From ripley at stats.ox.ac.uk  Mon Jan 23 12:50:49 2006
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Mon, 23 Jan 2006 11:50:49 +0000 (GMT)
Subject: [Rd] Minumum memory requirements to run R.
In-Reply-To: <43D4BAC6.2050904@cimr.cam.ac.uk>
References: <Pine.LNX.4.61.0601181149400.9400@gannet.stats>
	<43FA4711.2010103@gmail.com> <43D4BAC6.2050904@cimr.cam.ac.uk>
Message-ID: <Pine.LNX.4.61.0601231133410.12327@gannet.stats>

On Mon, 23 Jan 2006, Hin-Tak Leung wrote:

> Kjetil Brinchmann Halvorsen wrote:
>> Prof Brian Ripley wrote:
>> 
>>> Quite a while back we set the goal of running R in 16Mb RAM, as people (I 
>>> think Kjetil) had teaching labs that small.
>> 
>> It's a while since I actually har R used on such small machines, I think
>> 64 MB is quite acceptable now.
>
> May I add another note to this - I recently upgraded to 64-bits (AMD opteron) 
> and noticed the memory foot print of R has shot up. Just starting R takes up 
> 90+MB virtual.

That's a different question.  I said RAM, you quote virtual.  I am 
suprised at your figure though, as I am used to seeing 40-50Mb virtual at 
startup on an Opteron.

The distinction is important: even those small Windows machines had 100s 
of Mb of virtual memory available, it was RAM that was in short supply.

> There are correponding increases with Python and Perl as well; 
> I suspect R suffers a bit on 64-bit
> platform due to extensive use of pointers internally. The fundamental
> unit in R, SEXP, is 6 pointers + 1 int, (and another
> pointer for itself). So I would probably say 64MB is questionable on 64-bit, 
> but then probably nobody is stupid enough to do that...

We know: we even document it in the appropriate places.

Some of us were running 64-bit R last century on machines with 128Mb (and 
others with much more, of course).  When I tried in 1997, Solaris would 
not run in 64-bit mode with 64Mb RAM (which then cost ?1000 or so).

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595


[Rd] Minumum memory requirements to run R.
Prof Brian Ripley