[R] [OT] R on Atlas library

[Allan Engelhardt]

I don't know about the specific function (a simple, stand-alone 
reproducible example is always helpful, see the posting guide for 
details), but ATLAS certainly uses all my cores on a test like this:

s <- 7500  #  Adjust for your hardware
a <- matrix(rnorm(s*s), ncol = s, nrow = s)
b <- crossprod(a)  #  Uses all cores here.

My configuration of R with ATLAS on Linux (Fedora) is described at 
http://www.cybaea.net/Blogs/Data/Faster-R-through-better-BLAS.html

Maybe your distribution has single-threaded ATLAS and you forgot to 
rebuild it with "enable_native_atlas 1" or the equivalent for your platform?

Allan


On 06/08/10 15:12, Matthias Gondan wrote:
> Dear List,
>
> I am aware this is slightly off-topic, but I am sure there are people who already had the problem and who perhaps solved it.
>
> I am running long-lasting model fits using constrOptim command. At work
> there is a linux computer (Quad Core, debian) on which I already have
> compiled R and Atlas, in the hope that things will go faster on that
> machine.
>
> Atlas offers the possibility to be compiled for multiple cores, I used
> that option, but without success. Performance meter ("top") for Linux
> shows 25% CPU usage, and there is no loss of performance if I run
> 4 instances of R doing heavy matrix multiplications. Performance drops
> when a 5th instance of R is doing the same job, so I assume my attempt
> was not successful.
>
> I am sure I did something wrong. Is there anybody who sucessfully
> runs R with Atlas and all processors? A short description of the
> necessary steps would be helpful.
>
> Searching around the internet was not very encourageing. Some people
> wrote that it is not so simple to have Atlas fully exploit a multicore
> computer.
>
> I hope this is not too unspecific.
>
> Best wishes,
>
> Matthias
>
>