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SubjectRe: [PATCH v2 2/2] cpufreq: stats: clear statistics
On 04-11-16, 09:55, Markus Mayer wrote:
> From: Markus Mayer <mmayer@broadcom.com>
>
> Allow CPUfreq statistics to be cleared by writing anything to
> /sys/.../cpufreq/stats/reset.
>
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
> Documentation/cpu-freq/cpufreq-stats.txt | 6 ++++++
> drivers/cpufreq/cpufreq_stats.c | 22 ++++++++++++++++++++++
> 2 files changed, 28 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..66419e6 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_wr_perm(reset, 0200);

Just drop the perm argument and this patch looks fine as well.

--
viresh

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