numpy-discussion

[Numpy-discussion] compiling ATLAS for numpy

[Emanuele O. <oli...@it...>]

Hi,
I'm installing numpy on a 2 cpus intel pentium 4 Linux box. I'm installing BLAS and
LAPACK from sources too and I need to tune compiler flags. Here is the question: which
are the proper flags for compiling LAPACK? Inside lapack.tgz make.inc.LINUX says:
            OPTS     = -funroll-all-loops -fno-f2c -O3
instead on scipy.org[0] it's suggested:
            OPTS = -O2

I assume that using -O3 and unrolling loops should have definitely better performance
that just -O2 but I'm wondering if the speedy options can be a problem for current
numpy release (numpy-1.0rc1). Is it safe to use '-funroll-all-loops -fno-f2c -O3'?

Thanks in advance for answers,

Emanuele

[0]: http://scipy.org/Installing_SciPy

P.S.: my GCC is v3.4.5

Re: [Numpy-discussion] compiling ATLAS for numpy

[Emanuele O. <oli...@it...>]

Ops, sorry for the misleding subject: I wrote ATLAS but I meant LAPACK :)

Emanuele Olivetti wrote:
> Hi,
> I'm installing numpy on a 2 cpus intel pentium 4 Linux box. I'm installing BLAS and
> LAPACK from sources too and I need to tune compiler flags. Here is the question: which
> are the proper flags for compiling LAPACK? Inside lapack.tgz make.inc.LINUX says:
>             OPTS     = -funroll-all-loops -fno-f2c -O3
> instead on scipy.org[0] it's suggested:
>             OPTS = -O2
...

Re: [Numpy-discussion] compiling ATLAS for numpy

[Hanno K. <kl...@ph...>]

Emanuele, 

the scipy compiler flags under 

http://www.scipy.org/Installing_SciPy/BuildingGeneral

work well. However, if you happen to have to use gcc 3.2.3 (e.g. often
in Redhat Enterprise editions present), you have to turn off
optimization, otherwise lapack doesn't build properly.

The correct build flags are then 
OPTS     = -m64 -fPIC
(at least that's what worked for me)

Regards,
Hanno

Emanuele Olivetti <oli...@it...> said:

> Ops, sorry for the misleding subject: I wrote ATLAS but I meant
LAPACK :)
> 
> Emanuele Olivetti wrote:
> > Hi,
> > I'm installing numpy on a 2 cpus intel pentium 4 Linux box. I'm
installing BLAS and
> > LAPACK from sources too and I need to tune compiler flags. Here is
the question: which
> > are the proper flags for compiling LAPACK? Inside lapack.tgz
make.inc.LINUX says:
> >             OPTS     = -funroll-all-loops -fno-f2c -O3
> > instead on scipy.org[0] it's suggested:
> >             OPTS = -O2
> ...
> 
>
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-- 
Hanno Klemm
kl...@ph...