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. Other than that, Reviewed-by: Valentin Schneider <[email protected]> [...]
