Robert G. Brown wrote:
Dear List,
What are the current limits on the size of arrays that can be allocated
in g77? I know that this is almost a FAQ, but I cannot look back at the
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
arrays (presuming, of course, that one uses a long int for an index)? I
have seen references to "using an offset" in a few google hits (that
were not very informative) -- does that basically mean doing pointer
arithmetic in fortran?
it works without too much worrying about long ints
in g77 if you use the compile switch "-mcmodel=medium" ou -mcmodel=large.
(at least it is my experience on an Opteron64 box with Centos4.0 and
16Go of RAM)
d) Where commercial compilers aren't a viable option (although I
suggested them) -- the software has to build and be usable by e.g.
researchers in countries where there simply is no money to spend on
compilers.
isn't the Intel compiler available free of charge for students or demo
purposes if
you give up support ?
Besides I found that for the ifc the
"-mcmodel=medium -i_dynamic"
flag combination is helpful for large static arrays where heap
problems can appear
The last suggests that it would be ideal if large arrays were at least
approximately "transparent" -- so that the software would build on 32
bit systems and be runnable there with smaller arrays but would also
build and run on x64 big-memory systems without the need for extensive
instrumentation of the code.
Works for me with g77.
--
Florent Calvayrac |
Directeur du SC Informatique Ressources Num. de l'Universite du Maine
Lab. de Physique de l'Etat Condense UMR-CNRS 6087
Inst. de Rech. en Ingenierie Molec. et Matx Fonctionnels FR CNRS 2575
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