From: Florian Mickler <florian@mickler.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>,
lkml <linux-kernel@vger.kernel.org>, Mike Chan <mike@android.com>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 3/5] scheduler: cpuacct: Enable platform hooks to track cpuusage for CPU frequencies
Date: Mon, 22 Nov 2010 06:51:29 +0100 [thread overview]
Message-ID: <20101122065129.072bba06@schatten.dmk.lab> (raw)
In-Reply-To: <1290250104.2118.4.camel@laptop>
On Sat, 20 Nov 2010 11:48:24 +0100
Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, 2010-11-19 at 18:08 -0800, John Stultz wrote:
> > From: Mike Chan <mike@android.com>
> >
> > Introduce new platform callback hooks for cpuacct for tracking CPU frequencies
> >
> > Not all platforms / architectures have a set CPU_FREQ_TABLE defined
> > for CPU transition speeds. In order to track time spent in at various
> > CPU frequencies, we enable platform callbacks from cpuacct for this accounting.
> >
> > Architectures that support overclock boosting, or don't have pre-defined
> > frequency tables can implement their own bucketing system that makes sense
> > given their cpufreq scaling abilities.
> >
> > New file:
> > cpuacct.cpufreq reports the CPU time (in nanoseconds) spent at each CPU
> > frequency.
>
> I utterly detest all such accounting crap.. it adds ABI constraints it
> add runtime overhead. etc..
>
> Can't you get the same information by using the various perf bits? If
> you trace the cpufreq changes you can compute the time spend in each
> power state, if you additionally trace the sched_switch you can compute
> it for each task.
>
>
This is probably used for "on-site" debugging of production systems.
I.e. when someone sends them a problem report using an
bugreport-tool, they gather all useful information they can get on the
system because they only have one-way communication with their bug
reporters.
Do the perf bits work for such a usecase? If I guess correctly, the
perf bits need a userspace part that computes what would be in the
cpuacct.cpufreq file?
Regards,
Flo
next prev parent reply other threads:[~2010-11-22 5:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-20 2:08 [PATCH 0/5] [RFC] Trivial scheduler related Android patches John Stultz
2010-11-20 2:08 ` [PATCH 1/5] sched: Enable might_sleep before initializing drivers John Stultz
2010-11-20 10:42 ` Peter Zijlstra
2010-11-20 2:08 ` [PATCH 2/5] sched: make task dump print all 15 chars of proc comm John Stultz
2010-11-23 10:21 ` [tip:sched/core] sched: Make " tip-bot for Erik Gilling
2010-11-20 2:08 ` [PATCH 3/5] scheduler: cpuacct: Enable platform hooks to track cpuusage for CPU frequencies John Stultz
2010-11-20 10:48 ` Peter Zijlstra
2010-11-22 5:51 ` Florian Mickler [this message]
2010-11-22 10:43 ` Peter Zijlstra
2010-11-22 12:23 ` Florian Mickler
2010-11-23 2:05 ` Mike Chan
2010-11-23 11:35 ` Peter Zijlstra
2010-11-20 2:08 ` [PATCH 4/5] scheduler: cpuacct: Enable platform callbacks for cpuacct power tracking John Stultz
2010-11-20 2:08 ` [PATCH 5/5] sched: use the old min_vruntime when normalizing on dequeue John Stultz
2010-11-20 10:55 ` Peter Zijlstra
2010-11-20 12:33 ` Peter Zijlstra
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