[R-SIG-Mac] detecting cores

[David Winsemius]

> On Feb 5, 2016, at 4:26 AM, peter dalgaard <pdalgd at gmail.com> wrote:
> 
> Sorry, saw the bugzilla item first...
> 
> I have
> 
> Peters-iMac:IBP pd$ sysctl -n hw.ncpu
> 2
> Peters-iMac:IBP pd$ sysctl -n hw.physicalcpu
> 2
> Peters-iMac:IBP pd$ sysctl -n hw.logicalcpu
> 2
> Peters-iMac:IBP pd$ ssh appleserver
> Last login: Mon Dec 14 11:25:08 2015
> appleserver:~ pd$ sysctl -n hw.ncpu
> 24
> appleserver:~ pd$ sysctl -n hw.physicalcpu
> 12
> appleserver:~ pd$ sysctl -n hw.logicalcpu
> 24
> 
> both on Mavericks, 10.9.5. As you probably gathered (or remembered), the iMac is Core 2 Duo, so no hyperthreading. 

On El Cap running on the oldest macPro (early 2008), I think this earliest machine El Cap supports:

Model Identifier:	MacPro3,1
  Processor Name:	Quad-Core Intel Xeon
  Processor Speed:	2.8 GHz
  Number of Processors:	2
  Total Number of Cores:	8

I get:

$ /usr/sbin/sysctl -n hw.physicalcpu
8
$ /usr/sbin/sysctl -n hw.logicalcpu
8

-- 
David.

> 
> -pd
> 
> 
> On 05 Feb 2016, at 13:07 , Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:
> 
>> sysctl on 10.11 has options which would enable us to differentiate between logical and physical codes on parallel::detectCores --- however these are not documented in Apple's online man pages, which are for 10.9.  Could someone running 10.9 and someone for 10.10 report if
>> 
>> /usr/sbin/sysctl -n hw.physicalcpu
>> /usr/sbin/sysctl -n hw.logicalcpu
>> 
>> run in a terminal work and gives the correct result?  (Normally the second will be twice the first taking account of hyperthreading.)
>> 
>> Thanks in advance.
>> 
>> -- 
>> Brian D. Ripley,                  ripley at stats.ox.ac.uk
>> Emeritus Professor of Applied Statistics, University of Oxford
>> 
>> _______________________________________________
>> R-SIG-Mac mailing list
>> R-SIG-Mac at r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
> 
> -- 
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Office: A 4.23
> Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com
> 
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David Winsemius
Alameda, CA, USA