From mboxrd@z Thu Jan  1 00:00:00 1970
From: Folkert van Heusden <folkert@vanheusden.com>
Subject: Re: [GIT PULL] adaptive spinning mutexes
Date: Fri, 16 Jan 2009 15:07:34 +0100
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Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@elte.hu>, Matthew Wilcox <matthew@wil.cx>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
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	Andi Kleen <andi@firstfloor.org>,
	Chris Mason <chris.mason@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
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	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>,
	Dmitry Adamushko <dmitry.adamushko@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
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> So I don't dispute at all that "mutex with spinning" performs better than 
> a mutex, but I _do_ claim that it has some potentially huge downsides 
> compared to a real spinlock. It may perform as well as a spinlock in the 
> nice common case, but then when you hit the non-common case you see the 
> difference between well-written code and badly written code.

Make it mount-point dependant. Then your mail-spool can use the spinlock
version and e.g. the /usr filesystem uses regular mutexes. Might be
tricky to implement I guess.


Folkert van Heusden

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