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SubjectRe: [PATCH][RFC] Adding transition of CPU frequency counting support to perfcounters
From
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH][RFC] Adding transition of CPU frequency counting support to perfcounters
Date: Sat, 18 Jul 2009 18:09:15 +0200

> On Sat, 2009-07-18 at 23:11 +0900, mitake@dcl.info.waseda.ac.jp wrote:
> >
> > Oh, my perf could count cpufreq events!
> > Thanks for your nice advice!
> >
> > % perf stat -a sleep 60
> >
> > Performance counter stats for 'sleep 60':
> >
> > 479088.075595 task-clock-msecs # 7.984 CPUs
> > 199080 context-switches # 0.000 M/sec
> > 19584 CPU-migrations # 0.000 M/sec
> > 322978 page-faults # 0.001 M/sec
> > 29 cpufreq-up # 0.000 M/sec
> > 42 cpufreq-down # 0.000 M/sec
> > 73703367828 cycles # 153.841 M/sec
> > 52005203450 instructions # 0.706 IPC
> > 209762467 cache-references # 0.438 M/sec
> > 84916856 cache-misses # 0.177 M/sec
> >
> > 60.009508200 seconds time elapsed
> >
> > And I'm using ondemand governor now,
> > so kernel thread [kondemand] context causes freq transition.
> > I didn't notice that...
> >
> > Could you merge this patch?
> > Can I send this patch with descriptions and Signed-off-by?
>
> Why, what is the usecase?
>
>

Hmm, I considered, and I noticed that this patch makes no sense.
Because my first purpose "collecting CPU freq transitions per process level"
is completely nonsense. CPU freq transitions are global things, not one of processes.

In either case, "up" and "down" are too poor information.
At least freqs of each time should be recorded.

Sorry, please disregard this patch.


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