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Subject: Re: spinlock efficiency problem [was 2.5.57 IO slowdown with
	CONFIG_PREEMPT enabled)
From: Alan <alan@lxorguk.ukuu.org.uk>
To: Joe Korty <joe.korty@ccur.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
In-Reply-To: <200301202258.WAA02263@rudolph.ccur.com>
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Date: 21 Jan 2003 03:22:42 +0000
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On Mon, 2003-01-20 at 22:58, Joe Korty wrote:
> The new, preemptable spin_lock() spins on an atomic bus-locking
> read/write instead of an ordinary read, as the original spin_lock
> implementation did.  Perhaps that is the source of the inefficiency
> being seen.

Its a fairly critical "Never do this" on older intel processors and
kills the box very efficiently so your diagnosis is extremely 
plausible