[RFC] sched: nohz_idle_balance

Message ID 1347509486-8688-1-git-send-email-vincent.guittot@linaro.org
State Accepted
Commit 5ed4f1d96deee82ee92cd1ac1e0108c27e80e9b0
Headers show

Commit Message

Vincent Guittot Sept. 13, 2012, 4:11 a.m.
On tickless system, 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@linaro.org>
---
 kernel/sched/fair.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Patch

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;
 	}