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Message-ID: <1309545711.4303.2.camel@localhost.localdomain> Date: Sat, 02 Jul 2011 00:41:51 +0600 From: Rakib Mullick <rakib.mullick@...il.com> To: Ingo Molnar <mingo@...e.hu> Cc: Peter Zijlstra <peterz@...radead.org>, linux-kernel <linux-kernel@...r.kernel.org> Subject: [PATCH] sched: Check nr_running before calling pick_next_task in schedule(). Currently at schedule(), when we call pick_next_task we don't check whether current rq is empty or not. Since idle_balance can fail, its nice to check whether we really have any task on rq or not. If not, we can call idle_sched_class.pick_next_task straight. Signed-off-by: Rakib Mullick <rakib.mullick@...il.com> --- diff --git a/kernel/sched.c b/kernel/sched.c index 5925275..a4f4f58 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4273,7 +4273,14 @@ need_resched: idle_balance(cpu, rq); put_prev_task(rq, prev); - next = pick_next_task(rq); + /* Since idle_balance can fail, its better to check rq->nr_running. + * Otherwise we can call idle_sched_class.pick_next_task straight, + * cause we need to do some accounting. + */ + if (likely(rq->nr_running)) + next = pick_next_task(rq); + else + next = idle_sched_class.pick_next_task(rq); clear_tsk_need_resched(prev); rq->skip_clock_update = 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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