disabling threads when using Accelerate BLAS

On 08/09/2018 22:01, Kasper Daniel Hansen wrote:

For timing purposes, is it possible to control the number of threads /
cores when I have compiled R to use the BLAS in the Accelerate framework
(by building R using
   ./configure --with-blas="-framework Accelerate" --with-lapack
)

? (The alternative is of course to build R using the supplied
single-threaded BLAS)

This is a question about Accelerate not R.  But the R-admin manual does say

'In recent versions of macOS, threading in Accelerate is controlled by
?Grand Central Dispatch? and is said not to need user control.'

It has quite a few other caveats about Accelerate, not least that it
uses an LAPACK which is missing many bug fixes, some serious.

--
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford