Re: Compiling ATLAS with MinGW

[Tatsuro MATSUOKA]

--- On Wed, 2012/2/22, Michael Goffioul  wrote:

> On Sun, Feb 19, 2012 at 9:05 PM, Michael Goffioul
> <address@hidden> wrote:
> > I managed to complete the compilation process, but it wasn't really a
> > success. I specified MinGW as main compiler, but kept cygwin-GCC as
> > the XCC compiler. I had to hack a bit the Makefile in tune/sysinfo/,
> > because some support executables are compiled with the ICC compiler
> > (interface compiler), mingw-in-cygwin in this case, but are then
> > called with cygwin-style paths and fail. I also noticed a similar
> > issue that prevented a proper creation of files like
> > atlas_dtrsmXover.h (empty files are created), although these errors
> > were ignored by make.
> >
> > I created the DLL and tested the result with octave with this snippet:
> >
> > n=2000; A=randn(n); B=randn(n);tic; C=A*B; t=toc, MFLOPS=2*n^3/t*1e-6
> >
> > and verified that both CPU's were used (in the task manager). However
> > it seems that the generated multi-threaded ATLAS is suboptimal and
> > even with the 2 CPU's being used, it was slower than a single-threaded
> > ATLAS. I don't know the reason, but it may be related to the fact that
> > some files couldn't be properly generated. In the end, it seems like
> > trying to compile ATLAS with MinGW is a dead-end...
> 
> I've been tricked by Intel HT technology....
> 
> After some ATLAS patching, I could eventually compile ATLAS with MinGW
> and MSYS only (no cygwin required anymore), which allowed me to
> compile a multi-threaded version pretty easily. However the initial
> test I made on my main desktop showed that the MT version was slightly
> slower than the ST version. But this is due to the fact that my CPU is
> a P4 HT, which looks like a multi-CPU system, but it's actually not.
> In the case of ATLAS, HT does not really help and makes things worse.
> 
> I've then tested the same binaries on a Core2 Duo, and this time I got
> the expected result: the MT ATLAS was nearly 2x faster than the ST
> one.
> 
> Michael.

Hello

It's a great job! that ATLAS can be built on msys+ MinGW.

In the ATLAS Homepage,
http://math-atlas.sourceforge.net/atlas_install/atlas_install.html#SECTION000101000000000000000

**************************************
We have had requests to support MinGW (http://www.mingw.org/), but no one has 
submitted suggested code to help, and I have never successfully figured out how 
to install and use it, so this is probably not coming soon unless something 
changes.
**************************************

Can you send your patch to the ATLAS team?

Regards

Tatsuro