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Subject: Re: HyperThreading & Comp v Comp matches

Author: Martin Baumung

Date: 10:02:36 11/22/04

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On November 22, 2004 at 11:23:53, Robert Hyatt wrote:

>On November 22, 2004 at 10:48:02, Steve Maughan wrote:
>
>>I have a relatively new machine that has a P4 with Hyperthreading.  I've
>>recently installed Shredder 8 and Gandalf 6.  When playing a match I switched to
>>the Task Manager to look at the memory usage and noticed that when Gandalf was
>>thinking, according to the TM, it was only using 50% of the CPU while Shredder 8
>>was using 100% (both had Ponder = off).  On further investigation Shredder was
>>using 2 threads in the engine.  Looking at the speed, both were getting
>>approximately the same nps which is inline with other machines I have tested
>>them on.
>>
>>So the question is - does the Task Manager report the CPU resource usage
>>incorrectly in this situation i.e. 50% = 100% usage of 1 processor?  I'm
>>reasonably sure that this is the case but wanted to check.
>>
>>Thanks,
>>
>>Steve Maughan
>
>
>It is difficult for _any_ program to figure out what is going on, since
>hyper-threading makes the O/S think there are two equal CPUs, when there really
>is not...  for engine vs engine you should turn it off in the BIOS...

maybe a silly question, but why should one turn HT off - at least for engine
matches without pondering? So far I didn't encounter any problems. I've only
tried Shredder 8, but it gets a few extra nps with HT.

Cheers,

Martin



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