Re: Hardware considerations and Octave

[Joan Picanyol i Puig]

* Dmitri A. Sergatskov <address@hidden> [20050429 21:52]:
> Joan Picanyol i Puig wrote:
> >I'm afraid this is not so. I can't get my dual Athlon-MP system to
> >effectively use both processors for Octave (I'm on FreeBSD, YMMV). 
> 
> I had compiled octave against multithreaded ATLAS and that speeds up some
> matrix manipulations by almost 90%. But for some operations this also
> imposes some penalty (due to thread spawning overhead, I guess). So do
> not expect 2x speedup.

Mmmhh... I've tried this before and failed. In FreeBSD, the atlas ports
compiles and installs multithreaded ATLAS libraries (arch=THREADED_PIC
as *_r.so), but I haven't been able to convince Octave to link against
them (it always prefers the "normal" ones). On a related note, I was
unaware that octave was multithreaded, AFAIK it's a single process...

> Another advantage of dual system if you plot (and replot)
> large data sets. Since gnuplot runs as a separate process it can use
> a second cpu.

This is definitely a great advantage, gnuplot can take a lot of time.
One issue I've encountered are error messages of the form "gnuplot is
not responding" when using legend() from octave-forge, but it hasn't
bothered me enough to do anything else than commenting the legend()
call.

qvb
-- 
pica



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