Re: [v2 patch v3.18+ regression fix] sched: Further improve spurious CPU_IDLE active migrations

[Vincent Guittot]

On 6 September 2016 at 15:07, Mike Galbraith <umgwanakikbuti@xxxxxxxxx> wrote:
> On Tue, 2016-09-06 at 15:01 +0200, Vincent Guittot wrote:
>> Le Monday 05 Sep 2016 Ã 18:26:53 (+0200), Mike Galbraith a Ãcrit :
>> > Coming back to this, how about this instead, only increase the group
>> > imbalance threshold when sd_llc_size == 2.  Newer L3 equipped
>> > processors then aren't affected.
>> >
>>
>> Not sure that all systems with sd_llc_size == 2 wants this behavior.
>>
>> Why not adding a sched_feature for changing the 2nd half of the test
>> for some systems ?
>
> Because users won't know, and shouldn't need to know that they need to
> flip that switch.

fair enough

so how can we detect this specific system configuration ?

sd_llc_size == 2 is not enough IMHO

>
>         -Mike