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

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Date:	Thu, 06 Jun 2013 20:32:15 +0300
From:	Stratos Karafotis <stratosk@...aphore.gr>
To:	Borislav Petkov <bp@...e.de>
CC:	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, linux-pm@...r.kernel.org,
	cpufreq@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/3] cpufreq: ondemand: Change the calculation of target
 frequency

On 06/06/2013 08:11 PM, Borislav Petkov wrote:
> On Thu, Jun 06, 2013 at 07:46:17PM +0300, Stratos Karafotis wrote:
>> Apologies for top-posting. I was able to send email only from my phone.
>>
>> Thanks for you hint about turbostat.
>>
>> As you most probably understood, I'm individual amateur kernel developer.
>> I could provide some numbers from x86 architecture as Rafael suggested.
>> But unfortunately, I don't have access to more sources/infrastructure.
>> So, I will not be able to provide numbers from different platform(s).
>>
>> I've already provided some benchmarks from x86 (3.10-rc3) and also
>> tested the patch in 3.4.47 kernel (ARM, Nexus 4 phone, ~1000 installations)
>> and in 3.0.80 kernel (ARM, Samsung Galaxy S phone, ~1500 installations).
>>
>> Kindly let me know if "couple of platforms/vendors" is a show stopper
>> for this patch series. If yes, please ignore this patch and accept
>> my apologies for wasting your time. I am just trying to contribute
>> on this project (I believe there is space here for amateur developers).
>
> I'm in no way discouraging you in contributing to the kernel - on the
> opposite: you should continue doing that.

I will try! :)

> I'm just trying to make sure that a change like that doesn't hurt
> existing systems, thus the request to test on a couple of platforms. If
> you don't have other platforms, that's fine, we'll find them somewhere. :-)
>
> I'm hoping you can understand my aspect too, though - how would you feel
> if a patch shows improvement on my box but slows down yours - you won't
> be very happy with it, right? That's why we generally want to test such
> power/performance tweaks on a wider range of machines.

I'm totally understand your aspect and I think you are absolutely
right. I just wanted to declare that I am not able to provide numbers
for other platforms due to lack of hardware.

> But you said you have a i7-3770 CPU on which, I think, turbostat should
> be able to show you how the power consumption looks like.
>
> And if so, you could measure that consumption once with, and once
> without your patch. This will give us initial numbers, at least.
>
> How does that sound?
>

That sounds perfect! I will provide numbers for i7 soon.

Thanks for your comments!
Stratos

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