Valentin Schneider <[email protected]> writes: > On 23/08/2019 21:00, [email protected] wrote: > [...] >> Could you mention in the message that this a throttled cfs_rq can have >> account_cfs_rq_runtime called on it because it is throttled before >> idle_balance, and the idle_balance calls update_rq_clock to add time >> that is accounted to the task. >> > > Mayhaps even a comment for the extra condition. > >> I think this solution is less risky than unthrottling >> in this area, so other than that: >> >> Reviewed-by: Ben Segall <[email protected]> >> > > If you don't mind squashing this in: > > -----8<----- > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index b1d9cec9b1ed..b47b0bcf56bc 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -4630,6 +4630,10 @@ static u64 distribute_cfs_runtime(struct cfs_bandwidth > *cfs_b, u64 remaining) > if (!cfs_rq_throttled(cfs_rq)) > goto next; > > + /* By the above check, this should never be true */ > + WARN_ON(cfs_rq->runtime_remaining > 0); > + > + /* Pick the minimum amount to return to a positive quota state > */ > runtime = -cfs_rq->runtime_remaining + 1; > if (runtime > remaining) > runtime = remaining; > ----->8----- > > I'm not adamant about the extra comment, but the WARN_ON would be nice IMO. > > > @Ben, do you reckon we want to strap > > Cc: <[email protected]> > Fixes: ec12cb7f31e2 ("sched: Accumulate per-cfs_rq cpu usage and charge > against bandwidth") > > to the thing? AFAICT the pick_next_task_fair() + idle_balance() dance you > described should still be possible on that commit.
I'm not sure about stable policy in general, but it seems reasonable. The WARN_ON might want to be WARN_ON_ONCE, and it seems fine to have it or not. > > > Other than that, > > Reviewed-by: Valentin Schneider <[email protected]> > > [...]
