Look for an idle CPU close to the pack buddy CPU whenever possible. The goal is to prevent the wake up of a CPU which doesn't share the power domain of the pack buddy CPU.
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org Reviewed-by: Morten Rasmussen morten.rasmussen@arm.com --- kernel/sched/fair.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6adc57c..a985c98 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5469,7 +5469,26 @@ static struct {
static inline int find_new_ilb(int call_cpu) { + struct sched_domain *sd; int ilb = cpumask_first(nohz.idle_cpus_mask); + int buddy = per_cpu(sd_pack_buddy, call_cpu); + + /* + * If we have a pack buddy CPU, we try to run load balance on a CPU + * that is close to the buddy. + */ + if (buddy != -1) { + for_each_domain(buddy, sd) { + if (sd->flags & SD_SHARE_CPUPOWER) + continue; + + ilb = cpumask_first_and(sched_domain_span(sd), + nohz.idle_cpus_mask); + + if (ilb < nr_cpu_ids) + break; + } + }
if (ilb < nr_cpu_ids && idle_cpu(ilb)) return ilb;