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Subject: Re: Question of SMP Tiger from CSS

Author: Robert Hyatt

Date: 10:15:13 05/02/01

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On May 02, 2001 at 12:21:42, Uri Blass wrote:

>On May 02, 2001 at 11:43:10, Robert Hyatt wrote:
>
>>On May 02, 2001 at 02:32:27, Chessfun wrote:
>>
>>>
>>>
>>>>A SMP version of Tiger exists. Actually existed last year.
>>>>A friend of mine went on a long hollyday last year, and instead of leaving his
>>>>dual system unused at home, he lent it to me.
>>>>I developped a SMP version on top of Chess Tiger 12.2.
>>>>But as I already told several times SMP was not a priority for me. So once I had
>>>>SMP working, I disabled the code in Tiger's source code. I did not erase it of
>>>>course, I just deactivated the relevant parts of code.
>>>>Since then, Tiger has evolved on many points, including a different internal
>>>>move coding and a different hash table structure.
>>>>So now I cannot just reactivate the SMP code. It will not work directly. I need
>>>>to reactivate it and adapt it to what has changed in the latest Tiger engines.
>>>
>>>>It's not a lot of work. The principle of the SMP algorithm does not have to be
>>>>rewritten, it's just a matter of adapting the code.
>>>
>>>>I just asked for a little delay in order to do that and to double check that
>>>>everything was working.
>>>
>>>>You can have your doubts about this SMP version, but after all if I send a SMP
>>>>Tiger that crashes in Cadaques, I will be the one to look stupid, not the
>>>>organizers of the Kramnik match.
>>
>>
>>
>>I'm willing to let a lot of hype slip by, but not _everything_.  It seems you
>>are saying you developed an SMP search over a weekend.  I have too much
>>experience with parallel search to believe that.  I don't think I could even
>>steal my SMP code and move it into something like gnuchess in a single weekend,
>>and get it working reliably.
>>
>>Believe me, this is _not_ a weekend task.  It is not a month task.  It is really
>>not a year task.
>>
>>I would not ever believe there is an SMP Rebel until there is a windows version
>>of Rebel.  DOS is _not_ capable of running on an SMP platform itself, much less
>>managing threads in any way...  I have a _really_ hard time believing that a
>>robust SMP algorithm is a week-end project, unless I am a far worse programmer
>>than I believe.
>
>It is also possible that there is another way to do programs parallel that other
>did not think about and I do not know what is the speed improvement that
>Christophe got from the parallel program.
>
>I understand that patzer used a parallel version of their program and it was not
>hard for the programmer to do it parallel.
>The speed improvement from 2 processors in that case was 1.2
>
>The interesting question is what is the speed improvement that christophe got
>from the parallel tiger12.2
>
>Uri


1.2 I don't call a parallel search.  that might mean 1.3x or 1.4x with 4 cpus?
it would be better to spend the time cleaning up and optimizing the code, as
the speedup would probably be more...



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