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Subject: Re: A question for those with multiprocessor machines

Author: Vincent Diepeveen

Date: 17:24:26 02/01/01

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On February 01, 2001 at 20:17:34, Robert Pawlak wrote:

>Hello all,
>
>I was wondering what kind of performacne increase one could expect (if any) when
>running a chess engine that is _not_ designed for multiple processors on a
>multiprocessor machine.
>
>For example, say I have a performance of X on a single processor machine. What
>performance can I expect with two processors? I can see where this might
>approach 2X for a program designed for dual operation, but what about one that
>is not? Let's assume also that I am running win2K.
>
>The reason I ask is that I've looked at dual machines running Matlab 5.x, which
>I've been told is not compiled for dual processors. And when you look at the
>processor utilization under NT, it shows the same utilization for both
>processors.

Well they lie bigtime to you then. A program which is not designed
gotta be incredible lucky if it gets any speedup from running at
2 processors. Usually there is no speedup when a program is not designed
to run on a single cpu.

However if you do more as one thing at your computer, like render things,
then usually such a program has so many threats that do things that
there is a real good speedup of using 2 processors.

Without win2k you won't be able to adress more as 1 cpu so that's
very easy choice of software. win98 nor 95 will be able to boot 2 processors
for you, so that discussion is short and simple...

But in short the average program will not get a speedup out of 2
processors.

However all the CPU intensive programs nowadays slowly use either multithreading
a lot or area multicpu nowadays so there is no big problem there to get
a speedup.

Also speedup you get when you run 2 different programs at the same time.

Say i want to render something with a simple program and on the other
cpu i want to play a game. I can do both at the same time!!!

This is real cool from having 2 processors.

For example for testing of my program i have to use 1 full cpu.
dual is usually not accurate for very accurate tests so i need
to run the test at 1 cpu then for a very accurate outcome of node
counts. In the past that meant i couldn't use my computer when it
ran such a test!

Now i can go on and edit my source code and checkout played games
at the other cpu (of course i let the system automatically pick
the cpus i don't really tell it what cpu to pick to do something).

>Thanks!
>Bob

Wonder why Bob needs to answer specific windoze questions :)





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