My surprising experience in trying out REvolution's R

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:david at revolution-computing.com]
Sent: Thursday, April 23, 2009 6:05 PM
To: Jason Liao
Cc: r-help at 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 <JLIAO at 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 <david at 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
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