On 04-11-16, 01:28, Rafael J. Wysocki wrote:
> On Thu, Nov 3, 2016 at 9:46 PM, Markus Mayer <c...@mmayer.net> wrote:
> > From: Markus Mayer <mma...@broadcom.com>
> >
> > 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 <mma...@broadcom.com>
> > ---
> > drivers/cpufreq/Kconfig | 10 ++++++++++
> > drivers/cpufreq/cpufreq_stats.c | 32 ++++++++++++++++++++++++++++++++
> > 2 files changed, 42 insertions(+)
> >
> > diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
> > index d8b164a..97a458e 100644
> > --- a/drivers/cpufreq/Kconfig
> > +++ b/drivers/cpufreq/Kconfig
> > @@ -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
> > diff --git a/drivers/cpufreq/cpufreq_stats.c
> > b/drivers/cpufreq/cpufreq_stats.c
> > index 06d3abd..e4e1e3e 100644
> > --- a/drivers/cpufreq/cpufreq_stats.c
> > +++ b/drivers/cpufreq/cpufreq_stats.c
> > @@ -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);
> >
> > @@ -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?
Absolutely and there is no need to have read permissions for the file. Just make
it write only.
--
viresh
