sched: Optimize unused cgroup configuration
When cgroup group scheduling is built in, skip some code paths
if we don't have any (but the root) cgroups configured.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index 26976cd..ca1f76b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1629,8 +1629,14 @@
static void update_shares(struct sched_domain *sd)
{
- u64 now = cpu_clock(raw_smp_processor_id());
- s64 elapsed = now - sd->last_update;
+ s64 elapsed;
+ u64 now;
+
+ if (root_task_group_empty())
+ return;
+
+ now = cpu_clock(raw_smp_processor_id());
+ elapsed = now - sd->last_update;
if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) {
sd->last_update = now;
@@ -1640,6 +1646,9 @@
static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
{
+ if (root_task_group_empty())
+ return;
+
spin_unlock(&rq->lock);
update_shares(sd);
spin_lock(&rq->lock);
@@ -1647,6 +1656,9 @@
static void update_h_load(long cpu)
{
+ if (root_task_group_empty())
+ return;
+
walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
}