sched/nohz: Fix rq->cpu_load[] calculations

While investigating why the load-balancer did funny I found that the
rq->cpu_load[] tables were completely screwy.. a bit more digging
revealed that the updates that got through were missing ticks followed
by a catchup of 2 ticks.

The catchup assumes the cpu was idle during that time (since only nohz
can cause missed ticks and the machine is idle etc..) this means that
esp. the higher indices were significantly lower than they ought to
be.

The reason for this is that its not correct to compare against jiffies
on every jiffy on any other cpu than the cpu that updates jiffies.

This patch cludges around it by only doing the catch-up stuff from
nohz_idle_balance() and doing the regular stuff unconditionally from
the tick.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: pjt@google.com
Cc: Venkatesh Pallipadi <venki@google.com>
Link: http://lkml.kernel.org/n/tip-tp4kj18xdd5aj4vvj0qg55s2@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a259a614b39..124e6b6999a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5012,7 +5012,7 @@ static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
 
 		raw_spin_lock_irq(&this_rq->lock);
 		update_rq_clock(this_rq);
-		update_cpu_load(this_rq);
+		update_idle_cpu_load(this_rq);
 		raw_spin_unlock_irq(&this_rq->lock);
 
 		rebalance_domains(balance_cpu, CPU_IDLE);