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

[Ei-ji Nakama]

>    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'.

When people make by default option in GotoBLAS for Linux,
it raise a thread at the time of the initialization of the library
and set affinity.
Therefore openmp will not cause a thread.

The good method should control the number of the threads in
omp_set_num_threads and goto_set_num_threads.
!!!must perform this!!!
performance when there is a part to use the thread for elsewhere is the worst

MKL thinks that KMP_AFFINITY=verbose helps analysis.

and ... people remove the number of the CPU's of the hyper thread in
BLAS and should carry it out.
# BLAS may count the number of the cores precisely partly.

I wrote regret it in strange English.XD

Best Regards,
--
EI-JI Nakama  <nakama (a) ki.rim.or.jp>
"\u4e2d\u9593\u6804\u6cbb"  <nakama (a) ki.rim.or.jp>