enabeling openmp slows down R

[zarquon42]

Due to other issues, I found out, that R for Ubuntu is compiled with openmp enabled by default. This causes two issues:

1. General perfomance is decreased (on my desktop and my laptop its about 3[!] times slower)
2. revolution-mkl makes R stalling (which makes the entire package revolution-mkl useless with the R-version from the repos.

Are there distinct reasons for enabeling openmp by default?

Greetings
Stefan

[zarquon42 (zarquon42)]

Forget the first argument - it just happened to be an accident: As I am on 12.04 beta, there seemed to have been something fixed --before-- I recompiled R (I did it on both machines at the same time - unfortunately). And the speed results turned out to be better due to other causes. But the second point remains: revolution-mkl makes R stall under some circumstances (e.g. using mclapply from the parallel package).

Regards
Stefan

[zarquon42 (zarquon42)]

OK - I learned how to build an optimized version of the atlas library - which makes revolution-mkl obsolete (the pimped version of atlas is even faster on my machine - given the stuff I'm doing with R). Plus: atlas is LGPL.

Forget the openmp part.

Suggestion: Maybe revolution-mkl should be removed from the repos or being dependent on a alternative version of r-base built without openmp support. As apt-get install revolution-r leads to an R install not properly working.