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

From: Mike Galbraith
Date: Tue Sep 06 2016 - 09:07:51 EST


On Tue, 2016-09-06 at 15:01 +0200, Vincent Guittot wrote:
> Le Monday 05 Sep 2016 à 18:26:53 (+0200), Mike Galbraith a écrit :
> > 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.

-Mike