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authorSuresh Siddha <suresh.b.siddha@intel.com>2007-08-23 15:18:02 +0200
committerIngo Molnar <mingo@elte.hu>2007-08-23 15:18:02 +0200
commitf549da848eca595abca14ebc5e1bf00fd72aa53d (patch)
tree25069c378b06c23f9f12a9e08c8f670d899f188b /kernel
parentf8700df7c419781efb34696de7e7f49717f8ede7 (diff)
downloadlinux-linaro-f549da848eca595abca14ebc5e1bf00fd72aa53d.tar.gz
sched: skip updating rq's next_balance under null SD
Was playing with sched_smt_power_savings/sched_mc_power_savings and found out that while the scheduler domains are reconstructed when sysfs settings change, rebalance_domains() can get triggered with null domain on other cpus, which is setting next_balance to jiffies + 60*HZ. Resulting in no idle/busy balancing for 60 seconds. Fix this. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index d96030db8ff..a4b22d93e00 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3043,6 +3043,7 @@ static inline void rebalance_domains(int cpu, enum cpu_idle_type idle)
struct sched_domain *sd;
/* Earliest time when we have to do rebalance again */
unsigned long next_balance = jiffies + 60*HZ;
+ int update_next_balance = 0;
for_each_domain(cpu, sd) {
if (!(sd->flags & SD_LOAD_BALANCE))
@@ -3079,8 +3080,10 @@ static inline void rebalance_domains(int cpu, enum cpu_idle_type idle)
if (sd->flags & SD_SERIALIZE)
spin_unlock(&balancing);
out:
- if (time_after(next_balance, sd->last_balance + interval))
+ if (time_after(next_balance, sd->last_balance + interval)) {
next_balance = sd->last_balance + interval;
+ update_next_balance = 1;
+ }
/*
* Stop the load balance at this level. There is another
@@ -3090,7 +3093,14 @@ out:
if (!balance)
break;
}
- rq->next_balance = next_balance;
+
+ /*
+ * next_balance will be updated only when there is a need.
+ * When the cpu is attached to null domain for ex, it will not be
+ * updated.
+ */
+ if (likely(update_next_balance))
+ rq->next_balance = next_balance;
}
/*