David, thanks for following this through. I do not know how big a matrix needs to be before the multi-core multi-threading will start save time. But it seems useful to build this protection in your distribution so that it will not do multi-core when multi-threading is more likely to do harm.
Jason -----Original Message----- From: David M Smith [mailto:da...@revolution-computing.com] Sent: Thursday, April 23, 2009 6:05 PM To: Jason Liao Cc: r-help@r-project.org Subject: Re: [R] My surprising experience in trying out REvolution's R We've taken a look at this in a bit more detail; it's a very interesting example. Although the code uses several functions that exploit the parallel processing in REvolution R (notably %*% and chol), this was one of those situations where the overheads of threading pretty much balanced any performance gains: the individual matrices for the operations were too small. For some examples where the performance gains do show, see: http://www.revolution-computing.com/products/r-performance.php A more promising avenue for speeding up this code lies in parallelizing the outer for(i in 1:200) loop... # David Smith On Tue, Apr 21, 2009 at 9:26 AM, Jason Liao <jl...@hes.hmc.psu.edu> wrote: > I care a lot about R's speed. So I decided to give REvolution's R > (http://revolution-computing.com/) a try, which bills itself as an > optimized R. Note that I used the free version. > > My machine is a Intel core 2 duo under Windows XP professional. The code > I run is in the end of this post. > > First, the regular R 1.9. It takes 2 minutes and 6 seconds, CPU usage > 50% > > Next, REvolution's R. It takes 2 minutes and 10 seconds, CPU usage 100%. > > > In other words, REvolution's R consumes double the CPU with slightly > less speed. > > The above has been replicated a few times (as a statistician of course). > > > Anyone has any insight on this? Anyway, my high hope was dashed. -- David M Smith <da...@revolution-computing.com> Director of Community, REvolution Computing www.revolution-computing.com Tel: +1 (206) 577-4778 x3203 (San Francisco, USA) Check out our upcoming events schedule at www.revolution-computing.com/events ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
