Re: MPI (was Re: BIG libraries with self-compiled version)

[James R. Phillips]

--- Michael Creel  wrote:
> Hi, did you happen to build octave linking to it, and if so, what were 
> the effects on performance? Cheers, M.
> 

I don't have performance comparisons available, just a smoke test - it worked. 
I built this for a colleague with a 2 cpu machine (I don't have one).

As far as atlas itself is concerned, for medium sized matrix operations, a
factor of 8-10 speed-up over non-optimized libraries is typical.  The biggest
gain will come from using atlas; a smaller additional increment will accrue
from enabling threaded support during atlas configuration.

octave on cygwin uses shared libraries (dll's) for lapack and blas, so
relinking octave is not required to use optimized versions, as long as they
retain the same exported functions.  Just build the optimized libraries
according to instructions in the source package, and install them in
/usr/local/bin.  They will override the default versions in /usr/lib/lapack, as
long as you don't destroy their relative positions in the default PATH
(/usr/local/bin precedes /usr/lib/lapack).

If you carry this out, please report back on your results (including
performance).

Thanks,

jrp



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