On Wed, Jun 01, 2016 at 08:39:21PM +0100, Dietmar Eggemann wrote: > Since task utilization is accrued only on the root cfs_rq, there are a > couple of places where the se has to be synced with the root cfs_rq: > > (1) The root cfs_rq has to be updated in attach_entity_load_avg() for > an se representing a task in a tg other than the root tg before > the se utilization can be added to it. > > (2) The last_update_time value of the root cfs_rq can be higher > than the one of the cfs_rq the se is enqueued in. Call > __update_load_avg() on the se with the last_update_time value of > the root cfs_rq before removing se's utilization from the root > cfs_rq in [remove|detach]_entity_load_avg(). > > In case the difference between the last_update_time value of the cfs_rq > and the root cfs_rq is smaller than 1024ns, the additional calls to > __update_load_avg() will bail early. > > Signed-off-by: Dietmar Eggemann <dietmar.eggem...@arm.com> > --- > kernel/sched/fair.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 212becd3708f..3ae8e79fb687 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -2970,6 +2970,8 @@ static inline void update_load_avg(struct sched_entity > *se, int update_tg) > > static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct > sched_entity *se) > { > + struct cfs_rq* root_cfs_rq; > + > if (!sched_feat(ATTACH_AGE_LOAD)) > goto skip_aging; > > @@ -2995,8 +2997,16 @@ static void attach_entity_load_avg(struct cfs_rq > *cfs_rq, struct sched_entity *s > if (!entity_is_task(se)) > return; > > - rq_of(cfs_rq)->cfs.avg.util_avg += se->avg.util_avg; > - rq_of(cfs_rq)->cfs.avg.util_sum += se->avg.util_sum; > + root_cfs_rq = &rq_of(cfs_rq)->cfs; > + > + if (parent_entity(se)) > + __update_load_avg(cfs_rq_clock_task(root_cfs_rq), > + cpu_of(rq_of(root_cfs_rq)), &root_cfs_rq->avg, > + scale_load_down(root_cfs_rq->load.weight), > + upd_util_cfs_rq(root_cfs_rq), root_cfs_rq);
Maybe add below macro in this patch for more readable: #define upd_util_cfs_rq(cfs_rq) XXX > + > + root_cfs_rq->avg.util_avg += se->avg.util_avg; > + root_cfs_rq->avg.util_sum += se->avg.util_sum; > > cfs_rq_util_change(cfs_rq); > } > @@ -3013,6 +3023,10 @@ static void detach_entity_load_avg(struct cfs_rq > *cfs_rq, struct sched_entity *s > if (!entity_is_task(se)) > return; > > + __update_load_avg(rq_of(cfs_rq)->cfs.avg.last_update_time, > cpu_of(rq_of(cfs_rq)), > + &se->avg, se->on_rq * > scale_load_down(se->load.weight), > + cfs_rq->curr == se, NULL); > + > rq_of(cfs_rq)->cfs.avg.util_avg = > max_t(long, rq_of(cfs_rq)->cfs.avg.util_avg - se->avg.util_avg, 0); > rq_of(cfs_rq)->cfs.avg.util_sum = > @@ -3105,6 +3119,9 @@ void remove_entity_load_avg(struct sched_entity *se) > if (!entity_is_task(se)) > return; > > + last_update_time = cfs_rq_last_update_time(&rq_of(cfs_rq)->cfs); > + > + __update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, > 0, NULL); > atomic_long_add(se->avg.util_avg, &rq_of(cfs_rq)->cfs.removed_util_avg); > } > > -- > 1.9.1 >