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Subject[PATCH 6/6] sched: Add a lock break for PREEMPT=y
Since load-balancing can hold rq->locks for quite a long while, allow
breaking out early when there is lock contention.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/sched_fair.c | 4 ++++
1 file changed, 4 insertions(+)
Index: linux-2.6/kernel/sched_fair.c
===================================================================
--- linux-2.6.orig/kernel/sched_fair.c
+++ linux-2.6/kernel/sched_fair.c
@@ -2065,6 +2065,10 @@ static int move_tasks(struct rq *this_rq
*/
if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
break;
+
+ if (raw_spin_is_contended(&this_rq->lock) ||
+ raw_spin_is_contended(&busiest->lock))
+ break;
#endif
} while (load_moved && max_load_move > total_load_moved);

--



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