3471 lines
97 KiB
C
3471 lines
97 KiB
C
/* SPDX-License-Identifier: GPL-2.0
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*
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* IO cost model based controller.
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*
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* Copyright (C) 2019 Tejun Heo <tj@kernel.org>
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* Copyright (C) 2019 Andy Newell <newella@fb.com>
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* Copyright (C) 2019 Facebook
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*
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* One challenge of controlling IO resources is the lack of trivially
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* observable cost metric. This is distinguished from CPU and memory where
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* wallclock time and the number of bytes can serve as accurate enough
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* approximations.
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*
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* Bandwidth and iops are the most commonly used metrics for IO devices but
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* depending on the type and specifics of the device, different IO patterns
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* easily lead to multiple orders of magnitude variations rendering them
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* useless for the purpose of IO capacity distribution. While on-device
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* time, with a lot of clutches, could serve as a useful approximation for
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* non-queued rotational devices, this is no longer viable with modern
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* devices, even the rotational ones.
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*
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* While there is no cost metric we can trivially observe, it isn't a
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* complete mystery. For example, on a rotational device, seek cost
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* dominates while a contiguous transfer contributes a smaller amount
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* proportional to the size. If we can characterize at least the relative
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* costs of these different types of IOs, it should be possible to
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* implement a reasonable work-conserving proportional IO resource
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* distribution.
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*
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* 1. IO Cost Model
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*
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* IO cost model estimates the cost of an IO given its basic parameters and
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* history (e.g. the end sector of the last IO). The cost is measured in
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* device time. If a given IO is estimated to cost 10ms, the device should
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* be able to process ~100 of those IOs in a second.
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*
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* Currently, there's only one builtin cost model - linear. Each IO is
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* classified as sequential or random and given a base cost accordingly.
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* On top of that, a size cost proportional to the length of the IO is
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* added. While simple, this model captures the operational
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* characteristics of a wide varienty of devices well enough. Default
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* parameters for several different classes of devices are provided and the
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* parameters can be configured from userspace via
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* /sys/fs/cgroup/io.cost.model.
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*
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* If needed, tools/cgroup/iocost_coef_gen.py can be used to generate
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* device-specific coefficients.
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*
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* 2. Control Strategy
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*
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* The device virtual time (vtime) is used as the primary control metric.
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* The control strategy is composed of the following three parts.
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*
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* 2-1. Vtime Distribution
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*
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* When a cgroup becomes active in terms of IOs, its hierarchical share is
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* calculated. Please consider the following hierarchy where the numbers
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* inside parentheses denote the configured weights.
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*
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* root
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* / \
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* A (w:100) B (w:300)
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* / \
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* A0 (w:100) A1 (w:100)
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*
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* If B is idle and only A0 and A1 are actively issuing IOs, as the two are
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* of equal weight, each gets 50% share. If then B starts issuing IOs, B
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* gets 300/(100+300) or 75% share, and A0 and A1 equally splits the rest,
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* 12.5% each. The distribution mechanism only cares about these flattened
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* shares. They're called hweights (hierarchical weights) and always add
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* upto 1 (WEIGHT_ONE).
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*
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* A given cgroup's vtime runs slower in inverse proportion to its hweight.
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* For example, with 12.5% weight, A0's time runs 8 times slower (100/12.5)
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* against the device vtime - an IO which takes 10ms on the underlying
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* device is considered to take 80ms on A0.
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*
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* This constitutes the basis of IO capacity distribution. Each cgroup's
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* vtime is running at a rate determined by its hweight. A cgroup tracks
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* the vtime consumed by past IOs and can issue a new IO if doing so
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* wouldn't outrun the current device vtime. Otherwise, the IO is
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* suspended until the vtime has progressed enough to cover it.
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*
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* 2-2. Vrate Adjustment
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*
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* It's unrealistic to expect the cost model to be perfect. There are too
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* many devices and even on the same device the overall performance
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* fluctuates depending on numerous factors such as IO mixture and device
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* internal garbage collection. The controller needs to adapt dynamically.
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*
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* This is achieved by adjusting the overall IO rate according to how busy
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* the device is. If the device becomes overloaded, we're sending down too
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* many IOs and should generally slow down. If there are waiting issuers
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* but the device isn't saturated, we're issuing too few and should
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* generally speed up.
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*
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* To slow down, we lower the vrate - the rate at which the device vtime
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* passes compared to the wall clock. For example, if the vtime is running
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* at the vrate of 75%, all cgroups added up would only be able to issue
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* 750ms worth of IOs per second, and vice-versa for speeding up.
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*
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* Device business is determined using two criteria - rq wait and
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* completion latencies.
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*
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* When a device gets saturated, the on-device and then the request queues
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* fill up and a bio which is ready to be issued has to wait for a request
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* to become available. When this delay becomes noticeable, it's a clear
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* indication that the device is saturated and we lower the vrate. This
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* saturation signal is fairly conservative as it only triggers when both
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* hardware and software queues are filled up, and is used as the default
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* busy signal.
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*
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* As devices can have deep queues and be unfair in how the queued commands
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* are executed, soley depending on rq wait may not result in satisfactory
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* control quality. For a better control quality, completion latency QoS
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* parameters can be configured so that the device is considered saturated
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* if N'th percentile completion latency rises above the set point.
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*
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* The completion latency requirements are a function of both the
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* underlying device characteristics and the desired IO latency quality of
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* service. There is an inherent trade-off - the tighter the latency QoS,
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* the higher the bandwidth lossage. Latency QoS is disabled by default
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* and can be set through /sys/fs/cgroup/io.cost.qos.
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*
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* 2-3. Work Conservation
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*
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* Imagine two cgroups A and B with equal weights. A is issuing a small IO
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* periodically while B is sending out enough parallel IOs to saturate the
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* device on its own. Let's say A's usage amounts to 100ms worth of IO
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* cost per second, i.e., 10% of the device capacity. The naive
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* distribution of half and half would lead to 60% utilization of the
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* device, a significant reduction in the total amount of work done
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* compared to free-for-all competition. This is too high a cost to pay
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* for IO control.
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*
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* To conserve the total amount of work done, we keep track of how much
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* each active cgroup is actually using and yield part of its weight if
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* there are other cgroups which can make use of it. In the above case,
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* A's weight will be lowered so that it hovers above the actual usage and
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* B would be able to use the rest.
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*
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* As we don't want to penalize a cgroup for donating its weight, the
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* surplus weight adjustment factors in a margin and has an immediate
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* snapback mechanism in case the cgroup needs more IO vtime for itself.
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*
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* Note that adjusting down surplus weights has the same effects as
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* accelerating vtime for other cgroups and work conservation can also be
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* implemented by adjusting vrate dynamically. However, squaring who can
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* donate and should take back how much requires hweight propagations
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* anyway making it easier to implement and understand as a separate
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* mechanism.
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*
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* 3. Monitoring
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*
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* Instead of debugfs or other clumsy monitoring mechanisms, this
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* controller uses a drgn based monitoring script -
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* tools/cgroup/iocost_monitor.py. For details on drgn, please see
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* https://github.com/osandov/drgn. The output looks like the following.
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*
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* sdb RUN per=300ms cur_per=234.218:v203.695 busy= +1 vrate= 62.12%
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* active weight hweight% inflt% dbt delay usages%
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* test/a * 50/ 50 33.33/ 33.33 27.65 2 0*041 033:033:033
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* test/b * 100/ 100 66.67/ 66.67 17.56 0 0*000 066:079:077
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*
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* - per : Timer period
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* - cur_per : Internal wall and device vtime clock
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* - vrate : Device virtual time rate against wall clock
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* - weight : Surplus-adjusted and configured weights
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* - hweight : Surplus-adjusted and configured hierarchical weights
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* - inflt : The percentage of in-flight IO cost at the end of last period
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* - del_ms : Deferred issuer delay induction level and duration
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* - usages : Usage history
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/timer.h>
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#include <linux/time64.h>
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#include <linux/parser.h>
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#include <linux/sched/signal.h>
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#include <asm/local.h>
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#include <asm/local64.h>
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#include "blk-rq-qos.h"
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#include "blk-stat.h"
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#include "blk-wbt.h"
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#include "blk-cgroup.h"
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#ifdef CONFIG_TRACEPOINTS
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/* copied from TRACE_CGROUP_PATH, see cgroup-internal.h */
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#define TRACE_IOCG_PATH_LEN 1024
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static DEFINE_SPINLOCK(trace_iocg_path_lock);
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static char trace_iocg_path[TRACE_IOCG_PATH_LEN];
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#define TRACE_IOCG_PATH(type, iocg, ...) \
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do { \
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unsigned long flags; \
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if (trace_iocost_##type##_enabled()) { \
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spin_lock_irqsave(&trace_iocg_path_lock, flags); \
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cgroup_path(iocg_to_blkg(iocg)->blkcg->css.cgroup, \
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trace_iocg_path, TRACE_IOCG_PATH_LEN); \
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trace_iocost_##type(iocg, trace_iocg_path, \
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##__VA_ARGS__); \
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spin_unlock_irqrestore(&trace_iocg_path_lock, flags); \
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} \
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} while (0)
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#else /* CONFIG_TRACE_POINTS */
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#define TRACE_IOCG_PATH(type, iocg, ...) do { } while (0)
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#endif /* CONFIG_TRACE_POINTS */
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enum {
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MILLION = 1000000,
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/* timer period is calculated from latency requirements, bound it */
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MIN_PERIOD = USEC_PER_MSEC,
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MAX_PERIOD = USEC_PER_SEC,
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/*
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* iocg->vtime is targeted at 50% behind the device vtime, which
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* serves as its IO credit buffer. Surplus weight adjustment is
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* immediately canceled if the vtime margin runs below 10%.
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*/
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MARGIN_MIN_PCT = 10,
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MARGIN_LOW_PCT = 20,
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MARGIN_TARGET_PCT = 50,
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INUSE_ADJ_STEP_PCT = 25,
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/* Have some play in timer operations */
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TIMER_SLACK_PCT = 1,
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/* 1/64k is granular enough and can easily be handled w/ u32 */
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WEIGHT_ONE = 1 << 16,
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};
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enum {
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/*
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* As vtime is used to calculate the cost of each IO, it needs to
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* be fairly high precision. For example, it should be able to
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* represent the cost of a single page worth of discard with
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* suffificient accuracy. At the same time, it should be able to
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* represent reasonably long enough durations to be useful and
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* convenient during operation.
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*
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* 1s worth of vtime is 2^37. This gives us both sub-nanosecond
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* granularity and days of wrap-around time even at extreme vrates.
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*/
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VTIME_PER_SEC_SHIFT = 37,
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VTIME_PER_SEC = 1LLU << VTIME_PER_SEC_SHIFT,
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VTIME_PER_USEC = VTIME_PER_SEC / USEC_PER_SEC,
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VTIME_PER_NSEC = VTIME_PER_SEC / NSEC_PER_SEC,
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/* bound vrate adjustments within two orders of magnitude */
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VRATE_MIN_PPM = 10000, /* 1% */
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VRATE_MAX_PPM = 100000000, /* 10000% */
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VRATE_MIN = VTIME_PER_USEC * VRATE_MIN_PPM / MILLION,
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VRATE_CLAMP_ADJ_PCT = 4,
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/* switch iff the conditions are met for longer than this */
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AUTOP_CYCLE_NSEC = 10LLU * NSEC_PER_SEC,
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};
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enum {
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/* if IOs end up waiting for requests, issue less */
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RQ_WAIT_BUSY_PCT = 5,
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/* unbusy hysterisis */
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UNBUSY_THR_PCT = 75,
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/*
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* The effect of delay is indirect and non-linear and a huge amount of
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* future debt can accumulate abruptly while unthrottled. Linearly scale
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* up delay as debt is going up and then let it decay exponentially.
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* This gives us quick ramp ups while delay is accumulating and long
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* tails which can help reducing the frequency of debt explosions on
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* unthrottle. The parameters are experimentally determined.
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*
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* The delay mechanism provides adequate protection and behavior in many
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* cases. However, this is far from ideal and falls shorts on both
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* fronts. The debtors are often throttled too harshly costing a
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* significant level of fairness and possibly total work while the
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* protection against their impacts on the system can be choppy and
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* unreliable.
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*
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* The shortcoming primarily stems from the fact that, unlike for page
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* cache, the kernel doesn't have well-defined back-pressure propagation
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* mechanism and policies for anonymous memory. Fully addressing this
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* issue will likely require substantial improvements in the area.
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*/
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MIN_DELAY_THR_PCT = 500,
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MAX_DELAY_THR_PCT = 25000,
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MIN_DELAY = 250,
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MAX_DELAY = 250 * USEC_PER_MSEC,
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/* halve debts if avg usage over 100ms is under 50% */
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DFGV_USAGE_PCT = 50,
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DFGV_PERIOD = 100 * USEC_PER_MSEC,
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/* don't let cmds which take a very long time pin lagging for too long */
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MAX_LAGGING_PERIODS = 10,
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/*
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* Count IO size in 4k pages. The 12bit shift helps keeping
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* size-proportional components of cost calculation in closer
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* numbers of digits to per-IO cost components.
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*/
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IOC_PAGE_SHIFT = 12,
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IOC_PAGE_SIZE = 1 << IOC_PAGE_SHIFT,
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IOC_SECT_TO_PAGE_SHIFT = IOC_PAGE_SHIFT - SECTOR_SHIFT,
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/* if apart further than 16M, consider randio for linear model */
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LCOEF_RANDIO_PAGES = 4096,
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};
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enum ioc_running {
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IOC_IDLE,
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IOC_RUNNING,
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IOC_STOP,
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};
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/* io.cost.qos controls including per-dev enable of the whole controller */
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enum {
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QOS_ENABLE,
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QOS_CTRL,
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NR_QOS_CTRL_PARAMS,
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};
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/* io.cost.qos params */
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enum {
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QOS_RPPM,
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QOS_RLAT,
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QOS_WPPM,
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QOS_WLAT,
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QOS_MIN,
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QOS_MAX,
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NR_QOS_PARAMS,
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};
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/* io.cost.model controls */
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enum {
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COST_CTRL,
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COST_MODEL,
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NR_COST_CTRL_PARAMS,
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};
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/* builtin linear cost model coefficients */
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enum {
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I_LCOEF_RBPS,
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I_LCOEF_RSEQIOPS,
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I_LCOEF_RRANDIOPS,
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I_LCOEF_WBPS,
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I_LCOEF_WSEQIOPS,
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I_LCOEF_WRANDIOPS,
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NR_I_LCOEFS,
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};
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enum {
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LCOEF_RPAGE,
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LCOEF_RSEQIO,
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LCOEF_RRANDIO,
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LCOEF_WPAGE,
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LCOEF_WSEQIO,
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LCOEF_WRANDIO,
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NR_LCOEFS,
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};
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enum {
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AUTOP_INVALID,
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AUTOP_HDD,
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AUTOP_SSD_QD1,
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AUTOP_SSD_DFL,
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AUTOP_SSD_FAST,
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};
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struct ioc_params {
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u32 qos[NR_QOS_PARAMS];
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u64 i_lcoefs[NR_I_LCOEFS];
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u64 lcoefs[NR_LCOEFS];
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u32 too_fast_vrate_pct;
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u32 too_slow_vrate_pct;
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};
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struct ioc_margins {
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s64 min;
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s64 low;
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s64 target;
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};
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struct ioc_missed {
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local_t nr_met;
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local_t nr_missed;
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u32 last_met;
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u32 last_missed;
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};
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struct ioc_pcpu_stat {
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struct ioc_missed missed[2];
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local64_t rq_wait_ns;
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u64 last_rq_wait_ns;
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};
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/* per device */
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struct ioc {
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struct rq_qos rqos;
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bool enabled;
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struct ioc_params params;
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struct ioc_margins margins;
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u32 period_us;
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u32 timer_slack_ns;
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u64 vrate_min;
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u64 vrate_max;
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spinlock_t lock;
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struct timer_list timer;
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struct list_head active_iocgs; /* active cgroups */
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struct ioc_pcpu_stat __percpu *pcpu_stat;
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enum ioc_running running;
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atomic64_t vtime_rate;
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u64 vtime_base_rate;
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s64 vtime_err;
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seqcount_spinlock_t period_seqcount;
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u64 period_at; /* wallclock starttime */
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u64 period_at_vtime; /* vtime starttime */
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atomic64_t cur_period; /* inc'd each period */
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int busy_level; /* saturation history */
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bool weights_updated;
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atomic_t hweight_gen; /* for lazy hweights */
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/* debt forgivness */
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u64 dfgv_period_at;
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u64 dfgv_period_rem;
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u64 dfgv_usage_us_sum;
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u64 autop_too_fast_at;
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u64 autop_too_slow_at;
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int autop_idx;
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bool user_qos_params:1;
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bool user_cost_model:1;
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};
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struct iocg_pcpu_stat {
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local64_t abs_vusage;
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};
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struct iocg_stat {
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u64 usage_us;
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u64 wait_us;
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u64 indebt_us;
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u64 indelay_us;
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};
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/* per device-cgroup pair */
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struct ioc_gq {
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struct blkg_policy_data pd;
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struct ioc *ioc;
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/*
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* A iocg can get its weight from two sources - an explicit
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* per-device-cgroup configuration or the default weight of the
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* cgroup. `cfg_weight` is the explicit per-device-cgroup
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* configuration. `weight` is the effective considering both
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* sources.
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*
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* When an idle cgroup becomes active its `active` goes from 0 to
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* `weight`. `inuse` is the surplus adjusted active weight.
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* `active` and `inuse` are used to calculate `hweight_active` and
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* `hweight_inuse`.
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*
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* `last_inuse` remembers `inuse` while an iocg is idle to persist
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* surplus adjustments.
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*
|
|
* `inuse` may be adjusted dynamically during period. `saved_*` are used
|
|
* to determine and track adjustments.
|
|
*/
|
|
u32 cfg_weight;
|
|
u32 weight;
|
|
u32 active;
|
|
u32 inuse;
|
|
|
|
u32 last_inuse;
|
|
s64 saved_margin;
|
|
|
|
sector_t cursor; /* to detect randio */
|
|
|
|
/*
|
|
* `vtime` is this iocg's vtime cursor which progresses as IOs are
|
|
* issued. If lagging behind device vtime, the delta represents
|
|
* the currently available IO budget. If running ahead, the
|
|
* overage.
|
|
*
|
|
* `vtime_done` is the same but progressed on completion rather
|
|
* than issue. The delta behind `vtime` represents the cost of
|
|
* currently in-flight IOs.
|
|
*/
|
|
atomic64_t vtime;
|
|
atomic64_t done_vtime;
|
|
u64 abs_vdebt;
|
|
|
|
/* current delay in effect and when it started */
|
|
u64 delay;
|
|
u64 delay_at;
|
|
|
|
/*
|
|
* The period this iocg was last active in. Used for deactivation
|
|
* and invalidating `vtime`.
|
|
*/
|
|
atomic64_t active_period;
|
|
struct list_head active_list;
|
|
|
|
/* see __propagate_weights() and current_hweight() for details */
|
|
u64 child_active_sum;
|
|
u64 child_inuse_sum;
|
|
u64 child_adjusted_sum;
|
|
int hweight_gen;
|
|
u32 hweight_active;
|
|
u32 hweight_inuse;
|
|
u32 hweight_donating;
|
|
u32 hweight_after_donation;
|
|
|
|
struct list_head walk_list;
|
|
struct list_head surplus_list;
|
|
|
|
struct wait_queue_head waitq;
|
|
struct hrtimer waitq_timer;
|
|
|
|
/* timestamp at the latest activation */
|
|
u64 activated_at;
|
|
|
|
/* statistics */
|
|
struct iocg_pcpu_stat __percpu *pcpu_stat;
|
|
struct iocg_stat stat;
|
|
struct iocg_stat last_stat;
|
|
u64 last_stat_abs_vusage;
|
|
u64 usage_delta_us;
|
|
u64 wait_since;
|
|
u64 indebt_since;
|
|
u64 indelay_since;
|
|
|
|
/* this iocg's depth in the hierarchy and ancestors including self */
|
|
int level;
|
|
struct ioc_gq *ancestors[];
|
|
};
|
|
|
|
/* per cgroup */
|
|
struct ioc_cgrp {
|
|
struct blkcg_policy_data cpd;
|
|
unsigned int dfl_weight;
|
|
};
|
|
|
|
struct ioc_now {
|
|
u64 now_ns;
|
|
u64 now;
|
|
u64 vnow;
|
|
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 __maybe_unused *ioc_name(struct ioc *ioc)
|
|
{
|
|
struct gendisk *disk = ioc->rqos.q->disk;
|
|
|
|
if (!disk)
|
|
return "<unknown>";
|
|
return disk->disk_name;
|
|
}
|
|
|
|
static struct ioc_gq *pd_to_iocg(struct blkg_policy_data *pd)
|
|
{
|
|
return pd ? container_of(pd, struct ioc_gq, pd) : NULL;
|
|
}
|
|
|
|
static struct ioc_gq *blkg_to_iocg(struct blkcg_gq *blkg)
|
|
{
|
|
return pd_to_iocg(blkg_to_pd(blkg, &blkcg_policy_iocost));
|
|
}
|
|
|
|
static struct blkcg_gq *iocg_to_blkg(struct ioc_gq *iocg)
|
|
{
|
|
return pd_to_blkg(&iocg->pd);
|
|
}
|
|
|
|
static struct ioc_cgrp *blkcg_to_iocc(struct blkcg *blkcg)
|
|
{
|
|
return container_of(blkcg_to_cpd(blkcg, &blkcg_policy_iocost),
|
|
struct ioc_cgrp, cpd);
|
|
}
|
|
|
|
/*
|
|
* Scale @abs_cost to the inverse of @hw_inuse. The lower the hierarchical
|
|
* weight, the more expensive each IO. Must round up.
|
|
*/
|
|
static u64 abs_cost_to_cost(u64 abs_cost, u32 hw_inuse)
|
|
{
|
|
return DIV64_U64_ROUND_UP(abs_cost * WEIGHT_ONE, hw_inuse);
|
|
}
|
|
|
|
/*
|
|
* The inverse of abs_cost_to_cost(). Must round up.
|
|
*/
|
|
static u64 cost_to_abs_cost(u64 cost, u32 hw_inuse)
|
|
{
|
|
return DIV64_U64_ROUND_UP(cost * hw_inuse, WEIGHT_ONE);
|
|
}
|
|
|
|
static void iocg_commit_bio(struct ioc_gq *iocg, struct bio *bio,
|
|
u64 abs_cost, u64 cost)
|
|
{
|
|
struct iocg_pcpu_stat *gcs;
|
|
|
|
bio->bi_iocost_cost = cost;
|
|
atomic64_add(cost, &iocg->vtime);
|
|
|
|
gcs = get_cpu_ptr(iocg->pcpu_stat);
|
|
local64_add(abs_cost, &gcs->abs_vusage);
|
|
put_cpu_ptr(gcs);
|
|
}
|
|
|
|
static void iocg_lock(struct ioc_gq *iocg, bool lock_ioc, unsigned long *flags)
|
|
{
|
|
if (lock_ioc) {
|
|
spin_lock_irqsave(&iocg->ioc->lock, *flags);
|
|
spin_lock(&iocg->waitq.lock);
|
|
} else {
|
|
spin_lock_irqsave(&iocg->waitq.lock, *flags);
|
|
}
|
|
}
|
|
|
|
static void iocg_unlock(struct ioc_gq *iocg, bool unlock_ioc, unsigned long *flags)
|
|
{
|
|
if (unlock_ioc) {
|
|
spin_unlock(&iocg->waitq.lock);
|
|
spin_unlock_irqrestore(&iocg->ioc->lock, *flags);
|
|
} else {
|
|
spin_unlock_irqrestore(&iocg->waitq.lock, *flags);
|
|
}
|
|
}
|
|
|
|
#define CREATE_TRACE_POINTS
|
|
#include <trace/events/iocost.h>
|
|
|
|
static void ioc_refresh_margins(struct ioc *ioc)
|
|
{
|
|
struct ioc_margins *margins = &ioc->margins;
|
|
u32 period_us = ioc->period_us;
|
|
u64 vrate = ioc->vtime_base_rate;
|
|
|
|
margins->min = (period_us * MARGIN_MIN_PCT / 100) * vrate;
|
|
margins->low = (period_us * MARGIN_LOW_PCT / 100) * vrate;
|
|
margins->target = (period_us * MARGIN_TARGET_PCT / 100) * vrate;
|
|
}
|
|
|
|
/* latency Qos params changed, update period_us and all the dependent params */
|
|
static void ioc_refresh_period_us(struct ioc *ioc)
|
|
{
|
|
u32 ppm, lat, multi, period_us;
|
|
|
|
lockdep_assert_held(&ioc->lock);
|
|
|
|
/* pick the higher latency target */
|
|
if (ioc->params.qos[QOS_RLAT] >= ioc->params.qos[QOS_WLAT]) {
|
|
ppm = ioc->params.qos[QOS_RPPM];
|
|
lat = ioc->params.qos[QOS_RLAT];
|
|
} else {
|
|
ppm = ioc->params.qos[QOS_WPPM];
|
|
lat = ioc->params.qos[QOS_WLAT];
|
|
}
|
|
|
|
/*
|
|
* We want the period to be long enough to contain a healthy number
|
|
* of IOs while short enough for granular control. Define it as a
|
|
* multiple of the latency target. Ideally, the multiplier should
|
|
* be scaled according to the percentile so that it would nominally
|
|
* contain a certain number of requests. Let's be simpler and
|
|
* scale it linearly so that it's 2x >= pct(90) and 10x at pct(50).
|
|
*/
|
|
if (ppm)
|
|
multi = max_t(u32, (MILLION - ppm) / 50000, 2);
|
|
else
|
|
multi = 2;
|
|
period_us = multi * lat;
|
|
period_us = clamp_t(u32, period_us, MIN_PERIOD, MAX_PERIOD);
|
|
|
|
/* calculate dependent params */
|
|
ioc->period_us = period_us;
|
|
ioc->timer_slack_ns = div64_u64(
|
|
(u64)period_us * NSEC_PER_USEC * TIMER_SLACK_PCT,
|
|
100);
|
|
ioc_refresh_margins(ioc);
|
|
}
|
|
|
|
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(ioc->vtime_base_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) {
|
|
u64 bps_pages = DIV_ROUND_UP_ULL(bps, IOC_PAGE_SIZE);
|
|
|
|
if (bps_pages)
|
|
*page = DIV64_U64_ROUND_UP(VTIME_PER_SEC, bps_pages);
|
|
else
|
|
*page = 1;
|
|
}
|
|
|
|
if (seqiops) {
|
|
v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, seqiops);
|
|
if (v > *page)
|
|
*seqio = v - *page;
|
|
}
|
|
|
|
if (randiops) {
|
|
v = DIV64_U64_ROUND_UP(VTIME_PER_SEC, randiops);
|
|
if (v > *page)
|
|
*randio = v - *page;
|
|
}
|
|
}
|
|
|
|
static void ioc_refresh_lcoefs(struct ioc *ioc)
|
|
{
|
|
u64 *u = ioc->params.i_lcoefs;
|
|
u64 *c = ioc->params.lcoefs;
|
|
|
|
calc_lcoefs(u[I_LCOEF_RBPS], u[I_LCOEF_RSEQIOPS], u[I_LCOEF_RRANDIOPS],
|
|
&c[LCOEF_RPAGE], &c[LCOEF_RSEQIO], &c[LCOEF_RRANDIO]);
|
|
calc_lcoefs(u[I_LCOEF_WBPS], u[I_LCOEF_WSEQIOPS], u[I_LCOEF_WRANDIOPS],
|
|
&c[LCOEF_WPAGE], &c[LCOEF_WSEQIO], &c[LCOEF_WRANDIO]);
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* When an iocg accumulates too much vtime or gets deactivated, we throw away
|
|
* some vtime, which lowers the overall device utilization. As the exact amount
|
|
* which is being thrown away is known, we can compensate by accelerating the
|
|
* vrate accordingly so that the extra vtime generated in the current period
|
|
* matches what got lost.
|
|
*/
|
|
static void ioc_refresh_vrate(struct ioc *ioc, struct ioc_now *now)
|
|
{
|
|
s64 pleft = ioc->period_at + ioc->period_us - now->now;
|
|
s64 vperiod = ioc->period_us * ioc->vtime_base_rate;
|
|
s64 vcomp, vcomp_min, vcomp_max;
|
|
|
|
lockdep_assert_held(&ioc->lock);
|
|
|
|
/* we need some time left in this period */
|
|
if (pleft <= 0)
|
|
goto done;
|
|
|
|
/*
|
|
* Calculate how much vrate should be adjusted to offset the error.
|
|
* Limit the amount of adjustment and deduct the adjusted amount from
|
|
* the error.
|
|
*/
|
|
vcomp = -div64_s64(ioc->vtime_err, pleft);
|
|
vcomp_min = -(ioc->vtime_base_rate >> 1);
|
|
vcomp_max = ioc->vtime_base_rate;
|
|
vcomp = clamp(vcomp, vcomp_min, vcomp_max);
|
|
|
|
ioc->vtime_err += vcomp * pleft;
|
|
|
|
atomic64_set(&ioc->vtime_rate, ioc->vtime_base_rate + vcomp);
|
|
done:
|
|
/* bound how much error can accumulate */
|
|
ioc->vtime_err = clamp(ioc->vtime_err, -vperiod, vperiod);
|
|
}
|
|
|
|
static void ioc_adjust_base_vrate(struct ioc *ioc, u32 rq_wait_pct,
|
|
int nr_lagging, int nr_shortages,
|
|
int prev_busy_level, u32 *missed_ppm)
|
|
{
|
|
u64 vrate = ioc->vtime_base_rate;
|
|
u64 vrate_min = ioc->vrate_min, vrate_max = ioc->vrate_max;
|
|
|
|
if (!ioc->busy_level || (ioc->busy_level < 0 && nr_lagging)) {
|
|
if (ioc->busy_level != prev_busy_level || nr_lagging)
|
|
trace_iocost_ioc_vrate_adj(ioc, atomic64_read(&ioc->vtime_rate),
|
|
missed_ppm, rq_wait_pct,
|
|
nr_lagging, nr_shortages);
|
|
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* If vrate is out of bounds, apply clamp gradually as the
|
|
* bounds can change abruptly. Otherwise, apply busy_level
|
|
* based adjustment.
|
|
*/
|
|
if (vrate < vrate_min) {
|
|
vrate = div64_u64(vrate * (100 + VRATE_CLAMP_ADJ_PCT), 100);
|
|
vrate = min(vrate, vrate_min);
|
|
} else if (vrate > vrate_max) {
|
|
vrate = div64_u64(vrate * (100 - VRATE_CLAMP_ADJ_PCT), 100);
|
|
vrate = max(vrate, vrate_max);
|
|
} else {
|
|
int idx = min_t(int, abs(ioc->busy_level),
|
|
ARRAY_SIZE(vrate_adj_pct) - 1);
|
|
u32 adj_pct = vrate_adj_pct[idx];
|
|
|
|
if (ioc->busy_level > 0)
|
|
adj_pct = 100 - adj_pct;
|
|
else
|
|
adj_pct = 100 + adj_pct;
|
|
|
|
vrate = clamp(DIV64_U64_ROUND_UP(vrate * adj_pct, 100),
|
|
vrate_min, vrate_max);
|
|
}
|
|
|
|
trace_iocost_ioc_vrate_adj(ioc, vrate, missed_ppm, rq_wait_pct,
|
|
nr_lagging, nr_shortages);
|
|
|
|
ioc->vtime_base_rate = vrate;
|
|
ioc_refresh_margins(ioc);
|
|
}
|
|
|
|
/* take a snapshot of the current [v]time and vrate */
|
|
static void ioc_now(struct ioc *ioc, struct ioc_now *now)
|
|
{
|
|
unsigned seq;
|
|
|
|
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)
|
|
{
|
|
WARN_ON_ONCE(ioc->running != IOC_RUNNING);
|
|
|
|
write_seqcount_begin(&ioc->period_seqcount);
|
|
ioc->period_at = now->now;
|
|
ioc->period_at_vtime = now->vnow;
|
|
write_seqcount_end(&ioc->period_seqcount);
|
|
|
|
ioc->timer.expires = jiffies + usecs_to_jiffies(ioc->period_us);
|
|
add_timer(&ioc->timer);
|
|
}
|
|
|
|
/*
|
|
* Update @iocg's `active` and `inuse` to @active and @inuse, update level
|
|
* weight sums and propagate upwards accordingly. If @save, the current margin
|
|
* is saved to be used as reference for later inuse in-period adjustments.
|
|
*/
|
|
static void __propagate_weights(struct ioc_gq *iocg, u32 active, u32 inuse,
|
|
bool save, struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
int lvl;
|
|
|
|
lockdep_assert_held(&ioc->lock);
|
|
|
|
/*
|
|
* For an active leaf node, its inuse shouldn't be zero or exceed
|
|
* @active. An active internal node's inuse is solely determined by the
|
|
* inuse to active ratio of its children regardless of @inuse.
|
|
*/
|
|
if (list_empty(&iocg->active_list) && iocg->child_active_sum) {
|
|
inuse = DIV64_U64_ROUND_UP(active * iocg->child_inuse_sum,
|
|
iocg->child_active_sum);
|
|
} else {
|
|
inuse = clamp_t(u32, inuse, 1, active);
|
|
}
|
|
|
|
iocg->last_inuse = iocg->inuse;
|
|
if (save)
|
|
iocg->saved_margin = now->vnow - atomic64_read(&iocg->vtime);
|
|
|
|
if (active == iocg->active && inuse == iocg->inuse)
|
|
return;
|
|
|
|
for (lvl = iocg->level - 1; lvl >= 0; lvl--) {
|
|
struct ioc_gq *parent = iocg->ancestors[lvl];
|
|
struct ioc_gq *child = iocg->ancestors[lvl + 1];
|
|
u32 parent_active = 0, parent_inuse = 0;
|
|
|
|
/* update the level sums */
|
|
parent->child_active_sum += (s32)(active - child->active);
|
|
parent->child_inuse_sum += (s32)(inuse - child->inuse);
|
|
/* apply the updates */
|
|
child->active = active;
|
|
child->inuse = inuse;
|
|
|
|
/*
|
|
* The delta between inuse and active sums indicates that
|
|
* much of weight is being given away. Parent's inuse
|
|
* and active should reflect the ratio.
|
|
*/
|
|
if (parent->child_active_sum) {
|
|
parent_active = parent->weight;
|
|
parent_inuse = DIV64_U64_ROUND_UP(
|
|
parent_active * parent->child_inuse_sum,
|
|
parent->child_active_sum);
|
|
}
|
|
|
|
/* do we need to keep walking up? */
|
|
if (parent_active == parent->active &&
|
|
parent_inuse == parent->inuse)
|
|
break;
|
|
|
|
active = parent_active;
|
|
inuse = parent_inuse;
|
|
}
|
|
|
|
ioc->weights_updated = true;
|
|
}
|
|
|
|
static void commit_weights(struct ioc *ioc)
|
|
{
|
|
lockdep_assert_held(&ioc->lock);
|
|
|
|
if (ioc->weights_updated) {
|
|
/* paired with rmb in current_hweight(), see there */
|
|
smp_wmb();
|
|
atomic_inc(&ioc->hweight_gen);
|
|
ioc->weights_updated = false;
|
|
}
|
|
}
|
|
|
|
static void propagate_weights(struct ioc_gq *iocg, u32 active, u32 inuse,
|
|
bool save, struct ioc_now *now)
|
|
{
|
|
__propagate_weights(iocg, active, inuse, save, now);
|
|
commit_weights(iocg->ioc);
|
|
}
|
|
|
|
static void current_hweight(struct ioc_gq *iocg, u32 *hw_activep, u32 *hw_inusep)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
int lvl;
|
|
u32 hwa, hwi;
|
|
int ioc_gen;
|
|
|
|
/* hot path - if uptodate, use cached */
|
|
ioc_gen = atomic_read(&ioc->hweight_gen);
|
|
if (ioc_gen == iocg->hweight_gen)
|
|
goto out;
|
|
|
|
/*
|
|
* Paired with wmb in commit_weights(). If we saw the updated
|
|
* hweight_gen, all the weight updates from __propagate_weights() are
|
|
* visible too.
|
|
*
|
|
* We can race with weight updates during calculation and get it
|
|
* wrong. However, hweight_gen would have changed and a future
|
|
* reader will recalculate and we're guaranteed to discard the
|
|
* wrong result soon.
|
|
*/
|
|
smp_rmb();
|
|
|
|
hwa = hwi = WEIGHT_ONE;
|
|
for (lvl = 0; lvl <= iocg->level - 1; lvl++) {
|
|
struct ioc_gq *parent = iocg->ancestors[lvl];
|
|
struct ioc_gq *child = iocg->ancestors[lvl + 1];
|
|
u64 active_sum = READ_ONCE(parent->child_active_sum);
|
|
u64 inuse_sum = READ_ONCE(parent->child_inuse_sum);
|
|
u32 active = READ_ONCE(child->active);
|
|
u32 inuse = READ_ONCE(child->inuse);
|
|
|
|
/* we can race with deactivations and either may read as zero */
|
|
if (!active_sum || !inuse_sum)
|
|
continue;
|
|
|
|
active_sum = max_t(u64, active, active_sum);
|
|
hwa = div64_u64((u64)hwa * active, active_sum);
|
|
|
|
inuse_sum = max_t(u64, inuse, inuse_sum);
|
|
hwi = div64_u64((u64)hwi * inuse, inuse_sum);
|
|
}
|
|
|
|
iocg->hweight_active = max_t(u32, hwa, 1);
|
|
iocg->hweight_inuse = max_t(u32, hwi, 1);
|
|
iocg->hweight_gen = ioc_gen;
|
|
out:
|
|
if (hw_activep)
|
|
*hw_activep = iocg->hweight_active;
|
|
if (hw_inusep)
|
|
*hw_inusep = iocg->hweight_inuse;
|
|
}
|
|
|
|
/*
|
|
* Calculate the hweight_inuse @iocg would get with max @inuse assuming all the
|
|
* other weights stay unchanged.
|
|
*/
|
|
static u32 current_hweight_max(struct ioc_gq *iocg)
|
|
{
|
|
u32 hwm = WEIGHT_ONE;
|
|
u32 inuse = iocg->active;
|
|
u64 child_inuse_sum;
|
|
int lvl;
|
|
|
|
lockdep_assert_held(&iocg->ioc->lock);
|
|
|
|
for (lvl = iocg->level - 1; lvl >= 0; lvl--) {
|
|
struct ioc_gq *parent = iocg->ancestors[lvl];
|
|
struct ioc_gq *child = iocg->ancestors[lvl + 1];
|
|
|
|
child_inuse_sum = parent->child_inuse_sum + inuse - child->inuse;
|
|
hwm = div64_u64((u64)hwm * inuse, child_inuse_sum);
|
|
inuse = DIV64_U64_ROUND_UP(parent->active * child_inuse_sum,
|
|
parent->child_active_sum);
|
|
}
|
|
|
|
return max_t(u32, hwm, 1);
|
|
}
|
|
|
|
static void weight_updated(struct ioc_gq *iocg, struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
struct blkcg_gq *blkg = iocg_to_blkg(iocg);
|
|
struct ioc_cgrp *iocc = blkcg_to_iocc(blkg->blkcg);
|
|
u32 weight;
|
|
|
|
lockdep_assert_held(&ioc->lock);
|
|
|
|
weight = iocg->cfg_weight ?: iocc->dfl_weight;
|
|
if (weight != iocg->weight && iocg->active)
|
|
propagate_weights(iocg, weight, iocg->inuse, true, now);
|
|
iocg->weight = weight;
|
|
}
|
|
|
|
static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
u64 last_period, cur_period;
|
|
u64 vtime, vtarget;
|
|
int i;
|
|
|
|
/*
|
|
* If seem to be already active, just update the stamp to tell the
|
|
* timer that we're still active. We don't mind occassional races.
|
|
*/
|
|
if (!list_empty(&iocg->active_list)) {
|
|
ioc_now(ioc, now);
|
|
cur_period = atomic64_read(&ioc->cur_period);
|
|
if (atomic64_read(&iocg->active_period) != cur_period)
|
|
atomic64_set(&iocg->active_period, cur_period);
|
|
return true;
|
|
}
|
|
|
|
/* racy check on internal node IOs, treat as root level IOs */
|
|
if (iocg->child_active_sum)
|
|
return false;
|
|
|
|
spin_lock_irq(&ioc->lock);
|
|
|
|
ioc_now(ioc, now);
|
|
|
|
/* update period */
|
|
cur_period = atomic64_read(&ioc->cur_period);
|
|
last_period = atomic64_read(&iocg->active_period);
|
|
atomic64_set(&iocg->active_period, cur_period);
|
|
|
|
/* already activated or breaking leaf-only constraint? */
|
|
if (!list_empty(&iocg->active_list))
|
|
goto succeed_unlock;
|
|
for (i = iocg->level - 1; i > 0; i--)
|
|
if (!list_empty(&iocg->ancestors[i]->active_list))
|
|
goto fail_unlock;
|
|
|
|
if (iocg->child_active_sum)
|
|
goto fail_unlock;
|
|
|
|
/*
|
|
* Always start with the target budget. On deactivation, we throw away
|
|
* anything above it.
|
|
*/
|
|
vtarget = now->vnow - ioc->margins.target;
|
|
vtime = atomic64_read(&iocg->vtime);
|
|
|
|
atomic64_add(vtarget - vtime, &iocg->vtime);
|
|
atomic64_add(vtarget - vtime, &iocg->done_vtime);
|
|
vtime = vtarget;
|
|
|
|
/*
|
|
* Activate, propagate weight and start period timer if not
|
|
* running. Reset hweight_gen to avoid accidental match from
|
|
* wrapping.
|
|
*/
|
|
iocg->hweight_gen = atomic_read(&ioc->hweight_gen) - 1;
|
|
list_add(&iocg->active_list, &ioc->active_iocgs);
|
|
|
|
propagate_weights(iocg, iocg->weight,
|
|
iocg->last_inuse ?: iocg->weight, true, now);
|
|
|
|
TRACE_IOCG_PATH(iocg_activate, iocg, now,
|
|
last_period, cur_period, vtime);
|
|
|
|
iocg->activated_at = now->now;
|
|
|
|
if (ioc->running == IOC_IDLE) {
|
|
ioc->running = IOC_RUNNING;
|
|
ioc->dfgv_period_at = now->now;
|
|
ioc->dfgv_period_rem = 0;
|
|
ioc_start_period(ioc, now);
|
|
}
|
|
|
|
succeed_unlock:
|
|
spin_unlock_irq(&ioc->lock);
|
|
return true;
|
|
|
|
fail_unlock:
|
|
spin_unlock_irq(&ioc->lock);
|
|
return false;
|
|
}
|
|
|
|
static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
struct blkcg_gq *blkg = iocg_to_blkg(iocg);
|
|
u64 tdelta, delay, new_delay;
|
|
s64 vover, vover_pct;
|
|
u32 hwa;
|
|
|
|
lockdep_assert_held(&iocg->waitq.lock);
|
|
|
|
/* calculate the current delay in effect - 1/2 every second */
|
|
tdelta = now->now - iocg->delay_at;
|
|
if (iocg->delay)
|
|
delay = iocg->delay >> div64_u64(tdelta, USEC_PER_SEC);
|
|
else
|
|
delay = 0;
|
|
|
|
/* calculate the new delay from the debt amount */
|
|
current_hweight(iocg, &hwa, NULL);
|
|
vover = atomic64_read(&iocg->vtime) +
|
|
abs_cost_to_cost(iocg->abs_vdebt, hwa) - now->vnow;
|
|
vover_pct = div64_s64(100 * vover,
|
|
ioc->period_us * ioc->vtime_base_rate);
|
|
|
|
if (vover_pct <= MIN_DELAY_THR_PCT)
|
|
new_delay = 0;
|
|
else if (vover_pct >= MAX_DELAY_THR_PCT)
|
|
new_delay = MAX_DELAY;
|
|
else
|
|
new_delay = MIN_DELAY +
|
|
div_u64((MAX_DELAY - MIN_DELAY) *
|
|
(vover_pct - MIN_DELAY_THR_PCT),
|
|
MAX_DELAY_THR_PCT - MIN_DELAY_THR_PCT);
|
|
|
|
/* pick the higher one and apply */
|
|
if (new_delay > delay) {
|
|
iocg->delay = new_delay;
|
|
iocg->delay_at = now->now;
|
|
delay = new_delay;
|
|
}
|
|
|
|
if (delay >= MIN_DELAY) {
|
|
if (!iocg->indelay_since)
|
|
iocg->indelay_since = now->now;
|
|
blkcg_set_delay(blkg, delay * NSEC_PER_USEC);
|
|
return true;
|
|
} else {
|
|
if (iocg->indelay_since) {
|
|
iocg->stat.indelay_us += now->now - iocg->indelay_since;
|
|
iocg->indelay_since = 0;
|
|
}
|
|
iocg->delay = 0;
|
|
blkcg_clear_delay(blkg);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static void iocg_incur_debt(struct ioc_gq *iocg, u64 abs_cost,
|
|
struct ioc_now *now)
|
|
{
|
|
struct iocg_pcpu_stat *gcs;
|
|
|
|
lockdep_assert_held(&iocg->ioc->lock);
|
|
lockdep_assert_held(&iocg->waitq.lock);
|
|
WARN_ON_ONCE(list_empty(&iocg->active_list));
|
|
|
|
/*
|
|
* Once in debt, debt handling owns inuse. @iocg stays at the minimum
|
|
* inuse donating all of it share to others until its debt is paid off.
|
|
*/
|
|
if (!iocg->abs_vdebt && abs_cost) {
|
|
iocg->indebt_since = now->now;
|
|
propagate_weights(iocg, iocg->active, 0, false, now);
|
|
}
|
|
|
|
iocg->abs_vdebt += abs_cost;
|
|
|
|
gcs = get_cpu_ptr(iocg->pcpu_stat);
|
|
local64_add(abs_cost, &gcs->abs_vusage);
|
|
put_cpu_ptr(gcs);
|
|
}
|
|
|
|
static void iocg_pay_debt(struct ioc_gq *iocg, u64 abs_vpay,
|
|
struct ioc_now *now)
|
|
{
|
|
lockdep_assert_held(&iocg->ioc->lock);
|
|
lockdep_assert_held(&iocg->waitq.lock);
|
|
|
|
/* make sure that nobody messed with @iocg */
|
|
WARN_ON_ONCE(list_empty(&iocg->active_list));
|
|
WARN_ON_ONCE(iocg->inuse > 1);
|
|
|
|
iocg->abs_vdebt -= min(abs_vpay, iocg->abs_vdebt);
|
|
|
|
/* if debt is paid in full, restore inuse */
|
|
if (!iocg->abs_vdebt) {
|
|
iocg->stat.indebt_us += now->now - iocg->indebt_since;
|
|
iocg->indebt_since = 0;
|
|
|
|
propagate_weights(iocg, iocg->active, iocg->last_inuse,
|
|
false, now);
|
|
}
|
|
}
|
|
|
|
static int iocg_wake_fn(struct wait_queue_entry *wq_entry, unsigned mode,
|
|
int flags, void *key)
|
|
{
|
|
struct iocg_wait *wait = container_of(wq_entry, struct iocg_wait, wait);
|
|
struct iocg_wake_ctx *ctx = key;
|
|
u64 cost = abs_cost_to_cost(wait->abs_cost, ctx->hw_inuse);
|
|
|
|
ctx->vbudget -= cost;
|
|
|
|
if (ctx->vbudget < 0)
|
|
return -1;
|
|
|
|
iocg_commit_bio(ctx->iocg, wait->bio, wait->abs_cost, cost);
|
|
wait->committed = true;
|
|
|
|
/*
|
|
* autoremove_wake_function() removes the wait entry only when it
|
|
* actually changed the task state. We want the wait always removed.
|
|
* Remove explicitly and use default_wake_function(). Note that the
|
|
* order of operations is important as finish_wait() tests whether
|
|
* @wq_entry is removed without grabbing the lock.
|
|
*/
|
|
default_wake_function(wq_entry, mode, flags, key);
|
|
list_del_init_careful(&wq_entry->entry);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Calculate the accumulated budget, pay debt if @pay_debt and wake up waiters
|
|
* accordingly. When @pay_debt is %true, the caller must be holding ioc->lock in
|
|
* addition to iocg->waitq.lock.
|
|
*/
|
|
static void iocg_kick_waitq(struct ioc_gq *iocg, bool pay_debt,
|
|
struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
struct iocg_wake_ctx ctx = { .iocg = iocg };
|
|
u64 vshortage, expires, oexpires;
|
|
s64 vbudget;
|
|
u32 hwa;
|
|
|
|
lockdep_assert_held(&iocg->waitq.lock);
|
|
|
|
current_hweight(iocg, &hwa, NULL);
|
|
vbudget = now->vnow - atomic64_read(&iocg->vtime);
|
|
|
|
/* pay off debt */
|
|
if (pay_debt && iocg->abs_vdebt && vbudget > 0) {
|
|
u64 abs_vbudget = cost_to_abs_cost(vbudget, hwa);
|
|
u64 abs_vpay = min_t(u64, abs_vbudget, iocg->abs_vdebt);
|
|
u64 vpay = abs_cost_to_cost(abs_vpay, hwa);
|
|
|
|
lockdep_assert_held(&ioc->lock);
|
|
|
|
atomic64_add(vpay, &iocg->vtime);
|
|
atomic64_add(vpay, &iocg->done_vtime);
|
|
iocg_pay_debt(iocg, abs_vpay, now);
|
|
vbudget -= vpay;
|
|
}
|
|
|
|
if (iocg->abs_vdebt || iocg->delay)
|
|
iocg_kick_delay(iocg, now);
|
|
|
|
/*
|
|
* Debt can still be outstanding if we haven't paid all yet or the
|
|
* caller raced and called without @pay_debt. Shouldn't wake up waiters
|
|
* under debt. Make sure @vbudget reflects the outstanding amount and is
|
|
* not positive.
|
|
*/
|
|
if (iocg->abs_vdebt) {
|
|
s64 vdebt = abs_cost_to_cost(iocg->abs_vdebt, hwa);
|
|
vbudget = min_t(s64, 0, vbudget - vdebt);
|
|
}
|
|
|
|
/*
|
|
* Wake up the ones which are due and see how much vtime we'll need for
|
|
* the next one. As paying off debt restores hw_inuse, it must be read
|
|
* after the above debt payment.
|
|
*/
|
|
ctx.vbudget = vbudget;
|
|
current_hweight(iocg, NULL, &ctx.hw_inuse);
|
|
|
|
__wake_up_locked_key(&iocg->waitq, TASK_NORMAL, &ctx);
|
|
|
|
if (!waitqueue_active(&iocg->waitq)) {
|
|
if (iocg->wait_since) {
|
|
iocg->stat.wait_us += now->now - iocg->wait_since;
|
|
iocg->wait_since = 0;
|
|
}
|
|
return;
|
|
}
|
|
|
|
if (!iocg->wait_since)
|
|
iocg->wait_since = now->now;
|
|
|
|
if (WARN_ON_ONCE(ctx.vbudget >= 0))
|
|
return;
|
|
|
|
/* determine next wakeup, add a timer margin to guarantee chunking */
|
|
vshortage = -ctx.vbudget;
|
|
expires = now->now_ns +
|
|
DIV64_U64_ROUND_UP(vshortage, ioc->vtime_base_rate) *
|
|
NSEC_PER_USEC;
|
|
expires += ioc->timer_slack_ns;
|
|
|
|
/* if already active and close enough, don't bother */
|
|
oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->waitq_timer));
|
|
if (hrtimer_is_queued(&iocg->waitq_timer) &&
|
|
abs(oexpires - expires) <= ioc->timer_slack_ns)
|
|
return;
|
|
|
|
hrtimer_start_range_ns(&iocg->waitq_timer, ns_to_ktime(expires),
|
|
ioc->timer_slack_ns, HRTIMER_MODE_ABS);
|
|
}
|
|
|
|
static enum hrtimer_restart iocg_waitq_timer_fn(struct hrtimer *timer)
|
|
{
|
|
struct ioc_gq *iocg = container_of(timer, struct ioc_gq, waitq_timer);
|
|
bool pay_debt = READ_ONCE(iocg->abs_vdebt);
|
|
struct ioc_now now;
|
|
unsigned long flags;
|
|
|
|
ioc_now(iocg->ioc, &now);
|
|
|
|
iocg_lock(iocg, pay_debt, &flags);
|
|
iocg_kick_waitq(iocg, pay_debt, &now);
|
|
iocg_unlock(iocg, pay_debt, &flags);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
static void ioc_lat_stat(struct ioc *ioc, u32 *missed_ppm_ar, u32 *rq_wait_pct_p)
|
|
{
|
|
u32 nr_met[2] = { };
|
|
u32 nr_missed[2] = { };
|
|
u64 rq_wait_ns = 0;
|
|
int cpu, rw;
|
|
|
|
for_each_online_cpu(cpu) {
|
|
struct ioc_pcpu_stat *stat = per_cpu_ptr(ioc->pcpu_stat, cpu);
|
|
u64 this_rq_wait_ns;
|
|
|
|
for (rw = READ; rw <= WRITE; rw++) {
|
|
u32 this_met = local_read(&stat->missed[rw].nr_met);
|
|
u32 this_missed = local_read(&stat->missed[rw].nr_missed);
|
|
|
|
nr_met[rw] += this_met - stat->missed[rw].last_met;
|
|
nr_missed[rw] += this_missed - stat->missed[rw].last_missed;
|
|
stat->missed[rw].last_met = this_met;
|
|
stat->missed[rw].last_missed = this_missed;
|
|
}
|
|
|
|
this_rq_wait_ns = local64_read(&stat->rq_wait_ns);
|
|
rq_wait_ns += this_rq_wait_ns - stat->last_rq_wait_ns;
|
|
stat->last_rq_wait_ns = this_rq_wait_ns;
|
|
}
|
|
|
|
for (rw = READ; rw <= WRITE; rw++) {
|
|
if (nr_met[rw] + nr_missed[rw])
|
|
missed_ppm_ar[rw] =
|
|
DIV64_U64_ROUND_UP((u64)nr_missed[rw] * MILLION,
|
|
nr_met[rw] + nr_missed[rw]);
|
|
else
|
|
missed_ppm_ar[rw] = 0;
|
|
}
|
|
|
|
*rq_wait_pct_p = div64_u64(rq_wait_ns * 100,
|
|
ioc->period_us * NSEC_PER_USEC);
|
|
}
|
|
|
|
/* was iocg idle this period? */
|
|
static bool iocg_is_idle(struct ioc_gq *iocg)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
|
|
/* did something get issued this period? */
|
|
if (atomic64_read(&iocg->active_period) ==
|
|
atomic64_read(&ioc->cur_period))
|
|
return false;
|
|
|
|
/* is something in flight? */
|
|
if (atomic64_read(&iocg->done_vtime) != atomic64_read(&iocg->vtime))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Call this function on the target leaf @iocg's to build pre-order traversal
|
|
* list of all the ancestors in @inner_walk. The inner nodes are linked through
|
|
* ->walk_list and the caller is responsible for dissolving the list after use.
|
|
*/
|
|
static void iocg_build_inner_walk(struct ioc_gq *iocg,
|
|
struct list_head *inner_walk)
|
|
{
|
|
int lvl;
|
|
|
|
WARN_ON_ONCE(!list_empty(&iocg->walk_list));
|
|
|
|
/* find the first ancestor which hasn't been visited yet */
|
|
for (lvl = iocg->level - 1; lvl >= 0; lvl--) {
|
|
if (!list_empty(&iocg->ancestors[lvl]->walk_list))
|
|
break;
|
|
}
|
|
|
|
/* walk down and visit the inner nodes to get pre-order traversal */
|
|
while (++lvl <= iocg->level - 1) {
|
|
struct ioc_gq *inner = iocg->ancestors[lvl];
|
|
|
|
/* record traversal order */
|
|
list_add_tail(&inner->walk_list, inner_walk);
|
|
}
|
|
}
|
|
|
|
/* propagate the deltas to the parent */
|
|
static void iocg_flush_stat_upward(struct ioc_gq *iocg)
|
|
{
|
|
if (iocg->level > 0) {
|
|
struct iocg_stat *parent_stat =
|
|
&iocg->ancestors[iocg->level - 1]->stat;
|
|
|
|
parent_stat->usage_us +=
|
|
iocg->stat.usage_us - iocg->last_stat.usage_us;
|
|
parent_stat->wait_us +=
|
|
iocg->stat.wait_us - iocg->last_stat.wait_us;
|
|
parent_stat->indebt_us +=
|
|
iocg->stat.indebt_us - iocg->last_stat.indebt_us;
|
|
parent_stat->indelay_us +=
|
|
iocg->stat.indelay_us - iocg->last_stat.indelay_us;
|
|
}
|
|
|
|
iocg->last_stat = iocg->stat;
|
|
}
|
|
|
|
/* collect per-cpu counters and propagate the deltas to the parent */
|
|
static void iocg_flush_stat_leaf(struct ioc_gq *iocg, struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
u64 abs_vusage = 0;
|
|
u64 vusage_delta;
|
|
int cpu;
|
|
|
|
lockdep_assert_held(&iocg->ioc->lock);
|
|
|
|
/* collect per-cpu counters */
|
|
for_each_possible_cpu(cpu) {
|
|
abs_vusage += local64_read(
|
|
per_cpu_ptr(&iocg->pcpu_stat->abs_vusage, cpu));
|
|
}
|
|
vusage_delta = abs_vusage - iocg->last_stat_abs_vusage;
|
|
iocg->last_stat_abs_vusage = abs_vusage;
|
|
|
|
iocg->usage_delta_us = div64_u64(vusage_delta, ioc->vtime_base_rate);
|
|
iocg->stat.usage_us += iocg->usage_delta_us;
|
|
|
|
iocg_flush_stat_upward(iocg);
|
|
}
|
|
|
|
/* get stat counters ready for reading on all active iocgs */
|
|
static void iocg_flush_stat(struct list_head *target_iocgs, struct ioc_now *now)
|
|
{
|
|
LIST_HEAD(inner_walk);
|
|
struct ioc_gq *iocg, *tiocg;
|
|
|
|
/* flush leaves and build inner node walk list */
|
|
list_for_each_entry(iocg, target_iocgs, active_list) {
|
|
iocg_flush_stat_leaf(iocg, now);
|
|
iocg_build_inner_walk(iocg, &inner_walk);
|
|
}
|
|
|
|
/* keep flushing upwards by walking the inner list backwards */
|
|
list_for_each_entry_safe_reverse(iocg, tiocg, &inner_walk, walk_list) {
|
|
iocg_flush_stat_upward(iocg);
|
|
list_del_init(&iocg->walk_list);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Determine what @iocg's hweight_inuse should be after donating unused
|
|
* capacity. @hwm is the upper bound and used to signal no donation. This
|
|
* function also throws away @iocg's excess budget.
|
|
*/
|
|
static u32 hweight_after_donation(struct ioc_gq *iocg, u32 old_hwi, u32 hwm,
|
|
u32 usage, struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
u64 vtime = atomic64_read(&iocg->vtime);
|
|
s64 excess, delta, target, new_hwi;
|
|
|
|
/* debt handling owns inuse for debtors */
|
|
if (iocg->abs_vdebt)
|
|
return 1;
|
|
|
|
/* see whether minimum margin requirement is met */
|
|
if (waitqueue_active(&iocg->waitq) ||
|
|
time_after64(vtime, now->vnow - ioc->margins.min))
|
|
return hwm;
|
|
|
|
/* throw away excess above target */
|
|
excess = now->vnow - vtime - ioc->margins.target;
|
|
if (excess > 0) {
|
|
atomic64_add(excess, &iocg->vtime);
|
|
atomic64_add(excess, &iocg->done_vtime);
|
|
vtime += excess;
|
|
ioc->vtime_err -= div64_u64(excess * old_hwi, WEIGHT_ONE);
|
|
}
|
|
|
|
/*
|
|
* Let's say the distance between iocg's and device's vtimes as a
|
|
* fraction of period duration is delta. Assuming that the iocg will
|
|
* consume the usage determined above, we want to determine new_hwi so
|
|
* that delta equals MARGIN_TARGET at the end of the next period.
|
|
*
|
|
* We need to execute usage worth of IOs while spending the sum of the
|
|
* new budget (1 - MARGIN_TARGET) and the leftover from the last period
|
|
* (delta):
|
|
*
|
|
* usage = (1 - MARGIN_TARGET + delta) * new_hwi
|
|
*
|
|
* Therefore, the new_hwi is:
|
|
*
|
|
* new_hwi = usage / (1 - MARGIN_TARGET + delta)
|
|
*/
|
|
delta = div64_s64(WEIGHT_ONE * (now->vnow - vtime),
|
|
now->vnow - ioc->period_at_vtime);
|
|
target = WEIGHT_ONE * MARGIN_TARGET_PCT / 100;
|
|
new_hwi = div64_s64(WEIGHT_ONE * usage, WEIGHT_ONE - target + delta);
|
|
|
|
return clamp_t(s64, new_hwi, 1, hwm);
|
|
}
|
|
|
|
/*
|
|
* For work-conservation, an iocg which isn't using all of its share should
|
|
* donate the leftover to other iocgs. There are two ways to achieve this - 1.
|
|
* bumping up vrate accordingly 2. lowering the donating iocg's inuse weight.
|
|
*
|
|
* #1 is mathematically simpler but has the drawback of requiring synchronous
|
|
* global hweight_inuse updates when idle iocg's get activated or inuse weights
|
|
* change due to donation snapbacks as it has the possibility of grossly
|
|
* overshooting what's allowed by the model and vrate.
|
|
*
|
|
* #2 is inherently safe with local operations. The donating iocg can easily
|
|
* snap back to higher weights when needed without worrying about impacts on
|
|
* other nodes as the impacts will be inherently correct. This also makes idle
|
|
* iocg activations safe. The only effect activations have is decreasing
|
|
* hweight_inuse of others, the right solution to which is for those iocgs to
|
|
* snap back to higher weights.
|
|
*
|
|
* So, we go with #2. The challenge is calculating how each donating iocg's
|
|
* inuse should be adjusted to achieve the target donation amounts. This is done
|
|
* using Andy's method described in the following pdf.
|
|
*
|
|
* https://drive.google.com/file/d/1PsJwxPFtjUnwOY1QJ5AeICCcsL7BM3bo
|
|
*
|
|
* Given the weights and target after-donation hweight_inuse values, Andy's
|
|
* method determines how the proportional distribution should look like at each
|
|
* sibling level to maintain the relative relationship between all non-donating
|
|
* pairs. To roughly summarize, it divides the tree into donating and
|
|
* non-donating parts, calculates global donation rate which is used to
|
|
* determine the target hweight_inuse for each node, and then derives per-level
|
|
* proportions.
|
|
*
|
|
* The following pdf shows that global distribution calculated this way can be
|
|
* achieved by scaling inuse weights of donating leaves and propagating the
|
|
* adjustments upwards proportionally.
|
|
*
|
|
* https://drive.google.com/file/d/1vONz1-fzVO7oY5DXXsLjSxEtYYQbOvsE
|
|
*
|
|
* Combining the above two, we can determine how each leaf iocg's inuse should
|
|
* be adjusted to achieve the target donation.
|
|
*
|
|
* https://drive.google.com/file/d/1WcrltBOSPN0qXVdBgnKm4mdp9FhuEFQN
|
|
*
|
|
* The inline comments use symbols from the last pdf.
|
|
*
|
|
* b is the sum of the absolute budgets in the subtree. 1 for the root node.
|
|
* f is the sum of the absolute budgets of non-donating nodes in the subtree.
|
|
* t is the sum of the absolute budgets of donating nodes in the subtree.
|
|
* w is the weight of the node. w = w_f + w_t
|
|
* w_f is the non-donating portion of w. w_f = w * f / b
|
|
* w_b is the donating portion of w. w_t = w * t / b
|
|
* s is the sum of all sibling weights. s = Sum(w) for siblings
|
|
* s_f and s_t are the non-donating and donating portions of s.
|
|
*
|
|
* Subscript p denotes the parent's counterpart and ' the adjusted value - e.g.
|
|
* w_pt is the donating portion of the parent's weight and w'_pt the same value
|
|
* after adjustments. Subscript r denotes the root node's values.
|
|
*/
|
|
static void transfer_surpluses(struct list_head *surpluses, struct ioc_now *now)
|
|
{
|
|
LIST_HEAD(over_hwa);
|
|
LIST_HEAD(inner_walk);
|
|
struct ioc_gq *iocg, *tiocg, *root_iocg;
|
|
u32 after_sum, over_sum, over_target, gamma;
|
|
|
|
/*
|
|
* It's pretty unlikely but possible for the total sum of
|
|
* hweight_after_donation's to be higher than WEIGHT_ONE, which will
|
|
* confuse the following calculations. If such condition is detected,
|
|
* scale down everyone over its full share equally to keep the sum below
|
|
* WEIGHT_ONE.
|
|
*/
|
|
after_sum = 0;
|
|
over_sum = 0;
|
|
list_for_each_entry(iocg, surpluses, surplus_list) {
|
|
u32 hwa;
|
|
|
|
current_hweight(iocg, &hwa, NULL);
|
|
after_sum += iocg->hweight_after_donation;
|
|
|
|
if (iocg->hweight_after_donation > hwa) {
|
|
over_sum += iocg->hweight_after_donation;
|
|
list_add(&iocg->walk_list, &over_hwa);
|
|
}
|
|
}
|
|
|
|
if (after_sum >= WEIGHT_ONE) {
|
|
/*
|
|
* The delta should be deducted from the over_sum, calculate
|
|
* target over_sum value.
|
|
*/
|
|
u32 over_delta = after_sum - (WEIGHT_ONE - 1);
|
|
WARN_ON_ONCE(over_sum <= over_delta);
|
|
over_target = over_sum - over_delta;
|
|
} else {
|
|
over_target = 0;
|
|
}
|
|
|
|
list_for_each_entry_safe(iocg, tiocg, &over_hwa, walk_list) {
|
|
if (over_target)
|
|
iocg->hweight_after_donation =
|
|
div_u64((u64)iocg->hweight_after_donation *
|
|
over_target, over_sum);
|
|
list_del_init(&iocg->walk_list);
|
|
}
|
|
|
|
/*
|
|
* Build pre-order inner node walk list and prepare for donation
|
|
* adjustment calculations.
|
|
*/
|
|
list_for_each_entry(iocg, surpluses, surplus_list) {
|
|
iocg_build_inner_walk(iocg, &inner_walk);
|
|
}
|
|
|
|
root_iocg = list_first_entry(&inner_walk, struct ioc_gq, walk_list);
|
|
WARN_ON_ONCE(root_iocg->level > 0);
|
|
|
|
list_for_each_entry(iocg, &inner_walk, walk_list) {
|
|
iocg->child_adjusted_sum = 0;
|
|
iocg->hweight_donating = 0;
|
|
iocg->hweight_after_donation = 0;
|
|
}
|
|
|
|
/*
|
|
* Propagate the donating budget (b_t) and after donation budget (b'_t)
|
|
* up the hierarchy.
|
|
*/
|
|
list_for_each_entry(iocg, surpluses, surplus_list) {
|
|
struct ioc_gq *parent = iocg->ancestors[iocg->level - 1];
|
|
|
|
parent->hweight_donating += iocg->hweight_donating;
|
|
parent->hweight_after_donation += iocg->hweight_after_donation;
|
|
}
|
|
|
|
list_for_each_entry_reverse(iocg, &inner_walk, walk_list) {
|
|
if (iocg->level > 0) {
|
|
struct ioc_gq *parent = iocg->ancestors[iocg->level - 1];
|
|
|
|
parent->hweight_donating += iocg->hweight_donating;
|
|
parent->hweight_after_donation += iocg->hweight_after_donation;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Calculate inner hwa's (b) and make sure the donation values are
|
|
* within the accepted ranges as we're doing low res calculations with
|
|
* roundups.
|
|
*/
|
|
list_for_each_entry(iocg, &inner_walk, walk_list) {
|
|
if (iocg->level) {
|
|
struct ioc_gq *parent = iocg->ancestors[iocg->level - 1];
|
|
|
|
iocg->hweight_active = DIV64_U64_ROUND_UP(
|
|
(u64)parent->hweight_active * iocg->active,
|
|
parent->child_active_sum);
|
|
|
|
}
|
|
|
|
iocg->hweight_donating = min(iocg->hweight_donating,
|
|
iocg->hweight_active);
|
|
iocg->hweight_after_donation = min(iocg->hweight_after_donation,
|
|
iocg->hweight_donating - 1);
|
|
if (WARN_ON_ONCE(iocg->hweight_active <= 1 ||
|
|
iocg->hweight_donating <= 1 ||
|
|
iocg->hweight_after_donation == 0)) {
|
|
pr_warn("iocg: invalid donation weights in ");
|
|
pr_cont_cgroup_path(iocg_to_blkg(iocg)->blkcg->css.cgroup);
|
|
pr_cont(": active=%u donating=%u after=%u\n",
|
|
iocg->hweight_active, iocg->hweight_donating,
|
|
iocg->hweight_after_donation);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Calculate the global donation rate (gamma) - the rate to adjust
|
|
* non-donating budgets by.
|
|
*
|
|
* No need to use 64bit multiplication here as the first operand is
|
|
* guaranteed to be smaller than WEIGHT_ONE (1<<16).
|
|
*
|
|
* We know that there are beneficiary nodes and the sum of the donating
|
|
* hweights can't be whole; however, due to the round-ups during hweight
|
|
* calculations, root_iocg->hweight_donating might still end up equal to
|
|
* or greater than whole. Limit the range when calculating the divider.
|
|
*
|
|
* gamma = (1 - t_r') / (1 - t_r)
|
|
*/
|
|
gamma = DIV_ROUND_UP(
|
|
(WEIGHT_ONE - root_iocg->hweight_after_donation) * WEIGHT_ONE,
|
|
WEIGHT_ONE - min_t(u32, root_iocg->hweight_donating, WEIGHT_ONE - 1));
|
|
|
|
/*
|
|
* Calculate adjusted hwi, child_adjusted_sum and inuse for the inner
|
|
* nodes.
|
|
*/
|
|
list_for_each_entry(iocg, &inner_walk, walk_list) {
|
|
struct ioc_gq *parent;
|
|
u32 inuse, wpt, wptp;
|
|
u64 st, sf;
|
|
|
|
if (iocg->level == 0) {
|
|
/* adjusted weight sum for 1st level: s' = s * b_pf / b'_pf */
|
|
iocg->child_adjusted_sum = DIV64_U64_ROUND_UP(
|
|
iocg->child_active_sum * (WEIGHT_ONE - iocg->hweight_donating),
|
|
WEIGHT_ONE - iocg->hweight_after_donation);
|
|
continue;
|
|
}
|
|
|
|
parent = iocg->ancestors[iocg->level - 1];
|
|
|
|
/* b' = gamma * b_f + b_t' */
|
|
iocg->hweight_inuse = DIV64_U64_ROUND_UP(
|
|
(u64)gamma * (iocg->hweight_active - iocg->hweight_donating),
|
|
WEIGHT_ONE) + iocg->hweight_after_donation;
|
|
|
|
/* w' = s' * b' / b'_p */
|
|
inuse = DIV64_U64_ROUND_UP(
|
|
(u64)parent->child_adjusted_sum * iocg->hweight_inuse,
|
|
parent->hweight_inuse);
|
|
|
|
/* adjusted weight sum for children: s' = s_f + s_t * w'_pt / w_pt */
|
|
st = DIV64_U64_ROUND_UP(
|
|
iocg->child_active_sum * iocg->hweight_donating,
|
|
iocg->hweight_active);
|
|
sf = iocg->child_active_sum - st;
|
|
wpt = DIV64_U64_ROUND_UP(
|
|
(u64)iocg->active * iocg->hweight_donating,
|
|
iocg->hweight_active);
|
|
wptp = DIV64_U64_ROUND_UP(
|
|
(u64)inuse * iocg->hweight_after_donation,
|
|
iocg->hweight_inuse);
|
|
|
|
iocg->child_adjusted_sum = sf + DIV64_U64_ROUND_UP(st * wptp, wpt);
|
|
}
|
|
|
|
/*
|
|
* All inner nodes now have ->hweight_inuse and ->child_adjusted_sum and
|
|
* we can finally determine leaf adjustments.
|
|
*/
|
|
list_for_each_entry(iocg, surpluses, surplus_list) {
|
|
struct ioc_gq *parent = iocg->ancestors[iocg->level - 1];
|
|
u32 inuse;
|
|
|
|
/*
|
|
* In-debt iocgs participated in the donation calculation with
|
|
* the minimum target hweight_inuse. Configuring inuse
|
|
* accordingly would work fine but debt handling expects
|
|
* @iocg->inuse stay at the minimum and we don't wanna
|
|
* interfere.
|
|
*/
|
|
if (iocg->abs_vdebt) {
|
|
WARN_ON_ONCE(iocg->inuse > 1);
|
|
continue;
|
|
}
|
|
|
|
/* w' = s' * b' / b'_p, note that b' == b'_t for donating leaves */
|
|
inuse = DIV64_U64_ROUND_UP(
|
|
parent->child_adjusted_sum * iocg->hweight_after_donation,
|
|
parent->hweight_inuse);
|
|
|
|
TRACE_IOCG_PATH(inuse_transfer, iocg, now,
|
|
iocg->inuse, inuse,
|
|
iocg->hweight_inuse,
|
|
iocg->hweight_after_donation);
|
|
|
|
__propagate_weights(iocg, iocg->active, inuse, true, now);
|
|
}
|
|
|
|
/* walk list should be dissolved after use */
|
|
list_for_each_entry_safe(iocg, tiocg, &inner_walk, walk_list)
|
|
list_del_init(&iocg->walk_list);
|
|
}
|
|
|
|
/*
|
|
* A low weight iocg can amass a large amount of debt, for example, when
|
|
* anonymous memory gets reclaimed aggressively. If the system has a lot of
|
|
* memory paired with a slow IO device, the debt can span multiple seconds or
|
|
* more. If there are no other subsequent IO issuers, the in-debt iocg may end
|
|
* up blocked paying its debt while the IO device is idle.
|
|
*
|
|
* The following protects against such cases. If the device has been
|
|
* sufficiently idle for a while, the debts are halved and delays are
|
|
* recalculated.
|
|
*/
|
|
static void ioc_forgive_debts(struct ioc *ioc, u64 usage_us_sum, int nr_debtors,
|
|
struct ioc_now *now)
|
|
{
|
|
struct ioc_gq *iocg;
|
|
u64 dur, usage_pct, nr_cycles;
|
|
|
|
/* if no debtor, reset the cycle */
|
|
if (!nr_debtors) {
|
|
ioc->dfgv_period_at = now->now;
|
|
ioc->dfgv_period_rem = 0;
|
|
ioc->dfgv_usage_us_sum = 0;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Debtors can pass through a lot of writes choking the device and we
|
|
* don't want to be forgiving debts while the device is struggling from
|
|
* write bursts. If we're missing latency targets, consider the device
|
|
* fully utilized.
|
|
*/
|
|
if (ioc->busy_level > 0)
|
|
usage_us_sum = max_t(u64, usage_us_sum, ioc->period_us);
|
|
|
|
ioc->dfgv_usage_us_sum += usage_us_sum;
|
|
if (time_before64(now->now, ioc->dfgv_period_at + DFGV_PERIOD))
|
|
return;
|
|
|
|
/*
|
|
* At least DFGV_PERIOD has passed since the last period. Calculate the
|
|
* average usage and reset the period counters.
|
|
*/
|
|
dur = now->now - ioc->dfgv_period_at;
|
|
usage_pct = div64_u64(100 * ioc->dfgv_usage_us_sum, dur);
|
|
|
|
ioc->dfgv_period_at = now->now;
|
|
ioc->dfgv_usage_us_sum = 0;
|
|
|
|
/* if was too busy, reset everything */
|
|
if (usage_pct > DFGV_USAGE_PCT) {
|
|
ioc->dfgv_period_rem = 0;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Usage is lower than threshold. Let's forgive some debts. Debt
|
|
* forgiveness runs off of the usual ioc timer but its period usually
|
|
* doesn't match ioc's. Compensate the difference by performing the
|
|
* reduction as many times as would fit in the duration since the last
|
|
* run and carrying over the left-over duration in @ioc->dfgv_period_rem
|
|
* - if ioc period is 75% of DFGV_PERIOD, one out of three consecutive
|
|
* reductions is doubled.
|
|
*/
|
|
nr_cycles = dur + ioc->dfgv_period_rem;
|
|
ioc->dfgv_period_rem = do_div(nr_cycles, DFGV_PERIOD);
|
|
|
|
list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
|
|
u64 __maybe_unused old_debt, __maybe_unused old_delay;
|
|
|
|
if (!iocg->abs_vdebt && !iocg->delay)
|
|
continue;
|
|
|
|
spin_lock(&iocg->waitq.lock);
|
|
|
|
old_debt = iocg->abs_vdebt;
|
|
old_delay = iocg->delay;
|
|
|
|
if (iocg->abs_vdebt)
|
|
iocg->abs_vdebt = iocg->abs_vdebt >> nr_cycles ?: 1;
|
|
if (iocg->delay)
|
|
iocg->delay = iocg->delay >> nr_cycles ?: 1;
|
|
|
|
iocg_kick_waitq(iocg, true, now);
|
|
|
|
TRACE_IOCG_PATH(iocg_forgive_debt, iocg, now, usage_pct,
|
|
old_debt, iocg->abs_vdebt,
|
|
old_delay, iocg->delay);
|
|
|
|
spin_unlock(&iocg->waitq.lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check the active iocgs' state to avoid oversleeping and deactive
|
|
* idle iocgs.
|
|
*
|
|
* Since waiters determine the sleep durations based on the vrate
|
|
* they saw at the time of sleep, if vrate has increased, some
|
|
* waiters could be sleeping for too long. Wake up tardy waiters
|
|
* which should have woken up in the last period and expire idle
|
|
* iocgs.
|
|
*/
|
|
static int ioc_check_iocgs(struct ioc *ioc, struct ioc_now *now)
|
|
{
|
|
int nr_debtors = 0;
|
|
struct ioc_gq *iocg, *tiocg;
|
|
|
|
list_for_each_entry_safe(iocg, tiocg, &ioc->active_iocgs, active_list) {
|
|
if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
|
|
!iocg->delay && !iocg_is_idle(iocg))
|
|
continue;
|
|
|
|
spin_lock(&iocg->waitq.lock);
|
|
|
|
/* flush wait and indebt stat deltas */
|
|
if (iocg->wait_since) {
|
|
iocg->stat.wait_us += now->now - iocg->wait_since;
|
|
iocg->wait_since = now->now;
|
|
}
|
|
if (iocg->indebt_since) {
|
|
iocg->stat.indebt_us +=
|
|
now->now - iocg->indebt_since;
|
|
iocg->indebt_since = now->now;
|
|
}
|
|
if (iocg->indelay_since) {
|
|
iocg->stat.indelay_us +=
|
|
now->now - iocg->indelay_since;
|
|
iocg->indelay_since = now->now;
|
|
}
|
|
|
|
if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt ||
|
|
iocg->delay) {
|
|
/* might be oversleeping vtime / hweight changes, kick */
|
|
iocg_kick_waitq(iocg, true, now);
|
|
if (iocg->abs_vdebt || iocg->delay)
|
|
nr_debtors++;
|
|
} else if (iocg_is_idle(iocg)) {
|
|
/* no waiter and idle, deactivate */
|
|
u64 vtime = atomic64_read(&iocg->vtime);
|
|
s64 excess;
|
|
|
|
/*
|
|
* @iocg has been inactive for a full duration and will
|
|
* have a high budget. Account anything above target as
|
|
* error and throw away. On reactivation, it'll start
|
|
* with the target budget.
|
|
*/
|
|
excess = now->vnow - vtime - ioc->margins.target;
|
|
if (excess > 0) {
|
|
u32 old_hwi;
|
|
|
|
current_hweight(iocg, NULL, &old_hwi);
|
|
ioc->vtime_err -= div64_u64(excess * old_hwi,
|
|
WEIGHT_ONE);
|
|
}
|
|
|
|
TRACE_IOCG_PATH(iocg_idle, iocg, now,
|
|
atomic64_read(&iocg->active_period),
|
|
atomic64_read(&ioc->cur_period), vtime);
|
|
__propagate_weights(iocg, 0, 0, false, now);
|
|
list_del_init(&iocg->active_list);
|
|
}
|
|
|
|
spin_unlock(&iocg->waitq.lock);
|
|
}
|
|
|
|
commit_weights(ioc);
|
|
return nr_debtors;
|
|
}
|
|
|
|
static void ioc_timer_fn(struct timer_list *timer)
|
|
{
|
|
struct ioc *ioc = container_of(timer, struct ioc, timer);
|
|
struct ioc_gq *iocg, *tiocg;
|
|
struct ioc_now now;
|
|
LIST_HEAD(surpluses);
|
|
int nr_debtors, nr_shortages = 0, nr_lagging = 0;
|
|
u64 usage_us_sum = 0;
|
|
u32 ppm_rthr = 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;
|
|
|
|
/* 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;
|
|
}
|
|
|
|
nr_debtors = ioc_check_iocgs(ioc, &now);
|
|
|
|
/*
|
|
* Wait and indebt stat are flushed above and the donation calculation
|
|
* below needs updated usage stat. Let's bring stat up-to-date.
|
|
*/
|
|
iocg_flush_stat(&ioc->active_iocgs, &now);
|
|
|
|
/* calc usage and see whether some weights need to be moved around */
|
|
list_for_each_entry(iocg, &ioc->active_iocgs, active_list) {
|
|
u64 vdone, vtime, usage_us;
|
|
u32 hw_active, hw_inuse;
|
|
|
|
/*
|
|
* Collect unused and wind vtime closer to vnow to prevent
|
|
* iocgs from accumulating a large amount of budget.
|
|
*/
|
|
vdone = atomic64_read(&iocg->done_vtime);
|
|
vtime = atomic64_read(&iocg->vtime);
|
|
current_hweight(iocg, &hw_active, &hw_inuse);
|
|
|
|
/*
|
|
* Latency QoS detection doesn't account for IOs which are
|
|
* in-flight for longer than a period. Detect them by
|
|
* comparing vdone against period start. If lagging behind
|
|
* IOs from past periods, don't increase vrate.
|
|
*/
|
|
if ((ppm_rthr != MILLION || ppm_wthr != MILLION) &&
|
|
!atomic_read(&iocg_to_blkg(iocg)->use_delay) &&
|
|
time_after64(vtime, vdone) &&
|
|
time_after64(vtime, now.vnow -
|
|
MAX_LAGGING_PERIODS * period_vtime) &&
|
|
time_before64(vdone, now.vnow - period_vtime))
|
|
nr_lagging++;
|
|
|
|
/*
|
|
* Determine absolute usage factoring in in-flight IOs to avoid
|
|
* high-latency completions appearing as idle.
|
|
*/
|
|
usage_us = iocg->usage_delta_us;
|
|
usage_us_sum += usage_us;
|
|
|
|
/* see whether there's surplus vtime */
|
|
WARN_ON_ONCE(!list_empty(&iocg->surplus_list));
|
|
if (hw_inuse < hw_active ||
|
|
(!waitqueue_active(&iocg->waitq) &&
|
|
time_before64(vtime, now.vnow - ioc->margins.low))) {
|
|
u32 hwa, old_hwi, hwm, new_hwi, usage;
|
|
u64 usage_dur;
|
|
|
|
if (vdone != vtime) {
|
|
u64 inflight_us = DIV64_U64_ROUND_UP(
|
|
cost_to_abs_cost(vtime - vdone, hw_inuse),
|
|
ioc->vtime_base_rate);
|
|
|
|
usage_us = max(usage_us, inflight_us);
|
|
}
|
|
|
|
/* convert to hweight based usage ratio */
|
|
if (time_after64(iocg->activated_at, ioc->period_at))
|
|
usage_dur = max_t(u64, now.now - iocg->activated_at, 1);
|
|
else
|
|
usage_dur = max_t(u64, now.now - ioc->period_at, 1);
|
|
|
|
usage = clamp_t(u32,
|
|
DIV64_U64_ROUND_UP(usage_us * WEIGHT_ONE,
|
|
usage_dur),
|
|
1, WEIGHT_ONE);
|
|
|
|
/*
|
|
* Already donating or accumulated enough to start.
|
|
* Determine the donation amount.
|
|
*/
|
|
current_hweight(iocg, &hwa, &old_hwi);
|
|
hwm = current_hweight_max(iocg);
|
|
new_hwi = hweight_after_donation(iocg, old_hwi, hwm,
|
|
usage, &now);
|
|
/*
|
|
* Donation calculation assumes hweight_after_donation
|
|
* to be positive, a condition that a donor w/ hwa < 2
|
|
* can't meet. Don't bother with donation if hwa is
|
|
* below 2. It's not gonna make a meaningful difference
|
|
* anyway.
|
|
*/
|
|
if (new_hwi < hwm && hwa >= 2) {
|
|
iocg->hweight_donating = hwa;
|
|
iocg->hweight_after_donation = new_hwi;
|
|
list_add(&iocg->surplus_list, &surpluses);
|
|
} else if (!iocg->abs_vdebt) {
|
|
/*
|
|
* @iocg doesn't have enough to donate. Reset
|
|
* its inuse to active.
|
|
*
|
|
* Don't reset debtors as their inuse's are
|
|
* owned by debt handling. This shouldn't affect
|
|
* donation calculuation in any meaningful way
|
|
* as @iocg doesn't have a meaningful amount of
|
|
* share anyway.
|
|
*/
|
|
TRACE_IOCG_PATH(inuse_shortage, iocg, &now,
|
|
iocg->inuse, iocg->active,
|
|
iocg->hweight_inuse, new_hwi);
|
|
|
|
__propagate_weights(iocg, iocg->active,
|
|
iocg->active, true, &now);
|
|
nr_shortages++;
|
|
}
|
|
} else {
|
|
/* genuinely short on vtime */
|
|
nr_shortages++;
|
|
}
|
|
}
|
|
|
|
if (!list_empty(&surpluses) && nr_shortages)
|
|
transfer_surpluses(&surpluses, &now);
|
|
|
|
commit_weights(ioc);
|
|
|
|
/* surplus list should be dissolved after use */
|
|
list_for_each_entry_safe(iocg, tiocg, &surpluses, surplus_list)
|
|
list_del_init(&iocg->surplus_list);
|
|
|
|
/*
|
|
* If q is getting clogged or we're missing too much, we're issuing
|
|
* too much IO and should lower vtime rate. If we're not missing
|
|
* and experiencing shortages but not surpluses, we're too stingy
|
|
* and should increase vtime rate.
|
|
*/
|
|
prev_busy_level = ioc->busy_level;
|
|
if (rq_wait_pct > RQ_WAIT_BUSY_PCT ||
|
|
missed_ppm[READ] > ppm_rthr ||
|
|
missed_ppm[WRITE] > ppm_wthr) {
|
|
/* clearly missing QoS targets, slow down vrate */
|
|
ioc->busy_level = max(ioc->busy_level, 0);
|
|
ioc->busy_level++;
|
|
} else if (rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
|
|
missed_ppm[READ] <= ppm_rthr * UNBUSY_THR_PCT / 100 &&
|
|
missed_ppm[WRITE] <= ppm_wthr * UNBUSY_THR_PCT / 100) {
|
|
/* QoS targets are being met with >25% margin */
|
|
if (nr_shortages) {
|
|
/*
|
|
* We're throttling while the device has spare
|
|
* capacity. If vrate was being slowed down, stop.
|
|
*/
|
|
ioc->busy_level = min(ioc->busy_level, 0);
|
|
|
|
/*
|
|
* If there are IOs spanning multiple periods, wait
|
|
* them out before pushing the device harder.
|
|
*/
|
|
if (!nr_lagging)
|
|
ioc->busy_level--;
|
|
} else {
|
|
/*
|
|
* Nobody is being throttled and the users aren't
|
|
* issuing enough IOs to saturate the device. We
|
|
* simply don't know how close the device is to
|
|
* saturation. Coast.
|
|
*/
|
|
ioc->busy_level = 0;
|
|
}
|
|
} else {
|
|
/* inside the hysterisis margin, we're good */
|
|
ioc->busy_level = 0;
|
|
}
|
|
|
|
ioc->busy_level = clamp(ioc->busy_level, -1000, 1000);
|
|
|
|
ioc_adjust_base_vrate(ioc, rq_wait_pct, nr_lagging, nr_shortages,
|
|
prev_busy_level, missed_ppm);
|
|
|
|
ioc_refresh_params(ioc, false);
|
|
|
|
ioc_forgive_debts(ioc, usage_us_sum, nr_debtors, &now);
|
|
|
|
/*
|
|
* This period is done. Move onto the next one. If nothing's
|
|
* going on with the device, stop the timer.
|
|
*/
|
|
atomic64_inc(&ioc->cur_period);
|
|
|
|
if (ioc->running != IOC_STOP) {
|
|
if (!list_empty(&ioc->active_iocgs)) {
|
|
ioc_start_period(ioc, &now);
|
|
} else {
|
|
ioc->busy_level = 0;
|
|
ioc->vtime_err = 0;
|
|
ioc->running = IOC_IDLE;
|
|
}
|
|
|
|
ioc_refresh_vrate(ioc, &now);
|
|
}
|
|
|
|
spin_unlock_irq(&ioc->lock);
|
|
}
|
|
|
|
static u64 adjust_inuse_and_calc_cost(struct ioc_gq *iocg, u64 vtime,
|
|
u64 abs_cost, struct ioc_now *now)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
struct ioc_margins *margins = &ioc->margins;
|
|
u32 __maybe_unused old_inuse = iocg->inuse, __maybe_unused old_hwi;
|
|
u32 hwi, adj_step;
|
|
s64 margin;
|
|
u64 cost, new_inuse;
|
|
unsigned long flags;
|
|
|
|
current_hweight(iocg, NULL, &hwi);
|
|
old_hwi = hwi;
|
|
cost = abs_cost_to_cost(abs_cost, hwi);
|
|
margin = now->vnow - vtime - cost;
|
|
|
|
/* debt handling owns inuse for debtors */
|
|
if (iocg->abs_vdebt)
|
|
return cost;
|
|
|
|
/*
|
|
* We only increase inuse during period and do so if the margin has
|
|
* deteriorated since the previous adjustment.
|
|
*/
|
|
if (margin >= iocg->saved_margin || margin >= margins->low ||
|
|
iocg->inuse == iocg->active)
|
|
return cost;
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
|
|
/* we own inuse only when @iocg is in the normal active state */
|
|
if (iocg->abs_vdebt || list_empty(&iocg->active_list)) {
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
return cost;
|
|
}
|
|
|
|
/*
|
|
* Bump up inuse till @abs_cost fits in the existing budget.
|
|
* adj_step must be determined after acquiring ioc->lock - we might
|
|
* have raced and lost to another thread for activation and could
|
|
* be reading 0 iocg->active before ioc->lock which will lead to
|
|
* infinite loop.
|
|
*/
|
|
new_inuse = iocg->inuse;
|
|
adj_step = DIV_ROUND_UP(iocg->active * INUSE_ADJ_STEP_PCT, 100);
|
|
do {
|
|
new_inuse = new_inuse + adj_step;
|
|
propagate_weights(iocg, iocg->active, new_inuse, true, now);
|
|
current_hweight(iocg, NULL, &hwi);
|
|
cost = abs_cost_to_cost(abs_cost, hwi);
|
|
} while (time_after64(vtime + cost, now->vnow) &&
|
|
iocg->inuse != iocg->active);
|
|
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
TRACE_IOCG_PATH(inuse_adjust, iocg, now,
|
|
old_inuse, iocg->inuse, old_hwi, hwi);
|
|
|
|
return cost;
|
|
}
|
|
|
|
static void calc_vtime_cost_builtin(struct bio *bio, struct ioc_gq *iocg,
|
|
bool is_merge, u64 *costp)
|
|
{
|
|
struct ioc *ioc = iocg->ioc;
|
|
u64 coef_seqio, coef_randio, coef_page;
|
|
u64 pages = max_t(u64, bio_sectors(bio) >> IOC_SECT_TO_PAGE_SHIFT, 1);
|
|
u64 seek_pages = 0;
|
|
u64 cost = 0;
|
|
|
|
switch (bio_op(bio)) {
|
|
case REQ_OP_READ:
|
|
coef_seqio = ioc->params.lcoefs[LCOEF_RSEQIO];
|
|
coef_randio = ioc->params.lcoefs[LCOEF_RRANDIO];
|
|
coef_page = ioc->params.lcoefs[LCOEF_RPAGE];
|
|
break;
|
|
case REQ_OP_WRITE:
|
|
coef_seqio = ioc->params.lcoefs[LCOEF_WSEQIO];
|
|
coef_randio = ioc->params.lcoefs[LCOEF_WRANDIO];
|
|
coef_page = ioc->params.lcoefs[LCOEF_WPAGE];
|
|
break;
|
|
default:
|
|
goto out;
|
|
}
|
|
|
|
if (iocg->cursor) {
|
|
seek_pages = abs(bio->bi_iter.bi_sector - iocg->cursor);
|
|
seek_pages >>= IOC_SECT_TO_PAGE_SHIFT;
|
|
}
|
|
|
|
if (!is_merge) {
|
|
if (seek_pages > LCOEF_RANDIO_PAGES) {
|
|
cost += coef_randio;
|
|
} else {
|
|
cost += coef_seqio;
|
|
}
|
|
}
|
|
cost += pages * coef_page;
|
|
out:
|
|
*costp = cost;
|
|
}
|
|
|
|
static u64 calc_vtime_cost(struct bio *bio, struct ioc_gq *iocg, bool is_merge)
|
|
{
|
|
u64 cost;
|
|
|
|
calc_vtime_cost_builtin(bio, iocg, is_merge, &cost);
|
|
return cost;
|
|
}
|
|
|
|
static void calc_size_vtime_cost_builtin(struct request *rq, struct ioc *ioc,
|
|
u64 *costp)
|
|
{
|
|
unsigned int pages = blk_rq_stats_sectors(rq) >> IOC_SECT_TO_PAGE_SHIFT;
|
|
|
|
switch (req_op(rq)) {
|
|
case REQ_OP_READ:
|
|
*costp = pages * ioc->params.lcoefs[LCOEF_RPAGE];
|
|
break;
|
|
case REQ_OP_WRITE:
|
|
*costp = pages * ioc->params.lcoefs[LCOEF_WPAGE];
|
|
break;
|
|
default:
|
|
*costp = 0;
|
|
}
|
|
}
|
|
|
|
static u64 calc_size_vtime_cost(struct request *rq, struct ioc *ioc)
|
|
{
|
|
u64 cost;
|
|
|
|
calc_size_vtime_cost_builtin(rq, ioc, &cost);
|
|
return cost;
|
|
}
|
|
|
|
static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
|
|
{
|
|
struct blkcg_gq *blkg = bio->bi_blkg;
|
|
struct ioc *ioc = rqos_to_ioc(rqos);
|
|
struct ioc_gq *iocg = blkg_to_iocg(blkg);
|
|
struct ioc_now now;
|
|
struct iocg_wait wait;
|
|
u64 abs_cost, cost, vtime;
|
|
bool use_debt, ioc_locked;
|
|
unsigned long flags;
|
|
|
|
/* bypass IOs if disabled, still initializing, or for root cgroup */
|
|
if (!ioc->enabled || !iocg || !iocg->level)
|
|
return;
|
|
|
|
/* calculate the absolute vtime cost */
|
|
abs_cost = calc_vtime_cost(bio, iocg, false);
|
|
if (!abs_cost)
|
|
return;
|
|
|
|
if (!iocg_activate(iocg, &now))
|
|
return;
|
|
|
|
iocg->cursor = bio_end_sector(bio);
|
|
vtime = atomic64_read(&iocg->vtime);
|
|
cost = adjust_inuse_and_calc_cost(iocg, vtime, abs_cost, &now);
|
|
|
|
/*
|
|
* If no one's waiting and within budget, issue right away. The
|
|
* tests are racy but the races aren't systemic - we only miss once
|
|
* in a while which is fine.
|
|
*/
|
|
if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
|
|
time_before_eq64(vtime + cost, now.vnow)) {
|
|
iocg_commit_bio(iocg, bio, abs_cost, cost);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We're over budget. This can be handled in two ways. IOs which may
|
|
* cause priority inversions are punted to @ioc->aux_iocg and charged as
|
|
* debt. Otherwise, the issuer is blocked on @iocg->waitq. Debt handling
|
|
* requires @ioc->lock, waitq handling @iocg->waitq.lock. Determine
|
|
* whether debt handling is needed and acquire locks accordingly.
|
|
*/
|
|
use_debt = bio_issue_as_root_blkg(bio) || fatal_signal_pending(current);
|
|
ioc_locked = use_debt || READ_ONCE(iocg->abs_vdebt);
|
|
retry_lock:
|
|
iocg_lock(iocg, ioc_locked, &flags);
|
|
|
|
/*
|
|
* @iocg must stay activated for debt and waitq handling. Deactivation
|
|
* is synchronized against both ioc->lock and waitq.lock and we won't
|
|
* get deactivated as long as we're waiting or has debt, so we're good
|
|
* if we're activated here. In the unlikely cases that we aren't, just
|
|
* issue the IO.
|
|
*/
|
|
if (unlikely(list_empty(&iocg->active_list))) {
|
|
iocg_unlock(iocg, ioc_locked, &flags);
|
|
iocg_commit_bio(iocg, bio, abs_cost, cost);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We're over budget. If @bio has to be issued regardless, remember
|
|
* the abs_cost instead of advancing vtime. iocg_kick_waitq() will pay
|
|
* off the debt before waking more IOs.
|
|
*
|
|
* This way, the debt is continuously paid off each period with the
|
|
* actual budget available to the cgroup. If we just wound vtime, we
|
|
* would incorrectly use the current hw_inuse for the entire amount
|
|
* which, for example, can lead to the cgroup staying blocked for a
|
|
* long time even with substantially raised hw_inuse.
|
|
*
|
|
* An iocg with vdebt should stay online so that the timer can keep
|
|
* deducting its vdebt and [de]activate use_delay mechanism
|
|
* accordingly. We don't want to race against the timer trying to
|
|
* clear them and leave @iocg inactive w/ dangling use_delay heavily
|
|
* penalizing the cgroup and its descendants.
|
|
*/
|
|
if (use_debt) {
|
|
iocg_incur_debt(iocg, abs_cost, &now);
|
|
if (iocg_kick_delay(iocg, &now))
|
|
blkcg_schedule_throttle(rqos->q->disk,
|
|
(bio->bi_opf & REQ_SWAP) == REQ_SWAP);
|
|
iocg_unlock(iocg, ioc_locked, &flags);
|
|
return;
|
|
}
|
|
|
|
/* guarantee that iocgs w/ waiters have maximum inuse */
|
|
if (!iocg->abs_vdebt && iocg->inuse != iocg->active) {
|
|
if (!ioc_locked) {
|
|
iocg_unlock(iocg, false, &flags);
|
|
ioc_locked = true;
|
|
goto retry_lock;
|
|
}
|
|
propagate_weights(iocg, iocg->active, iocg->active, true,
|
|
&now);
|
|
}
|
|
|
|
/*
|
|
* Append self to the waitq and schedule the wakeup timer if we're
|
|
* the first waiter. The timer duration is calculated based on the
|
|
* current vrate. vtime and hweight changes can make it too short
|
|
* or too long. Each wait entry records the absolute cost it's
|
|
* waiting for to allow re-evaluation using a custom wait entry.
|
|
*
|
|
* If too short, the timer simply reschedules itself. If too long,
|
|
* the period timer will notice and trigger wakeups.
|
|
*
|
|
* All waiters are on iocg->waitq and the wait states are
|
|
* synchronized using waitq.lock.
|
|
*/
|
|
init_waitqueue_func_entry(&wait.wait, iocg_wake_fn);
|
|
wait.wait.private = current;
|
|
wait.bio = bio;
|
|
wait.abs_cost = abs_cost;
|
|
wait.committed = false; /* will be set true by waker */
|
|
|
|
__add_wait_queue_entry_tail(&iocg->waitq, &wait.wait);
|
|
iocg_kick_waitq(iocg, ioc_locked, &now);
|
|
|
|
iocg_unlock(iocg, ioc_locked, &flags);
|
|
|
|
while (true) {
|
|
set_current_state(TASK_UNINTERRUPTIBLE);
|
|
if (wait.committed)
|
|
break;
|
|
io_schedule();
|
|
}
|
|
|
|
/* waker already committed us, proceed */
|
|
finish_wait(&iocg->waitq, &wait.wait);
|
|
}
|
|
|
|
static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg);
|
|
struct ioc *ioc = rqos_to_ioc(rqos);
|
|
sector_t bio_end = bio_end_sector(bio);
|
|
struct ioc_now now;
|
|
u64 vtime, abs_cost, cost;
|
|
unsigned long flags;
|
|
|
|
/* bypass if disabled, still initializing, or for root cgroup */
|
|
if (!ioc->enabled || !iocg || !iocg->level)
|
|
return;
|
|
|
|
abs_cost = calc_vtime_cost(bio, iocg, true);
|
|
if (!abs_cost)
|
|
return;
|
|
|
|
ioc_now(ioc, &now);
|
|
|
|
vtime = atomic64_read(&iocg->vtime);
|
|
cost = adjust_inuse_and_calc_cost(iocg, vtime, abs_cost, &now);
|
|
|
|
/* update cursor if backmerging into the request at the cursor */
|
|
if (blk_rq_pos(rq) < bio_end &&
|
|
blk_rq_pos(rq) + blk_rq_sectors(rq) == iocg->cursor)
|
|
iocg->cursor = bio_end;
|
|
|
|
/*
|
|
* Charge if there's enough vtime budget and the existing request has
|
|
* cost assigned.
|
|
*/
|
|
if (rq->bio && rq->bio->bi_iocost_cost &&
|
|
time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow)) {
|
|
iocg_commit_bio(iocg, bio, abs_cost, cost);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Otherwise, account it as debt if @iocg is online, which it should
|
|
* be for the vast majority of cases. See debt handling in
|
|
* ioc_rqos_throttle() for details.
|
|
*/
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
spin_lock(&iocg->waitq.lock);
|
|
|
|
if (likely(!list_empty(&iocg->active_list))) {
|
|
iocg_incur_debt(iocg, abs_cost, &now);
|
|
if (iocg_kick_delay(iocg, &now))
|
|
blkcg_schedule_throttle(rqos->q->disk,
|
|
(bio->bi_opf & REQ_SWAP) == REQ_SWAP);
|
|
} else {
|
|
iocg_commit_bio(iocg, bio, abs_cost, cost);
|
|
}
|
|
|
|
spin_unlock(&iocg->waitq.lock);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
}
|
|
|
|
static void ioc_rqos_done_bio(struct rq_qos *rqos, struct bio *bio)
|
|
{
|
|
struct ioc_gq *iocg = blkg_to_iocg(bio->bi_blkg);
|
|
|
|
if (iocg && bio->bi_iocost_cost)
|
|
atomic64_add(bio->bi_iocost_cost, &iocg->done_vtime);
|
|
}
|
|
|
|
static void ioc_rqos_done(struct rq_qos *rqos, struct request *rq)
|
|
{
|
|
struct ioc *ioc = rqos_to_ioc(rqos);
|
|
struct ioc_pcpu_stat *ccs;
|
|
u64 on_q_ns, rq_wait_ns, size_nsec;
|
|
int pidx, rw;
|
|
|
|
if (!ioc->enabled || !rq->alloc_time_ns || !rq->start_time_ns)
|
|
return;
|
|
|
|
switch (req_op(rq)) {
|
|
case REQ_OP_READ:
|
|
pidx = QOS_RLAT;
|
|
rw = READ;
|
|
break;
|
|
case REQ_OP_WRITE:
|
|
pidx = QOS_WLAT;
|
|
rw = WRITE;
|
|
break;
|
|
default:
|
|
return;
|
|
}
|
|
|
|
on_q_ns = ktime_get_ns() - rq->alloc_time_ns;
|
|
rq_wait_ns = rq->start_time_ns - rq->alloc_time_ns;
|
|
size_nsec = div64_u64(calc_size_vtime_cost(rq, ioc), VTIME_PER_NSEC);
|
|
|
|
ccs = get_cpu_ptr(ioc->pcpu_stat);
|
|
|
|
if (on_q_ns <= size_nsec ||
|
|
on_q_ns - size_nsec <= ioc->params.qos[pidx] * NSEC_PER_USEC)
|
|
local_inc(&ccs->missed[rw].nr_met);
|
|
else
|
|
local_inc(&ccs->missed[rw].nr_missed);
|
|
|
|
local64_add(rq_wait_ns, &ccs->rq_wait_ns);
|
|
|
|
put_cpu_ptr(ccs);
|
|
}
|
|
|
|
static void ioc_rqos_queue_depth_changed(struct rq_qos *rqos)
|
|
{
|
|
struct ioc *ioc = rqos_to_ioc(rqos);
|
|
|
|
spin_lock_irq(&ioc->lock);
|
|
ioc_refresh_params(ioc, false);
|
|
spin_unlock_irq(&ioc->lock);
|
|
}
|
|
|
|
static void ioc_rqos_exit(struct rq_qos *rqos)
|
|
{
|
|
struct ioc *ioc = rqos_to_ioc(rqos);
|
|
|
|
blkcg_deactivate_policy(rqos->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 gendisk *disk)
|
|
{
|
|
struct request_queue *q = disk->queue;
|
|
struct ioc *ioc;
|
|
struct rq_qos *rqos;
|
|
int i, cpu, ret;
|
|
|
|
ioc = kzalloc(sizeof(*ioc), GFP_KERNEL);
|
|
if (!ioc)
|
|
return -ENOMEM;
|
|
|
|
ioc->pcpu_stat = alloc_percpu(struct ioc_pcpu_stat);
|
|
if (!ioc->pcpu_stat) {
|
|
kfree(ioc);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct ioc_pcpu_stat *ccs = per_cpu_ptr(ioc->pcpu_stat, cpu);
|
|
|
|
for (i = 0; i < ARRAY_SIZE(ccs->missed); i++) {
|
|
local_set(&ccs->missed[i].nr_met, 0);
|
|
local_set(&ccs->missed[i].nr_missed, 0);
|
|
}
|
|
local64_set(&ccs->rq_wait_ns, 0);
|
|
}
|
|
|
|
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;
|
|
ioc->vtime_base_rate = VTIME_PER_USEC;
|
|
atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC);
|
|
seqcount_spinlock_init(&ioc->period_seqcount, &ioc->lock);
|
|
ioc->period_at = ktime_to_us(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);
|
|
|
|
/*
|
|
* rqos must be added before activation to allow iocg_pd_init() to
|
|
* lookup the ioc from q. This means that the rqos methods may get
|
|
* called before policy activation completion, can't assume that the
|
|
* target bio has an iocg associated and need to test for NULL iocg.
|
|
*/
|
|
ret = rq_qos_add(q, rqos);
|
|
if (ret)
|
|
goto err_free_ioc;
|
|
|
|
ret = blkcg_activate_policy(q, &blkcg_policy_iocost);
|
|
if (ret)
|
|
goto err_del_qos;
|
|
return 0;
|
|
|
|
err_del_qos:
|
|
rq_qos_del(q, rqos);
|
|
err_free_ioc:
|
|
free_percpu(ioc->pcpu_stat);
|
|
kfree(ioc);
|
|
return ret;
|
|
}
|
|
|
|
static struct blkcg_policy_data *ioc_cpd_alloc(gfp_t gfp)
|
|
{
|
|
struct ioc_cgrp *iocc;
|
|
|
|
iocc = kzalloc(sizeof(struct ioc_cgrp), gfp);
|
|
if (!iocc)
|
|
return NULL;
|
|
|
|
iocc->dfl_weight = CGROUP_WEIGHT_DFL * WEIGHT_ONE;
|
|
return &iocc->cpd;
|
|
}
|
|
|
|
static void ioc_cpd_free(struct blkcg_policy_data *cpd)
|
|
{
|
|
kfree(container_of(cpd, struct ioc_cgrp, cpd));
|
|
}
|
|
|
|
static struct blkg_policy_data *ioc_pd_alloc(gfp_t gfp, struct request_queue *q,
|
|
struct blkcg *blkcg)
|
|
{
|
|
int levels = blkcg->css.cgroup->level + 1;
|
|
struct ioc_gq *iocg;
|
|
|
|
iocg = kzalloc_node(struct_size(iocg, ancestors, levels), gfp, q->node);
|
|
if (!iocg)
|
|
return NULL;
|
|
|
|
iocg->pcpu_stat = alloc_percpu_gfp(struct iocg_pcpu_stat, gfp);
|
|
if (!iocg->pcpu_stat) {
|
|
kfree(iocg);
|
|
return NULL;
|
|
}
|
|
|
|
return &iocg->pd;
|
|
}
|
|
|
|
static void ioc_pd_init(struct blkg_policy_data *pd)
|
|
{
|
|
struct ioc_gq *iocg = pd_to_iocg(pd);
|
|
struct blkcg_gq *blkg = pd_to_blkg(&iocg->pd);
|
|
struct ioc *ioc = q_to_ioc(blkg->q);
|
|
struct ioc_now now;
|
|
struct blkcg_gq *tblkg;
|
|
unsigned long flags;
|
|
|
|
ioc_now(ioc, &now);
|
|
|
|
iocg->ioc = ioc;
|
|
atomic64_set(&iocg->vtime, now.vnow);
|
|
atomic64_set(&iocg->done_vtime, now.vnow);
|
|
atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
|
|
INIT_LIST_HEAD(&iocg->active_list);
|
|
INIT_LIST_HEAD(&iocg->walk_list);
|
|
INIT_LIST_HEAD(&iocg->surplus_list);
|
|
iocg->hweight_active = WEIGHT_ONE;
|
|
iocg->hweight_inuse = WEIGHT_ONE;
|
|
|
|
init_waitqueue_head(&iocg->waitq);
|
|
hrtimer_init(&iocg->waitq_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
|
|
iocg->waitq_timer.function = iocg_waitq_timer_fn;
|
|
|
|
iocg->level = blkg->blkcg->css.cgroup->level;
|
|
|
|
for (tblkg = blkg; tblkg; tblkg = tblkg->parent) {
|
|
struct ioc_gq *tiocg = blkg_to_iocg(tblkg);
|
|
iocg->ancestors[tiocg->level] = tiocg;
|
|
}
|
|
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
weight_updated(iocg, &now);
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
}
|
|
|
|
static void ioc_pd_free(struct blkg_policy_data *pd)
|
|
{
|
|
struct ioc_gq *iocg = pd_to_iocg(pd);
|
|
struct ioc *ioc = iocg->ioc;
|
|
unsigned long flags;
|
|
|
|
if (ioc) {
|
|
spin_lock_irqsave(&ioc->lock, flags);
|
|
|
|
if (!list_empty(&iocg->active_list)) {
|
|
struct ioc_now now;
|
|
|
|
ioc_now(ioc, &now);
|
|
propagate_weights(iocg, 0, 0, false, &now);
|
|
list_del_init(&iocg->active_list);
|
|
}
|
|
|
|
WARN_ON_ONCE(!list_empty(&iocg->walk_list));
|
|
WARN_ON_ONCE(!list_empty(&iocg->surplus_list));
|
|
|
|
spin_unlock_irqrestore(&ioc->lock, flags);
|
|
|
|
hrtimer_cancel(&iocg->waitq_timer);
|
|
}
|
|
free_percpu(iocg->pcpu_stat);
|
|
kfree(iocg);
|
|
}
|
|
|
|
static void ioc_pd_stat(struct blkg_policy_data *pd, struct seq_file *s)
|
|
{
|
|
struct ioc_gq *iocg = pd_to_iocg(pd);
|
|
struct ioc *ioc = iocg->ioc;
|
|
|
|
if (!ioc->enabled)
|
|
return;
|
|
|
|
if (iocg->level == 0) {
|
|
unsigned vp10k = DIV64_U64_ROUND_CLOSEST(
|
|
ioc->vtime_base_rate * 10000,
|
|
VTIME_PER_USEC);
|
|
seq_printf(s, " cost.vrate=%u.%02u", vp10k / 100, vp10k % 100);
|
|
}
|
|
|
|
seq_printf(s, " cost.usage=%llu", iocg->last_stat.usage_us);
|
|
|
|
if (blkcg_debug_stats)
|
|
seq_printf(s, " cost.wait=%llu cost.indebt=%llu cost.indelay=%llu",
|
|
iocg->last_stat.wait_us,
|
|
iocg->last_stat.indebt_us,
|
|
iocg->last_stat.indelay_us);
|
|
}
|
|
|
|
static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
|
|
int off)
|
|
{
|
|
const char *dname = blkg_dev_name(pd->blkg);
|
|
struct ioc_gq *iocg = pd_to_iocg(pd);
|
|
|
|
if (dname && iocg->cfg_weight)
|
|
seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight / WEIGHT_ONE);
|
|
return 0;
|
|
}
|
|
|
|
|
|
static int ioc_weight_show(struct seq_file *sf, void *v)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
|
|
struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
|
|
|
|
seq_printf(sf, "default %u\n", iocc->dfl_weight / WEIGHT_ONE);
|
|
blkcg_print_blkgs(sf, blkcg, ioc_weight_prfill,
|
|
&blkcg_policy_iocost, seq_cft(sf)->private, false);
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
|
|
size_t nbytes, loff_t off)
|
|
{
|
|
struct blkcg *blkcg = css_to_blkcg(of_css(of));
|
|
struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
|
|
struct blkg_conf_ctx ctx;
|
|
struct ioc_now now;
|
|
struct ioc_gq *iocg;
|
|
u32 v;
|
|
int ret;
|
|
|
|
if (!strchr(buf, ':')) {
|
|
struct blkcg_gq *blkg;
|
|
|
|
if (!sscanf(buf, "default %u", &v) && !sscanf(buf, "%u", &v))
|
|
return -EINVAL;
|
|
|
|
if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX)
|
|
return -EINVAL;
|
|
|
|
spin_lock_irq(&blkcg->lock);
|
|
iocc->dfl_weight = v * WEIGHT_ONE;
|
|
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
|
|
struct ioc_gq *iocg = blkg_to_iocg(blkg);
|
|
|
|
if (iocg) {
|
|
spin_lock(&iocg->ioc->lock);
|
|
ioc_now(iocg->ioc, &now);
|
|
weight_updated(iocg, &now);
|
|
spin_unlock(&iocg->ioc->lock);
|
|
}
|
|
}
|
|
spin_unlock_irq(&blkcg->lock);
|
|
|
|
return nbytes;
|
|
}
|
|
|
|
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_ONE;
|
|
ioc_now(iocg->ioc, &now);
|
|
weight_updated(iocg, &now);
|
|
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 block_device *bdev;
|
|
struct gendisk *disk;
|
|
struct ioc *ioc;
|
|
u32 qos[NR_QOS_PARAMS];
|
|
bool enable, user;
|
|
char *p;
|
|
int ret;
|
|
|
|
bdev = blkcg_conf_open_bdev(&input);
|
|
if (IS_ERR(bdev))
|
|
return PTR_ERR(bdev);
|
|
|
|
disk = bdev->bd_disk;
|
|
ioc = q_to_ioc(disk->queue);
|
|
if (!ioc) {
|
|
ret = blk_iocost_init(disk);
|
|
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_stat_enable_accounting(disk->queue);
|
|
blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
|
|
ioc->enabled = true;
|
|
} else {
|
|
blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue);
|
|
ioc->enabled = false;
|
|
}
|
|
|
|
if (user) {
|
|
memcpy(ioc->params.qos, qos, sizeof(qos));
|
|
ioc->user_qos_params = true;
|
|
} else {
|
|
ioc->user_qos_params = false;
|
|
}
|
|
|
|
ioc_refresh_params(ioc, true);
|
|
spin_unlock_irq(&ioc->lock);
|
|
|
|
blkdev_put_no_open(bdev);
|
|
return nbytes;
|
|
einval:
|
|
ret = -EINVAL;
|
|
err:
|
|
blkdev_put_no_open(bdev);
|
|
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 block_device *bdev;
|
|
struct ioc *ioc;
|
|
u64 u[NR_I_LCOEFS];
|
|
bool user;
|
|
char *p;
|
|
int ret;
|
|
|
|
bdev = blkcg_conf_open_bdev(&input);
|
|
if (IS_ERR(bdev))
|
|
return PTR_ERR(bdev);
|
|
|
|
ioc = q_to_ioc(bdev_get_queue(bdev));
|
|
if (!ioc) {
|
|
ret = blk_iocost_init(bdev->bd_disk);
|
|
if (ret)
|
|
goto err;
|
|
ioc = q_to_ioc(bdev_get_queue(bdev));
|
|
}
|
|
|
|
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);
|
|
|
|
blkdev_put_no_open(bdev);
|
|
return nbytes;
|
|
|
|
einval:
|
|
ret = -EINVAL;
|
|
err:
|
|
blkdev_put_no_open(bdev);
|
|
return ret;
|
|
}
|
|
|
|
static struct cftype ioc_files[] = {
|
|
{
|
|
.name = "weight",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = ioc_weight_show,
|
|
.write = ioc_weight_write,
|
|
},
|
|
{
|
|
.name = "cost.qos",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = ioc_qos_show,
|
|
.write = ioc_qos_write,
|
|
},
|
|
{
|
|
.name = "cost.model",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = ioc_cost_model_show,
|
|
.write = ioc_cost_model_write,
|
|
},
|
|
{}
|
|
};
|
|
|
|
static struct blkcg_policy blkcg_policy_iocost = {
|
|
.dfl_cftypes = ioc_files,
|
|
.cpd_alloc_fn = ioc_cpd_alloc,
|
|
.cpd_free_fn = ioc_cpd_free,
|
|
.pd_alloc_fn = ioc_pd_alloc,
|
|
.pd_init_fn = ioc_pd_init,
|
|
.pd_free_fn = ioc_pd_free,
|
|
.pd_stat_fn = ioc_pd_stat,
|
|
};
|
|
|
|
static int __init ioc_init(void)
|
|
{
|
|
return blkcg_policy_register(&blkcg_policy_iocost);
|
|
}
|
|
|
|
static void __exit ioc_exit(void)
|
|
{
|
|
blkcg_policy_unregister(&blkcg_policy_iocost);
|
|
}
|
|
|
|
module_init(ioc_init);
|
|
module_exit(ioc_exit);
|