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authorPeter Zijlstra <peterz@infradead.org>2012-09-06 00:03:50 +0200
committerIngo Molnar <mingo@kernel.org>2012-09-13 16:52:05 +0200
commit08bedae1d0acd8c9baf514fb69fa199d0c8345f6 (patch)
tree82cda177bc9c52658d350c9686ea2b8b07b8ee5b /kernel/sched
parentf3e947867478af9a12b9956bcd000ac7613a8a95 (diff)
sched: Fix load avg vs. cpu-hotplug
Commit f319da0c68 ("sched: Fix load avg vs cpu-hotplug") was an incomplete fix: In particular, the problem is that at the point it calls calc_load_migrate() nr_running := 1 (the stopper thread), so move the call to CPU_DEAD where we're sure that nr_running := 0. Also note that we can call calc_load_migrate() without serialization, we know the state of rq is stable since its cpu is dead, and we modify the global state using appropriate atomic ops. Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1346882630.2600.59.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8b51b2d9b1fd..ba144b121f3d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5048,7 +5048,9 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
migrate_tasks(cpu);
BUG_ON(rq->nr_running != 1); /* the migration thread */
raw_spin_unlock_irqrestore(&rq->lock, flags);
+ break;
+ case CPU_DEAD:
calc_load_migrate(rq);
break;
#endif