OpenMP and fortran

John Deas

Hi, my configuration is

Red Hat Linux 9.0 Intel Fortran Compiler (and debugger) 9.1 Intel 2x3.6 ghz 3.6 gig of ram

I have a program which manipulate large arrays (speed vectors for direct numerical simulation, CFD), and I a trying to modify and debug it with ifort and idb. The code contains openmp sections. When compiled without the openmp option, everything looks fine, but when I try to compile it with openmp, and I run it, I had crash early in the run at trivial functions call. After some research, I thought it might be linked to the stack size. I set "ulimit -s 2000000" and "export KMP_STACKSIZE=2g" and the program get further when it run, but, I got segmentation fault at a point later (I run it with 2 threads). A step-by-step debugging show me that, inside an omp do loop, the values of some SHARED variables where modified, but no line inside the do loop does this modification. Since those variables store arrays boundaries, once they are modified the do loop get outside the corresponding array and I got segfault.

If you have any advice on this problem, I would really appreciate it, since I have no clue why the openmp version version modify those values.

Thanks,

J.D.