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 <mgor...@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);
-
cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
+ if (sched_feat(SIS_PROP))
+ time = cpu_clock(this);
for_each_cpu_wrap(cpu, cpus, target) {
if (!--nr)
return -1;
@@ -6187,8 +6187,10 @@ static int select_idle_cpu(struct task_struct *p, struct
sched_domain *sd, int t
break;
}
- time = cpu_clock(this) - time;
- update_avg(&this_sd->avg_scan_cost, time);
+ if (sched_feat(SIS_PROP)) {
+ time = cpu_clock(this) - time;
+ update_avg(&this_sd->avg_scan_cost, time);
+ }
return cpu;
}
