[PATCH 2/5] sched/fair: Move avg_scan_cost calculations under SIS_PROP

Mel Gorman
2021-01-19T11:39:49Z

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>
---
kernel/sched/fair.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9f5682aeda2e..c8d8e185cf3b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6153,6 +6153,8 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
if (!this_sd)
return -1;

+ cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
+
if (sched_feat(SIS_PROP)) {
u64 avg_cost, avg_idle, span_avg;

@@ -6168,11 +6170,9 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
nr = div_u64(span_avg, avg_cost);
else
nr = 4;
- }
-
- time = cpu_clock(this);

- cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
+ time = cpu_clock(this);
+ }

for_each_cpu_wrap(cpu, cpus, target) {
if (!--nr)
@@ -6181,8 +6181,10 @@ 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;
}
--
2.26.2