[R-SIG-Mac] How to make Mac 64-bit version feature complete?

Adam Strzelecki ono at java.pl
Fri Dec 16 19:38:28 CET 2011

Just to give you some numbers, on my iMac Lion 10.7.2, i5 Sandy Bridge.

• When allocating matrix 10000x10000 R64 takes 798MB vs R32 taking 785MB, so 14MB is wasted for 64-bit handling
• Running R-benchmark-25.R from http://r.research.att.com/benchmarks/ in R64 renders about ~5% performance gain

I am aware these number can really differ on older OSX, notably on Leopard, also 64-bit performance can be very bad for 64-bit using vecLib on older OSX, vecLib was somehow borked by Apple.

On other side Apple depreciates slowly 32-bit in newer systems, in Lion there's no 32-bit kernel anymore, most of built-in apps are 64-bit only. Still is can run 32-bit apps, but it cannot run PPC anymore (no Rosetta).

So IMHO the picking 64-bit on 10.6+ (or 10.7+) is good option for the future, as the scientific datasets grow every year and RAM installed by default by Apple will be soon min 8GB. 

(Some tech blather: 64-bit program can allocate in fact more than 4GB when having only 4GB RAM - implies paging and swapping, unless allocated pages remain non-written. In theory 64-bit program can allocate few 1TB on 4GB RAM system, with no physical memory usage bump. Memory will be used only when user will 1st access the allocated pages.)

Adam Strzelecki

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