Re: [PATCH v4 04/11] sched/fair: rework load_balance

From: Ingo Molnar
Date: Mon Nov 18 2019 - 08:50:24 EST



* Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:

> s/groupe_type/group_type/
>
> > enum group_type {
> > - group_other = 0,
> > + group_has_spare = 0,
> > + group_fully_busy,
> > group_misfit_task,
> > + group_asym_packing,
> > group_imbalanced,
> > - group_overloaded,
> > + group_overloaded
> > +};
> > +
>
> While not your fault, it would be nice to comment on the meaning of each
> group type. From a glance, it's not obvious to me why a misfit task should
> be a high priority to move a task than a fully_busy (but not overloaded)
> group given that moving the misfit task might make a group overloaded.

This part of your feedback should now be addressed in the scheduler tree
via:

a9723389cc75: sched/fair: Add comments for group_type and balancing at SD_NUMA level

> > +enum migration_type {
> > + migrate_load = 0,
> > + migrate_util,
> > + migrate_task,
> > + migrate_misfit
> > };
> >
>
> Could do with a comment explaining what migration_type is for because
> the name is unhelpful. I *think* at a glance it's related to what sort
> of imbalance is being addressed which is partially addressed by the
> group_type. That understanding may change as I continue reading the series
> but now I have to figure it out which means it'll be forgotten again in
> 6 months.

Agreed. Vincent, is any patch brewing here, or should I take a stab?

Thanks,

Ingo