lkml.org 
[lkml]   [2020]   [Dec]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/4] sched/fair: Remove SIS_AVG_CPU
On Tue, Dec 08, 2020 at 02:43:10PM +0100, Vincent Guittot wrote:
> On Tue, 8 Dec 2020 at 14:36, Mel Gorman <mgorman@techsingularity.net> wrote:
> >
> > On Tue, Dec 08, 2020 at 02:24:32PM +0100, Vincent Guittot wrote:
> > > > > Nitpick:
> > > > >
> > > > > Since now avg_cost and avg_idle are only used w/ SIS_PROP, they could go
> > > > > completely into the SIS_PROP if condition.
> > > > >
> > > >
> > > > Yeah, I can do that. In the initial prototype, that happened in a
> > > > separate patch that split out SIS_PROP into a helper function and I
> > > > never merged it back. It's a trivial change.
> > >
> > > while doing this, should you also put the update of
> > > this_sd->avg_scan_cost under the SIS_PROP feature ?
> > >
> >
> > It's outside the scope of the series but why not. This?
> >
> > --8<--
> > sched/fair: Move avg_scan_cost calculations under SIS_PROP
> >
> > As noted by Vincent Guittot, avg_scan_costs are calculated for SIS_PROP
> > even if SIS_PROP is disabled. Move the time calculations under a SIS_PROP
> > check and while we are at it, exclude the cost of initialising the CPU
> > mask from the average scan cost.
> >
> > Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 19ca0265f8aa..0fee53b1aae4 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -6176,10 +6176,10 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
> > nr = 4;
> > }
> >
> > - time = cpu_clock(this);
>
> I would move it in the if (sched_feat(SIS_PROP)) above.
>

I considered it but made the choice to exclude the cost of cpumask_and()
from the avg_scan_cost instead. It's minor but when doing the original
prototype, I didn't think it was appropriate to count the cpumask
clearing as part of the scan cost as it's not directly related.

--
Mel Gorman
SUSE Labs

\
 
 \ /
  Last update: 2020-12-08 14:57    [W:0.061 / U:0.712 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site