linux-kernel - [tip:sched/core] sched/rt: Further simplify pick_rt

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Date:	Sun, 3 Feb 2013 11:30:47 -0800
From:	tip-bot for Kirill Tkhai <tkhai@...dex.ru>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org, linux-rt-users@...r.kernel.org,
	rostedt@...dmis.org, tkhai@...dex.ru, tglx@...utronix.de
Subject: [tip:sched/core] sched/rt: Further simplify pick_rt_task()

Commit-ID:  60334caf37dc7c59120b21faa625534a6fffead0
Gitweb:     http://git.kernel.org/tip/60334caf37dc7c59120b21faa625534a6fffead0
Author:     Kirill Tkhai <tkhai@...dex.ru>
AuthorDate: Thu, 31 Jan 2013 18:56:17 +0400
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Sun, 3 Feb 2013 19:54:58 +0100

sched/rt: Further simplify pick_rt_task()

Function next_prio() has been removed and pull_rt_task() is the
only user of pick_next_highest_task_rt() at the moment.

pull_rt_task is not interested in p->nr_cpus_allowed, its only
interest is the fact that cpu is allowed to execute p. If
nr_cpus_allowed == 1, cpu != task_cpu(p) and cpu is allowed then
it means that task p is in the middle of the migration
techniques; the task waits until it is moved by migration
thread. So, lets pull it earlier.

Signed-off-by: Kirill V Tkhai <tkhai@...dex.ru>
Acked-by: Steven Rostedt <rostedt@...dmis.org>
Cc: Peter Zijlstra <peterz@...radead.org>
CC: linux-rt-users <linux-rt-users@...r.kernel.org>
Link: http://lkml.kernel.org/r/70871359644177@web16d.yandex.ru
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/rt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 94abca4..c25de14 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1427,8 +1427,7 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
 static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
 {
 	if (!task_running(rq, p) &&
-	    (cpu < 0 || cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) &&
-	    (p->nr_cpus_allowed > 1))
+	    cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
 		return 1;
 	return 0;
 }
--
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