[Rd] OpenBLAS in everyday R?

[Kenny Bell]

On Sun, Dec 17, 2017 at 10:01 AM, Dirk Eddelbuettel <edd at debian.org> wrote:

>
> Kenny,
>
> On 17 December 2017 at 09:28, Kenny Bell wrote:
> | Hi R-devel list,
> |
> | OpenBLAS is readily available for unix-likes:
> |
> | https://cloud.r-project.org/web/packages/gcbd/vignettes/gcbd.pdf
>
> Please consider re-reading this vignette of mine. BLAS is an interface,
> OpenBLAS is but one implementation.  R has allowed you to switch between
> different implementations for a long time (if you used a shared library
> build), and illustrating / measuring the possible performance differences
> is
> the whole point of the gcbd benchmarking package.
>

Understood. To be clear, my suggestion is to change the *default* BLAS
implementation to multithreaded OpenBLAS.


> | However, my questions are:
> |
> | 1) Would R-devel consider using OpenBLAS for the main distribution of R
> for
> | all platforms including Windows?
> | 2) If so, would R-devel set the default multi-thread level to the number
> of
> | (real) cores on a machine?
>
> It's complicated. If you fork at the process-level (with package parallel
> or
> one of the many other mechansim) and then also used multi-threaded BLAS you
> can starve yourself for resources quickly.
>
>
This indeed was my experience if not being careful when using MRO, which
also has a multithreaded algebra library as the default. However, the
overall speed benefits far outweighed the costs. MRO helped to overcome
this problem with an interface to change the number of threads to use. In
MRO, it is on the user to switch this before using any explicit parallel
functionality. Another question, does using multithreaded OpenBLAS mess
with RcppParallel?


> | My sense is there're a lot of wasted resources on laptops and personal
> | desktops around the world that could be utilised by such a switch. I
> | believe most unix-like users don't know about OpenBLAS and are blissfully
> | ignorant of the available speed gains. It seems to be quite difficult
> for a
> | typical Windows user to get this done today.
>
> Many things a developer / power-user would do are very difficult on
> Windows. It is one of the charms of the platform. On the other hand you do
> get a few solitaire games so I guess everybody is happy.
>
> Dirk
>
> | Thanks heaps,
> | Kenny
> |
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> |
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>
> --
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
>

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