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[Condor-users] Condor on Suns with Studio compiler



We have Condor set up on an array of Suns, and use the Sun Studio Fortran compiler.

One of our users is testing the stability of his models by tweaking some values, and looking at how this affects the results. He has asked the following:

"What level of compiler optimisation can I safely apply to a FORTRAN
executable to be used with Condor? i.e. what level of optimisation
produces an object that gives the same results (at least on all our
Suns)?

"High levels of optimisation (eg -fast) introduce options such as
-xtarget, which may or may not be the reason why  the same job can give
different answers on different machines. I want to be sure (or as sure
as possible) that differences between runs are not just because Condor
has run them on different machines. I suspect I can use -O2 (which is
actually the highest the code can cope with), but it would be nice to
know if this is true, without resorting to trial and error. I could
avoid optimising at all, by the code runs considerably slower in that
case."

Has anyone done any experiments to see how different levels of Studio optimisation affect output in a Condor environment, or can provide me with input so I can answer this user?

Any input gratefully received.

Dick

--
Richard Gillman
iTSS UNIX Systems Group, Maclean Building, Wallingford OX10 8BB
Tel: 01491 - 692 339