Re: [PATCH v3 08/12] sched: move cfs task on a CPU with higher capacity

[Vincent Guittot]

On 10 July 2014 13:18, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Mon, Jun 30, 2014 at 06:05:39PM +0200, Vincent Guittot wrote:
>> +             /*
>> +              * If the CPUs share their cache and the src_cpu's capacity is
>> +              * reduced because of other sched_class or IRQs, we trig an
>> +              * active balance to move the task
>> +              */
>> +             if ((sd->flags & SD_SHARE_PKG_RESOURCES)
>> +              && ((capacity_orig_of(src_cpu) * 100) > (capacity_of(src_cpu) *
>> +                                                     sd->imbalance_pct)))
>>                       return 1;
>
> Why is this tied to shared caches?

It's just to limit the change of the policy to a level that can have
benefit without performance regression. I'm not sure that we can do
that at any level without risk
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