From rossini at blindglobe.net  Tue Nov 25 23:24:58 2003
From: rossini at blindglobe.net (A.J. Rossini)
Date: Tue Nov 25 23:25:55 2003
Subject: [Rd] Re: 64-bit R on Opteron
In-Reply-To: <6r3ccc85j5.fsf@bates4.stat.wisc.edu> (Douglas Bates's message
	of "25 Nov 2003 16:09:02 -0600")
References: <3A822319EB35174CA3714066D590DCD50205CEA0@usrymx25.merck.com>
	<6r3ccc85j5.fsf@bates4.stat.wisc.edu>
Message-ID: <85fzgc3x39.fsf@blindglobe.net>

Douglas Bates <bates@stat.wisc.edu> writes:

> (Reply moved to R-devel where it may be more appropriate.)
>
> "Liaw, Andy" <andy_liaw@merck.com> writes:
>
>> > From: Douglas Bates [mailto:bates@bates4.stat.wisc.edu]
>> > 
>> > "Liaw, Andy" <andy_liaw@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
>
> Amazing!

Dave Henderson reported similar data last summer.  It's the main
reason I've got 2 high-memory opterons on order...

The only catch will be setting them up -- pay for SuSE, go with
Mandrake, go with Gentoo, or roll-ones-own pre-release Debian
variant...

best,
-tony

-- 
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[Rd] Re: 64-bit R on Opteron
A.J. Rossini