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Message-Id: <20161107180223.44536-1-code@mmayer.net>
Date: Mon, 7 Nov 2016 10:02:23 -0800
From: Markus Mayer <code@...yer.net>
To: Viresh Kumar <viresh.kumar@...aro.org>,
"Rafael J . Wysocki" <rjw@...ysocki.net>
Cc: Power Management List <linux-pm@...r.kernel.org>,
Broadcom Kernel List <bcm-kernel-feedback-list@...adcom.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Markus Mayer <mmayer@...adcom.com>
Subject: [PATCH v3] cpufreq: stats: clear statistics
From: Markus Mayer <mmayer@...adcom.com>
Allow CPUfreq statistics to be cleared by writing anything to
/sys/.../cpufreq/stats/reset.
Signed-off-by: Markus Mayer <mmayer@...adcom.com>
---
Changes since v2:
- changed name of write-only macro to cpufreq_freq_attr_wo()
- removed "perm" parameter from write-only macro
- squashed the two separate commits into a single one
Changes since v1:
- add new cpufreq_freq_attr_wr_perm() macro for write-only
attributes (because this is a separate commit, this patch has
turned into a series)
- remove the Kconfig option, compiling the code unconditionally
- remove show_reset()
- cpufreq_stats_clear_table() takes a struct cpufreq_stats * as
argument rather than a struct cpufreq_policy *
Documentation/cpu-freq/cpufreq-stats.txt | 6 ++++++
drivers/cpufreq/cpufreq_stats.c | 22 ++++++++++++++++++++++
include/linux/cpufreq.h | 4 ++++
3 files changed, 32 insertions(+)
diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.txt
index 8d9773f..3c355f6 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 06d3abd..ac284e6 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 5fa55fc..490573e 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,
--
2.7.4
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