On Tue, Aug 23, 2016 at 03:28:19PM +0200, Vincent Guittot wrote: > I still wonder if using a flat util hierarchy is the right solution to > solve this problem with utilization and task group. I have noticed > exact same issues with load that generates weird task placement > decision and i think that we should probably try to solve both wrong > behavior with same mechanism. but this is not possible with flat > hierarchy for load > > Let me take an example. > TA is a always running task on CPU1 in group /root/level1/ > TB wakes up on CPU0 and moves TA into group /root/level2/ > Even if TA stays on CPU1, runnable_load_avg of CPU1 root cfs rq will become 0.
Because while we migrate the load_avg on /root/level2, we do not propagate the load_avg up the hierarchy? And always propagating everyrthing up will indeed also fix the utilization issue. Of course, doing that propagation has its costs.. Didn't you post a patch doing just this a while ago?
