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Subject: Re: SURPRISING RESULTS P4 Xeon dual 2.8Ghz

Author: Robert Hyatt

Date: 12:19:34 12/17/02

Go up one level in this thread


On December 17, 2002 at 14:21:10, Gian-Carlo Pascutto wrote:

>On December 17, 2002 at 13:15:36, Robert Hyatt wrote:
>
>>On December 17, 2002 at 11:58:21, Gian-Carlo Pascutto wrote:
>>
>>>On December 17, 2002 at 11:27:18, Matt Taylor wrote:
>>>
>>>>Crafty gets better results with HT,
>>>
>>>In addition to what Vincent said, the data we currently
>>>have is saying exactly the opposite.
>>>
>>
>>I don't follow.  I posted the following twice already:
>
>I've done my own tests.
>
>>1 thread, SMT disabled, 24 positions, run twice, 1001.5K nps
>>2 threads, SMT disabled, same conditions,        1604.5K nps
>>3 threads, SMT enabled, same conditions,         1820.25K nps
>>4 threads, SMT enabled, same conditions,         1923.0K nps
>>
>>Hyperthreading took the 16.04.5K nps for two bare xeon processors and
>>improved that by 20%.  I can certainly post the raw data if it is important.
>>I believe 20% is definitely better than 11%.  And 20% is not something to wave
>>off as unimportant.
>
>I measured similar numbers for 1->2 cpus (24%). But this is only
>NPS increase, not the actual speedup which will be lower.

So?  That's outside the scope of the SMT/HT discussion.  The question is "does
it
work" not "does it work well for chess applications."


>
>--
>GCP



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