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Date:	Wed, 01 Feb 2012 21:12:40 -0500
From:	Tim Prince <n8tm AT aol DOT com>
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To:	cygwin AT cygwin DOT com
Subject:	Re: MinGW gfortran and OpenMP issues...
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On 2/1/2012 7:03 PM, Nick Chilton wrote:
> Hi,
>
> 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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