linux-kernel - [PATCH 2/2] sched/rt: Optimizate task_woken

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Date:	Fri,  1 May 2015 00:33:18 +0800
From:	Xunlei Pang <xlpang@....com>
To:	linux-kernel@...r.kernel.org
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Juri Lelli <juri.lelli@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Xunlei Pang <pang.xunlei@...aro.org>
Subject: [PATCH 2/2] sched/rt: Optimizate task_woken_rt()

From: Xunlei Pang <pang.xunlei@...aro.org>

- Remove "has_pushable_tasks(rq)" condition, because for queued p,
"!task_running(rq, p)" and "p->nr_cpus_allowed > 1" implies true
"has_pushable_tasks(rq)".

- Remove "!test_tsk_need_resched(rq->curr)" condition, because
the flag might be set right before the waking up, but we still
need to push equal or lower priority tasks, it should be removed.
Without this condition, we actually get the right logic.

Signed-off-by: Xunlei Pang <pang.xunlei@...aro.org>
---
 kernel/sched/rt.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index a9d33a3..9d735da 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2233,8 +2233,6 @@ out:
 static void task_woken_rt(struct rq *rq, struct task_struct *p)
 {
 	if (!task_running(rq, p) &&
-	    !test_tsk_need_resched(rq->curr) &&
-	    has_pushable_tasks(rq) &&
 	    p->nr_cpus_allowed > 1 &&
 	    (dl_task(rq->curr) || rt_task(rq->curr)) &&
 	    (rq->curr->nr_cpus_allowed < 2 ||
-- 
1.9.1


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