Displaying 2 results from an estimated 2 matches for "debianscience".
2016 Jan 15
0
Multiple cores are used in simple for loop
...Reducing n from 100 to 4
> causes four cores to work.
It depends on what backend R is using for linear algebra. Some will
split large matrix calculations over multiple threads. On Debian, you
can set the blas and lapack libraries to the implementation of your
choice.
https://wiki.debian.org/DebianScience/LinearAlgebraLibraries
As far as I know reference blas and lapack are still single threaded.
Alternatively, you may be able to control the maximum number of threads
by setting and exporting an appropriate environment variable depending
on what backend you are using, e.g. OPENBLAS_NUM_THREADS or
M...
2016 Jan 15
2
Multiple cores are used in simple for loop
Dear all,
I run different R versions (3.2.1, 3.2.2 and 3.2.3) on different
platforms (Arch, Ubuntu, Debian) with a different number of available
cores (24, 4, 24). The following line produces very different behavior
on the three machines:
for(i in 1:1e6) {n <- 100; M <- matrix(rnorm(n^2), n, n); M %*% M}
On the Ubuntu and Arch machine one core is used, but on the Debian
machine ALL