Messages in this thread Patch in this message | | | Date | Thu, 13 Sep 2012 23:14:08 -0700 | From | tip-bot for Peter Zijlstra <> | Subject | [tip:sched/core] sched: Fix load avg vs. cpu-hotplug |
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Commit-ID: 08bedae1d0acd8c9baf514fb69fa199d0c8345f6 Gitweb: http://git.kernel.org/tip/08bedae1d0acd8c9baf514fb69fa199d0c8345f6 Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Thu, 6 Sep 2012 00:03:50 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Thu, 13 Sep 2012 16:52:05 +0200
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> --- kernel/sched/core.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8b51b2d..ba144b1 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
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