Messages in this thread Patch in this message | | | Date | Tue, 21 Sep 2010 14:13:01 GMT | From | tip-bot for Suresh Siddha <> | Subject | [tip:sched/urgent] sched: Fix nohz balance kick |
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Commit-ID: f6c3f1686e7ec1dd8725a9a3dcb857dfd0c7a5bf Gitweb: http://git.kernel.org/tip/f6c3f1686e7ec1dd8725a9a3dcb857dfd0c7a5bf Author: Suresh Siddha <suresh.b.siddha@intel.com> AuthorDate: Mon, 13 Sep 2010 11:02:21 -0700 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Tue, 21 Sep 2010 13:50:50 +0200
sched: Fix nohz balance kick
There's a situation where the nohz balancer will try to wake itself:
cpu-x is idle which is also ilb_cpu got a scheduler tick during idle and the nohz_kick_needed() in trigger_load_balance() checks for rq_x->nr_running which might not be zero (because of someone waking a task on this rq etc) and this leads to the situation of the cpu-x sending a kick to itself.
And this can cause a lockup.
Avoid this by not marking ourself eligible for kicking.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1284400941.2684.19.camel@sbsiddha-MOBL3.sc.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- kernel/sched_fair.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index a171138..db3f674 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -3630,7 +3630,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu) if (time_before(now, nohz.next_balance)) return 0; - if (!rq->nr_running) + if (rq->idle_at_tick) return 0; first_pick_cpu = atomic_read(&nohz.first_pick_cpu);
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