From tlumley at u.washington.edu  Mon Mar  6 19:37:37 2006
From: tlumley at u.washington.edu (Thomas Lumley)
Date: Mon, 6 Mar 2006 10:37:37 -0800 (PST)
Subject: [Rd] Running R on dual/quad Opteron machines
In-Reply-To: <3c12769c0603060929k3c974861h6badd72e47ebe4af@mail.gmail.com>
References: <3c12769c0603060850pd3bbc73gb40a5e9f324d8050@mail.gmail.com>
	<Pine.LNX.4.64.0603060906130.24583@homer24.u.washington.edu>
	<3c12769c0603060929k3c974861h6badd72e47ebe4af@mail.gmail.com>
Message-ID: <Pine.LNX.4.64.0603061035570.17097@homer23.u.washington.edu>

On Mon, 6 Mar 2006, Simone Giannerini wrote:

> On 3/6/06, Thomas Lumley <tlumley at u.washington.edu> wrote:
>> On Mon, 6 Mar 2006, Simone Giannerini wrote:
>>> The environment will probably be either Unix/Linux or Solaris and the
>>> amount of RAM will be 8-16Gb, depending on the number of processors.
>>> My main concerns are the following:
>>>
>>> 1. How much does R  benefit from passing from one processor to
>>> two/four processor machines? Consider that the typical intensive use
>>> of the server
>>> will be represented by simulation studies with many repeated loops.
>>
>> The typical way that R is used on multiprocessor systems is running more
>> than one program, rather than parallel processing. If four people are
>> using the computer or if one person splits 10,000 iterations of a
>> simulation into 4 sets of 2,500 you will be using all four processors.
>>
> Many thanks, if I have understood correctly, in this case I would need
> running four separate instances of R, since a single thread cannot
> exploit more than one cpu, am I correct?
>

You *can* exploit more than one CPU using eg the "snow" package, but it's 
often easier to just run multiple instances of R, and for a shared 
computing system there are often multiple people each running one instance 
of R.

 	-thomas



[Rd] Running R on dual/quad Opteron machines
Thomas Lumley