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Date: Fri, 13 Apr 2007 12:31:13 +0100
Subject: Re: [PATCH 0/4] i386 - pte update optimizations
From: Keir Fraser <keir@xensource.com>
To: Andi Kleen <andi@firstfloor.org>
CC: Zachary Amsden <zach@vmware.com>, "H. Peter Anvin" <hpa@zytor.com>,
       Andrew Morton <akpm@osdl.org>,
       Virtualization Mailing List <virtualization@lists.osdl.org>,
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       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On 13/4/07 13:27, "Andi Kleen" <andi@firstfloor.org> wrote:

>> LOCKed instruction suck really badly on the netburst microarchitecture (like
>> factor of 10x, or not far off). I think it's probably because of their side
>> effect of serialising memory accesses, causing horrible pipeline stalls.
> 
> Unfortunately they tend to be HyperThreaded usually (except for early ones
> and Celerons) and need the LOCK anyways.

Fair point, although quite a few people disable HT.

 -- Keir