg_policy_register(&blkcg_policy_iocost); } static void __exit ioc_exit(void) { blkcg_policy_unregister(&blkcg_policy_iocost); } module_init(ioc_init); module_exit(ioc_exit);
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