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Commit ee7930ee authored by Markus Mayer's avatar Markus Mayer Committed by Rafael J. Wysocki
Browse files

cpufreq: stats: New sysfs attribute for clearing statistics 



Allow CPUfreq statistics to be cleared by writing anything to
/sys/.../cpufreq/stats/reset.

Signed-off-by: default avatarMarkus Mayer <mmayer@broadcom.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 26f0dbc9

Documentation/cpu-freq/cpufreq-stats.txt

+6 −0
Original line number Diff line number Diff line
@@ -44,11 +44,17 @@ the stats driver insertion. 
total 0

drwxr-xr-x  2 root root    0 May 14 16:06 .

drwxr-xr-x  3 root root    0 May 14 15:58 ..

--w-------  1 root root 4096 May 14 16:06 reset

-r--r--r--  1 root root 4096 May 14 16:06 time_in_state

-r--r--r--  1 root root 4096 May 14 16:06 total_trans

-r--r--r--  1 root root 4096 May 14 16:06 trans_table

--------------------------------------------------------------------------------



-  reset

Write-only attribute that can be used to reset the stat counters. This can be

useful for evaluating system behaviour under different governors without the

need for a reboot.



-  time_in_state

This gives the amount of time spent in each of the frequencies supported by

this CPU. The cat output will have "<frequency> <time>" pair in each line, which

drivers/cpufreq/cpufreq_stats.c

+22 −0
Original line number Diff line number Diff line
@@ -41,6 +41,18 @@ static int cpufreq_stats_update(struct cpufreq_stats *stats) 
	return 0;

}



static void cpufreq_stats_clear_table(struct cpufreq_stats *stats)

{

	unsigned int count = stats->max_state;



	memset(stats->time_in_state, 0, count * sizeof(u64));

#ifdef CONFIG_CPU_FREQ_STAT_DETAILS

	memset(stats->trans_table, 0, count * count * sizeof(int));

#endif

	stats->last_time = get_jiffies_64();

	stats->total_trans = 0;

}



static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)

{

	return sprintf(buf, "%d\n", policy->stats->total_trans);
@@ -64,6 +76,14 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf) 
	return len;

}



static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,

			   size_t count)

{

	/* We don't care what is written to the attribute. */

	cpufreq_stats_clear_table(policy->stats);

	return count;

}



#ifdef CONFIG_CPU_FREQ_STAT_DETAILS

static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)

{
@@ -113,10 +133,12 @@ cpufreq_freq_attr_ro(trans_table); 


cpufreq_freq_attr_ro(total_trans);

cpufreq_freq_attr_ro(time_in_state);

cpufreq_freq_attr_wo(reset);



static struct attribute *default_attrs[] = {

	&total_trans.attr,

	&time_in_state.attr,

	&reset.attr,

#ifdef CONFIG_CPU_FREQ_STAT_DETAILS

	&trans_table.attr,

#endif

include/linux/cpufreq.h

+4 −0
Original line number Diff line number Diff line
@@ -234,6 +234,10 @@ __ATTR(_name, _perm, show_##_name, NULL) 
static struct freq_attr _name =			\

__ATTR(_name, 0644, show_##_name, store_##_name)



#define cpufreq_freq_attr_wo(_name)		\

static struct freq_attr _name =			\

__ATTR(_name, 0200, NULL, store_##_name)



struct global_attr {

	struct attribute attr;

	ssize_t (*show)(struct kobject *kobj,