sched: Weaken SD_POWERSAVINGS_BALANCE
One of the problems of power-saving balancing is that under certain
scenarios it is too slow and allows tons of real work to pile up.
Avoid this by ignoring the powersave stuff when there's real work
to be done.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 09d19f7..eaa0001 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1333,10 +1333,25 @@
for_each_domain(cpu, tmp) {
/*
- * If power savings logic is enabled for a domain, stop there.
+ * If power savings logic is enabled for a domain, see if we
+ * are not overloaded, if so, don't balance wider.
*/
- if (tmp->flags & SD_POWERSAVINGS_BALANCE)
- break;
+ if (tmp->flags & SD_POWERSAVINGS_BALANCE) {
+ unsigned long power = 0;
+ unsigned long nr_running = 0;
+ unsigned long capacity;
+ int i;
+
+ for_each_cpu(i, sched_domain_span(tmp)) {
+ power += power_of(i);
+ nr_running += cpu_rq(i)->cfs.nr_running;
+ }
+
+ capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
+
+ if (nr_running/2 < capacity)
+ break;
+ }
switch (flag) {
case SD_BALANCE_WAKE: