[OT] Maximum performance on single processor ?

Robert G. Brown rgb at phy.duke.edu
Fri Jun 20 12:32:10 EDT 2003

On Fri, 20 Jun 2003, Marc Baaden wrote:

> Thanks for all your comments and suggestions. I realize (and some
> of you mentioned it) that you need more information to understand
> better what I am looking for.
> I have an existing application which is part of a project. I have
> the source code. It is Fortran. It *can* be parallelized, but we
> would rather spend our time on the other parts of the project
> which need to be written from scratch *first*.
> The application is to run in real time, that is the user does something
> and as a function of user input and the calculation with the fortran
> program that I described, there is a correponding feedback to the
> user on the screen (and in some Virtual Reality equipment).
> Right now, even on simple test cases, the "response time" (eg calculation
> time for a single step) of our program is on the order of the second.
> (this is for an athlon MP 2600+)
> We need to get that down to a fraction of seconds, best milli-seconds,
> in order to be usable in real time. (makes it a factor of roughly 1000)
> As I said the code can indeed be parallelized - maybe even simply cleaned
> up in some parts - but unfortunately there remains very much other important
> stuff to do. So we'd rather spend some money on a really fast CPU and not
> touch the code at the moment.
> So my question was more, what is the fastest CPU I can get for $20000
> at the moment (without explicitly parallelizing, hyperthreading or
> vectorizing my code).

Ain't happenin'.  The factor of 1000, I mean.  Not no way, not no how,
not without completely rewriting your code.

>From this description, the ONLY thing you should be working on is
rewriting the code from scratch, doing a serious job of algorithm
analysis, optimization, vectorization, parallelization, and (IMHO) not
in fortran.

If it is graphics/visualization, consider studying things like computer
games, render farms, openGL, and various libraries and hardware devices
that can move the work required into custom processors.  It could be
that you are using Fortran to do various data transformations in poorly
written software that are now done extremely rapidly in highly
specialized hardware (not even on a "CPU" -- on an offboard coprocessor
with its own memory and instruction set).  Or not.

However, you're not getting a factor of 1000 relative to an Athlon 2600
on any hardware in existence for $20K.  I only wish...:-)


> Cheers,
>   Marc Baaden

Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu

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