On Fri, Apr 16, 2021 at 10:43:38AM +0100 Valentin Schneider wrote: > On 15/04/21 16:39, Rik van Riel wrote: > > On Thu, 2021-04-15 at 18:58 +0100, Valentin Schneider wrote: > >> Consider the following topology: > >> > >> Long story short, preempted misfit tasks are affected by task_hot(), > >> while > >> currently running misfit tasks are intentionally preempted by the > >> stopper > >> task to migrate them over to a higher-capacity CPU. > >> > >> Align detach_tasks() with the active-balance logic and let it pick a > >> cache-hot misfit task when the destination CPU can provide a capacity > >> uplift. > >> > >> Signed-off-by: Valentin Schneider <valentin.schnei...@arm.com> > > > > Reviewed-by: Rik van Riel <r...@surriel.com> > > > > Thanks! > > > > > This patch looks good, but... > > > >> @@ -7672,6 +7698,15 @@ int can_migrate_task(struct task_struct *p, > >> struct lb_env *env) > >> if (tsk_cache_hot == -1) > >> tsk_cache_hot = task_hot(p, env); > >> > >> + /* > >> + * On a (sane) asymmetric CPU capacity system, the increase in > >> compute > >> + * capacity should offset any potential performance hit caused > >> by a > >> + * migration. > >> + */ > >> + if ((env->dst_grp_type == group_has_spare) && > >> + !migrate_degrades_capacity(p, env)) > >> + tsk_cache_hot = 0; > > > > ... I'm starting to wonder if we should not rename the > > tsk_cache_hot variable to something else to make this > > code more readable. Probably in another patch :) > > > > I'd tend to agree, but naming is hard. "migration_harmful" ?
I thought Rik meant tsk_cache_hot, for which I'd suggest at least buying a vowel and putting an 'a' in there :) Cheers, Phil > > > -- > > All Rights Reversed. > --
