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
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