![Fabio Baltieri](/assets/img/avatar_default.png)
Modify conservative timer to not resample CPU utilization if recently sampled from another SW coordinated core. Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
400 lines
10 KiB
C
400 lines
10 KiB
C
/*
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* drivers/cpufreq/cpufreq_conservative.c
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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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* Jun Nakajima <jun.nakajima@intel.com>
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* (C) 2009 Alexander Clouter <alex@digriz.org.uk>
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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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#include <linux/cpufreq.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/kernel_stat.h>
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/notifier.h>
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#include <linux/percpu-defs.h>
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#include <linux/sysfs.h>
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#include <linux/types.h>
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#include "cpufreq_governor.h"
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/* Conservative governor macors */
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#define DEF_FREQUENCY_UP_THRESHOLD (80)
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#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
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#define DEF_SAMPLING_DOWN_FACTOR (1)
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#define MAX_SAMPLING_DOWN_FACTOR (10)
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static struct dbs_data cs_dbs_data;
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static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
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static struct cs_dbs_tuners cs_tuners = {
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.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
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.down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
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.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
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.ignore_nice = 0,
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.freq_step = 5,
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};
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/*
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* Every sampling_rate, we check, if current idle time is less than 20%
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* (default), then we try to increase frequency Every sampling_rate *
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* sampling_down_factor, we check, if current idle time is more than 80%, then
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* we try to decrease frequency
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*
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* Any frequency increase takes it to the maximum frequency. Frequency reduction
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* happens at minimum steps of 5% (default) of maximum frequency
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*/
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static void cs_check_cpu(int cpu, unsigned int load)
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{
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struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
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struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
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unsigned int freq_target;
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/*
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* break out if we 'cannot' reduce the speed as the user might
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* want freq_step to be zero
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*/
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if (cs_tuners.freq_step == 0)
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return;
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/* Check for frequency increase */
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if (load > cs_tuners.up_threshold) {
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dbs_info->down_skip = 0;
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/* if we are already at full speed then break out early */
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if (dbs_info->requested_freq == policy->max)
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return;
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freq_target = (cs_tuners.freq_step * policy->max) / 100;
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/* max freq cannot be less than 100. But who knows.... */
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if (unlikely(freq_target == 0))
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freq_target = 5;
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dbs_info->requested_freq += freq_target;
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if (dbs_info->requested_freq > policy->max)
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dbs_info->requested_freq = policy->max;
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__cpufreq_driver_target(policy, dbs_info->requested_freq,
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CPUFREQ_RELATION_H);
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return;
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}
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/*
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* The optimal frequency is the frequency that is the lowest that can
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* support the current CPU usage without triggering the up policy. To be
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* safe, we focus 10 points under the threshold.
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*/
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if (load < (cs_tuners.down_threshold - 10)) {
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freq_target = (cs_tuners.freq_step * policy->max) / 100;
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dbs_info->requested_freq -= freq_target;
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if (dbs_info->requested_freq < policy->min)
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dbs_info->requested_freq = policy->min;
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/*
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* if we cannot reduce the frequency anymore, break out early
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*/
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if (policy->cur == policy->min)
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return;
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__cpufreq_driver_target(policy, dbs_info->requested_freq,
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CPUFREQ_RELATION_H);
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return;
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}
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}
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static void cs_timer_update(struct cs_cpu_dbs_info_s *dbs_info, bool sample,
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struct delayed_work *dw)
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{
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unsigned int cpu = dbs_info->cdbs.cpu;
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int delay = delay_for_sampling_rate(cs_tuners.sampling_rate);
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if (sample)
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dbs_check_cpu(&cs_dbs_data, cpu);
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schedule_delayed_work_on(smp_processor_id(), dw, delay);
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}
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static void cs_timer_coordinated(struct cs_cpu_dbs_info_s *dbs_info_local,
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struct delayed_work *dw)
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{
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struct cs_cpu_dbs_info_s *dbs_info;
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ktime_t time_now;
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s64 delta_us;
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bool sample = true;
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/* use leader CPU's dbs_info */
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dbs_info = &per_cpu(cs_cpu_dbs_info, dbs_info_local->cdbs.cpu);
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mutex_lock(&dbs_info->cdbs.timer_mutex);
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time_now = ktime_get();
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delta_us = ktime_us_delta(time_now, dbs_info->cdbs.time_stamp);
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/* Do nothing if we recently have sampled */
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if (delta_us < (s64)(cs_tuners.sampling_rate / 2))
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sample = false;
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else
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dbs_info->cdbs.time_stamp = time_now;
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cs_timer_update(dbs_info, sample, dw);
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mutex_unlock(&dbs_info->cdbs.timer_mutex);
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}
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static void cs_dbs_timer(struct work_struct *work)
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{
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struct delayed_work *dw = to_delayed_work(work);
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struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
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struct cs_cpu_dbs_info_s, cdbs.work.work);
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if (dbs_sw_coordinated_cpus(&dbs_info->cdbs)) {
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cs_timer_coordinated(dbs_info, dw);
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} else {
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mutex_lock(&dbs_info->cdbs.timer_mutex);
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cs_timer_update(dbs_info, true, dw);
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mutex_unlock(&dbs_info->cdbs.timer_mutex);
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}
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}
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static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
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void *data)
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{
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struct cpufreq_freqs *freq = data;
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struct cs_cpu_dbs_info_s *dbs_info =
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&per_cpu(cs_cpu_dbs_info, freq->cpu);
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struct cpufreq_policy *policy;
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if (!dbs_info->enable)
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return 0;
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policy = dbs_info->cdbs.cur_policy;
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/*
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* we only care if our internally tracked freq moves outside the 'valid'
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* ranges of freqency available to us otherwise we do not change it
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*/
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if (dbs_info->requested_freq > policy->max
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|| dbs_info->requested_freq < policy->min)
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dbs_info->requested_freq = freq->new;
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return 0;
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}
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/************************** sysfs interface ************************/
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static ssize_t show_sampling_rate_min(struct kobject *kobj,
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struct attribute *attr, char *buf)
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{
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return sprintf(buf, "%u\n", cs_dbs_data.min_sampling_rate);
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}
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static ssize_t store_sampling_down_factor(struct kobject *a,
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struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
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return -EINVAL;
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cs_tuners.sampling_down_factor = input;
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return count;
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}
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static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1)
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return -EINVAL;
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cs_tuners.sampling_rate = max(input, cs_dbs_data.min_sampling_rate);
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return count;
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}
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static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1 || input > 100 || input <= cs_tuners.down_threshold)
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return -EINVAL;
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cs_tuners.up_threshold = input;
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return count;
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}
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static ssize_t store_down_threshold(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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/* cannot be lower than 11 otherwise freq will not fall */
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if (ret != 1 || input < 11 || input > 100 ||
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input >= cs_tuners.up_threshold)
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return -EINVAL;
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cs_tuners.down_threshold = input;
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return count;
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}
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static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input, j;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1)
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return -EINVAL;
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if (input > 1)
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input = 1;
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if (input == cs_tuners.ignore_nice) /* nothing to do */
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return count;
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cs_tuners.ignore_nice = input;
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/* we need to re-evaluate prev_cpu_idle */
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for_each_online_cpu(j) {
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struct cs_cpu_dbs_info_s *dbs_info;
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dbs_info = &per_cpu(cs_cpu_dbs_info, j);
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dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
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&dbs_info->cdbs.prev_cpu_wall);
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if (cs_tuners.ignore_nice)
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dbs_info->cdbs.prev_cpu_nice =
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kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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}
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return count;
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}
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static ssize_t store_freq_step(struct kobject *a, struct attribute *b,
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const char *buf, size_t count)
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{
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unsigned int input;
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int ret;
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ret = sscanf(buf, "%u", &input);
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if (ret != 1)
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return -EINVAL;
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if (input > 100)
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input = 100;
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/*
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* no need to test here if freq_step is zero as the user might actually
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* want this, they would be crazy though :)
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*/
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cs_tuners.freq_step = input;
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return count;
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}
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show_one(cs, sampling_rate, sampling_rate);
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show_one(cs, sampling_down_factor, sampling_down_factor);
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show_one(cs, up_threshold, up_threshold);
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show_one(cs, down_threshold, down_threshold);
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show_one(cs, ignore_nice_load, ignore_nice);
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show_one(cs, freq_step, freq_step);
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define_one_global_rw(sampling_rate);
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define_one_global_rw(sampling_down_factor);
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define_one_global_rw(up_threshold);
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define_one_global_rw(down_threshold);
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define_one_global_rw(ignore_nice_load);
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define_one_global_rw(freq_step);
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define_one_global_ro(sampling_rate_min);
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static struct attribute *dbs_attributes[] = {
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&sampling_rate_min.attr,
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&sampling_rate.attr,
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&sampling_down_factor.attr,
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&up_threshold.attr,
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&down_threshold.attr,
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&ignore_nice_load.attr,
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&freq_step.attr,
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NULL
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};
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static struct attribute_group cs_attr_group = {
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.attrs = dbs_attributes,
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.name = "conservative",
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};
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/************************** sysfs end ************************/
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define_get_cpu_dbs_routines(cs_cpu_dbs_info);
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static struct notifier_block cs_cpufreq_notifier_block = {
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.notifier_call = dbs_cpufreq_notifier,
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};
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static struct cs_ops cs_ops = {
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.notifier_block = &cs_cpufreq_notifier_block,
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};
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static struct dbs_data cs_dbs_data = {
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.governor = GOV_CONSERVATIVE,
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.attr_group = &cs_attr_group,
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.tuners = &cs_tuners,
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.get_cpu_cdbs = get_cpu_cdbs,
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.get_cpu_dbs_info_s = get_cpu_dbs_info_s,
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.gov_dbs_timer = cs_dbs_timer,
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.gov_check_cpu = cs_check_cpu,
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.gov_ops = &cs_ops,
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};
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static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
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unsigned int event)
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{
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return cpufreq_governor_dbs(&cs_dbs_data, policy, event);
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}
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#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
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static
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#endif
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struct cpufreq_governor cpufreq_gov_conservative = {
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.name = "conservative",
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.governor = cs_cpufreq_governor_dbs,
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.max_transition_latency = TRANSITION_LATENCY_LIMIT,
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.owner = THIS_MODULE,
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};
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static int __init cpufreq_gov_dbs_init(void)
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{
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mutex_init(&cs_dbs_data.mutex);
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return cpufreq_register_governor(&cpufreq_gov_conservative);
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}
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static void __exit cpufreq_gov_dbs_exit(void)
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{
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cpufreq_unregister_governor(&cpufreq_gov_conservative);
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}
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MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
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MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
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"Low Latency Frequency Transition capable processors "
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"optimised for use in a battery environment");
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MODULE_LICENSE("GPL");
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#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
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fs_initcall(cpufreq_gov_dbs_init);
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#else
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module_init(cpufreq_gov_dbs_init);
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#endif
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module_exit(cpufreq_gov_dbs_exit);
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