/* 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] = 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 *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? */
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;
/*
* 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);
}
succeed_unlock:
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 bool 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 false;
}
if (!atomic_read(&blkg->use_delay) &&
time_before_eq64(vtime, now->vnow + vmargin))
return false;
/* 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 true;
hrtimer_start_range_ns(&iocg->delay_timer, ns_to_ktime(expires),
margin_ns / 4, HRTIMER_MODE_ABS);
return true;
}
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 prev_busy_level, 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 ((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++;
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.
*/
prev_busy_level = ioc->busy_level;
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 (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) {
/* take action iff there is contention */
if (nr_shortages && !nr_lagging) {
ioc->busy_level = min(ioc->busy_level, 0);
/* redistribute surpluses first */
if (!nr_surpluses)
ioc->busy_level--;
}
} else {
ioc->busy_level = 0;
}
ioc->busy_level = clamp(ioc->busy_level, -1000, 1000);
if (ioc->busy_level > 0 || (ioc->busy_level < 0 && !nr_lagging)) {
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);
} else if (ioc->busy_level != prev_busy_level || nr_lagging) {
trace_iocost_ioc_vrate_adj(ioc, atomic64_read(&ioc->vtime_rate),
&missed_ppm, rq_wait_pct, nr_lagging,
nr_shortages, nr_surpluses);
}
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);
if (iocg_kick_delay(iocg, &now, cost))
blkcg_schedule_throttle(rqos->q,
(bio->bi_opf & REQ_SWAP) == REQ_SWAP);
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(&iocg->ioc->lock);
iocg->cfg_weight = v;
weight_updated(iocg);
spin_unlock(&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);
