linux-kernel - Re: [PATCH] cpufreq: Fix ondemand governor powersave

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Message-ID: <4CD77D6A.9070901@linux.intel.com>
Date:	Sun, 07 Nov 2010 20:32:42 -0800
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	Youquan Song <youquan.song@...ux.intel.com>
CC:	davej@...hat.com, venki@...gle.com, youquan.song@...el.com,
	cpufreq@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: Fix ondemand governor powersave_bias	execution
 time misuse

On 11/8/2010 6:45 AM, Youquan Song wrote:
>> On 11/5/2010 11:19 AM, Youquan Song wrote:
>>> Ondemand governor use powersave_bias tunable to do aggressive power save by
>>> decrease CPU average frequency. The average frequency achieve by adjust low and
>>> high frequency's execution time proportion during one sample time interval.
>>>
>>> Current kernel, only the high frequency executes in time proportion, but the low
>>> frequency wrongly execute in one whole sample time interval when powersave_bias
>>> is set.
>>>
>>> The patch fix it by set low frequency execution time to it deserved.
>>>
>>> Signed-off-by: Youquan Song<youquan.song@...el.com>
>>> ---
>>
>> while your patch looks correct, I think the whole feature is wonky and
>> likely ought to be removed...........
> powersave_bias should be a useful feature, which give user an
> opportunity to set the CPU to work at wider average frequency accord to real
>   workload requirement, not just CPU frequency specific at P0,P1,...Pn.
> At the same time, it meets end user power comsumpation requirement in
> some degree.
> Unfortunately, it does not work for a long time.

in all measurements I've done... the intermediate states (between P1 and 
Pn) seem to not be power efficient.....

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