On Thu, Aug 08, 2019 at 09:39:45AM -0700, Tim Chen wrote: > On 8/8/19 5:55 AM, Aaron Lu wrote: > > On Mon, Aug 05, 2019 at 08:55:28AM -0700, Tim Chen wrote: > >> On 8/2/19 8:37 AM, Julien Desfossez wrote: > >>> We tested both Aaron's and Tim's patches and here are our results. > > > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index 26fea68f7f54..542974a8da18 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -3888,7 +3888,7 @@ next_class:; > > WARN_ON_ONCE(!rq_i->core_pick); > > > > if (is_idle_task(rq_i->core_pick) && rq_i->nr_running) > > - rq->core_forceidle = true; > > + rq_i->core_forceidle = true; > > Good catch! > > > > > rq_i->core_pick->core_occupation = occ; > > > > With this fixed and together with the patch to let schedule always > > happen, your latest 2 patches work well for the 10s cpuhog test I > > described previously: > > https://lore.kernel.org/lkml/20190725143003.GA992@aaronlu/ > > That's encouraging. You are talking about my patches > that try to keep the force idle time between sibling threads > balanced, right?
Yes. > > > > overloaded workload without any cpu binding doesn't work well though, I > > haven't taken a closer look yet. > > > > I think we need a load balancing scheme among the cores that will try > to minimize force idle. Agree. > > One possible metric to measure load compatibility imbalance that leads to > force idle is > > Say i, j are sibling threads of a cpu core > imbalanace = \sum_tagged_cgroup abs(Load_cgroup_cpui - Load_cgroup_cpuj) > > This gives us a metric to decide if migrating a task will improve > load compatability imbalance. As we already track cgroup load on a CPU, > it should be doable without adding too much overhead.