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![Oleg Nesterov](/assets/img/avatar_default.png)
Looks like dbs_timer() is very careful wrt per_cpu(cpu_dbs_info), and it doesn't need the help of WORK_STRUCT_NOAUTOREL. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-By: David Howells <dhowells@redhat.com> Signed-off-by: Dave Jones <davej@redhat.com>
607 lines
16 KiB
C
607 lines
16 KiB
C
/*
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* drivers/cpufreq/cpufreq_ondemand.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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*
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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/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/cpufreq.h>
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#include <linux/cpu.h>
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#include <linux/jiffies.h>
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#include <linux/kernel_stat.h>
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#include <linux/mutex.h>
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/*
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* dbs is used in this file as a shortform for demandbased switching
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* It helps to keep variable names smaller, simpler
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*/
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#define DEF_FREQUENCY_UP_THRESHOLD (80)
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#define MIN_FREQUENCY_UP_THRESHOLD (11)
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#define MAX_FREQUENCY_UP_THRESHOLD (100)
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/*
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* The polling frequency of this governor depends on the capability of
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* the processor. Default polling frequency is 1000 times the transition
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* latency of the processor. The governor will work on any processor with
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* transition latency <= 10mS, using appropriate sampling
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* rate.
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* For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
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* this governor will not work.
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* All times here are in uS.
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*/
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static unsigned int def_sampling_rate;
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#define MIN_SAMPLING_RATE_RATIO (2)
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/* for correct statistics, we need at least 10 ticks between each measure */
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#define MIN_STAT_SAMPLING_RATE \
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(MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
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#define MIN_SAMPLING_RATE \
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(def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
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#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
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#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
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#define TRANSITION_LATENCY_LIMIT (10 * 1000)
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static void do_dbs_timer(struct work_struct *work);
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/* Sampling types */
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enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
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struct cpu_dbs_info_s {
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cputime64_t prev_cpu_idle;
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cputime64_t prev_cpu_wall;
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struct cpufreq_policy *cur_policy;
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struct delayed_work work;
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struct cpufreq_frequency_table *freq_table;
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unsigned int freq_lo;
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unsigned int freq_lo_jiffies;
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unsigned int freq_hi_jiffies;
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int cpu;
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unsigned int enable:1,
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sample_type:1;
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};
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static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
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static unsigned int dbs_enable; /* number of CPUs using this policy */
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/*
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* DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
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* lock and dbs_mutex. cpu_hotplug lock should always be held before
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* dbs_mutex. If any function that can potentially take cpu_hotplug lock
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* (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
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* cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
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* is recursive for the same process. -Venki
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*/
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static DEFINE_MUTEX(dbs_mutex);
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static struct workqueue_struct *kondemand_wq;
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static struct dbs_tuners {
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unsigned int sampling_rate;
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unsigned int up_threshold;
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unsigned int ignore_nice;
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unsigned int powersave_bias;
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} dbs_tuners_ins = {
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.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
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.ignore_nice = 0,
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.powersave_bias = 0,
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};
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static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
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{
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cputime64_t retval;
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retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
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kstat_cpu(cpu).cpustat.iowait);
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if (dbs_tuners_ins.ignore_nice)
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retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
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return retval;
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}
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/*
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* Find right freq to be set now with powersave_bias on.
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* Returns the freq_hi to be used right now and will set freq_hi_jiffies,
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* freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
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*/
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static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
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unsigned int freq_next,
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unsigned int relation)
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{
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unsigned int freq_req, freq_reduc, freq_avg;
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unsigned int freq_hi, freq_lo;
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unsigned int index = 0;
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unsigned int jiffies_total, jiffies_hi, jiffies_lo;
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struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu);
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if (!dbs_info->freq_table) {
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dbs_info->freq_lo = 0;
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dbs_info->freq_lo_jiffies = 0;
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return freq_next;
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}
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cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
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relation, &index);
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freq_req = dbs_info->freq_table[index].frequency;
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freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
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freq_avg = freq_req - freq_reduc;
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/* Find freq bounds for freq_avg in freq_table */
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index = 0;
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cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
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CPUFREQ_RELATION_H, &index);
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freq_lo = dbs_info->freq_table[index].frequency;
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index = 0;
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cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
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CPUFREQ_RELATION_L, &index);
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freq_hi = dbs_info->freq_table[index].frequency;
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/* Find out how long we have to be in hi and lo freqs */
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if (freq_hi == freq_lo) {
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dbs_info->freq_lo = 0;
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dbs_info->freq_lo_jiffies = 0;
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return freq_lo;
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}
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jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
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jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
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jiffies_hi += ((freq_hi - freq_lo) / 2);
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jiffies_hi /= (freq_hi - freq_lo);
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jiffies_lo = jiffies_total - jiffies_hi;
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dbs_info->freq_lo = freq_lo;
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dbs_info->freq_lo_jiffies = jiffies_lo;
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dbs_info->freq_hi_jiffies = jiffies_hi;
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return freq_hi;
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}
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static void ondemand_powersave_bias_init(void)
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{
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int i;
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for_each_online_cpu(i) {
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struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
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dbs_info->freq_table = cpufreq_frequency_get_table(i);
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dbs_info->freq_lo = 0;
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}
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}
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/************************** sysfs interface ************************/
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static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
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{
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return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
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}
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static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
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{
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return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
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}
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#define define_one_ro(_name) \
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static struct freq_attr _name = \
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__ATTR(_name, 0444, show_##_name, NULL)
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define_one_ro(sampling_rate_max);
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define_one_ro(sampling_rate_min);
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/* cpufreq_ondemand Governor Tunables */
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#define show_one(file_name, object) \
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static ssize_t show_##file_name \
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(struct cpufreq_policy *unused, char *buf) \
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{ \
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return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
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}
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show_one(sampling_rate, sampling_rate);
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show_one(up_threshold, up_threshold);
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show_one(ignore_nice_load, ignore_nice);
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show_one(powersave_bias, powersave_bias);
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static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
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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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mutex_lock(&dbs_mutex);
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if (ret != 1 || input > MAX_SAMPLING_RATE
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|| input < MIN_SAMPLING_RATE) {
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mutex_unlock(&dbs_mutex);
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return -EINVAL;
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}
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dbs_tuners_ins.sampling_rate = input;
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mutex_unlock(&dbs_mutex);
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return count;
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}
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static ssize_t store_up_threshold(struct cpufreq_policy *unused,
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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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mutex_lock(&dbs_mutex);
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if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
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input < MIN_FREQUENCY_UP_THRESHOLD) {
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mutex_unlock(&dbs_mutex);
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return -EINVAL;
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}
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dbs_tuners_ins.up_threshold = input;
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mutex_unlock(&dbs_mutex);
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return count;
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}
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static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
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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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unsigned int j;
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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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mutex_lock(&dbs_mutex);
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if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
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mutex_unlock(&dbs_mutex);
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return count;
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}
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dbs_tuners_ins.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 cpu_dbs_info_s *dbs_info;
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dbs_info = &per_cpu(cpu_dbs_info, j);
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dbs_info->prev_cpu_idle = get_cpu_idle_time(j);
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dbs_info->prev_cpu_wall = get_jiffies_64();
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}
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mutex_unlock(&dbs_mutex);
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return count;
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}
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static ssize_t store_powersave_bias(struct cpufreq_policy *unused,
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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 > 1000)
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input = 1000;
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mutex_lock(&dbs_mutex);
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dbs_tuners_ins.powersave_bias = input;
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ondemand_powersave_bias_init();
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mutex_unlock(&dbs_mutex);
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return count;
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}
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#define define_one_rw(_name) \
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static struct freq_attr _name = \
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__ATTR(_name, 0644, show_##_name, store_##_name)
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define_one_rw(sampling_rate);
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define_one_rw(up_threshold);
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define_one_rw(ignore_nice_load);
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define_one_rw(powersave_bias);
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static struct attribute * dbs_attributes[] = {
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&sampling_rate_max.attr,
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&sampling_rate_min.attr,
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&sampling_rate.attr,
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&up_threshold.attr,
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&ignore_nice_load.attr,
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&powersave_bias.attr,
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NULL
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};
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static struct attribute_group dbs_attr_group = {
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.attrs = dbs_attributes,
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.name = "ondemand",
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};
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/************************** sysfs end ************************/
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static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
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{
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unsigned int idle_ticks, total_ticks;
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unsigned int load;
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cputime64_t cur_jiffies;
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struct cpufreq_policy *policy;
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unsigned int j;
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if (!this_dbs_info->enable)
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return;
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this_dbs_info->freq_lo = 0;
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policy = this_dbs_info->cur_policy;
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cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
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total_ticks = (unsigned int) cputime64_sub(cur_jiffies,
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this_dbs_info->prev_cpu_wall);
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this_dbs_info->prev_cpu_wall = cur_jiffies;
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if (!total_ticks)
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return;
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/*
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* Every sampling_rate, we check, if current idle time is less
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* than 20% (default), then we try to increase frequency
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* Every sampling_rate, we look for a the lowest
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* frequency which can sustain the load while keeping idle time over
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* 30%. If such a frequency exist, we try to decrease to this frequency.
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*
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* Any frequency increase takes it to the maximum frequency.
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* Frequency reduction happens at minimum steps of
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* 5% (default) of current frequency
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*/
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/* Get Idle Time */
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idle_ticks = UINT_MAX;
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for_each_cpu_mask(j, policy->cpus) {
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cputime64_t total_idle_ticks;
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unsigned int tmp_idle_ticks;
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struct cpu_dbs_info_s *j_dbs_info;
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j_dbs_info = &per_cpu(cpu_dbs_info, j);
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total_idle_ticks = get_cpu_idle_time(j);
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tmp_idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
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j_dbs_info->prev_cpu_idle);
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j_dbs_info->prev_cpu_idle = total_idle_ticks;
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if (tmp_idle_ticks < idle_ticks)
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idle_ticks = tmp_idle_ticks;
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}
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load = (100 * (total_ticks - idle_ticks)) / total_ticks;
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/* Check for frequency increase */
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if (load > dbs_tuners_ins.up_threshold) {
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/* if we are already at full speed then break out early */
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if (!dbs_tuners_ins.powersave_bias) {
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if (policy->cur == policy->max)
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return;
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__cpufreq_driver_target(policy, policy->max,
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CPUFREQ_RELATION_H);
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} else {
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int freq = powersave_bias_target(policy, policy->max,
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CPUFREQ_RELATION_H);
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__cpufreq_driver_target(policy, freq,
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CPUFREQ_RELATION_L);
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}
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return;
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}
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/* Check for frequency decrease */
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/* if we cannot reduce the frequency anymore, break out early */
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if (policy->cur == policy->min)
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return;
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/*
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* The optimal frequency is the frequency that is the lowest that
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* can support the current CPU usage without triggering the up
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* policy. To be safe, we focus 10 points under the threshold.
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*/
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if (load < (dbs_tuners_ins.up_threshold - 10)) {
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unsigned int freq_next, freq_cur;
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freq_cur = __cpufreq_driver_getavg(policy);
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if (!freq_cur)
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freq_cur = policy->cur;
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freq_next = (freq_cur * load) /
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(dbs_tuners_ins.up_threshold - 10);
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if (!dbs_tuners_ins.powersave_bias) {
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__cpufreq_driver_target(policy, freq_next,
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CPUFREQ_RELATION_L);
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} else {
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int freq = powersave_bias_target(policy, freq_next,
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CPUFREQ_RELATION_L);
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__cpufreq_driver_target(policy, freq,
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CPUFREQ_RELATION_L);
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}
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}
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}
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static void do_dbs_timer(struct work_struct *work)
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{
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struct cpu_dbs_info_s *dbs_info =
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container_of(work, struct cpu_dbs_info_s, work.work);
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unsigned int cpu = dbs_info->cpu;
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int sample_type = dbs_info->sample_type;
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/* We want all CPUs to do sampling nearly on same jiffy */
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int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
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delay -= jiffies % delay;
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if (lock_policy_rwsem_write(cpu) < 0)
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return;
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if (!dbs_info->enable) {
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unlock_policy_rwsem_write(cpu);
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return;
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}
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/* Common NORMAL_SAMPLE setup */
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dbs_info->sample_type = DBS_NORMAL_SAMPLE;
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if (!dbs_tuners_ins.powersave_bias ||
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sample_type == DBS_NORMAL_SAMPLE) {
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dbs_check_cpu(dbs_info);
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if (dbs_info->freq_lo) {
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/* Setup timer for SUB_SAMPLE */
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dbs_info->sample_type = DBS_SUB_SAMPLE;
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delay = dbs_info->freq_hi_jiffies;
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}
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} else {
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__cpufreq_driver_target(dbs_info->cur_policy,
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dbs_info->freq_lo,
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CPUFREQ_RELATION_H);
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}
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queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
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unlock_policy_rwsem_write(cpu);
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}
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static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
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{
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/* We want all CPUs to do sampling nearly on same jiffy */
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int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
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delay -= jiffies % delay;
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dbs_info->enable = 1;
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ondemand_powersave_bias_init();
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dbs_info->sample_type = DBS_NORMAL_SAMPLE;
|
|
INIT_DELAYED_WORK(&dbs_info->work, do_dbs_timer);
|
|
queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
|
|
delay);
|
|
}
|
|
|
|
static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
|
|
{
|
|
dbs_info->enable = 0;
|
|
cancel_delayed_work(&dbs_info->work);
|
|
}
|
|
|
|
static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
|
|
unsigned int event)
|
|
{
|
|
unsigned int cpu = policy->cpu;
|
|
struct cpu_dbs_info_s *this_dbs_info;
|
|
unsigned int j;
|
|
int rc;
|
|
|
|
this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
|
|
|
|
switch (event) {
|
|
case CPUFREQ_GOV_START:
|
|
if ((!cpu_online(cpu)) || (!policy->cur))
|
|
return -EINVAL;
|
|
|
|
if (policy->cpuinfo.transition_latency >
|
|
(TRANSITION_LATENCY_LIMIT * 1000)) {
|
|
printk(KERN_WARNING "ondemand governor failed to load "
|
|
"due to too long transition latency\n");
|
|
return -EINVAL;
|
|
}
|
|
if (this_dbs_info->enable) /* Already enabled */
|
|
break;
|
|
|
|
mutex_lock(&dbs_mutex);
|
|
dbs_enable++;
|
|
|
|
rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
|
|
if (rc) {
|
|
dbs_enable--;
|
|
mutex_unlock(&dbs_mutex);
|
|
return rc;
|
|
}
|
|
|
|
for_each_cpu_mask(j, policy->cpus) {
|
|
struct cpu_dbs_info_s *j_dbs_info;
|
|
j_dbs_info = &per_cpu(cpu_dbs_info, j);
|
|
j_dbs_info->cur_policy = policy;
|
|
|
|
j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j);
|
|
j_dbs_info->prev_cpu_wall = get_jiffies_64();
|
|
}
|
|
this_dbs_info->cpu = cpu;
|
|
/*
|
|
* Start the timerschedule work, when this governor
|
|
* is used for first time
|
|
*/
|
|
if (dbs_enable == 1) {
|
|
unsigned int latency;
|
|
/* policy latency is in nS. Convert it to uS first */
|
|
latency = policy->cpuinfo.transition_latency / 1000;
|
|
if (latency == 0)
|
|
latency = 1;
|
|
|
|
def_sampling_rate = latency *
|
|
DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
|
|
|
|
if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
|
|
def_sampling_rate = MIN_STAT_SAMPLING_RATE;
|
|
|
|
dbs_tuners_ins.sampling_rate = def_sampling_rate;
|
|
}
|
|
dbs_timer_init(this_dbs_info);
|
|
|
|
mutex_unlock(&dbs_mutex);
|
|
break;
|
|
|
|
case CPUFREQ_GOV_STOP:
|
|
mutex_lock(&dbs_mutex);
|
|
dbs_timer_exit(this_dbs_info);
|
|
sysfs_remove_group(&policy->kobj, &dbs_attr_group);
|
|
dbs_enable--;
|
|
mutex_unlock(&dbs_mutex);
|
|
|
|
break;
|
|
|
|
case CPUFREQ_GOV_LIMITS:
|
|
mutex_lock(&dbs_mutex);
|
|
if (policy->max < this_dbs_info->cur_policy->cur)
|
|
__cpufreq_driver_target(this_dbs_info->cur_policy,
|
|
policy->max,
|
|
CPUFREQ_RELATION_H);
|
|
else if (policy->min > this_dbs_info->cur_policy->cur)
|
|
__cpufreq_driver_target(this_dbs_info->cur_policy,
|
|
policy->min,
|
|
CPUFREQ_RELATION_L);
|
|
mutex_unlock(&dbs_mutex);
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static struct cpufreq_governor cpufreq_gov_dbs = {
|
|
.name = "ondemand",
|
|
.governor = cpufreq_governor_dbs,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static int __init cpufreq_gov_dbs_init(void)
|
|
{
|
|
kondemand_wq = create_workqueue("kondemand");
|
|
if (!kondemand_wq) {
|
|
printk(KERN_ERR "Creation of kondemand failed\n");
|
|
return -EFAULT;
|
|
}
|
|
return cpufreq_register_governor(&cpufreq_gov_dbs);
|
|
}
|
|
|
|
static void __exit cpufreq_gov_dbs_exit(void)
|
|
{
|
|
cpufreq_unregister_governor(&cpufreq_gov_dbs);
|
|
destroy_workqueue(kondemand_wq);
|
|
}
|
|
|
|
|
|
MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
|
|
MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
|
|
MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
|
|
"Low Latency Frequency Transition capable processors");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
module_init(cpufreq_gov_dbs_init);
|
|
module_exit(cpufreq_gov_dbs_exit);
|
|
|