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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Roland McGrath <roland@redhat.com>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	Steven Rostedt <srostedt@redhat.com>
Subject: [PATCH 1/3 v2] sched: remove unlikely in pre_schedule_rt
Date: Wed, 25 Mar 2009 11:45:39 -0400	[thread overview]
Message-ID: <20090325154742.804667566@goodmis.org> (raw)
In-Reply-To: 20090325154538.916038098@goodmis.org

[-- Attachment #1: 0001-sched-remove-unlikely-in-pre_schedule_rt.patch --]
[-- Type: text/plain, Size: 1309 bytes --]

From: Steven Rostedt <rostedt@goodmis.org>

Impact: clean up

The annotated branch profiler shows that the unlikely used by
pre_schedule_rt is always incorrect. This makes sense because in
sched.c we have:

	if (prev->sched_class->pre_schedule)
		prev->sched_class->pre_schedule(rq, prev);

And we are saying that prev is unlikely to be an rt task. This looks
more like a likely candidate to me.

Here's the annotated branch profiler output:

 correct incorrect  %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
       0     4244 100 pre_schedule_rt                sched_rt.c           1263

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/sched_rt.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index bac1061..537af77 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1260,7 +1260,7 @@ static int pull_rt_task(struct rq *this_rq)
 static void pre_schedule_rt(struct rq *rq, struct task_struct *prev)
 {
 	/* Try to pull RT tasks here if we lower this rq's prio */
-	if (unlikely(rt_task(prev)) && rq->rt.highest_prio > prev->prio)
+	if (rt_task(prev) && rq->rt.highest_prio > prev->prio)
 		pull_rt_task(rq);
 }
 
-- 
1.6.2

-- 

  reply	other threads:[~2009-03-25 15:48 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-03-25 15:45 [PATCH 0/3 v2] [GIT PULL] remove unlikelys Steven Rostedt
2009-03-25 15:45 ` Steven Rostedt [this message]
2009-03-25 15:45 ` [PATCH 2/3 v2] sched: remove unlikelys from sched_move_task Steven Rostedt
2009-03-25 15:45 ` [PATCH 3/3 v2] mm: remove unlikelys for unlock in rmap.c Steven Rostedt
2009-03-25 15:49 ` [PATCH 0/3 v2] [GIT PULL] remove unlikelys Steven Rostedt
2009-03-25 16:19 ` Ingo Molnar

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