OpenMP on CRAN

Moving to a compiler that drops support for OpenMP seems a sad choice, especially now we?ve all climbed the learning curve of the non-Apple compiler (the real barrier was lack of a pkg installer and that?s done now).

Losing OpenMP for the CRAN version of OpenMx/umx (our SEM packages) would be a big loss for users (for whom the CRAN version now supports OpenMP giving them a 2-12x speed up). In general, R on Mac is made more viable by having OpenMP

Re Brian?s points, I?d say that the distribution problem is crucial: Packages not on CRAN have dramatically diminished accessibility/useage.

Second, a great range of compute-intensive problems are amenable to division amongst cores, including nearly all models that take more than a nominal amount of time to run: So simulations, CIs, bootstrapping, nearly everything in genetics all speeds up.

I?d say especially on desktop/laptop. The big advantage of multi blade systems requires snowfall-type solutions, but desktops profit automatically from their multi-core structure and don;?t have multiple processors (except graphics, which no-one seems to be exploiting on CRAN-style R), so OpenMP is their one trick. I?d hope not to lose it.

Best, t

On 2 Apr 2020, at 05:18, Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:

On 01/04/2020 22:02, Simon Urbanek wrote:

JJB,
1. correct, there was too much trouble in this. But please feel free to start a new thread about this here if you have strong opinions.

Also note that it is possible (and not hard) to install packages from source with an OpenMP-supporting compiler, and how to do so is in the R-admin manual.  The problems come in distributing them.

The benefits of OpenMP are often overestimated, especially on desktop/laptop level hardware.  But it is available for the small (tiny?) proportion of users who need it.

The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.