OpenMP on Windows vs Linux causes solver errors

nilsoberg · ‎12-21-2011

Hello,

I have a code written in Fortran that runs fine with OpenMP directives on Linux. On Windows however my solver fails to converge. If I turn off OpenMP on Windows x64 the serial code runs fine. Also in order for the OpenMP code to run without immediately having a stack overflow I had to set the stack size in the linker options. The Linux version doesn't specify stack size. Here are my compiler options:

[bash]-- COMPILER --
/nologo /extend_source:132 /Qopenmp /module:"x64\Release OpenMP\\" /object:"x64\Release OpenMP\\" /c

-- LINKER --
/OUT:"x64\bin\Release OpenMP\efdc.exe" /INCREMENTAL:NO /NOLOGO /MANIFEST /MANIFESTFILE:"E:\projects\code\EFDC\EFDC\x64\bin\release openmp\efdc.exe.intermediate.manifest" /SUBSYSTEM:CONSOLE /STACK:160000000 /IMPLIB:"E:\projects\code\EFDC\EFDC\x64\bin\release openmp\efdc.lib"[/bash]

The options are the same on Windows and Linux.

The Linux version is:

Intel Fortran Compiler for applications running on Intel 64, Version 10.1 Build 20080212 Package ID: l_fc_p_10.1.013

The Windows version is:
Intel Fortran Compiler Integration for Microsoft Visual Studio 2008, 10.1.3440.2008, Copyright (C) 2002-2008 Intel Corporation

Is this a known issue? Any suggestions for working around this?

Thanks,

Nils

Steven_L_Intel1 · ‎12-21-2011

My first guess is that you have references to uninitialized variables, as enabling OpenMP causes the stack to be used for all allocations. This is the #1 cause of "failure to converge" and similar issues.

However, I will comment that your Fortran version is three and a half years old and is unsupported. Please install the current version and try again, though it is still likely you have uninitialized variables.