Re: R

[Ricardo Wurmus <ricardo.wurmus@mdc-berlin.de>]

Andreas Enge <andreas@enge.fr> writes:

> I did get a reply, but not using R, I do not quite know what to make of it:
>    https://bugs.r-project.org/bugzilla/show_bug.cgi?id=16697
> It would be nice if someone using R could help me out; if you send me an
> ssh key, I could give you access to an arm machine.
>
> To start, a probably simple question: Why do we use "--with-blas=openblas"?

I did this when we switched from ATLAS to OpenBLAS (for substitutability
reasons).  It is possible I have misunderstood the meaning of this
configure flag.

Here’s the installation manual on building with a specific BLAS
implementation:

    https://cran.r-project.org/doc/manuals/r-release/R-admin.html#BLAS

According to this section,

    “R can make use of enhanced BLAS (Basic Linear Algebra Subprograms,
    http://www.netlib.org/blas/faq.html) routines. However, these have
    to be explicitly requested at configure time: R provides an internal
    BLAS which is well-tested and will be adequate for most uses of R.”

There’s a separate section for OpenBLAS, which also mentions that using
a “shared BLAS” is a preferred alternative to linking with a particular
BLAS implementation.  We already pass “--enable-BLAS-shlib”, so we
actually do use a shared BLAS, IIUC.

I guess we could drop the “--with-blas” flag and see if that helps.  I
remember struggling with this a lot in the past.  I’ll try building R
again without that flag and see if it still works.

I’m sorry if that’s what’s responsible for the failures, but it’s pretty
hard for me to understand how linking with a high-performance BLAS
implementation could have caused these build/test failures on other
platforms.  I’ll report back when I have a successful build or an
interesting failure to share.

~~ Ricardo