Subject: Re: [PATCH 04/11] powerpc/smp: Enable small core scheduling sooner

From: Srikar Dronamraju <[email-masked]>
Date: Mon, 20 Jul 2020 14:22:14 +0530

* Jordan Niethe <[email-masked]> [2020-07-20 17:47:27]:

> On Tue, Jul 14, 2020 at 2:44 PM Srikar Dronamraju
> <[email-masked]> wrote:
> >
> > Enable small core scheduling as soon as we detect that we are in a
> > system that supports thread group. Doing so would avoid a redundant
> > check.
> >
> > Cc: linuxppc-dev <[email-masked]>
> > Cc: Michael Ellerman <[email-masked]>
> > Cc: Nick Piggin <[email-masked]>
> > Cc: Oliver OHalloran <[email-masked]>
> > Cc: Nathan Lynch <[email-masked]>
> > Cc: Michael Neuling <[email-masked]>
> > Cc: Anton Blanchard <[email-masked]>
> > Cc: Gautham R Shenoy <[email-masked]>
> > Cc: Vaidyanathan Srinivasan <[email-masked]>
> > Signed-off-by: Srikar Dronamraju <[email-masked]>
> > ---
> >  arch/powerpc/kernel/smp.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> > index 24529f6134aa..7d430fc536cc 100644
> > --- a/arch/powerpc/kernel/smp.c
> > +++ b/arch/powerpc/kernel/smp.c
> > @@ -892,6 +892,12 @@ static int init_big_cores(void)
> >         }
> >
> >         has_big_cores = true;
> > +
> > +#ifdef CONFIG_SCHED_SMT
> > +       pr_info("Big cores detected. Using small core scheduling\n");
> Why change the wording from "Big cores detected but using small core
> scheduling\n"?
> > +       powerpc_topology[0].mask = smallcore_smt_mask;
> > +#endif
> > +

To me, "but" in the message sounded as if we detected Big cores *but* we want
to continue using smallcore scheduling. However the code was always meaning
to say, "Since we detected big core, i.e thread grouping within a core, System would
benefit by using small core scheduling".

If you think, "but" was adding more info and not misleading, then I can add it back.

> >         return 0;
> >  }

-- 
Thanks and Regards
Srikar Dronamraju