sched: Reduce update_group_power() calls

Currently we update cpu_power() too often, update_group_power() only
updates the local group's cpu_power but it gets called for all groups.

Furthermore, CPU_NEWLY_IDLE invocations will result in all cpus
calling it, even though a slow update of cpu_power is sufficient.

Therefore move the update under 'idle != CPU_NEWLY_IDLE &&
local_group' to reduce superfluous invocations.

Reported-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1278612989.1900.176.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 6 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index e44a591531a1..c9ac09760953 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -2425,14 +2425,14 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
          * domains. In the newly idle case, we will allow all the cpu's
          * to do the newly idle load balance.
          */
-        if (idle != CPU_NEWLY_IDLE && local_group &&
-            balance_cpu != this_cpu) {
-                *balance = 0;
-                return;
+        if (idle != CPU_NEWLY_IDLE && local_group) {
+                if (balance_cpu != this_cpu) {
+                        *balance = 0;
+                        return;
+                }
+                update_group_power(sd, this_cpu);
         }
 
-        update_group_power(sd, this_cpu);
-
         /* Adjust by relative CPU power of the group */
         sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;