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authorMarkus Mayer <mmayer@broadcom.com>2016-11-07 21:02:23 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-11-11 03:51:11 +0300
commitee7930ee27fe5240398cc302fa8eb4454725f188 (patch)
tree4ad6af7f88a71a8238e3e48778876c3fff64f6f5
parent26f0dbc9ab158afe86bac5ece2fcaf873d6bd8ad (diff)
downloadlinux-ee7930ee27fe5240398cc302fa8eb4454725f188.tar.xz
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: Markus Mayer <mmayer@broadcom.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--Documentation/cpu-freq/cpufreq-stats.txt6
-rw-r--r--drivers/cpufreq/cpufreq_stats.c22
-rw-r--r--include/linux/cpufreq.h4
3 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.txt
index 8d9773f23550..3c355f6ad834 100644
--- a/Documentation/cpu-freq/cpufreq-stats.txt
+++ b/Documentation/cpu-freq/cpufreq-stats.txt
@@ -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
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 06d3abdffd3a..ac284e66839c 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -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
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 32dc0cbd51ca..40dc2e29f480 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -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,