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Subject: Re: Quad scaling ?

Author: Robert Hyatt

Date: 09:27:11 08/24/05

Go up one level in this thread


On August 24, 2005 at 12:05:09, Vincent Diepeveen wrote:

>On August 24, 2005 at 08:59:28, Thomas Logan wrote:
>
>>On August 24, 2005 at 08:47:33, Vincent Diepeveen wrote:
>>
>>>On August 24, 2005 at 08:20:25, Thomas Logan wrote:
>>>
>>>>Does anyone have scaling figures for various deep programs
>>>>
>>>>and systems with 2 dual core processors
>>>>
>>>>Tom
>>>
>>>hi, i just started a test at my k7 single cpu machine
>>>to compare an output created at a quad dual core 1.8Ghz.
>>>
>>>The test is over 213 positiosn and statistical significant.
>>>
>>>I expect results within 2 weeks.
>>>
>>>You can calculate what time it takes 70 minutes * 213 positions.
>>>
>>>one thing already seems sure:
>>>
>>>x86-64 has no scaling problems with big hashtables, x86 has.
>>>
>>>Vincent
>>
>>Hello Vincent
>>
>>Thank you
>>
>>Are you using Diep ?
>>
>>Any knowledge concerning Fritz, Junior or Shredder
>>Please post your results when obtained
>
>Shredder is scaling 3.3 at quad single core, so that'll be like scaling of 4 at
>dual core quad or so?
>
>junior was single core and fritz will not be scaling well either (deepfritz8).
>
>We know all this already from 8 cpu Xeon machines in fact. See results donninger
>posted once.
>
>If you don't run well at 8 cpu xeon then forget dual core.


Not necessarily.  8cpu xeon was a kludge.  Has same memory bandwidth as a 4-cpu
xeon.  Which means extra 4 cpus just cause a significant memory bottleneck.  I
ran on one of these multiple times.  Programs with little memory traffic scale
well, but those that require any reasonable memory access fall flat.  Dual cores
are not quite that bad but have the same basic problem, two cpus sharing a
single hypertransport and single memory controller, so each node (AMD
terminology) has internal contention that the single-core boxes do not.

But the problems are solvable...  except perhaps for the 8-way xeon which is
just a bad box...  at least the ones I tested on (Dell was one vendor) were...


>
>>Thanks again
>>
>>Tom



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