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 <[email protected]> --- kernel/sched/fair.c | 41 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 37 insertions(+), 4 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index aebf3e2..a32d6eb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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; -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
