Re: [PATCH v3 1/3] cpufreq: ondemand: Change the calculation of target frequency

From: Rafael J. Wysocki
Date: Sun Jun 09 2013 - 18:02:14 EST

On Sunday, June 09, 2013 11:14:49 PM Borislav Petkov wrote:
> On Sun, Jun 09, 2013 at 10:58:51PM +0200, Rafael J. Wysocki wrote:
> > Can you possibly prepare a graph showing both the execution time
> > and energy consumption for several different loop durations in your
> > program (let's keep the 5000 us sleep for now), including multiples of
> > sampling_rate as well as some other durations?
> Judgind by the times in C0 one of the cores spent, this small program
> is single-threaded and is a microbenchmark.

Yes, it is single-threaded, but that can be easily addressed by running
multiple copies of it in parallel. :-)

And yes, it is a microbenchmark, ->

> And you know how optimizing against a microbenchmark doesn't really make
> a lot of sense.

-> but this is more about finding possible issues that about optimizing.

I'm regarding this change as a substantial code simplification in the first
place, both in terms of conceptual complexity and the actual code size, so I'd
like to know what is *likely* to be affected by it (be it a microbenchmark or

IOW, try to play a devil's advocate and find something that get's worse after
applying these changes. If we can't find anything like that, there won't be
any reason not to apply them.

> I wonder if lmbench or aim9 or whatever would make more sense to try here...

I think we'll need to try them too.


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