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Diffstat (limited to 'block/blk-iocost.c')
| -rw-r--r-- | block/blk-iocost.c | 2457 |
1 files changed, 2457 insertions, 0 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c new file mode 100644 index 000000000000..3b39deb8b9f8 --- /dev/null +++ b/block/blk-iocost.c @@ -0,0 +1,2457 @@ +/* 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 + * paramters 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. + * + * 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 (HWEIGHT_WHOLE). + * + * 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 iff 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, soley 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 ouput 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 <linux/blk-cgroup.h> +#include "blk-rq-qos.h" +#include "blk-stat.h" +#include "blk-wbt.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, + + /* + * A cgroup's vtime can run 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_PCT = 50, + INUSE_MARGIN_PCT = 10, + + /* Have some play in waitq timer operations */ + WAITQ_TIMER_MARGIN_PCT = 5, + + /* + * vtime can wrap well within a reasonable uptime when vrate is + * consistently raised. Don't trust recorded cgroup vtime if the + * period counter indicates that it's older than 5mins. + */ + VTIME_VALID_DUR = 300 * USEC_PER_SEC, + + /* + * Remember the past three non-zero usages and use the max for + * surplus calculation. Three slots guarantee that we remember one + * full period usage from the last active stretch even after + * partial deactivation and re-activation periods. Don't start + * giving away weight before collecting two data points to prevent + * hweight adjustments based on one partial activation period. + */ + NR_USAGE_SLOTS = 3, + MIN_VALID_USAGES = 2, + + /* 1/64k is granular enough and can easily be handled w/ u32 */ + HWEIGHT_WHOLE = 1 << 16, + + /* + * 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, + + /* 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, + + /* if IOs end up waiting for requests, issue less */ + RQ_WAIT_BUSY_PCT = 5, + + /* unbusy hysterisis */ + UNBUSY_THR_PCT = 75, + + /* don't let cmds which take a very long time pin lagging for too long */ + MAX_LAGGING_PERIODS = 10, + + /* + * If usage% * 1.25 + 2% is lower than hweight% by more than 3%, + * donate the surplus. + */ + SURPLUS_SCALE_PCT = 125, /* * 125% */ + SURPLUS_SCALE_ABS = HWEIGHT_WHOLE / 50, /* + 2% */ + SURPLUS_MIN_ADJ_DELTA = HWEIGHT_WHOLE / 33, /* 3% */ + + /* switch iff the conditions are met for longer than this */ + AUTOP_CYCLE_NSEC = 10LLU * NSEC_PER_SEC, + + /* + * 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_gq; + +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_missed { + u32 nr_met; + u32 nr_missed; + u32 last_met; + u32 last_missed; +}; + +struct ioc_pcpu_stat { + struct ioc_missed missed[2]; + + u64 rq_wait_ns; + u64 last_rq_wait_ns; +}; + +/* per device */ +struct ioc { + struct rq_qos rqos; + + bool enabled; + + struct ioc_params params; + u32 period_us; + u32 margin_us; + 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; + + seqcount_t period_seqcount; + u32 period_at; /* wallclock starttime */ + u64 period_at_vtime; /* vtime starttime */ + + atomic64_t cur_period; /* inc'd each period */ + int busy_level; /* saturation history */ + + u64 inuse_margin_vtime; + bool weights_updated; + atomic_t hweight_gen; /* for lazy hweights */ + + u64 autop_too_fast_at; + u64 autop_too_slow_at; + int autop_idx; + bool user_qos_params:1; + bool user_cost_model:1; +}; + +/* 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. + */ + u32 cfg_weight; + u32 weight; + u32 active; + u32 inuse; + u32 last_inuse; + + 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 runnning 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. + * + * `last_vtime` is used to remember `vtime` at the end of the last + * period to calculate utilization. + */ + atomic64_t vtime; + atomic64_t done_vtime; + atomic64_t abs_vdebt; + u64 last_vtime; + + /* + * 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_active_weight() and current_hweight() for details */ + u64 child_active_sum; + u64 child_inuse_sum; + int hweight_gen; + u32 hweight_active; + u32 hweight_inuse; + bool has_surplus; + + struct wait_queue_head waitq; + struct hrtimer waitq_timer; + struct hrtimer delay_timer; + + /* usage is recorded as fractions of HWEIGHT_WHOLE */ + int usage_idx; + u32 usages[NR_USAGE_SLOTS]; + + /* 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; + u32 now; + u64 vnow; + u64 vrate; +}; + +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] = 50000, /* 50ms */ + [QOS_WLAT] = 50000, + [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 *q_name(struct request_queue *q) +{ + if (test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags)) + return kobject_name(q->kobj.parent); + else + return "<unknown>"; +} + +static const char __maybe_unused *ioc_name(struct ioc *ioc) +{ + return q_name(ioc->rqos.q); +} + +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 * HWEIGHT_WHOLE, 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, HWEIGHT_WHOLE); +} + +static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio, u64 cost) +{ + bio->bi_iocost_cost = cost; + atomic64_add(cost, &iocg->vtime); +} + +#define CREATE_TRACE_POINTS +#include <trace/events/iocost.h> + +/* 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->margin_us = period_us * MARGIN_PCT / 100; + ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP( + period_us * VTIME_PER_USEC * INUSE_MARGIN_PCT, 100); +} + +static int ioc_autop_idx(struct ioc *ioc) +{ + int idx = ioc->autop_idx; + const struct ioc_params *p = &autop[idx]; + u32 vrate_pct; + u64 now_ns; + + /* rotational? */ + if (!blk_queue_nonrot(ioc->rqos.q)) + return AUTOP_HDD; + + /* handle SATA SSDs w/ broken NCQ */ + if (blk_queue_depth(ioc->rqos.q) == 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(atomic64_read(&ioc->vtime_rate) * 100, + VTIME_PER_USEC); + now_ns = ktime_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) + *page = DIV64_U64_ROUND_UP(VTIME_PER_SEC, + DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE)); + + 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]); +} + +static bool ioc_refresh_params(struct ioc *ioc, bool force) +{ + const struct ioc_params *p; + int idx; + + lockdep_assert_held(&ioc->lock); + + idx = ioc_autop_idx(ioc); + 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->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((u64)ioc->params.qos[QOS_MAX] * + VTIME_PER_USEC, MILLION); + + return true; +} + +/* take a snapshot of the current [v]time and vrate */ +static void ioc_now(struct ioc *ioc, struct ioc_now *now) +{ + unsigned seq; + + now->now_ns = ktime_get(); + now->now = ktime_to_us(now->now_ns); + now->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) * now->vrate; + } while (read_seqcount_retry(&ioc->period_seqcount, seq)); +} + +static void ioc_start_period(struct ioc *ioc, struct ioc_now *now) +{ + lockdep_assert_held(&ioc->lock); + 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. + */ +static void __propagate_active_weight(struct ioc_gq *iocg, u32 active, u32 inuse) +{ + struct ioc *ioc = iocg->ioc; + int lvl; + + lockdep_assert_held(&ioc->lock); + + inuse = min(active, inuse); + + 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 udpates */ + child->active = active; + child->inuse = inuse; + + /* + * The delta between inuse and active sums indicates that + * 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_active_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_active_weight(struct ioc_gq *iocg, u32 active, u32 inuse) +{ + __propagate_active_weight(iocg, active, inuse); + commit_active_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_active_weights(). If we saw the + * updated hweight_gen, all the weight updates from + * __propagate_active_weight() 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 = HWEIGHT_WHOLE; + for (lvl = 0; lvl <= iocg->level - 1; lvl++) { + struct ioc_gq *parent = iocg->ancestors[lvl]; + struct ioc_gq *child = iocg->ancestors[lvl + 1]; + u32 active_sum = READ_ONCE(parent->child_active_sum); + u32 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(active, active_sum); + hwa = hwa * active / active_sum; /* max 16bits * 10000 */ + + inuse_sum = max(inuse, inuse_sum); + hwi = hwi * inuse / inuse_sum; /* max 16bits * 10000 */ + } + + 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; +} + +static void weight_updated(struct ioc_gq *iocg) +{ + 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_active_weight(iocg, weight, + DIV64_U64_ROUND_UP(iocg->inuse * weight, iocg->weight)); + iocg->weight = weight; +} + +static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now) +{ + struct ioc *ioc = iocg->ioc; + u64 last_period, cur_period, max_period_delta; + u64 vtime, vmargin, vmin; + 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? */ + for (i = iocg->level; i > 0; i--) + if (!list_empty(&iocg->active_list)) + goto fail_unlock; + if (iocg->child_active_sum) + goto fail_unlock; + + /* + * vtime may wrap when vrate is raised substantially due to + * underestimated IO costs. Look at the period and ignore its + * vtime if the iocg has been idle for too long. Also, cap the + * budget it can start with to the margin. + */ + max_period_delta = DIV64_U64_ROUND_UP(VTIME_VALID_DUR, ioc->period_us); + vtime = atomic64_read(&iocg->vtime); + vmargin = ioc->margin_us * now->vrate; + vmin = now->vnow - vmargin; + + if (last_period + max_period_delta < cur_period || + time_before64(vtime, vmin)) { + atomic64_add(vmin - vtime, &iocg->vtime); + atomic64_add(vmin - vtime, &iocg->done_vtime); + vtime = vmin; + } + + /* + * 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_active_weight(iocg, iocg->weight, + iocg->last_inuse ?: iocg->weight); + + TRACE_IOCG_PATH(iocg_activate, iocg, now, + last_period, cur_period, vtime); + + iocg->last_vtime = vtime; + + if (ioc->running == IOC_IDLE) { + ioc->running = IOC_RUNNING; + ioc_start_period(ioc, now); + } + + spin_unlock_irq(&ioc->lock); + return true; + +fail_unlock: + spin_unlock_irq(&ioc->lock); + return false; +} + +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 = (struct iocg_wake_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, cost); + + /* + * 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(). + */ + list_del_init(&wq_entry->entry); + wait->committed = true; + + default_wake_function(wq_entry, mode, flags, key); + return 0; +} + +static void iocg_kick_waitq(struct ioc_gq *iocg, struct ioc_now *now) +{ + struct ioc *ioc = iocg->ioc; + struct iocg_wake_ctx ctx = { .iocg = iocg }; + u64 margin_ns = (u64)(ioc->period_us * + WAITQ_TIMER_MARGIN_PCT / 100) * NSEC_PER_USEC; + u64 abs_vdebt, vdebt, vshortage, expires, oexpires; + s64 vbudget; + u32 hw_inuse; + + lockdep_assert_held(&iocg->waitq.lock); + + current_hweight(iocg, NULL, &hw_inuse); + vbudget = now->vnow - atomic64_read(&iocg->vtime); + + /* pay off debt */ + abs_vdebt = atomic64_read(&iocg->abs_vdebt); + vdebt = abs_cost_to_cost(abs_vdebt, hw_inuse); + if (vdebt && vbudget > 0) { + u64 delta = min_t(u64, vbudget, vdebt); + u64 abs_delta = min(cost_to_abs_cost(delta, hw_inuse), + abs_vdebt); + + atomic64_add(delta, &iocg->vtime); + atomic64_add(delta, &iocg->done_vtime); + atomic64_sub(abs_delta, &iocg->abs_vdebt); + if (WARN_ON_ONCE(atomic64_read(&iocg->abs_vdebt) < 0)) + atomic64_set(&iocg->abs_vdebt, 0); + } + + /* + * Wake up the ones which are due and see how much vtime we'll need + * for the next one. + */ + ctx.hw_inuse = hw_inuse; + ctx.vbudget = vbudget - vdebt; + __wake_up_locked_key(&iocg->waitq, TASK_NORMAL, &ctx); + if (!waitqueue_active(&iocg->waitq)) + return; + if (WARN_ON_ONCE(ctx.vbudget >= 0)) + return; + + /* determine next wakeup, add a quarter margin to guarantee chunking */ + vshortage = -ctx.vbudget; + expires = now->now_ns + + DIV64_U64_ROUND_UP(vshortage, now->vrate) * NSEC_PER_USEC; + expires += margin_ns / 4; + + /* 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) <= margin_ns / 4) + return; + + hrtimer_start_range_ns(&iocg->waitq_timer, ns_to_ktime(expires), + margin_ns / 4, 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); + struct ioc_now now; + unsigned long flags; + + ioc_now(iocg->ioc, &now); + + spin_lock_irqsave(&iocg->waitq.lock, flags); + iocg_kick_waitq(iocg, &now); + spin_unlock_irqrestore(&iocg->waitq.lock, flags); + + return HRTIMER_NORESTART; +} + +static void iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now, u64 cost) +{ + struct ioc *ioc = iocg->ioc; + struct blkcg_gq *blkg = iocg_to_blkg(iocg); + u64 vtime = atomic64_read(&iocg->vtime); + u64 vmargin = ioc->margin_us * now->vrate; + u64 margin_ns = ioc->margin_us * NSEC_PER_USEC; + u64 expires, oexpires; + u32 hw_inuse; + + /* debt-adjust vtime */ + current_hweight(iocg, NULL, &hw_inuse); + vtime += abs_cost_to_cost(atomic64_read(&iocg->abs_vdebt), hw_inuse); + + /* clear or maintain depending on the overage */ + if (time_before_eq64(vtime, now->vnow)) { + blkcg_clear_delay(blkg); + return; + } + if (!atomic_read(&blkg->use_delay) && + time_before_eq64(vtime, now->vnow + vmargin)) + return; + + /* use delay */ + if (cost) { + u64 cost_ns = DIV64_U64_ROUND_UP(cost * NSEC_PER_USEC, + now->vrate); + blkcg_add_delay(blkg, now->now_ns, cost_ns); + } + blkcg_use_delay(blkg); + + expires = now->now_ns + DIV64_U64_ROUND_UP(vtime - now->vnow, + now->vrate) * NSEC_PER_USEC; + + /* if already active and close enough, don't bother */ + oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->delay_timer)); + if (hrtimer_is_queued(&iocg->delay_timer) && + abs(oexpires - expires) <= margin_ns / 4) + return; + + hrtimer_start_range_ns(&iocg->delay_timer, ns_to_ktime(expires), + margin_ns / 4, HRTIMER_MODE_ABS); +} + +static enum hrtimer_restart iocg_delay_timer_fn(struct hrtimer *timer) +{ + struct ioc_gq *iocg = container_of(timer, struct ioc_gq, delay_timer); + struct ioc_now now; + + ioc_now(iocg->ioc, &now); + iocg_kick_delay(iocg, &now, 0); + + 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 = READ_ONCE(stat->missed[rw].nr_met); + u32 this_missed = READ_ONCE(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 = READ_ONCE(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; +} + +/* returns usage with margin added if surplus is large enough */ +static u32 surplus_adjusted_hweight_inuse(u32 usage, u32 hw_inuse) +{ + /* add margin */ + usage = DIV_ROUND_UP(usage * SURPLUS_SCALE_PCT, 100); + usage += SURPLUS_SCALE_ABS; + + /* don't bother if the surplus is too small */ + if (usage + SURPLUS_MIN_ADJ_DELTA > hw_inuse) + return 0; + + return usage; +} + +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; + int nr_surpluses = 0, nr_shortages = 0, nr_lagging = 0; + u32 ppm_rthr = MILLION - ioc->params.qos[QOS_RPPM]; + u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM]; + u32 missed_ppm[2], rq_wait_pct; + u64 period_vtime; + int i; + + /* 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); + + ioc_now(ioc, &now); + + period_vtime = now.vnow - ioc->period_at_vtime; + if (WARN_ON_ONCE(!period_vtime)) { + spin_unlock_irq(&ioc->lock); + return; + } + + /* + * 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. + */ + list_for_each_entry_safe(iocg, tiocg, &ioc->active_iocgs, active_list) { + if (!waitqueue_active(&iocg->waitq) && + !atomic64_read(&iocg->abs_vdebt) && !iocg_is_idle(iocg)) + continue; + + spin_lock(&iocg->waitq.lock); + + if (waitqueue_active(&iocg->waitq) || + atomic64_read(&iocg->abs_vdebt)) { + /* might be oversleeping vtime / hweight changes, kick */ + iocg_kick_waitq(iocg, &now); + iocg_kick_delay(iocg, &now, 0); + } else if (iocg_is_idle(iocg)) { + /* no waiter and idle, deactivate */ + iocg->last_inuse = iocg->inuse; + __propagate_active_weight(iocg, 0, 0); + list_del_init(&iocg->active_list); + } + + spin_unlock(&iocg->waitq.lock); + } + commit_active_weights(ioc); + + /* calc usages and see whether some weights need to be moved around */ + list_for_each_entry(iocg, &ioc->active_iocgs, active_list) { + u64 vdone, vtime, vusage, vmargin, vmin; + u32 hw_active, hw_inuse, usage; + + /* + * 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 (!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++; + + if (waitqueue_active(&iocg->waitq)) + vusage = now.vnow - iocg->last_vtime; + else if (time_before64(iocg->last_vtime, vtime)) + vusage = vtime - iocg->last_vtime; + else + vusage = 0; + + iocg->last_vtime += vusage; + /* + * Factor in in-flight vtime into vusage to avoid + * high-latency completions appearing as idle. This should + * be done after the above ->last_time adjustment. + */ + vusage = max(vusage, vtime - vdone); + + /* calculate hweight based usage ratio and record */ + if (vusage) { + usage = DIV64_U64_ROUND_UP(vusage * hw_inuse, + period_vtime); + iocg->usage_idx = (iocg->usage_idx + 1) % NR_USAGE_SLOTS; + iocg->usages[iocg->usage_idx] = usage; + } else { + usage = 0; + } + + /* see whether there's surplus vtime */ + vmargin = ioc->margin_us * now.vrate; + vmin = now.vnow - vmargin; + + iocg->has_surplus = false; + + if (!waitqueue_active(&iocg->waitq) && + time_before64(vtime, vmin)) { + u64 delta = vmin - vtime; + + /* throw away surplus vtime */ + atomic64_add(delta, &iocg->vtime); + atomic64_add(delta, &iocg->done_vtime); + iocg->last_vtime += delta; + /* if usage is sufficiently low, maybe it can donate */ + if (surplus_adjusted_hweight_inuse(usage, hw_inuse)) { + iocg->has_surplus = true; + nr_surpluses++; + } + } else if (hw_inuse < hw_active) { + u32 new_hwi, new_inuse; + + /* was donating but might need to take back some */ + if (waitqueue_active(&iocg->waitq)) { + new_hwi = hw_active; + } else { + new_hwi = max(hw_inuse, + usage * SURPLUS_SCALE_PCT / 100 + + SURPLUS_SCALE_ABS); + } + + new_inuse = div64_u64((u64)iocg->inuse * new_hwi, + hw_inuse); + new_inuse = clamp_t(u32, new_inuse, 1, iocg->active); + + if (new_inuse > iocg->inuse) { + TRACE_IOCG_PATH(inuse_takeback, iocg, &now, + iocg->inuse, new_inuse, + hw_inuse, new_hwi); + __propagate_active_weight(iocg, iocg->weight, + new_inuse); + } + } else { + /* genuninely out of vtime */ + nr_shortages++; + } + } + + if (!nr_shortages || !nr_surpluses) + goto skip_surplus_transfers; + + /* there are both shortages and surpluses, transfer surpluses */ + list_for_each_entry(iocg, &ioc->active_iocgs, active_list) { + u32 usage, hw_active, hw_inuse, new_hwi, new_inuse; + int nr_valid = 0; + + if (!iocg->has_surplus) + continue; + + /* base the decision on max historical usage */ + for (i = 0, usage = 0; i < NR_USAGE_SLOTS; i++) { + if (iocg->usages[i]) { + usage = max(usage, iocg->usages[i]); + nr_valid++; + } + } + if (nr_valid < MIN_VALID_USAGES) + continue; + + current_hweight(iocg, &hw_active, &hw_inuse); + new_hwi = surplus_adjusted_hweight_inuse(usage, hw_inuse); + if (!new_hwi) + continue; + + new_inuse = DIV64_U64_ROUND_UP((u64)iocg->inuse * new_hwi, + hw_inuse); + if (new_inuse < iocg->inuse) { + TRACE_IOCG_PATH(inuse_giveaway, iocg, &now, + iocg->inuse, new_inuse, + hw_inuse, new_hwi); + __propagate_active_weight(iocg, iocg->weight, new_inuse); + } + } +skip_surplus_transfers: + commit_active_weights(ioc); + + /* + * 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. + */ + if (rq_wait_pct > RQ_WAIT_BUSY_PCT || + missed_ppm[READ] > ppm_rthr || + missed_ppm[WRITE] > ppm_wthr) { + ioc->busy_level = max(ioc->busy_level, 0); + ioc->busy_level++; + } else if (nr_lagging) { + ioc->busy_level = max(ioc->busy_level, 0); + } else if (nr_shortages && !nr_surpluses && + 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) { + ioc->busy_level = min(ioc->busy_level, 0); + ioc->busy_level--; + } else { + ioc->busy_level = 0; + } + + ioc->busy_level = clamp(ioc->busy_level, -1000, 1000); + + if (ioc->busy_level) { + u64 vrate = atomic64_read(&ioc->vtime_rate); + u64 vrate_min = ioc->vrate_min, vrate_max = ioc->vrate_max; + + /* rq_wait signal is always reliable, ignore user vrate_min */ + if (rq_wait_pct > RQ_WAIT_BUSY_PCT) + vrate_min = VRATE_MIN; + + /* + * 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, + nr_surpluses); + + atomic64_set(&ioc->vtime_rate, vrate); + ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP( + ioc->period_us * vrate * INUSE_MARGIN_PCT, 100); + } + + ioc_refresh_params(ioc, false); + + /* + * 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->running = IOC_IDLE; + } + } + + spin_unlock_irq(&ioc->lock); +} + +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; + + 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 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; + u32 hw_active, hw_inuse; + u64 abs_cost, cost, vtime; + + /* bypass IOs if disabled or for root cgroup */ + if (!ioc->enabled || !iocg->level) + return; + + /* always activate so that even 0 cost IOs get protected to some level */ + if (!iocg_activate(iocg, &now)) + return; + + /* calculate the absolute vtime cost */ + abs_cost = calc_vtime_cost(bio, iocg, false); + if (!abs_cost) + return; + + iocg->cursor = bio_end_sector(bio); + + vtime = atomic64_read(&iocg->vtime); + current_hweight(iocg, &hw_active, &hw_inuse); + + if (hw_inuse < hw_active && + time_after_eq64(vtime + ioc->inuse_margin_vtime, now.vnow)) { + TRACE_IOCG_PATH(inuse_reset, iocg, &now, + iocg->inuse, iocg->weight, hw_inuse, hw_active); + spin_lock_irq(&ioc->lock); + propagate_active_weight(iocg, iocg->weight, iocg->weight); + spin_unlock_irq(&ioc->lock); + current_hweight(iocg, &hw_active, &hw_inuse); + } + + cost = abs_cost_to_cost(abs_cost, hw_inuse); + + /* + * 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) && + !atomic64_read(&iocg->abs_vdebt) && + time_before_eq64(vtime + cost, now.vnow)) { + iocg_commit_bio(iocg, bio, 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. + */ + if (bio_issue_as_root_blkg(bio) || fatal_signal_pending(current)) { + atomic64_add(abs_cost, &iocg->abs_vdebt); + iocg_kick_delay(iocg, &now, cost); + return; + } + + /* + * 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. + */ + spin_lock_irq(&iocg->waitq.lock); + + /* + * We activated above but w/o any synchronization. Deactivation is + * synchronized with waitq.lock and we won't get deactivated as + * long as we're waiting, so we're good if we're activated here. + * In the unlikely case that we are deactivated, just issue the IO. + */ + if (unlikely(list_empty(&iocg->active_list))) { + spin_unlock_irq(&iocg->waitq.lock); + iocg_commit_bio(iocg, bio, cost); + return; + } + + 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, &now); + + spin_unlock_irq(&iocg->waitq.lock); + + 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 = iocg->ioc; + sector_t bio_end = bio_end_sector(bio); + struct ioc_now now; + u32 hw_inuse; + u64 abs_cost, cost; + + /* bypass if disabled or for root cgroup */ + if (!ioc->enabled || !iocg->level) + return; + + abs_cost = calc_vtime_cost(bio, iocg, true); + if (!abs_cost) + return; + + ioc_now(ioc, &now); + current_hweight(iocg, NULL, &hw_inuse); + cost = abs_cost_to_cost(abs_cost, hw_inuse); + + /* 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. Otherwise, account it as debt. See debt + * handling in ioc_rqos_throttle() for details. + */ + if (rq->bio && rq->bio->bi_iocost_cost && + time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow)) + iocg_commit_bio(iocg, bio, cost); + else + atomic64_add(abs_cost, &iocg->abs_vdebt); +} + +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); + u64 on_q_ns, rq_wait_ns; + int pidx, rw; + + if (!ioc->enabled || !rq->alloc_time_ns || !rq->start_time_ns) + return; + + switch (req_op(rq) & REQ_OP_MASK) { + 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 = ktime_get_ns() - rq->alloc_time_ns; + rq_wait_ns = rq->start_time_ns - rq->alloc_time_ns; + + if (on_q_ns <= ioc->params.qos[pidx] * NSEC_PER_USEC) + this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_met); + else + this_cpu_inc(ioc->pcpu_stat->missed[rw].nr_missed); + + this_cpu_add(ioc->pcpu_stat->rq_wait_ns, rq_wait_ns); +} + +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->q, &blkcg_policy_iocost); + + spin_lock_irq(&ioc->lock); + ioc->running = IOC_STOP; + spin_unlock_irq(&ioc->lock); + + del_timer_sync(&ioc->timer); + free_percpu(ioc->pcpu_stat); + kfree(ioc); +} + +static 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 request_queue *q) +{ + struct ioc *ioc; + struct rq_qos *rqos; + int 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; + } + + rqos = &ioc->rqos; + rqos->id = RQ_QOS_COST; + rqos->ops = &ioc_rqos_ops; + rqos->q = q; + + spin_lock_init(&ioc->lock); + timer_setup(&ioc->timer, ioc_timer_fn, 0); + INIT_LIST_HEAD(&ioc->active_iocgs); + + ioc->running = IOC_IDLE; + atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC); + seqcount_init(&ioc->period_seqcount); + ioc->period_at = ktime_to_us(ktime_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(ioc, true); + spin_unlock_irq(&ioc->lock); + + rq_qos_add(q, rqos); + ret = blkcg_activate_policy(q, &blkcg_policy_iocost); + if (ret) { + rq_qos_del(q, rqos); + free_percpu(ioc->pcpu_stat); + kfree(ioc); + return ret; + } + return 0; +} + +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; + 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(gfp_t gfp, struct request_queue *q, + struct blkcg *blkcg) +{ + int levels = blkcg->css.cgroup->level + 1; + struct ioc_gq *iocg; + + iocg = kzalloc_node(sizeof(*iocg) + levels * sizeof(iocg->ancestors[0]), + gfp, q->node); + if (!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->abs_vdebt, 0); + atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period)); + INIT_LIST_HEAD(&iocg->active_list); + iocg->hweight_active = HWEIGHT_WHOLE; + iocg->hweight_inuse = HWEIGHT_WHOLE; + + init_waitqueue_head(&iocg->waitq); + hrtimer_init(&iocg->waitq_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); + iocg->waitq_timer.function = iocg_waitq_timer_fn; + hrtimer_init(&iocg->delay_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); + iocg->delay_timer.function = iocg_delay_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); + 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; + + if (ioc) { + spin_lock(&ioc->lock); + if (!list_empty(&iocg->active_list)) { + propagate_active_weight(iocg, 0, 0); + list_del_init(&iocg->active_list); + } + spin_unlock(&ioc->lock); + + hrtimer_cancel(&iocg->waitq_timer); + hrtimer_cancel(&iocg->delay_timer); + } + kfree(iocg); +} + +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); + 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); + 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_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(&blkcg->lock); + iocc->dfl_weight = v; + hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { + struct ioc_gq *iocg = blkg_to_iocg(blkg); + + if (iocg) { + spin_lock_irq(&iocg->ioc->lock); + weight_updated(iocg); + spin_unlock_irq(&iocg->ioc->lock); + } + } + spin_unlock(&blkcg->lock); + + return nbytes; + } + + ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, buf, &ctx); + if (ret) + return ret; + + 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_irq(&iocg->ioc->lock); + iocg->cfg_weight = v; + weight_updated(iocg); + spin_unlock_irq(&iocg->ioc->lock); + + blkg_conf_finish(&ctx); + return nbytes; + +einval: + blkg_conf_finish(&ctx); + return -EINVAL; +} + +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; + + 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); + 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 gendisk *disk; + struct ioc *ioc; + u32 qos[NR_QOS_PARAMS]; + bool enable, user; + char *p; + int ret; + + disk = blkcg_conf_get_disk(&input); + if (IS_ERR(disk)) + return PTR_ERR(disk); + + ioc = q_to_ioc(disk->queue); + if (!ioc) { + ret = blk_iocost_init(disk->queue); + if (ret) + goto err; + ioc = q_to_ioc(disk->queue); + } + + spin_lock_irq(&ioc->lock); + memcpy(qos, ioc->params.qos, sizeof(qos)); + enable = ioc->enabled; + user = ioc->user_qos_params; + spin_unlock_irq(&ioc->lock); + + while ((p = strsep(&input, " \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: + match_u64(&args[0], &v); + 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; + + spin_lock_irq(&ioc->lock); + + if (enable) { + blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q); + ioc->enabled = true; + } else { + blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, ioc->rqos.q); + 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); + + put_disk_and_module(disk); + return nbytes; +einval: + ret = -EINVAL; +err: + put_disk_and_module(disk); + 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; + + 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]); + 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 gendisk *disk; + struct ioc *ioc; + u64 u[NR_I_LCOEFS]; + bool user; + char *p; + int ret; + + disk = blkcg_conf_get_disk(&input); + if (IS_ERR(disk)) + return PTR_ERR(disk); + + ioc = q_to_ioc(disk->queue); + if (!ioc) { + ret = blk_iocost_init(disk->queue); + if (ret) + goto err; + ioc = q_to_ioc(disk->queue); + } + + spin_lock_irq(&ioc->lock); + memcpy(u, ioc->params.i_lcoefs, sizeof(u)); + user = ioc->user_cost_model; + spin_unlock_irq(&ioc->lock); + + while ((p = strsep(&input, " \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; + } + + spin_lock_irq(&ioc->lock); + 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); + + put_disk_and_module(disk); + return nbytes; + +einval: + ret = -EINVAL; +err: + put_disk_and_module(disk); + 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, +}; + +static int __init ioc_init(void) +{ + return blkcg_policy_register(&blkcg_policy_iocost); +} + +static void __exit ioc_exit(void) +{ + return blkcg_policy_unregister(&blkcg_policy_iocost); +} + +module_init(ioc_init); +module_exit(ioc_exit); |