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From: Ingo Molnar <mingo@elte.hu>
To: Nick Piggin <piggin@cyberone.com.au>
Cc: Andrew Morton <akpm@osdl.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/5] 2.6.0 fix preempt ctx switch accounting
Date: Sat, 20 Dec 2003 20:22:38 +0100	[thread overview]
Message-ID: <20031220192238.GA30970@elte.hu> (raw)
In-Reply-To: <3FE46885.2030905@cyberone.com.au>

* Nick Piggin <piggin@cyberone.com.au> wrote:

> Make sure to count kernel preemption as a context switch. A short cut
> has been preventing it.

i'd prefer the much simpler patch below. This also keeps the kernel
preemption logic isolated instead of mixing it into the normal path.

	Ingo

--- linux/kernel/sched.c.orig	
+++ linux/kernel/sched.c	
@@ -1520,8 +1520,10 @@ need_resched:
 	 * if entering off of a kernel preemption go straight
 	 * to picking the next task.
 	 */
-	if (unlikely(preempt_count() & PREEMPT_ACTIVE))
+	if (unlikely(preempt_count() & PREEMPT_ACTIVE)) {
+		prev->nivcsw++;
 		goto pick_next_task;
+	}
 
 	switch (prev->state) {
 	case TASK_INTERRUPTIBLE:

  parent reply	other threads:[~2003-12-20 19:23 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-20 15:19 [PATCH 1/5] 2.6.0 fix preempt ctx switch accounting Nick Piggin
2003-12-20 15:20 ` [PATCH 2/5] 2.6.0 sched fork cleanup Nick Piggin
2003-12-20 15:21   ` [PATCH 3/5] 2.6.0 sched migrate comment Nick Piggin
2003-12-20 15:22     ` [PATCH 4/5] 2.6.0 sched style fixes Nick Piggin
2003-12-20 15:24       ` [PATCH 5/5] 2.6.0 sched affinity race Nick Piggin
2003-12-20 21:07       ` [PATCH 4/5] 2.6.0 sched style fixes Ingo Molnar
2003-12-20 20:26     ` [PATCH 3/5] 2.6.0 sched migrate comment Ingo Molnar
2003-12-20 23:19       ` Nick Piggin
2003-12-20 19:55   ` [PATCH 2/5] 2.6.0 sched fork cleanup Ingo Molnar
2003-12-20 23:17     ` Nick Piggin
2003-12-20 19:22 ` Ingo Molnar [this message]
2003-12-20 19:52   ` [PATCH 1/5] 2.6.0 fix preempt ctx switch accounting Rob Love
2003-12-20 20:07   ` Linus Torvalds
2003-12-20 21:32     ` Ingo Molnar
2003-12-20 23:15     ` Nick Piggin

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