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![Viresh Kumar](/assets/img/avatar_default.png)
The cpufreq core and governors aren't supposed to set a limit on how fast we want to try changing the frequency. This is currently done for the legacy governors with help of min_sampling_rate. At worst, we may end up setting the sampling rate to a value lower than the rate at which frequency can be changed and then one of the CPUs in the policy will be only changing frequency for ever. But that is something for the user to decide and there is no need to have special handling for such cases in the core. Leave it for the user to figure out. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
354 lines
9.1 KiB
C
354 lines
9.1 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/slab.h>
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#include "cpufreq_governor.h"
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struct cs_policy_dbs_info {
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struct policy_dbs_info policy_dbs;
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unsigned int down_skip;
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unsigned int requested_freq;
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};
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static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
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{
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return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
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}
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struct cs_dbs_tuners {
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unsigned int down_threshold;
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unsigned int freq_step;
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};
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/* Conservative governor macros */
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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_FREQUENCY_STEP (5)
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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 inline unsigned int get_freq_step(struct cs_dbs_tuners *cs_tuners,
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struct cpufreq_policy *policy)
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{
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unsigned int freq_step = (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_step == 0))
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freq_step = DEF_FREQUENCY_STEP;
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return freq_step;
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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%
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* (default), then we try to decrease frequency
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*
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* Frequency updates happen at minimum steps of 5% (default) of maximum
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* frequency
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*/
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static unsigned int cs_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 cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
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unsigned int requested_freq = dbs_info->requested_freq;
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struct dbs_data *dbs_data = policy_dbs->dbs_data;
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struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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unsigned int load = dbs_update(policy);
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unsigned int freq_step;
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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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goto out;
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/*
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* If requested_freq is out of range, it is likely that the limits
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* changed in the meantime, so fall back to current frequency in that
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* case.
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*/
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if (requested_freq > policy->max || requested_freq < policy->min)
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requested_freq = policy->cur;
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freq_step = get_freq_step(cs_tuners, policy);
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/*
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* Decrease requested_freq one freq_step for each idle period that
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* we didn't update the frequency.
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*/
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if (policy_dbs->idle_periods < UINT_MAX) {
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unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
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if (requested_freq > freq_steps)
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requested_freq -= freq_steps;
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else
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requested_freq = policy->min;
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policy_dbs->idle_periods = UINT_MAX;
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}
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/* Check for frequency increase */
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if (load > dbs_data->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 (requested_freq == policy->max)
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goto out;
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requested_freq += freq_step;
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if (requested_freq > policy->max)
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requested_freq = policy->max;
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__cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_H);
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dbs_info->requested_freq = requested_freq;
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goto out;
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}
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/* if sampling_down_factor is active break out early */
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if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
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goto out;
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dbs_info->down_skip = 0;
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/* Check for frequency decrease */
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if (load < cs_tuners->down_threshold) {
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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 (requested_freq == policy->min)
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goto out;
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if (requested_freq > freq_step)
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requested_freq -= freq_step;
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else
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requested_freq = policy->min;
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__cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_L);
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dbs_info->requested_freq = requested_freq;
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}
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out:
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return dbs_data->sampling_rate;
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}
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/************************** sysfs interface ************************/
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static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
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const char *buf, 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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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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dbs_data->sampling_down_factor = input;
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return count;
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}
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static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
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const char *buf, 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 cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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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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dbs_data->up_threshold = input;
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return count;
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}
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static ssize_t store_down_threshold(struct gov_attr_set *attr_set,
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const char *buf, 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 cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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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 1 otherwise freq will not fall */
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if (ret != 1 || input < 1 || input > 100 ||
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input >= dbs_data->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 gov_attr_set *attr_set,
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const char *buf, 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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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 > 1)
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input = 1;
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if (input == dbs_data->ignore_nice_load) /* nothing to do */
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return count;
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dbs_data->ignore_nice_load = input;
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/* we need to re-evaluate prev_cpu_idle */
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gov_update_cpu_data(dbs_data);
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return count;
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}
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static ssize_t store_freq_step(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 cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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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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gov_show_one_common(sampling_rate);
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gov_show_one_common(sampling_down_factor);
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gov_show_one_common(up_threshold);
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gov_show_one_common(ignore_nice_load);
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gov_show_one(cs, down_threshold);
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gov_show_one(cs, freq_step);
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gov_attr_rw(sampling_rate);
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gov_attr_rw(sampling_down_factor);
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gov_attr_rw(up_threshold);
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gov_attr_rw(ignore_nice_load);
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gov_attr_rw(down_threshold);
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gov_attr_rw(freq_step);
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static struct attribute *cs_attributes[] = {
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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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/************************** sysfs end ************************/
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static struct policy_dbs_info *cs_alloc(void)
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{
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struct cs_policy_dbs_info *dbs_info;
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dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
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return dbs_info ? &dbs_info->policy_dbs : NULL;
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}
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static void cs_free(struct policy_dbs_info *policy_dbs)
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{
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kfree(to_dbs_info(policy_dbs));
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}
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static int cs_init(struct dbs_data *dbs_data)
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{
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struct cs_dbs_tuners *tuners;
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tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
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if (!tuners)
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return -ENOMEM;
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tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
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tuners->freq_step = DEF_FREQUENCY_STEP;
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dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
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dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
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dbs_data->ignore_nice_load = 0;
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dbs_data->tuners = tuners;
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return 0;
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}
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static void cs_exit(struct dbs_data *dbs_data)
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{
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kfree(dbs_data->tuners);
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}
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static void cs_start(struct cpufreq_policy *policy)
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{
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struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
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dbs_info->down_skip = 0;
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dbs_info->requested_freq = policy->cur;
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}
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static struct dbs_governor cs_governor = {
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.gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
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.kobj_type = { .default_attrs = cs_attributes },
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.gov_dbs_update = cs_dbs_update,
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.alloc = cs_alloc,
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.free = cs_free,
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.init = cs_init,
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.exit = cs_exit,
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.start = cs_start,
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};
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#define CPU_FREQ_GOV_CONSERVATIVE (&cs_governor.gov)
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static int __init cpufreq_gov_dbs_init(void)
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{
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return cpufreq_register_governor(CPU_FREQ_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(CPU_FREQ_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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struct cpufreq_governor *cpufreq_default_governor(void)
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{
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return CPU_FREQ_GOV_CONSERVATIVE;
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}
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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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