> > Yes, I understand that numa should have more priority over cache.
> > But the schedstats will not be updated about whether the task was hot or
> > cold.
> >
> > So lets say the task was cache hot but numa wants it to move, then we
> > should certainly move it but we should update the schedstats to mention that we
> > moved a cache hot task.
> >
> > Something akin to this.
> >
> > tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
> > if (tsk_cache_hot) {
> > if (migrate_improves_locality(p, env) ||
> > (env->sd->nr_balance_failed > env->sd->cache_nice_tries)) {
> > #ifdef CONFIG_SCHEDSTATS
> > schedstat_inc(env->sd, lb_hot_gained[env->idle]);
> > schedstat_inc(p, se.statistics.nr_forced_migrations);
> > #endif
> > return 1;
> > }
> > schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
> > return 0;
> > }
> > return 1;
> >
>
> Thanks. Is this acceptable?
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index b3848e0..c3a153e 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4088,8 +4088,13 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
> * 3) too many balance attempts have failed.
> */
>
> - if (migrate_improves_locality(p, env))
> + if (migrate_improves_locality(p, env)) {
> +#ifdef CONFIG_SCHEDSTATS
> + schedstat_inc(env->sd, lb_hot_gained[env->idle]);
> + schedstat_inc(p, se.statistics.nr_forced_migrations);
> +#endif
> return 1;
> + }
>
In this case, we account even cache cold threads as _cache hot_ in
schedstats.
We need the task_hot() call to determine if task is cache hot or not.
So the migrate_improves_locality(), I think should be called within the
tsk_cache_hot check.
Do you have issues with the above snippet that I posted earlier?
> tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
> if (!tsk_cache_hot)
>
> --
> Mel Gorman
> SUSE Labs
>
--
Thanks and Regards
Srikar Dronamraju
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