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

Prof Brian Ripley ripley @ending from @t@t@@ox@@c@uk
Sun Sep 9 10:12:56 CEST 2018

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

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