Re: [PATCH RFC 5/7] sched: cfs: cpu frequency scaling arch functions

From: Mike Turquette
Date: Wed Oct 22 2014 - 19:20:51 EST


On Wed, Oct 22, 2014 at 1:06 PM, Rik van Riel <riel@xxxxxxxxxx> wrote:
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> On 10/22/2014 02:07 AM, Mike Turquette wrote:
>> arch_eval_cpu_freq and arch_scale_cpu_freq are added to allow the
>> scheduler to evaluate if cpu frequency should change and to invoke
>> that change from a safe context.
>>
>> They are weakly defined arch functions that do nothing by default.
>> A CPUfreq governor could use these functions to implement a
>> frequency scaling policy based on updates to per-task statistics or
>> updates to per-cpu utilization.
>>
>> As discussed at Linux Plumbers Conference 2014, the goal will be
>> to focus on a single cpu frequency scaling policy that works for
>> everyone. That may mean that the weak arch functions definitions
>> can be removed entirely and a single policy implements that logic
>> for all architectures.
>
> On virtual machines, we probably want to use both frequency and
> steal time to calculate the factor.

You mean for calculating desired cpu frequency on a virtual guest? Is
that something we want to do?

Thanks,
Mike

>
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