Re: [PATCH 2/2] sched/fair: Simple runqueue order on migrate

[Tim Chen]

On Tue, 2022-03-29 at 18:09 +0800, Abel Wu wrote:
> > 
> 
> >   
> > +static void place_entity_migrate(struct cfs_rq *cfs_rq, struct sched_entity *se)
> > +{
> > +	if (!sched_feat(PLACE_MIGRATE))
> > +		return;
> > +
> > +	if (cfs_rq->nr_running < se->migrated) {
> > +		/*
> > +		 * Migrated to a shorter runqueue, go first because
> > +		 * we were under-served on the old runqueue.
> > +		 */
> > +		se->vruntime = cfs_rq->min_vruntime;
> > +		return;
> > +	}
> > +
> > +	/*
> > +	 * Migrated to a longer runqueue, go last because
> > +	 * we got over-served on the old runqueue.
> > +	 */
> > +	se->vruntime = cfs_rq->min_vruntime + sched_vslice(cfs_rq, se);
> > +}
> 
> Should se->migrated be cleared after place_entity_migrate?
> 

It is cleared in update_stats_curr_start() before we actually run the task.
If the task gets migrated again before we run it, the se->migrated will also
be updated in migrate_task_rq_fair().  Looks like there is no need to
clear it here.

Tim