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 13:23:06 +0100 [thread overview]
Message-ID: <20101122132306.245e0bcb@schatten.dmk.lab> (raw)
In-Reply-To: <1290422639.2110.3.camel@laptop>
On Mon, 22 Nov 2010 11:43:59 +0100
Peter Zijlstra <peterz@infradead.org> wrote:
> On Mon, 2010-11-22 at 06:51 +0100, Florian Mickler wrote:
> > 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.
>
> Dude, its from the _android_ tree... its cpufreq crud.. it must be some
> crack induced power management scheme.
>
>
:)
what I wanted to get at, was that they probably need these stats
aggregated somewhere neat and tidy and can not compute them on the fly
recording massive amounts of data...
I wonder why they didn't put this in the
idle-driver. I don't know.
Regards,
Flo
next prev parent reply other threads:[~2010-11-22 12:23 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
2010-11-22 10:43 ` Peter Zijlstra
2010-11-22 12:23 ` Florian Mickler [this message]
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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