[R-sig-Fedora] R 2.12.0 in Fedora Updates Testing

[Paul Johnson]

On Mon, Nov 15, 2010 at 11:45 AM, Tom "spot" Callaway
<tcallawa at redhat.com> wrote:
> On 11/07/2010 11:33 PM, Paul Johnson wrote:

>> I believe it is recommended to use R_LIBS_SITE. That way, they don't
>> block non root users from getting packages "automatically" installed
>> in their home dirs.
>
> I decided shortly after our last conversation to just go ahead and make
> this change, so as of the last R update, we're now leaving R_LIBS_USER
> alone and using R_LIBS_SITE.
>

Thanks! :)

>
>> Oh, one more thing. What about "shared" R libraries?
>>
>> In the Radmin manual, it claims that R built with shared libraries
>> enabled can be 20% slower.  On several Redhat systems here, I've taken
>> your RPM and cut the shared option out of configure and I don't notice
>> that anything suffers as a result. I don't have any  evidence it is
>> faster,either.
>
> I doubt that is valid on Linux, where shared library performance is
> almost always on par with static, not to mention the potential benefit
> of providing a consistent libRmath library for all packages to use.
>
> I would be willing to reconsider this approach if there were tangible
> (and not apocryphal) evidence to show a significant performance gap.
>
> Thanks for the reminder,
>
> ~tom
>

I have no evidence except the comment in the Rinstall and admin guide, page 38.

==============================================
"Flag ‘--enable-R-shlib’ causes the make process to build R as a
dynamic (shared) library,
typically called ‘libR.so’, and link the main R executable ‘R.bin’
against that library. This can
only be done if all the code (including system libraries) can be
compiled into a dynamic library,
and there may be a performance[1] penalty."

[1] We have measured 15–20% on ‘i686’ Linux and around 10% on ‘x86_64’ Linux.
==============================================

This may be apocryphal, I don't have the spare time to track this
down.  In our cluster, I turned off the shared flag.  That created bad
ripple effects because users who had packages installed in their home
accounts started to get errors. Aside from that, I can't say what
benefit/trouble I caused.

The only R package that I know of that requires R shared is Rinside,
but there may be more.   There is a warning about building R without
shared libraries in the BLAS section.  Apparently if BLAS is shared
but R is not, then some bumbling about in the dark occurs :)





-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas