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Re: MinGW gfortran and OpenMP issues...

On 2/1/2012 7:03 PM, Nick Chilton wrote:

I'm still having problems with OpenMP and the x86_64 MinGW compilers -
code which can run fine on Linux with any number of threads (mapped to
different cores) still will only use  one core on an i5 quad core
windows box. Is this a windows limitation or a compiler one?

Compile with:

x86_64-w64-mingw32-gfortran.exe -o a.exe -mno-cygwin -static -O3
-fopenmp -cpp -Domp $(SOURCES) -L/home/Nick/lib/ -llapack -lblas

According to my understanding, mingw compiler versions aren't supported on this list, notwithstanding that cygwin install is probably the best way to get them. However, that compiler gives me good OpenMP performance on 6 of 10 test cases, running on an early core I7 with HyperThread disabled, Win7SP1. GOMP_AFFINITY setting as well as avoiding Hyper-Threading are likely more important on Windows than linux. Win7SP1 is particularly important when using Hyper-Threading.

-- Tim Prince

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