[tip:sched/core] sched: Fix nr_uninterruptible count

[tip-bot for Peter Zijlstra]

Commit-ID:  cc87f76a601d2d256118f7bab15e35254356ae21
Gitweb:     http://git.kernel.org/tip/cc87f76a601d2d256118f7bab15e35254356ae21
Author:     Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Fri, 26 Mar 2010 12:22:14 +0100
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Fri, 2 Apr 2010 20:12:04 +0200

sched: Fix nr_uninterruptible count

The cpuload calculation in calc_load_account_active() assumes
rq->nr_uninterruptible will not change on an offline cpu after
migrate_nr_uninterruptible(). However the recent migrate on wakeup
changes broke that and would result in decrementing the offline cpu's
rq->nr_uninterruptible.

Fix this by accounting the nr_uninterruptible on the waking cpu.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 kernel/sched.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 51d336e..14c8d2a 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2378,8 +2378,12 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
 	 *
 	 * First fix up the nr_uninterruptible count:
 	 */
-	if (task_contributes_to_load(p))
-		rq->nr_uninterruptible--;
+	if (task_contributes_to_load(p)) {
+		if (likely(cpu_online(orig_cpu)))
+			rq->nr_uninterruptible--;
+		else
+			this_rq()->nr_uninterruptible--;
+	}
 	p->state = TASK_WAKING;
 
 	if (p->sched_class->task_waking)
--
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