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Subject: Re: Intel Hyperthreading and Ponder (Permanent Brain)

Author: Matthew McKnight

Date: 08:45:57 01/02/04

Go up one level in this thread


On January 02, 2004 at 11:24:19, Steven J. Brann wrote:

>On January 02, 2004 at 11:05:41, Anthony Cozzie wrote:
>
>>On January 02, 2004 at 09:57:38, Jasmine Baer wrote:
>>
>>>I've seen it written that under the following conditions:
>>>
>>>1.  Engine vs. Engine match or tournament
>>>2.  Held on a single computer with a single processor
>>>
>>>having ponder=ON(or Permanent Brain in the Fritz GUI) will impact the play of
>>>the engines since the each individual engine would not have full access to the
>>>processor during its own turn.
>>>
>>>First, is this true?
>>>
>>>Second, is this issue, if it actually is an issue, something that is eliminated
>>>by running a two-processor system?
>>>
>>>And, finally, does anyone have any solid insight on how ponder=off/on or
>>>Permanent Brain works on a Pentium 4 with Hyperthreading?
>>>
>>>Thanks.
>>
>>Ponder means that the engine thinks while its opponent moves.  Since there is
>>only 1 cpu, and both engines are thinking, they get half the cpu.
>>
>>HT is garbage for computer chess.  A pentium 4 is ONE core.  HT is designed for
>>applications that spend most of their time in the memory system.
>>
>>anthony
>
>To me, my 3.0G HT machine is NOT garbage for computer chess.  When it is
>thinking about a position it takes up 50% of the CPU and is still much much
>faster than my 1.9G P4 machine.  When analyzing a position with my 1.9G P4, the
>machine would be rendered useless for using any other application while it was
>thinking about a position.
>
>So, HT enables me to accomplish other things on the machine at the same time ...
>email, reviewing this site, chat with video, Word, Excel ... and
>performance-wise its as if the chess program isn't running at all.  I'm
>analyzing a position as I write this.

Yes this is what HT does, but it's also what every other modern CPU does...
It's just Intel's latest buzzword for a well-known technology called pipelining.
 I believe what the author meant by the word "garbage" is simply that you
shouldn't believe you _need_ a machine with HT for computer chess.

Interestingly enough, pipelining benefits from you running more than one program
at a time.  That is to say that if you were to run two processes, each using 50%
of the cpu for 1 hour, they would get more work done than the sum of work done
from both processes individually at 100% for one hour each.  The increased
difference between the types of programs in the experiment, increases the
results.  This is a product of the enormous clock rate!! The only way to get
such a speed is to try and run instructions simultaneously, and this is why you
do better when you run two completely different programs (i.e. working on
different things).

Personally, I would love to have a PIV 3.0ghz HT regardless of HT's
significance, that machine is smokin.

>
>That means a lot to ME.  Certainly not garbage in my opinion.
>
>Steve



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