From hin-tak.leung at cimr.cam.ac.uk  Mon Jan 23 16:18:29 2006
From: hin-tak.leung at cimr.cam.ac.uk (Hin-Tak Leung)
Date: Mon, 23 Jan 2006 15:18:29 +0000
Subject: [Rd] Minumum memory requirements to run R.
In-Reply-To: <Pine.LNX.4.61.0601231133410.12327@gannet.stats>
References: <Pine.LNX.4.61.0601181149400.9400@gannet.stats>
	<43FA4711.2010103@gmail.com> <43D4BAC6.2050904@cimr.cam.ac.uk>
	<Pine.LNX.4.61.0601231133410.12327@gannet.stats>
Message-ID: <43D4F3C5.6060005@cimr.cam.ac.uk>

Prof Brian Ripley wrote:
<snipped>
> 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.

I am somewhat surprised by it as well. But there is nothing unusual 
about the build - it is just rebuilding the rpm on CRAN on a FC4 system
with everything as shipped, and should be quite reproducible.
I'll probably have a better look in time.

"R --vanilla" doesn't improve. Still 90+ MB virtual, 20+MB resident.

> 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.

Yes and no. Virtual means it will possibly be used - and it is a big 
gray scale between unresponsible/intolerably-slow and slow.

>> 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.

I went and have a look - it is the last section of R-admin (and of 
course, for those who "read the source", R/include/Rinternals.h). It 
would be good to mention this in the FAQ (which it doesn't, or maybe I 
didn't look hard enough), or the beginning of R-admin?

> 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).
>



[Rd] Minumum memory requirements to run R.
Hin-Tak Leung