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

Author: Jasmine Baer

Date: 12:53:06 01/02/04

Go up one level in this thread


On January 02, 2004 at 12:16:35, Anthony Cozzie wrote:

>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.
>>
>>That means a lot to ME.  Certainly not garbage in my opinion.
>>
>>Steve
>
>I'm only going to say this once, so pay attention.
>
>A P4 with hyperthreading is _A SINGLE CPU_ that _TRICKS_ windows into thinking
>it is two.  If you still think you have two CPUs, try running two chess engines
>at once.  I did not say "P4 is worthless for computer chess" (although I prefer
>my dual opteron :).  My point is just that if Intel removed HT from the chip you
>would not know the difference.  Everywhere I go I run into people that think its
>two CPUs.  Its unbelievably annoying.
>
>The reason Intel put hyperthreading in the P4 is to help it with databases.
>When a running a database, the processor spends a lot of time waiting for
>memory.  With HT, it can get useful work to do from the other thread while one
>blocks on the memory system.
>
>anthony

Just so people don't freak out and turn this into a flame session, or a
nauseating AMD vs. Intel session...

I guess the question about these P4 processors with Hyperthreading can be broken
into two parts:

1.  Does hyperthreading help the computer chess program user get more "stuff"
done simultaneously on his/her PC?

So far, in my limited experience, I've been happy with the processor.  Like a
previous poster mentioned, the PC is no longer useless when it is evaluating a
position.  This is really great for me - I can let ol' Fritz run his little buns
off on a position while at the same time scanning a picture for my son's
project, download egtb from Dr. Hyatt's ftp site, get the latest virus
definitions installed, zip up a large file, and work on a presentation for work.

2.  Does hyperthreading increase the performance of a chess engine when playing
against another chess engine?

In other words, say I have two nearly identical PCs hooked to the Internet, with
the only difference being that one PC had the P4 2.8 Ghz w/HT and the other had
the P4 2.8 Ghz w/o HT.  I log on to playchess.com with both PCs, and started
playing a bunch of computer games against all comers.  If I were to play enough
games to have a large enough sample, would the PC with HT perform better than,
the same as, or worse than the PC w/o HT?  In other words, which PC would
produce higher quality games?

What if both PCs played against each other with an identical chess engine?




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