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) > @@ -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 >