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Message-Id: <1231524964.442.103.camel@twins>
Date: Fri, 09 Jan 2009 19:16:04 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Chris Mason <chris.mason@...cle.com>,
Ingo Molnar <mingo@...e.hu>, paulmck@...ux.vnet.ibm.com,
Gregory Haskins <ghaskins@...ell.com>,
Matthew Wilcox <matthew@....cx>,
Andi Kleen <andi@...stfloor.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
linux-btrfs <linux-btrfs@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Nick Piggin <npiggin@...e.de>,
Peter Morreale <pmorreale@...ell.com>,
Sven Dietrich <SDietrich@...ell.com>
Subject: Re: [PATCH -v7][RFC]: mutex: implement adaptive spinning
On Fri, 2009-01-09 at 11:44 -0500, Steven Rostedt wrote:
> When we get to the schedule() it then needs to be a:
>
> preempt_enable_no_resched();
> schedule();
On that note:
Index: linux-2.6/kernel/mutex.c
===================================================================
--- linux-2.6.orig/kernel/mutex.c
+++ linux-2.6/kernel/mutex.c
@@ -220,7 +220,9 @@ __mutex_lock_common(struct mutex *lock,
__set_task_state(task, state);
/* didnt get the lock, go to sleep: */
+ preempt_disable();
spin_unlock_mutex(&lock->wait_lock, flags);
+ preempt_enable_no_resched();
schedule();
spin_lock_mutex(&lock->wait_lock, flags);
}
actually improves mutex performance on PREEMPT=y
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