[Beowulf] g77 limits...

Kozin, I (Igor) i.kozin at dl.ac.uk
Wed Feb 22 17:10:48 PST 2006

> > > > archives because it is so time dependent an answer.  In particular, can
> > > > an x64 box with a modern linux kernel and a modern g77 allocate 4-8 GB
> > >
> > > isn't "modern g77" a bit of an oxymoron?  
> > > (given the existence of gfortran, I mean).
> > 
> > Oh, I was totally confused by the combination "g77" and "allocate".
> > 
> > Robert, try g95. Although it is not part of the gnu stream but
> > it seems more stable at the moment. It works stand alone.
> why g95?  gfortran _is_ part of the normal GCC stream, and 4.02
> seems fairly mature (4.1 is about to come out).

it is and is being improved as we speak (i hope).
but i'd still claim g95 is a bit more reliable at the moment
than gfortran.

> > However in terms of performance you may lose considerably
> > compared to commercial compilers.
> these days, gcc does pretty well compared to commercial compilers, if you
> take care to -march, -msse2 and other tweaks.  I can't see why this 
> pretty respectable code quality for c/c++/etc wouldn't also apply to
> fortran.  even the ada and java people seem to be almost happy with 
> gcc's code-gen...

in addition to what Greg said in the respect to fortran there are two other 
factors: 1) the transition 3.x -> 4.x was a major one;
2) g77 has nothing in common with gfortran/g95.
while we gained more features the performance dropped
simply because gfortran/g95/gcc4 are not mature enough.
let's hope that in time gfortran will be where g77 was but we are not there yet.
even as far as gcc goes people are not rushing up to upgrade to gcc 4.0

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