linux-kernel - Re: [RESEND][PATCH] cpufreq: stats: Add 'load_table' sysfs file to show accumulated data of CPU

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Date:	Wed, 12 Jun 2013 13:05:09 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Chanwoo Choi <cw00.choi@...sung.com>, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, cpufreq@...r.kernel.org,
	kyungmin.park@...sung.com, myungjoo.ham@...sung.com
Subject: Re: [RESEND][PATCH] cpufreq: stats: Add 'load_table' sysfs file to show accumulated data of CPU

On Wednesday, June 12, 2013 09:32:16 AM Viresh Kumar wrote:
> On 12 June 2013 03:44, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > On Wednesday, June 05, 2013 05:11:22 PM Chanwoo Choi wrote:
> >> This patch add new sysfs file to show previous accumulated data of CPU load
> >> as following path. This sysfs file is used to judge the correct system state
> >> or determine suitable system resource on user-space.
> >> - /sys/devices/system/cpu/cpu0/cpufreq/stats/load_table
> >>
> >> This sysfs file include following data:
> >> - Measurement point of time
> >> - CPU frequency
> >> - Per-CPU load
> >>
> >> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> >> Signed-off-by: Myungjoo Ham <myungjoo.ham@...sung.com>
> >> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> >
> > Well, first of all, there is the "one value per file" rule for sysfs attributes
> > which is evidently violated by this code.
> 
> Even this was enclosed in CONFIG_CPU_FREQ_STAT_DETAILS,
> so even sysfs isn't that bad as we already had something similar here.

Yes, we did, and yes, it was a mistake.  It should have been in debugfs from
the very beginning.

> > Second, this looks like a feature needed to handle one particular platform, so
> > why do you want to add it to the cpufreq core?
> 
> I really felt this would be useful to others. They can track the load on
> all cores for some time and that will really be useful. People can
> understand their loads and system more easily with this patch in.

If it were in debugfs, I'd have no objections.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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