[tip:sched/urgent] sched: Fix rebalance interval calculation

[tip-bot for Sisir Koppaka]

Commit-ID:  3436ae1298cb22d722a6520fc97f112dd767a9e1
Gitweb:     http://git.kernel.org/tip/3436ae1298cb22d722a6520fc97f112dd767a9e1
Author:     Sisir Koppaka <sisir.koppaka@xxxxxxxxx>
AuthorDate: Sat, 26 Mar 2011 18:22:55 +0530
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 31 Mar 2011 13:00:37 +0200

sched: Fix rebalance interval calculation

The interval for checking scheduling domains if they are due to be
balanced currently depends on boot state NR_CPUS, which may not
accurately reflect the number of online CPUs at the time of check.

Thus replace NR_CPUS with num_online_cpus().

 (ed: Should only affect those who set NR_CPUS really high, such as 4096
      or so :-)

Signed-off-by: Sisir Koppaka <sisir.koppaka@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <AANLkTikqHWid2Q93F5U5Qw5snJH8C5PXoa7J6=6hYO94@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 kernel/sched_fair.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 3f7ec9e..c7ec5c8 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -22,6 +22,7 @@
 
 #include <linux/latencytop.h>
 #include <linux/sched.h>
+#include <linux/cpumask.h>
 
 /*
  * Targeted preemption latency for CPU-bound tasks:
@@ -3850,8 +3851,8 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
 		interval = msecs_to_jiffies(interval);
 		if (unlikely(!interval))
 			interval = 1;
-		if (interval > HZ*NR_CPUS/10)
-			interval = HZ*NR_CPUS/10;
+		if (interval > HZ*num_online_cpus()/10)
+			interval = HZ*num_online_cpus()/10;
 
 		need_serialize = sd->flags & SD_SERIALIZE;
 
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