64-bit R on Opteron [was Re: [R] Windows R 1.8.0 hangs when M em Usage >1.8GB]

[Liaw, Andy]

> From: Douglas Bates [mailto:bates at bates4.stat.wisc.edu]
> 
> "Liaw, Andy" <andy_liaw at merck.com> writes:
> 
> > Sorry.  I need to retract my claim.  There seems to be a 3G 
> limit, even
> > though the OS could handle nearly 8G.  (I can have two 
> simultaneous R
> > processes each using near 3G.)
> > 
> > On another note, on our dual Opteron box R (compiled as 
> 64-bit) could easily
> > use nearly all the 16G in that box (that's one of the 
> reason for having that
> > box).
> 
> Does "could" mean you have verified that it did or is this a
> theoretical statement?  I.e., have you compiled and tested R on your
> dual Opteron?

Given my questionable memory of things, this question is very fair.
Here's the evidence:

> x <- matrix(0, 5e5, 5e5)
> x2 <- matrix(0, 5e5, 5e5)
> gc()
             used    (Mb) gc trigger    (Mb)
Ncells     413379    22.1     741108    39.6
Vcells 1783900405 13610.1 1784288128 13613.1

Best,
Andy