[OT] Maximum performance on single processor ?

Craig Tierney ctierney at hpti.com
Fri Jun 20 13:43:39 EDT 2003


stuff deleted....
> 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 someone else had said this I would probably have had some snide
comment and caused some sort of flame war.  However after noticing the
comment came from a helpful and knowledgeable list member I will have
to hold back.  However, I really want to know why 'not in fortran'?
Not everyone is a programming god and can visualise how a particular
piece of code is going to end up in assembler.  You can get good 
performance out of C and C++ but you have to be careful, and I still
don't know if you can beat Fortran in many cases.

In a nutshell, without starting a flamewar (too late), what's wrong
with Fortran for high performance numerical codes?

PS.  I still hate Fortran, never liked it.  However I have found that it
     does the job.

Craig


> 
> 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...:-)
> 
>    rgb
> 
> > 
> > 
> > Cheers,
> >   Marc Baaden
> > 
> > 
-- 
Craig Tierney <ctierney at hpti.com>

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