Hello.
I'm trying to compile the file <nbody.f90> from
<http://shootout.alioth.debian.org/> [The Computer Language Benchmarks Game] in
a Toshiba Satellite A200-1C0 with the specifications shown below. The problem
I've got is that when I compile the file with GNU FORTRAN 95 4.3.2-1-1 and G95
FORTRAN 0.91, and the options shown below, the difference in computing time
between the binaries created by both compilers is huge. Does anybody know what
it is so?? I thought both compilers would yield executables with 'similar
results' for the elapsed time when running. I think it is very frustrating,
even if we compare it to gcc, the Intel FORTRAN Compiler or the Portland Group
FORTRAN.
]$ gcc -O3 -lm -march=nocona -o nbody.x nbody.c
]$ time ./-o nbody.x 50000000
Energy 0: -0.169075164
Energy 1: -0.169059907
Elapsed time: 1m 17.4s
]$ f95 -O3 -lm -march=nocona -o nbody.x nbody.f90
]$ time ./nbody.x 50000000
Energy 0: -0.169075164
Energy 1: -0.169059907
Elapsed time: 2m 31.7s
]$ g95 -O3 -lm -march=nocona -o nbody.x nbody.f90
]$ time ./nbody.x 50000000
Energy 0: -0.169075164
Energy 1: -0.169059907
Elapsed time: 1m 40.3s
Looking forward to hearing from you, and sincerely,
Adolfo
PS. Laptop specifications:
Processor: 2x Intel(R) Core(TM) Duo CPU T2350 @ 1.86GHz / FSB @ 800 MHz
Memory: 2066MB (366MB used)
Operating System: Debian GNU/Linux 5.0.3 (Kernel 2.6.26-2-686)
---
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University of Liverpool
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