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Date: Tue, 24 Sep 2002 23:03:50 -0700
From: "Martin J. Bligh" <mbligh@aracnet.com>
Reply-To: "Martin J. Bligh" <mbligh@aracnet.com>
To: Andrew Morton <akpm@digeo.com>, William Lee Irwin III <wli@holomorphy.com>
cc: linux-kernel@vger.kernel.org
Subject: Re: 2.5.38-mm2 dbench $N times
Message-ID: <297318451.1032908628@[10.10.2.3]>
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>> Not sure. This is boot bay SCSI crud, but single-disk FC looks
>> *worse* for no obvious reason. Multiple disk tests do much better
>> (about matching the el-scruffo PC numbers above).
> 
> dbench 16 on that sort of machine is a memory bandwidth test.
> And a dcache lock exerciser.  It basically doesn't touch the
> disk.  Something very bad is happening.

Does dbench have any sort of CPU locality between who read it 
into pagecache, and who read it out again? If not, you stand
7/8 chance of being on the wrong node, and getting 1/20 of the
mem bandwidth ....

M.

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