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Subject: Re: ChessBrain Result

Author: Robert Hyatt

Date: 19:51:46 02/02/04

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On February 02, 2004 at 17:16:15, Vincent Diepeveen wrote:

>On February 02, 2004 at 11:47:08, Colin Frayn wrote:
>
>>On February 02, 2004 at 10:30:29, Vincent Diepeveen wrote:
>>
>>>On February 02, 2004 at 07:29:19, Colin Frayn wrote:
>>>
>>>Where can i find the logfile from this game showing search depths from
>>>chessbrain, so that i can compare at home with a single cpu engine?
>>
>>We didn't store everything so it's unlikely that this could be found.  I don't
>
>There is a central point where the decision gets made to play the move. Each
>move is based upon a certain depth, no matter how the thing searches.
>
>Trivially it has a horrible speedup, this is not important.

Then why are you so interested in it?  Didn't you say that after the WCCC
_you_ were going to post all your logs and speedup data for everyone to see?
Have you posted it?  And you ask/bug others to post theirs???

> Important is to have
>that logfile. I'm not even asking that you make things like collecting the total
>number of nodes searched (without losing system time in diep i collect
>statistics in DIEP at a central point this gets logged to the logfile).
>
>If you can save the total number of nodes searched for a team, you sure can save
>for that single game you play against a GM the logfile with the search depth in
>it that the central point had.
>
>How selective it was or wasn't is not important now. Trivially you must be
>creative the first few plies or you won't be able to get all nodes to work. In
>diep i'm forced at 460 processors to sometimes already split before nullmove
>gets made, otherwise i don't get all nodes to work simply. This where it is well
>known by everybody that splitting before or during nullmove is horrible for your
>speedup.
>

It isn't known by me.  You can split _in_ a null-move search just fine.  I do it
now, I did it in Cray Blitz.  Everyone else I know of also does it with no
problems...

of course don't let small facts get in the way of big nonsense...



>>know exact figures, but I can certainly tell you that during testing we were
>>finding the move b6! in WAC100 in well under a minute with a few hundred
>>PeerNodes whereas standalone Beowulf on my machine couldn't find it within 10
>>minutes at the time.  Part of the benefit of much more memory being thrown at
>>the problem, even if it was not linked together.
>>
>>>I am very interested knowing in how much of a speedup efficiency you get out of
>>>the thing.
>>
>>At the moment it's hideously inefficient - I noticed that when (for the first
>>time) I saw the thing running the night before the match!  At some points we
>>were wasting almost a minute each move (that I now know about, and we can fix)
>>
>>>When i ran a simulation with diep distributed at the supercomputer at 460
>>>processors, the speedup was not so good.
>>
>>It's certainly not a huge speedup at the moment, but we've got a lot of possible
>>avenues for improvement, that's for sure.  All I know is that Beo is a 2400
>>engine at best, probably worse, and we got a better performance than that, at
>>least after the first few out-of-book moves (which weren't very strong).
>>
>>Search depth is also complicated because if, e.g., the server sends out a node
>>at ply 2 and it searches for 8 ply depth, this isn't the same as searching the
>>root position to 10 ply because we're being much more creative with the depth of
>>search and pruning etc, so the exact search depth is quite variable along the
>>first ply.
>>
>>>Good luck in your effort finding sponsors.
>>
>>Thanks.  Hopefully we won't need luck any more....
>>
>>Cheers,
>>Col



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