> > >
> > > - 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?
> >
>
> The migrate_improves_locality call had already happened so it cannot be
> true after the tsk_cache_hot check is made so I was confused. If the call is
> moved within task cache hot then it changes the intent of the patch because
Yes, I was suggesting moving it inside.
> cache hotness then trumps memory locality which is not intended. Memory
> locality is expected to trump cache hotness.
>
But whether the memory locality trumps or the cache hotness, the result
would still be the same but a little concise code.
> How about this?
>
> tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
>
> if (migrate_improves_locality(p, env)) {
> #ifdef CONFIG_SCHEDSTATS
> if (tsk_cache_hot) {
> schedstat_inc(env->sd, lb_hot_gained[env->idle]);
> schedstat_inc(p, se.statistics.nr_forced_migrations);
> }
> #endif
> return 1;
> }
>
> if (!tsk_cache_hot ||
> env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
> #ifdef CONFIG_SCHEDSTATS
> if (tsk_cache_hot) {
> schedstat_inc(env->sd, lb_hot_gained[env->idle]);
> schedstat_inc(p, se.statistics.nr_forced_migrations);
> }
> #endif
> return 1;
> }
Yes, this looks fine to me.
>
--
Thanks and Regards
Srikar Dronamraju
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