Re: [patch] clockevents: Reinstate the per cpu tick skew

[Mike Galbraith <efault@xxxxxx>]

On Wed, 2011-12-28 at 09:22 +0100, Mike Galbraith wrote:

> (Hm, wonder if nohz is usable now... nope.  Tell nohz that isolated
> cores don't play balancer again, maybe it'll work now)

Yup, worked.  60 core jitter test is approaching single digit.  Woohoo.

---
 kernel/sched_fair.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -4517,6 +4517,10 @@ void select_nohz_load_balancer(int stop_
 {
 	int cpu = smp_processor_id();
 
+	/* Isolated cores do not play */
+	if (!cpu_rq(cpu)->sd)
+		return;
+
 	if (stop_tick) {
 		if (!cpu_active(cpu)) {
 			if (atomic_read(&nohz.load_balancer) != cpu)



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