Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg

From: Peter Zijlstra
Date: Wed May 03 2017 - 09:09:58 EST

On Wed, May 03, 2017 at 12:37:37PM +0200, Vincent Guittot wrote:
> On 3 May 2017 at 11:37, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> > Of course, it could be I overlooked something, in which case, please
> > tell :-)
> That's mainly based on the regression i see on my platform. I haven't
> find the root cause of the regression but it's there which means that
> using group_entity's load_avg to propagate child cfs_rq
> runnable_load_avg breaks something

(as mentioned on IRC)

Right.. so looking through the code, (group) se->avg.load_avg is used in
effective_load() (and thereby wake_affine()) and update_cfs_rq_h_load()
(and therefore task_h_load()).

So changing it will affect those two functions, which could well lead to
your regression.