From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH -v7][RFC]: mutex: implement adaptive spinning
Date: Thu, 8 Jan 2009 10:00:57 -0800 (PST)
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Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
	Steven Rostedt <rostedt@goodmis.org>,
	paulmck@linux.vnet.ibm.com, Gregory Haskins <ghaskins@novell.com>,
	Matthew Wilcox <matthew@wil.cx>,
	Andi Kleen <andi@firstfloor.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-btrfs <linux-btrfs@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nick Piggin <npiggin@suse.de>,
	Peter Morreale <pmorreale@novell.com>,
	Sven Dietrich <SDietrich@novell.com>
To: Chris Mason <chris.mason@oracle.com>
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Unrelated:

On Thu, 8 Jan 2009, Chris Mason wrote:
>
> RIP: 0010:[<ffffffff8024f4de>]  [<ffffffff8024f4de>] __cmpxchg+0x36/0x3f

Ouch. HOW THE HELL DID THAT NOT GET INLINED?

cmpxchg() is a _single_ instruction if it's inlined, but it's a horrible 
mess of dynamic conditionals on the (constant - per call-site) size 
argument if it isn't.

It looks like you probably enabled the "let gcc mess up inlining" config 
option.

Ingo - I think we need to remove that crap again. Because gcc gets the 
inlining horribly horribly wrong. As usual.

				Linus