From: Chen, Kenneth W <kenneth.w.chen@intel.com>
Date: Wed, 9 Nov 2005 23:45:29 +0000 (-0800)
Subject: [PATCH] optimize activate_task()
X-Git-Tag: v2.6.15-rc1~56
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a47ab9371e664952b1104a70ec8e9b74db3f7a5f;p=linux-2.6

[PATCH] optimize activate_task()

recalc_task_prio() is called from activate_task() to calculate dynamic
priority and interactive credit for the activating task.  For real-time
scheduling process, all that dynamic calculation is thrown away at the end
because rt priority is fixed.  Patch to optimize recalc_task_prio() away
for rt processes.

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <piggin@cyberone.com.au>
Cc: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index ac3f5cc3bb..b6506671b2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -815,7 +815,8 @@ static void activate_task(task_t *p, runqueue_t *rq, int local)
 	}
 #endif
 
-	p->prio = recalc_task_prio(p, now);
+	if (!rt_task(p))
+		p->prio = recalc_task_prio(p, now);
 
 	/*
 	 * This checks to make sure it's not an uninterruptible task