On Fri, Jun 7, 2013 at 12:20 AM, Alex Shi <[email protected]> wrote: > The wakeuped migrated task will __synchronize_entity_decay(se); in > migrate_task_fair, then it needs to set > `se->avg.last_runnable_update -= (-se->avg.decay_count) << 20' > before update_entity_load_avg, in order to avoid slept time is updated > twice for se.avg.load_avg_contrib in both __syncchronize and > update_entity_load_avg. > > but if the slept task is waked up from self cpu, it miss the > last_runnable_update before update_entity_load_avg(se, 0, 1), then the > slept time was used twice in both functions. > So we need to remove the double slept time counting.
Good catch. > > Signed-off-by: Alex Shi <[email protected]> > --- > kernel/sched/fair.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 1fc30b9..42c7be0 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -1570,7 +1570,8 @@ static inline void enqueue_entity_load_avg(struct > cfs_rq *cfs_rq, > } > wakeup = 0; > } else { > - __synchronize_entity_decay(se); > + se->avg.last_runnable_update += __synchronize_entity_decay(se) > + << 20; Can you add something like: + /* + * Task re-woke on same cpu (or else migrate_task_rq_fair() + * would have made count negative); we must be careful to avoid + * double-accounting blocked time after synchronizing decays. + */ Reviewed-by: Paul Turner <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
