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Subject: Re: A "mystery" with dual core

Author: James T. Walker

Date: 09:45:14 11/02/05

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On November 02, 2005 at 12:37:09, Chessfun wrote:

>On November 02, 2005 at 12:28:37, Gregory Owett wrote:
>
>>On November 02, 2005 at 11:24:10, Chessfun wrote:
>>
>>>On November 02, 2005 at 10:57:35, Gregory Owett wrote:
>>>
>>>>Recently, I launched two tournaments (ponder off) with the same participants, on
>>>>two different machines.  Here results:
>>>>
>>>>On P4 2.2 T=15'+5" :
>>>>
>>>>1. Fruit 2.2.1 KS104     7,5 / 10
>>>>2. Shredder 9 UCI        5,5
>>>>3. Shredder 7.04 CLm1    5            25,00
>>>>4. Fruit 2.2.1 Uri       5            23,00
>>>>5. Shredder 8 CLD        3,5          17,25
>>>>6. Fruit 2.2.1           3,5          16,50
>>>>
>>>>
>>>>On AMD x2 dual core 4800+   T=15'+5" :
>>>>
>>>>1. Shredder 8 CLD        6,5 / 10
>>>>2. Fruit 2.2.1 Uri       6
>>>>3. Fruit 2.2.1 KS104     5            25,75
>>>>4. Fruit 2.2.1           5            24,25
>>>>5. Shredder 9 UCI        4,5
>>>>6. Shredder 7.04 CLm1    3
>>>>
>>>>
>>>>The success of Shredder 8 CLD (UCI) on the dual core machine, confirms what the
>>>>task manager indicated, i.e. which Shredder 8 CLD, in spite of it is
>>>>single-threaded engine, used 99% of the two processors, while all the others
>>>>used 50%, in other words, only one processor.
>>>>
>>>
>>>Well both Shredder 7 and 8 were SMP capable. So you must edit engine parameters
>>>and tell it to use only one thread.
>>>
>>>>(Native engines, as F8, J9, H9, CT15 etc...use 99% too.)
>>>None of those in single versions are SMP capable so I would say on a dual that
>>>is impossible.
>>>
>>>>Peter Kasinski thinks that Windows task manager is confused and carryforwards
>>>>incorrectly.
>>>
>>>I have run every engine and observed task manager and it seems to switch all
>>>correctly I've seen no odd behavior at all.
>>>
>>>Sarah.
>>
>>The goal, it is rather than the engines use two processors instead of one!  But
>>by editing the parameters, for example for Shredder, there is no possibility of
>>choosing one or two processors to be used.
>
>Of course there is. Open the engine parameters and change threads from 2 to 1
>it's there believe me I've done it.
>
>Sarah.

Yes Sarah I just started a match between Fruit and Shredder 8 in Chessbase GUI.
I left pondering on and left Shredder at 2 threads.  It seems that sometimes
Fruit gets 50% and sometimes it's fighting Shredder for cpu time and only gets
25%.  Also sometimes it's inbetween 25%-50% for Fruit.  So It's only fair to set
Shredder to 1 thread in this case.
Jim



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