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Subject: Re: Crafty on dual core

Author: Robert Hyatt

Date: 13:07:29 11/07/05

Go up one level in this thread


On November 07, 2005 at 03:29:49, Gregory Owett wrote:

>On November 06, 2005 at 19:57:38, Robert Hyatt wrote:
>
>>On November 06, 2005 at 09:40:13, Bryan Hofmann wrote:
>>
>>>On November 06, 2005 at 09:03:04, Andreas Guettinger wrote:
>>>
>>>>On November 06, 2005 at 07:48:20, Bryan Hofmann wrote:
>>>>
>>>>>On November 06, 2005 at 07:29:56, Gregory Owett wrote:
>>>>>
>>>>>>On November 06, 2005 at 07:13:26, Bryan Hofmann wrote:
>>>>>>
>>>>>>>On November 05, 2005 at 08:47:34, Gregory Owett wrote:
>>>>>>>
>>>>>>>>When Crafty plays vs another engine, in adjustment "ponder=off", it is pondering
>>>>>>>>and the taskmrg indicates 99% to Crafty and 0% to the other. Even if its
>>>>>>>>adversary plays, the indicator gives him 50% and 50% to the other engine,
>>>>>>>>whereas Crafty should have 0%.  Does it profit from the time of reflection of
>>>>>>>>the other engine?  If not, why it does not release the processor?
>>>>>>>>
>>>>>>>>Gregory
>>>>>>>
>>>>>>>If you are using a version prior to 19.16 then you will see this behavior. In
>>>>>>>version prior to 19.16 Crafty does not release the parallel CPUs, even tho it is
>>>>>>>not using them (pondering/thinking).
>>>>>>>
>>>>>>>
>>>>>>>Bryan
>>>>>>
>>>>>>That explains all. I used the version 19.11 SE.
>>>>>>It is one of the best, isn't it?  Is there a better according to you?
>>>>>>
>>>>>>Thanks.
>>>>>>
>>>>>>Gregory
>>>>>
>>>>>
>>>>>I just did some checking, version 19.16 and higher will terminate the additional
>>>>>threads only when the game has ended. It will still hold on to the additional
>>>>>threads during the game even though it is not think/pondering the move. So the
>>>>>issue described still exists in all SMP version of Crafty.
>>>>>
>>>>>
>>>>>Bryan
>>>>
>>>>I don't see the problem there. Crafty could hold 100 threads and still use 0% of
>>>>CPU time. It dosen't need to release the threads when the opponent is thinking.
>>>>
>>>>regards
>>>>Andy
>>>
>>>If you have a dual core and wanted to run a match with with SMP engines with
>>>pondering off it would be a issue. Crafty even with ponder off will keep CPUs 1
>>>busy, only CPU 0 would be free for the other engine.
>>>
>>>
>>>Bryan
>>
>>
>>This is correct.  I use a "thread pool" concept where I fire up the extra
>>threads on the first search, and those processes do not terminate until the game
>>ends, to avoid the repeated overhead of starting/stopping threads throughout the
>>game.
>>
>>Moral of this is if you have two cpus, use each engine with just one CPU and
>>this won't be a problem, then you can also play ponder=on since each program can
>>use 100% of one cpu all the time...
>
>If I set ponder=on, there would not be a problem at the end-game, when the two
>programs call the tablabase at the same time?
>
>Gregory


Nope.  Windoes caches filesystem reads anyway, so things will actually be faster
for both programs...



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