Re: [PATCH v5 4/5] sched/fair: Skip SIS domain scan if fully busy

[Abel Wu]

On 9/15/22 8:22 AM, Tim Chen wrote:
> On Fri, 2022-09-09 at 13:53 +0800, Abel Wu wrote:
> > If a full domain scan failed, then no unoccupied cpus available
> > and the LLC is fully busy.  In this case we'd better use cpus
> > more wisely, rather than wasting it trying to find an idle cpu
> > that probably not exist. The fully busy status will be cleared
> > when any cpu of that LLC goes idle and everything goes back to
> > normal again.
> >
> > Make the has_idle_cores boolean hint more rich by turning it
> > into a state machine.
> >
> > Signed-off-by: Abel Wu <wuyun.abel@xxxxxxxxxxxxx>
> > ---
> >   include/linux/sched/topology.h | 35 +++++++++++++++++-
> >   kernel/sched/fair.c            | 67 ++++++++++++++++++++++++++++------
> >   2 files changed, 89 insertions(+), 13 deletions(-)
> >
> > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> > index 816df6cc444e..cc6089765b64 100644
> > --- a/include/linux/sched/topology.h
> > +++ b/include/linux/sched/topology.h
> > @@ -77,10 +77,43 @@ extern int sched_domain_level_max;
> >   
> >   struct sched_group;
> >   
> > +/*
> > + * States of the sched-domain
> > + *
> > + * - sd_has_icores
> > + *	This state is only used in LLC domains to indicate worthy
> > + *	of a full scan in SIS due to idle cores available.
> > + *
> > + * - sd_has_icpus
> > + *	This state indicates that unoccupied (sched-idle/idle) cpus
> > + *	might exist in this domain. For the LLC domains it is the
> > + *	default state since these cpus are the main targets of SIS
> > + *	search, and is also used as a fallback state of the other
> > + *	states.
> > + *
> > + * - sd_is_busy
> > + *	This state indicates there are no unoccupied cpus in this
>
> Suggest reword to
>
> .. indicates that all cpus are occupied in this ...

OK, I will make a update in next version!

Thanks,
Abel