Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758258AbcKDCMM (ORCPT ); Thu, 3 Nov 2016 22:12:12 -0400 Received: from mail-pf0-f170.google.com ([209.85.192.170]:34230 "EHLO mail-pf0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756594AbcKDCMK (ORCPT ); Thu, 3 Nov 2016 22:12:10 -0400 Date: Fri, 4 Nov 2016 07:42:06 +0530 From: Viresh Kumar To: "Rafael J. Wysocki" Cc: Markus Mayer , "Rafael J . Wysocki" , Power Management List , Broadcom Kernel List , Linux Kernel Mailing List , Markus Mayer Subject: Re: [PATCH] cpufreq: stats: clear statistics Message-ID: <20161104021206.GJ10786@vireshk-i7> References: <20161103204615.85395-1-code@mmayer.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3448 Lines: 98 On 04-11-16, 01:28, Rafael J. Wysocki wrote: > On Thu, Nov 3, 2016 at 9:46 PM, Markus Mayer wrote: > > From: Markus Mayer > > > > 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 > > --- > > 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