forked from Minki/linux
f6709b8aa7
There's no reason for gov_cancel_work() to exist at all, as it only has one caller and the only thing done by that caller is to invoke gov_cancel_work(). Accordingly, drop gov_cancel_work() and move its contents to the caller. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
557 lines
16 KiB
C
557 lines
16 KiB
C
/*
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* drivers/cpufreq/cpufreq_governor.c
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*
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* CPUFREQ governors common code
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*
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* Copyright (C) 2001 Russell King
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* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
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* (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
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* (C) 2009 Alexander Clouter <alex@digriz.org.uk>
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* (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/export.h>
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#include <linux/kernel_stat.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include "cpufreq_governor.h"
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static DEFINE_PER_CPU(struct cpu_dbs_info, cpu_dbs);
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static DEFINE_MUTEX(gov_dbs_data_mutex);
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/* Common sysfs tunables */
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/**
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* store_sampling_rate - update sampling rate effective immediately if needed.
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*
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* If new rate is smaller than the old, simply updating
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* dbs.sampling_rate might not be appropriate. For example, if the
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* original sampling_rate was 1 second and the requested new sampling rate is 10
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* ms because the user needs immediate reaction from ondemand governor, but not
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* sure if higher frequency will be required or not, then, the governor may
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* change the sampling rate too late; up to 1 second later. Thus, if we are
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* reducing the sampling rate, we need to make the new value effective
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* immediately.
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*
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* This must be called with dbs_data->mutex held, otherwise traversing
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* policy_dbs_list isn't safe.
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*/
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ssize_t store_sampling_rate(struct gov_attr_set *attr_set, const char *buf,
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size_t count)
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{
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struct dbs_data *dbs_data = to_dbs_data(attr_set);
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struct policy_dbs_info *policy_dbs;
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unsigned int rate;
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int ret;
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ret = sscanf(buf, "%u", &rate);
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if (ret != 1)
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return -EINVAL;
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dbs_data->sampling_rate = max(rate, dbs_data->min_sampling_rate);
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/*
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* We are operating under dbs_data->mutex and so the list and its
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* entries can't be freed concurrently.
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*/
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list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
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mutex_lock(&policy_dbs->timer_mutex);
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/*
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* On 32-bit architectures this may race with the
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* sample_delay_ns read in dbs_update_util_handler(), but that
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* really doesn't matter. If the read returns a value that's
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* too big, the sample will be skipped, but the next invocation
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* of dbs_update_util_handler() (when the update has been
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* completed) will take a sample.
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*
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* If this runs in parallel with dbs_work_handler(), we may end
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* up overwriting the sample_delay_ns value that it has just
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* written, but it will be corrected next time a sample is
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* taken, so it shouldn't be significant.
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*/
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gov_update_sample_delay(policy_dbs, 0);
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mutex_unlock(&policy_dbs->timer_mutex);
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}
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return count;
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}
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EXPORT_SYMBOL_GPL(store_sampling_rate);
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/**
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* gov_update_cpu_data - Update CPU load data.
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* @dbs_data: Top-level governor data pointer.
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*
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* Update CPU load data for all CPUs in the domain governed by @dbs_data
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* (that may be a single policy or a bunch of them if governor tunables are
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* system-wide).
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*
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* Call under the @dbs_data mutex.
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*/
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void gov_update_cpu_data(struct dbs_data *dbs_data)
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{
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struct policy_dbs_info *policy_dbs;
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list_for_each_entry(policy_dbs, &dbs_data->attr_set.policy_list, list) {
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unsigned int j;
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for_each_cpu(j, policy_dbs->policy->cpus) {
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struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
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j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time,
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dbs_data->io_is_busy);
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if (dbs_data->ignore_nice_load)
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j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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}
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}
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}
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EXPORT_SYMBOL_GPL(gov_update_cpu_data);
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unsigned int dbs_update(struct cpufreq_policy *policy)
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{
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struct policy_dbs_info *policy_dbs = policy->governor_data;
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struct dbs_data *dbs_data = policy_dbs->dbs_data;
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unsigned int ignore_nice = dbs_data->ignore_nice_load;
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unsigned int max_load = 0;
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unsigned int sampling_rate, io_busy, j;
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/*
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* Sometimes governors may use an additional multiplier to increase
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* sample delays temporarily. Apply that multiplier to sampling_rate
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* so as to keep the wake-up-from-idle detection logic a bit
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* conservative.
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*/
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sampling_rate = dbs_data->sampling_rate * policy_dbs->rate_mult;
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/*
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* For the purpose of ondemand, waiting for disk IO is an indication
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* that you're performance critical, and not that the system is actually
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* idle, so do not add the iowait time to the CPU idle time then.
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*/
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io_busy = dbs_data->io_is_busy;
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/* Get Absolute Load */
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for_each_cpu(j, policy->cpus) {
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struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
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u64 update_time, cur_idle_time;
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unsigned int idle_time, time_elapsed;
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unsigned int load;
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cur_idle_time = get_cpu_idle_time(j, &update_time, io_busy);
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time_elapsed = update_time - j_cdbs->prev_update_time;
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j_cdbs->prev_update_time = update_time;
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idle_time = cur_idle_time - j_cdbs->prev_cpu_idle;
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j_cdbs->prev_cpu_idle = cur_idle_time;
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if (ignore_nice) {
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u64 cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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idle_time += cputime_to_usecs(cur_nice - j_cdbs->prev_cpu_nice);
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j_cdbs->prev_cpu_nice = cur_nice;
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}
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if (unlikely(!time_elapsed)) {
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/*
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* That can only happen when this function is called
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* twice in a row with a very short interval between the
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* calls, so the previous load value can be used then.
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*/
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load = j_cdbs->prev_load;
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} else if (unlikely(time_elapsed > 2 * sampling_rate &&
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j_cdbs->prev_load)) {
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/*
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* If the CPU had gone completely idle and a task has
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* just woken up on this CPU now, it would be unfair to
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* calculate 'load' the usual way for this elapsed
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* time-window, because it would show near-zero load,
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* irrespective of how CPU intensive that task actually
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* was. This is undesirable for latency-sensitive bursty
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* workloads.
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*
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* To avoid this, reuse the 'load' from the previous
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* time-window and give this task a chance to start with
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* a reasonably high CPU frequency. However, that
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* shouldn't be over-done, lest we get stuck at a high
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* load (high frequency) for too long, even when the
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* current system load has actually dropped down, so
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* clear prev_load to guarantee that the load will be
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* computed again next time.
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*
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* Detecting this situation is easy: the governor's
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* utilization update handler would not have run during
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* CPU-idle periods. Hence, an unusually large
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* 'time_elapsed' (as compared to the sampling rate)
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* indicates this scenario.
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*/
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load = j_cdbs->prev_load;
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j_cdbs->prev_load = 0;
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} else {
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if (time_elapsed >= idle_time) {
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load = 100 * (time_elapsed - idle_time) / time_elapsed;
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} else {
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/*
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* That can happen if idle_time is returned by
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* get_cpu_idle_time_jiffy(). In that case
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* idle_time is roughly equal to the difference
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* between time_elapsed and "busy time" obtained
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* from CPU statistics. Then, the "busy time"
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* can end up being greater than time_elapsed
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* (for example, if jiffies_64 and the CPU
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* statistics are updated by different CPUs),
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* so idle_time may in fact be negative. That
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* means, though, that the CPU was busy all
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* the time (on the rough average) during the
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* last sampling interval and 100 can be
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* returned as the load.
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*/
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load = (int)idle_time < 0 ? 100 : 0;
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}
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j_cdbs->prev_load = load;
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}
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if (load > max_load)
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max_load = load;
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}
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return max_load;
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}
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EXPORT_SYMBOL_GPL(dbs_update);
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static void dbs_work_handler(struct work_struct *work)
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{
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struct policy_dbs_info *policy_dbs;
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struct cpufreq_policy *policy;
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struct dbs_governor *gov;
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policy_dbs = container_of(work, struct policy_dbs_info, work);
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policy = policy_dbs->policy;
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gov = dbs_governor_of(policy);
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/*
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* Make sure cpufreq_governor_limits() isn't evaluating load or the
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* ondemand governor isn't updating the sampling rate in parallel.
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*/
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mutex_lock(&policy_dbs->timer_mutex);
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gov_update_sample_delay(policy_dbs, gov->gov_dbs_timer(policy));
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mutex_unlock(&policy_dbs->timer_mutex);
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/* Allow the utilization update handler to queue up more work. */
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atomic_set(&policy_dbs->work_count, 0);
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/*
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* If the update below is reordered with respect to the sample delay
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* modification, the utilization update handler may end up using a stale
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* sample delay value.
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*/
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smp_wmb();
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policy_dbs->work_in_progress = false;
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}
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static void dbs_irq_work(struct irq_work *irq_work)
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{
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struct policy_dbs_info *policy_dbs;
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policy_dbs = container_of(irq_work, struct policy_dbs_info, irq_work);
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schedule_work_on(smp_processor_id(), &policy_dbs->work);
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}
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static void dbs_update_util_handler(struct update_util_data *data, u64 time,
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unsigned long util, unsigned long max)
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{
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struct cpu_dbs_info *cdbs = container_of(data, struct cpu_dbs_info, update_util);
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struct policy_dbs_info *policy_dbs = cdbs->policy_dbs;
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u64 delta_ns, lst;
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/*
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* The work may not be allowed to be queued up right now.
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* Possible reasons:
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* - Work has already been queued up or is in progress.
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* - It is too early (too little time from the previous sample).
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*/
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if (policy_dbs->work_in_progress)
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return;
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/*
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* If the reads below are reordered before the check above, the value
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* of sample_delay_ns used in the computation may be stale.
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*/
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smp_rmb();
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lst = READ_ONCE(policy_dbs->last_sample_time);
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delta_ns = time - lst;
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if ((s64)delta_ns < policy_dbs->sample_delay_ns)
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return;
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/*
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* If the policy is not shared, the irq_work may be queued up right away
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* at this point. Otherwise, we need to ensure that only one of the
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* CPUs sharing the policy will do that.
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*/
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if (policy_dbs->is_shared) {
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if (!atomic_add_unless(&policy_dbs->work_count, 1, 1))
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return;
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/*
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* If another CPU updated last_sample_time in the meantime, we
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* shouldn't be here, so clear the work counter and bail out.
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*/
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if (unlikely(lst != READ_ONCE(policy_dbs->last_sample_time))) {
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atomic_set(&policy_dbs->work_count, 0);
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return;
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}
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}
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policy_dbs->last_sample_time = time;
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policy_dbs->work_in_progress = true;
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irq_work_queue(&policy_dbs->irq_work);
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}
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static void gov_set_update_util(struct policy_dbs_info *policy_dbs,
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unsigned int delay_us)
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{
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struct cpufreq_policy *policy = policy_dbs->policy;
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int cpu;
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gov_update_sample_delay(policy_dbs, delay_us);
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policy_dbs->last_sample_time = 0;
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for_each_cpu(cpu, policy->cpus) {
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struct cpu_dbs_info *cdbs = &per_cpu(cpu_dbs, cpu);
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cpufreq_add_update_util_hook(cpu, &cdbs->update_util,
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dbs_update_util_handler);
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}
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}
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static inline void gov_clear_update_util(struct cpufreq_policy *policy)
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{
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int i;
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for_each_cpu(i, policy->cpus)
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cpufreq_remove_update_util_hook(i);
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synchronize_sched();
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}
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static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy,
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struct dbs_governor *gov)
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{
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struct policy_dbs_info *policy_dbs;
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int j;
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/* Allocate memory for per-policy governor data. */
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policy_dbs = gov->alloc();
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if (!policy_dbs)
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return NULL;
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policy_dbs->policy = policy;
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mutex_init(&policy_dbs->timer_mutex);
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atomic_set(&policy_dbs->work_count, 0);
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init_irq_work(&policy_dbs->irq_work, dbs_irq_work);
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INIT_WORK(&policy_dbs->work, dbs_work_handler);
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/* Set policy_dbs for all CPUs, online+offline */
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for_each_cpu(j, policy->related_cpus) {
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struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
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j_cdbs->policy_dbs = policy_dbs;
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}
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return policy_dbs;
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}
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static void free_policy_dbs_info(struct policy_dbs_info *policy_dbs,
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struct dbs_governor *gov)
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{
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int j;
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mutex_destroy(&policy_dbs->timer_mutex);
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for_each_cpu(j, policy_dbs->policy->related_cpus) {
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struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
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j_cdbs->policy_dbs = NULL;
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j_cdbs->update_util.func = NULL;
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}
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gov->free(policy_dbs);
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}
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int cpufreq_dbs_governor_init(struct cpufreq_policy *policy)
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{
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struct dbs_governor *gov = dbs_governor_of(policy);
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struct dbs_data *dbs_data;
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struct policy_dbs_info *policy_dbs;
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unsigned int latency;
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int ret = 0;
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/* State should be equivalent to EXIT */
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if (policy->governor_data)
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return -EBUSY;
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policy_dbs = alloc_policy_dbs_info(policy, gov);
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if (!policy_dbs)
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return -ENOMEM;
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/* Protect gov->gdbs_data against concurrent updates. */
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mutex_lock(&gov_dbs_data_mutex);
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dbs_data = gov->gdbs_data;
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if (dbs_data) {
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if (WARN_ON(have_governor_per_policy())) {
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ret = -EINVAL;
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goto free_policy_dbs_info;
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}
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policy_dbs->dbs_data = dbs_data;
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policy->governor_data = policy_dbs;
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gov_attr_set_get(&dbs_data->attr_set, &policy_dbs->list);
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goto out;
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}
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dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
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if (!dbs_data) {
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ret = -ENOMEM;
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goto free_policy_dbs_info;
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}
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gov_attr_set_init(&dbs_data->attr_set, &policy_dbs->list);
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ret = gov->init(dbs_data);
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if (ret)
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goto free_policy_dbs_info;
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/* policy latency is in ns. Convert it to us first */
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latency = policy->cpuinfo.transition_latency / 1000;
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if (latency == 0)
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latency = 1;
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/* Bring kernel and HW constraints together */
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dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
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MIN_LATENCY_MULTIPLIER * latency);
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dbs_data->sampling_rate = max(dbs_data->min_sampling_rate,
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LATENCY_MULTIPLIER * latency);
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if (!have_governor_per_policy())
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gov->gdbs_data = dbs_data;
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policy_dbs->dbs_data = dbs_data;
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policy->governor_data = policy_dbs;
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gov->kobj_type.sysfs_ops = &governor_sysfs_ops;
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ret = kobject_init_and_add(&dbs_data->attr_set.kobj, &gov->kobj_type,
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get_governor_parent_kobj(policy),
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"%s", gov->gov.name);
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if (!ret)
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goto out;
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/* Failure, so roll back. */
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pr_err("initialization failed (dbs_data kobject init error %d)\n", ret);
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policy->governor_data = NULL;
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if (!have_governor_per_policy())
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gov->gdbs_data = NULL;
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gov->exit(dbs_data);
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kfree(dbs_data);
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free_policy_dbs_info:
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free_policy_dbs_info(policy_dbs, gov);
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out:
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mutex_unlock(&gov_dbs_data_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_init);
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void cpufreq_dbs_governor_exit(struct cpufreq_policy *policy)
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{
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struct dbs_governor *gov = dbs_governor_of(policy);
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struct policy_dbs_info *policy_dbs = policy->governor_data;
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struct dbs_data *dbs_data = policy_dbs->dbs_data;
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unsigned int count;
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/* Protect gov->gdbs_data against concurrent updates. */
|
|
mutex_lock(&gov_dbs_data_mutex);
|
|
|
|
count = gov_attr_set_put(&dbs_data->attr_set, &policy_dbs->list);
|
|
|
|
policy->governor_data = NULL;
|
|
|
|
if (!count) {
|
|
if (!have_governor_per_policy())
|
|
gov->gdbs_data = NULL;
|
|
|
|
gov->exit(dbs_data);
|
|
kfree(dbs_data);
|
|
}
|
|
|
|
free_policy_dbs_info(policy_dbs, gov);
|
|
|
|
mutex_unlock(&gov_dbs_data_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_exit);
|
|
|
|
int cpufreq_dbs_governor_start(struct cpufreq_policy *policy)
|
|
{
|
|
struct dbs_governor *gov = dbs_governor_of(policy);
|
|
struct policy_dbs_info *policy_dbs = policy->governor_data;
|
|
struct dbs_data *dbs_data = policy_dbs->dbs_data;
|
|
unsigned int sampling_rate, ignore_nice, j;
|
|
unsigned int io_busy;
|
|
|
|
if (!policy->cur)
|
|
return -EINVAL;
|
|
|
|
policy_dbs->is_shared = policy_is_shared(policy);
|
|
policy_dbs->rate_mult = 1;
|
|
|
|
sampling_rate = dbs_data->sampling_rate;
|
|
ignore_nice = dbs_data->ignore_nice_load;
|
|
io_busy = dbs_data->io_is_busy;
|
|
|
|
for_each_cpu(j, policy->cpus) {
|
|
struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
|
|
|
|
j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time, io_busy);
|
|
/*
|
|
* Make the first invocation of dbs_update() compute the load.
|
|
*/
|
|
j_cdbs->prev_load = 0;
|
|
|
|
if (ignore_nice)
|
|
j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
|
|
}
|
|
|
|
gov->start(policy);
|
|
|
|
gov_set_update_util(policy_dbs, sampling_rate);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_start);
|
|
|
|
void cpufreq_dbs_governor_stop(struct cpufreq_policy *policy)
|
|
{
|
|
struct policy_dbs_info *policy_dbs = policy->governor_data;
|
|
|
|
gov_clear_update_util(policy_dbs->policy);
|
|
irq_work_sync(&policy_dbs->irq_work);
|
|
cancel_work_sync(&policy_dbs->work);
|
|
atomic_set(&policy_dbs->work_count, 0);
|
|
policy_dbs->work_in_progress = false;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop);
|
|
|
|
void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy)
|
|
{
|
|
struct policy_dbs_info *policy_dbs = policy->governor_data;
|
|
|
|
mutex_lock(&policy_dbs->timer_mutex);
|
|
cpufreq_policy_apply_limits(policy);
|
|
gov_update_sample_delay(policy_dbs, 0);
|
|
|
|
mutex_unlock(&policy_dbs->timer_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);
|