On Mon, Apr 19, 2021 at 06:17:47PM +0100 Valentin Schneider wrote: > On 19/04/21 08:59, Phil Auld wrote: > > 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: > >> >> @@ -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 :) > > > > That's the one I was eyeing: s/tsk_cache_hot/migration_harmful/ or > somesuch. Right now we're feeding it: >
Fair enough, my bad, the migration part immediately drew me to migrate_degrades_capacity(). > o migrate_degrades_locality() > o task_hot() > > and I'm adding another one, so that's 2/3 which don't actually care about > cache hotness, but rather "does doing this migration degrade/improve > $criterion?" > prefer_no_migrate? Cheers, Phil --
