Re: [PATCH 08/15] sched: Commit to EEVDF

[Joel Fernandes]

On 6/22/23 08:01, Ingo Molnar wrote:
> * Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote:
>
> > On Wed, May 31, 2023 at 01:58:47PM +0200, Peter Zijlstra wrote:
> > > EEVDF is a better defined scheduling policy, as a result it has less
> > > heuristics/tunables. There is no compelling reason to keep CFS around.
> > >
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > > ---
> > >   kernel/sched/debug.c    |    6
> > >   kernel/sched/fair.c     |  465 +++---------------------------------------------
> >
> > Whether EEVDF helps us improve our CFS latency issues or not, I do like the
> > merits of this diffstat alone and the lesser complexity and getting rid of
> > those horrible knobs is kinda nice.
>
> To to be fair, the "removal" in this patch is in significant part an
> artifact of the patch series itself, because first EEVDF bits get added by
> three earlier patches, in parallel to CFS:
>
>   kernel/sched/fair.c     |  137 +++++++++++++++++++++++++++++++++++++++++++++++++--
>   kernel/sched/fair.c     |  162 +++++++++++++++++++++++++++++++++++++-----------
>   kernel/sched/fair.c     |  338 +++++++++++++++++++++++++++++++++++++++++-------
>
> ... and then we remove the old CFS policy code in this 'commit to EEVDF' patch:
>
>   kernel/sched/fair.c     |  465 +++---------------------------------------------
>
> The combined diffstat is close to 50% / 50% balanced:
>
>   kernel/sched/fair.c              | 1105 ++++++++++++++++++--------------------
>
> But having said that, I do agree that EEVDF as submitted by Peter is better
> defined, with fewer heuristics, which is an overall win - so no complaints
> from me!

Agreed, thank you for correcting me on the statistics.

 - Joel