On 8/16/12, Alex Shi <alex....@intel.com> wrote:
> On 08/15/2012 10:24 PM, Rakib Mullick wrote:
>
>> On 8/13/12, Alex Shi <alex....@intel.com> wrote:
>>> Since there is no power saving consideration in scheduler CFS, I has a
>>> very rough idea for enabling a new power saving schema in CFS.
>>>
>>> It bases on the following assumption:
>>> 1, If there are many task crowd in system, just let few domain cpus
>>> running and let other cpus idle can not save power. Let all cpu take the
>>> load, finish tasks early, and then get into idle. will save more power
>>> and have better user experience.
>>>
>> This assumption indirectly point towards the scheme when performance
>> is enabled, isn't it? Cause you're trying to spread the load equally
>> amongst all the CPUs.
>
>
> It is.
>
Okay, then what would be the default mechanism? Performance or
powersavings ? Your proposal deals with performance and power saving,
but there should be a default mechanism too, what that default
mechanism would be? Shouldn't performance be the default one and
discard checking for performance?
>>
>>>
>>> select_task_rq_fair()
>>> {
>
> int powersaving = 0;
>
>>> for_each_domain(cpu, tmp) {
>>> if (policy == power && tmp_has_capacity &&
>>> tmp->flags & sd_flag) {
>>> sd = tmp;
>>> //It is fine to got cpu in the domain
>
> powersaving = 1;
>
>>> break;
>>> }
>>> }
>>>
>>> while(sd) {
> if (policy == power && powersaving == 1)
>>> find_busiest_and_capable_group()
>>
>> I'm not sure what find_busiest_and_capable_group() would really be, it
>> seems it'll find the busiest and capable group, but isn't it a
>> conflict with the first assumption you proposed on your proposal?
>
>
> This pseudo code missed a power saving workable flag , adding it into
> above code should solved your concern.
>
I think I should take a look at this one when it'll be prepared for RFC.
Thanks,
Rakib.
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