linux-kernel - Re: [PATCH] cpufreq: governor: Be friendly towards latency-sensitive bursty workloads

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Message-ID: <53840368.4030004@linux.vnet.ibm.com>
Date:	Tue, 27 May 2014 08:45:52 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	viresh.kumar@...aro.org, svaidy@...ux.vnet.ibm.com,
	ego@...ux.vnet.ibm.com, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: governor: Be friendly towards latency-sensitive
 bursty workloads

On 05/27/2014 04:57 AM, Rafael J. Wysocki wrote:
> Hi Srivatsa,
> 
> On Tuesday, May 27, 2014 02:23:38 AM Srivatsa S. Bhat wrote:
>> Cpufreq governors like the ondemand governor calculate the load on the CPU
>> periodically by employing deferrable timers. A deferrable timer won't fire
>> if the CPU is completely idle (and there are no other timers to be run), in
>> order to avoid unnecessary wakeups and thus save CPU power.
>>
>> However, the load calculation logic is agnostic to all this, and this can
>> lead to the problem described below.
> 
> This is subtle enough that I need some more time to chew on it, but since the
> merge window is coming, I'm not sure when that's going to happen honestly.
>

Sure, I completely understand. Please take your time, no hurry!

Thank you very much!

Regards,
Srivatsa S. Bhat

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