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[CPUFREQ][6/6] cpufreq: Add idle microaccounting in ondemand governor 

Use get_cpu_idle_time_us() to get micro-accounted idle information.
This enables ondemand to get more accurate idle and busy timings
than the jiffy based calculation. As a result, we can decrease
the ondemand safety gaurd band from 80-10 to 95-3.

Results in more aggressive power savings.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
venkatesh.pallipadi@intel.com 2008-08-04 11:59:12 -07:00 committed by Dave Jones
parent 8083e4ad97
commit 8080091310
1 changed files with 44 additions and 1 deletions
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45
drivers/cpufreq/cpufreq_ondemand.c
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@ -18,6 +18,9 @@
#include <linux/jiffies.h>
#include <linux/kernel_stat.h>
#include <linux/mutex.h>
#include <linux/hrtimer.h>
#include <linux/tick.h>
#include <linux/ktime.h>
/*
* dbs is used in this file as a shortform for demandbased switching
@ -26,6 +29,8 @@
#define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
#define DEF_FREQUENCY_UP_THRESHOLD (80)
#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
#define MICRO_FREQUENCY_UP_THRESHOLD (95)
#define MIN_FREQUENCY_UP_THRESHOLD (11)
#define MAX_FREQUENCY_UP_THRESHOLD (100)
@ -58,6 +63,7 @@ enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
struct cpu_dbs_info_s {
cputime64_t prev_cpu_idle;
cputime64_t prev_cpu_wall;
cputime64_t prev_cpu_nice;
struct cpufreq_policy *cur_policy;
struct delayed_work work;
struct cpufreq_frequency_table *freq_table;
@ -97,7 +103,8 @@ static struct dbs_tuners {
.powersave_bias = 0,
};
static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
cputime64_t *wall)
{
cputime64_t idle_time;
cputime64_t cur_wall_time;
@ -123,6 +130,33 @@ static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
return idle_time;
}
static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
{
u64 idle_time = get_cpu_idle_time_us(cpu, wall);
if (idle_time == -1ULL)
return get_cpu_idle_time_jiffy(cpu, wall);
if (dbs_tuners_ins.ignore_nice) {
cputime64_t cur_nice;
unsigned long cur_nice_jiffies;
struct cpu_dbs_info_s *dbs_info;
dbs_info = &per_cpu(cpu_dbs_info, cpu);
cur_nice = cputime64_sub(kstat_cpu(cpu).cpustat.nice,
dbs_info->prev_cpu_nice);
/*
* Assumption: nice time between sampling periods will be
* less than 2^32 jiffies for 32 bit sys
*/
cur_nice_jiffies = (unsigned long)
cputime64_to_jiffies64(cur_nice);
dbs_info->prev_cpu_nice = kstat_cpu(cpu).cpustat.nice;
return idle_time + jiffies_to_usecs(cur_nice_jiffies);
}
return idle_time;
}
/*
* Find right freq to be set now with powersave_bias on.
* Returns the freq_hi to be used right now and will set freq_hi_jiffies,
@ -603,6 +637,15 @@ EXPORT_SYMBOL(cpufreq_gov_ondemand);
static int __init cpufreq_gov_dbs_init(void)
{
int err;
cputime64_t wall;
u64 idle_time = get_cpu_idle_time_us(smp_processor_id(), &wall);
if (idle_time != -1ULL) {
/* Idle micro accounting is supported. Use finer thresholds */
dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
dbs_tuners_ins.down_differential =
MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
}
kondemand_wq = create_workqueue("kondemand");
if (!kondemand_wq) {