[R-sig-hpc] Choosing Intel MKL BLAS when compiling R

Dirk Eddelbuettel edd at debian.org
Wed Nov 2 16:35:00 CET 2011

On 2 November 2011 at 11:18, Simon Urbanek wrote:
| On Nov 2, 2011, at 10:57 AM, Michael Braun wrote:
| > Interesting.  Incidentally, I mis-typed my link link below.  Usually I link to MKL using -lmkl_rt -liomp5 (without the -lpthread).  I'm still learning the vagaries of C++ and system libraries, but does this mean that I have been bypassing the Apple implementation?  If Intel's libiomp5 does not have this problem, would that explain why my code seems to be working?  Or is this an unrelated issue?
| > 
| I think you may be misunderstanding - what Dirk said is that MKL and OMP in R don't mix well and I said that we don't use OMP in R on OS X so it is irrelevant for OS X.

>From NEWS (and the text is still identical between r-devel and 2.14.0)

    o configure looks for support for OpenMP and if found compiles R
      with appropriate flags and also makes them available for use in
      packages: see 'Writing R Extensions'.

      This is currently experimental, and is only used in R with a
      single thread for colSums() and colMeans().  Expect it to be more
      widely used in later versions of R.

      This can be disabled by the --disable-openmp flag.

It is my understanding that more of this will be forthcoming. Is that not correct?

Michael Rutter actually gets the credit in noticing the issue.


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