[tip:sched/core] sched: Fix nohz_idle_balance()
From: tip-bot for Vincent Guittot
Date: Fri Sep 14 2012 - 02:12:26 EST
Commit-ID: 5ed4f1d96deee82ee92cd1ac1e0108c27e80e9b0
Gitweb: http://git.kernel.org/tip/5ed4f1d96deee82ee92cd1ac1e0108c27e80e9b0
Author: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
AuthorDate: Thu, 13 Sep 2012 06:11:26 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 13 Sep 2012 16:52:03 +0200
sched: Fix nohz_idle_balance()
On tickless systems, one CPU runs load balance for all idle CPUs.
The cpu_load of this CPU is updated before starting the load balance
of each other idle CPUs. We should instead update the cpu_load of
the balance_cpu.
Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Venkatesh Pallipadi <venki@xxxxxxxxxx>
Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1347509486-8688-1-git-send-email-vincent.guittot@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/fair.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1ca4fe4..9ae3a5b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4794,14 +4794,15 @@ static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
if (need_resched())
break;
- raw_spin_lock_irq(&this_rq->lock);
- update_rq_clock(this_rq);
- update_idle_cpu_load(this_rq);
- raw_spin_unlock_irq(&this_rq->lock);
+ rq = cpu_rq(balance_cpu);
+
+ raw_spin_lock_irq(&rq->lock);
+ update_rq_clock(rq);
+ update_idle_cpu_load(rq);
+ raw_spin_unlock_irq(&rq->lock);
rebalance_domains(balance_cpu, CPU_IDLE);
- rq = cpu_rq(balance_cpu);
if (time_after(this_rq->next_balance, rq->next_balance))
this_rq->next_balance = rq->next_balance;
}
--
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