Re: Greased Lightning: ATLAS

[Johan Kullstam]

Keith Goodman <address@hidden> writes:

> SSE2
> 
> I removed atlas3-base-dev but not atlas3-base (since some of my
> programs depend on it) and I kept atlas3-headers. I then installed
> atlas3-sse2 and atlas3-sse2-dev. (I'm running debian.)
> 
> When I run "./configure --enable-shared --disable-static" I get "BLAS
> libraries: -lblas". So atlas is not being picked up when I use sse2
> (but it is when I use atlas3).
> 
> DOES OCTAVE KNOW?

Yes, for debian.  Debian has some sort of indirection magic which uses
the right blas if you install, e.g., atlas3-sse2.  You may also want
to install libc6-i686 which works similarly.

Unfortunately, debian does not provide fine-grained tuned atlas/blas.
A pentiumpro is not a pentium or i486 but debian treats them the same.
Similarly, mmx covers pentium-ii, pentium-iii-katmai,
pentium-iii-copermine.  3dnow covers all flavor of athlon and sse2
covers all the pentium-4 and pentium-M cpus.  Since the best stride
size of stepping through a vector and such are detail dependent, I am
not sure if there doesn't need to be some more options.  Does anyone
have any more than my wild conjecture?

> From your replies it sounds like I have to get configure right and get
> the LD_LIBRARY_PATH right. Does Octave itself know whether it is using
> atlas? Would it be hard to write a function that returned this sort of
> information so a user could enter, say, 'configuration' at the Octave
> prompt to find out whether or not Octave is using things like atlas?

Use "ldd /usr/bin/octave" at the prompt and look to see what it wants
to load.

-- 
Johan KULLSTAM



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