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Subject: Re: Neverending story with incomplete tablebases

Author: Robert Hyatt

Date: 07:29:51 08/19/03

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On August 18, 2003 at 12:08:35, Christophe Theron wrote:

>On August 17, 2003 at 22:15:53, Robert Hyatt wrote:
>
>>On August 17, 2003 at 03:37:22, Johan de Koning wrote:
>>
>>>On August 16, 2003 at 05:13:23, Gian-Carlo Pascutto wrote:
>>>
>>>>On August 16, 2003 at 03:24:47, Johan de Koning wrote:
>>>>
>>>>>>Nondeterminism is something you can live with. Forget about getting
>>>>>>the engine working on multiprocessor if you don't.
>>>>>
>>>>>So far you sound like someone trying to mimic Vincent. :-)
>>>>
>>>>But you sound like someone who avoided my point :)
>>>>
>>>>At some point you must choose between determinism and performance.
>>>>I don't want to go to lengths to keep the engine deterministic only
>>>>to find out later it can't be maintained AND I've lost time and
>>>>speed trying to put off the inevitable.
>>>
>>>I'm not avoiding your point, I'm simply denying it. :-)
>>>
>>>There isn't such a thing as the point of no determinism, there are many points
>>>at which choices can be made. If performance gain is small (playing games) I
>>>will prefer determinism and simplicity. If gain is large (interactive analysis)
>>>I will prefer determinism and perfection. In case determinism is impossible
>>>(deep) I will prefer to maintain determinism for all other cases.
>>>
>>>>Hence the Santa Claus reference. You can stubbornly keep believing,
>>>>but one day, he'll stop bringing presents. Or maybe it was just me who
>>>>was a bad boy.
>>>
>>>If you quit being a bad boy Santa will return. :-)
>>>
>>>... Johan
>>
>>
>>If you ever do a parallel search, forget about determinism.  If you don't,
>>forget about winning games.  :)  In another 5 years _all_ computers will
>>have more than one cpu, on the same chip.
>
>
>
>Bob it seems that you have a very selective definition of the term "computer"
>and that you have chosen to ignore a very large part of the computerized devices
>that real people use every day.
>
>Less than 5% of all the computers on the planet will have more than one CPU in
>10 years from now.

Would you care to make a wager?  100% of _all_ intel processors sold today
have two procesors, in a form called "hyper-threading".  This will be extended
over the next few years until a single "cpu" is really two or four completely
independent processors.

Just hide and watch...

And no, I don't care about palms and the like.  I'm talking about the
traditional desktop/laptop PC.  Times they are a'changing...

>
>I would even tend to think that at this time and in the foreseeable future the
>percentage of multiple CPU computers is not going to grow (in the population of
>all the computers built every year).

You had better check your numbers.  I just taught a parallel programming
class with 52 students.  9 of them had dual-processor machines.


>
>In the context of this discussion, multiple CPU computers are for me computers
>that require explicit programming in order to take advantage of the extra CPUs.
>
>

Same here...  to an extent.  However, if you do as my wife does, and fire
off a huge database query, and then do something _else_ while she is waiting,
then that second processor comes in very handy, with no additional programming
on her part...

Or if you are compiling lots of stuff.

Or -you-name-it ...

>
>    Christophe
>
>
>
>
>
>>Therefore, determinism can't realistically be avoided.  Clearing the hash
>>table between searches is one of those "theoretical" issues.  It is _clearly_
>>better not to do so, from a raw performance perspective.  For testing, it has
>>its merits, and I often turn it on myself when debugging.  But _only_ when
>>debugging.



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