[R-SIG-Mac] disabling threads when using Accelerate BLAS

[Prof Brian Ripley]

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 using stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford