On 2020/12/9 0:03, Vincent Guittot wrote: > On Tue, 8 Dec 2020 at 16:35, Mel Gorman <mgor...@techsingularity.net> wrote: >> >> 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> >> --- >> 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 ac7b34e7372b..5c41875aec23 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; > > Just noticed while reviewing the patch that the above related to > this_sd can also go under sched_feat(SIS_PROP) > >> >> + 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)
nr is the key of this throttling mechanism, need to be placed under sched_feat(SIS_PROP) as well. Thanks, -Aubrey