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authorvenkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>2008-08-04 11:59:12 -0700
committerDave Jones <davej@redhat.com>2008-10-09 13:52:44 -0400
commit808009131046b62ac434dbc796c0fe8accaab415 (patch)
tree64b5c755b8eb5d43f8e00554032de372f36e7b4c /drivers/cpufreq
parent8083e4ad970e4eb567e31037060cdd4ba346f0c0 (diff)
[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>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq_ondemand.c45
1 files changed, 44 insertions, 1 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 3f898606e68..39253d6d51e 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -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) {