[R] 64-bit R and cache memory

[Joram Posma]

Dear all,

I have a few questions regarding the 64 bit version of R and the cache 
memory R uses.

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Computer & software info:

OS: kUbuntu Feasty Fawn 7.04 (64-bit)
Processor: AMD Opteron 64-bit
R: version 2.7.0 (64-bit)
Cache memory: currently 16 GB (was 2 GB)
Outcome of 'limit' command in shell: cputime unlimited, filesize 
unlimited, datasize unlimited, stacksize 8192 kbytes, coredumpsize 0 
kbytes, memoryuse unlimited, vmemoryuse unlimited, descriptors 1024, 
memorylocked unlimited, maxproc unlimited
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a. We have recently upgraded the cache memory from 2 to 16 GB. However, 
we have noticed that somehow R still swaps memory when datasets 
exceeding 2 GB in size are used. An indication that R uses approx. 2 GB 
of cache memory is that sometimes R also kills the session when datasets 
 > 2 GB are loaded. How/where can we see how much cache memory R uses 
(since memory.size and memory.limit are only for windows, and to us 
those might be what we need)? Could this be caused by the limit of the 
stack size (we are not exactly sure what the stack size is either) ?
b. And how can we increase the cache memory used by R to 14 or even 16 
GB (which might be tricky when running other programs, but still)?

So in general: how can we get R to use the full memory capacity of the 
computer?

-- 
Joram Posma

Department of Analytical Chemistry – Chemometics Radboud University 
Nijmegen (Netherlands) http://www.science.ru.nl/cac