cpufreq: stats: clear statistics

From: Markus Mayer <[email protected]>

Allow cpufreq statistics to be cleared by writing anything to /sys/.../cpufreq/stats/reset. Reading this new sysfs entry returns nothing.

Resetting the statistics can be useful in a test environment (test governor, retrieve stats, reset stats, test other governor, etc.). This feature is not meant for production use.

Signed-off-by Markus Mayer <[email protected]>

---
 drivers/cpufreq/Kconfig         | 10 ++++++++++
 drivers/cpufreq/cpufreq_stats.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

drivers/cpufreq/Kconfig +10 -0

index d8b164a..97a458e 100644
@@ -45,6 +45,16 @@ config CPU_FREQ_STAT_DETAILS
 
          If in doubt, say N.
 
+config CPU_FREQ_STAT_RESET
+       bool "Allow reset of CPU frequency transition statistics"
+       depends on CPU_FREQ_STAT
+       help
+         If enabled, writing to /sys/[...]/cpufreq/stats/reset will reset the
+         current CPUfreq statistics. This is primarily meant for testing. It
+         should not be enabled on a production system.
+
+         If in doubt, say N.
+
 choice
        prompt "Default CPUFreq governor"
        default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ

drivers/cpufreq/cpufreq_stats.c +29 -0

index 06d3abd..e4e1e3e 100644
@@ -111,6 +111,35 @@ static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
 cpufreq_freq_attr_ro(trans_table);
 #endif
 
+#ifdef CONFIG_CPU_FREQ_STAT_RESET
+static void cpufreq_stats_clear_table(struct cpufreq_policy *policy)
+{
+       struct cpufreq_stats *stats = policy->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_reset(struct cpufreq_policy *policy, char *buf)
+{
+       buf[0] = '\0';
+       return 0;
+}
+
+static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,
+                          size_t count)
+{
+       cpufreq_stats_clear_table(policy);
+       return count;
+}
+cpufreq_freq_attr_rw(reset);
+#endif
+
 cpufreq_freq_attr_ro(total_trans);
 cpufreq_freq_attr_ro(time_in_state);
 

Quoted 77 lines · Markus Mayer

From: Markus Mayer <[email protected]>

Allow cpufreq statistics to be cleared by writing anything to /sys/.../cpufreq/stats/reset. Reading this new sysfs entry returns nothing.

Resetting the statistics can be useful in a test environment (test governor, retrieve stats, reset stats, test other governor, etc.). This feature is not meant for production use.

Signed-off-by Markus Mayer <[email protected]>

---
 drivers/cpufreq/Kconfig         | 10 ++++++++++
 drivers/cpufreq/cpufreq_stats.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

drivers/cpufreq/Kconfig +10 -0

index d8b164a..97a458e 100644
@@ -45,6 +45,16 @@ config CPU_FREQ_STAT_DETAILS
 
          If in doubt, say N.
 
+config CPU_FREQ_STAT_RESET
+       bool "Allow reset of CPU frequency transition statistics"
+       depends on CPU_FREQ_STAT
+       help
+         If enabled, writing to /sys/[...]/cpufreq/stats/reset will reset the
+         current CPUfreq statistics. This is primarily meant for testing. It
+         should not be enabled on a production system.
+
+         If in doubt, say N.
+
 choice
        prompt "Default CPUFreq governor"
        default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ

drivers/cpufreq/cpufreq_stats.c +29 -0

index 06d3abd..e4e1e3e 100644
@@ -111,6 +111,35 @@ static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
 cpufreq_freq_attr_ro(trans_table);
 #endif
 
+#ifdef CONFIG_CPU_FREQ_STAT_RESET
+static void cpufreq_stats_clear_table(struct cpufreq_policy *policy)
+{
+       struct cpufreq_stats *stats = policy->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_reset(struct cpufreq_policy *policy, char *buf)
+{
+       buf[0] = '\0';
+       return 0;
+}
+
+static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,
+                          size_t count)
+{
+       cpufreq_stats_clear_table(policy);
+       return count;
+}
+cpufreq_freq_attr_rw(reset);
+#endif
+
 cpufreq_freq_attr_ro(total_trans);
 cpufreq_freq_attr_ro(time_in_state);
 

drivers/cpufreq/cpufreq_stats.c static struct attribute *default_attrs[] = {

Quoted 11 lines

drivers/cpufreq/cpufreq_stats.c +3 -1

@@ -120,6 +149,9 @@ static struct attribute *default_attrs[] = {
 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
        &trans_table.attr,
 #endif
+#ifdef CONFIG_CPU_FREQ_STAT_RESET
+       &reset.attr,
+#endif
        NULL
 };
 static struct attribute_group stats_attr_group = {
--

What would be wrong with adding this unconditionally?