On Tue, May 31, 2016 at 10:34:02AM +0200, Peter Zijlstra wrote:
> On Tue, May 31, 2016 at 06:32:54AM +0800, Yuyang Du wrote:
> > +++ b/kernel/sched/fair.c
> > @@ -2961,24 +2961,6 @@ 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)
> > {
> > - if (!sched_feat(ATTACH_AGE_LOAD))
> > - goto skip_aging;
> > -
> > - /*
> > - * If we got migrated (either between CPUs or between cgroups) we'll
> > - * have aged the average right before clearing @last_update_time.
> > - */
> > - if (se->avg.last_update_time) {
> > - __update_load_avg(cfs_rq->avg.last_update_time,
> > cpu_of(rq_of(cfs_rq)),
> > - &se->avg, 0, 0, NULL);
> > -
> > - /*
> > - * XXX: we could have just aged the entire load away if we've
> > been
> > - * absent from the fair class for too long.
> > - */
> > - }
> > -
> > -skip_aging:
> > se->avg.last_update_time = cfs_rq->avg.last_update_time;
> > cfs_rq->avg.load_avg += se->avg.load_avg;
> > cfs_rq->avg.load_sum += se->avg.load_sum;
>
> So I'm not a big fan of this patch; the aging is a conceptual part of
> attaching the load, the fact that it only happens in one callsite is a
> mere 'accident'.
Yes, and we have to put the following to make it an "accident".
static void task_move_group_fair(struct task_struct *p)
{
detach_task_cfs_rq(p);
set_task_rq(p, task_cpu(p));
#ifdef CONFIG_SMP
/* Tell se's cfs_rq has been changed -- migrated */
p->se.avg.last_update_time = 0;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#endif
attach_task_cfs_rq(p);
}
So let me give it another try to keep this cleanup. Will send another version.
