@@ -4747,9 +4747,19 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
*/
static int select_idle_sibling(struct task_struct *p, int target)
{
- struct sched_domain *sd;
+ struct sched_domain *sd = NULL, *tmp;
struct sched_group *sg;
int i = task_cpu(p);
+ int target_nrg;
+ int nrg_min, nrg_cpu = -1;
+
+ if (energy_aware()) {
+ /* When energy-aware, go above sd_llc */
+ for_each_domain(target, tmp)
+ sd = tmp;
+
+ goto loop;
+ }
if (idle_cpu(target))
return target;
@@ -4764,6 +4774,10 @@ static int select_idle_sibling(struct task_struct *p, int target)
* Otherwise, iterate the domains and find an elegible idle cpu.
*/
sd = rcu_dereference(per_cpu(sd_llc, target));
+
+loop:
+ target_nrg = nrg_min = energy_diff_task(target, p);
+
for_each_lower_domain(sd) {
sg = sd->groups;
do {
@@ -4772,16 +4786,35 @@ static int select_idle_sibling(struct task_struct *p, int target)
goto next;
for_each_cpu(i, sched_group_cpus(sg)) {
+ int nrg_diff;
+ if (energy_aware()) {
+ if (!idle_cpu(i))
+ continue;
+
+ nrg_diff = energy_diff_task(i, p);
+ if (nrg_diff < nrg_min) {
+ nrg_min = nrg_diff;
+ nrg_cpu = i;
+ }
+ }
+
if (i == target || !idle_cpu(i))
goto next;
}
- target = cpumask_first_and(sched_group_cpus(sg),
- tsk_cpus_allowed(p));
- goto done;
+ if (!energy_aware()) {
+ target = cpumask_first_and(sched_group_cpus(sg),
+ tsk_cpus_allowed(p));
+ goto done;
+ }
next:
sg = sg->next;
} while (sg != sd->groups);
+
+ if (nrg_cpu >= 0) {
+ target = nrg_cpu;
+ goto done;
+ }
}
done:
return target;
Make select_idle_sibling() consider energy when picking an idle cpu. This implies having to look beyond sd_llc. Otherwise, consolidating short frequently running tasks on fewer llc domains will not happen when that is feasible. The fix is to start select_idle_sibling() at the highest sched_domain level. A more refined approach causing less overhead will be considered later. That could be to only look beyond sd_llc occasionally. Only idle cpus are still considered. A more aggressive energy conserving approach could go further and consider partially utilized cpus. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> --- kernel/sched/fair.c | 41 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 37 insertions(+), 4 deletions(-)