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Subject: Re: To Vasik - What is the progress of MP Rybka ?

Author: Jay Urbanski

Date: 15:41:30 01/19/06

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On January 19, 2006 at 08:18:35, Vasik Rajlich wrote:

>On January 19, 2006 at 03:48:34, Tord Romstad wrote:
>
>>On January 18, 2006 at 22:26:06, Jay Urbanski wrote:
>>
>>>On January 18, 2006 at 17:55:55, Dann Corbit wrote:
>>>
>>>>Executables are heavyweight processes that heavily consume resources and threads
>>>>are lightweight processes which consume less resources.  But a threaded server
>>>>needs any global variables to have write-access gated with a critical section
>>>>whereas a global in a spawned server has no effect (since each server is a
>>>>single process running a single thread of execution).
>>>>
>>>>It is better, but much harder, to write a threaded chess engine.
>>>
>>>
>>>Very true but with nearly all processor improvements in the immediate future
>>>coming from more cores/threads - it will likely be worth the effort to bite the
>>>bullet and learn to write good threaded code at some point.
>>
>>Why?  Wouldn't a chess engine using multiple processes and
>>shared memory be just as fast as a similar program with
>>multiple threads on a computer with several CPUs (or CPUs
>>with multiple cores)?  I thought the engine using processes
>>would just consume a bit more memory, and not have any
>>significant disadvantages apart from that.
>>
>>I'm not saying that you are wrong, of course.  I am totally
>>ignorant about this subject, and I ask in order to learn more.
>>
>>Tord
>
>Dann and Jay are I guess talking about the mp implementation of just sharing the
>hash table. It's a very cheap way to get some performance benefit, and I am
>thinking about it as a lazy way out for the time being.
>
>Indeed I realize that multi-threaded apps are probably the future. It's just a
>question of finding the time to do this (and taking this time away from other
>tasks).
>
>Vas

So, my $0.02 is that I'd prefer an SMP version sooner even if it's non-optimal,
and you can take the time to a better job with it at your leisure. :)

Idle CPUs seem like such a waste to me...



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