Dear Carolyn, list,
I can second Satra's post. We run analyses of multiple users simultanuously on a dual proc 64 bit opteron system. Note that matlab jobs itself cannot (yet) be divided over 2 procs. Still, a major advantage is that when one user runs an analyses, the next user has almost as good a performance, provided your license allows you to run multiple matlab instances simultanuously. A second advantage I really appreciate is that when you run an analysis, it consumes all the CPU power of 1 proc, and the other does operating system related things, and you work as smoothly on your system as when no job is currently running. With one proc working on the system when an analyses is runnen is a nuisance.
I also read on the list some time ago that there apparently are efforts out there to make the compiled C routines (that do all the hard work for SPM and matlab) multithreadable so that even with 1 job running you might be able to use both processors. You would have to search the list for that.
Good luck,
Bas
-------------------------------------------
Dr. S.F.W. Neggers
dept. of Psychonomics,Helmholtz Institute
Utrecht University
Heidelberglaan 2
3584 CS, Utrecht, room 17.09
the Netherlands
Tel: (+31) 30 253 4582 Fax: (+31) 30 534511
E-mail: [log in to unmask]
Web: http://www.fss.uu.nl/psn/pionier
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-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]On
Behalf Of Satrajit Ghosh
Sent: dinsdag 4 januari 2005 18:28
To: [log in to unmask]
Subject: Re: [SPM] single vs dual processor
We have been very happy with our dual processors, particularly because
we get to do several things simultaneously. However, given the
increasing size of data sets and memory bottlenecks that come with a
32-bit machine, I would recommend purchasing a 64 bit processor with
lots of memory. Matlab 7.1 has support for 64 bit machines.
Satra
--
Satrajit Ghosh
Postdoctoral Associate
Speech Communications Group
Research Lab of Electronics, MIT
On Tue, 4 Jan 2005 11:42:42 +0000, Cinly Ooi <[log in to unmask]> wrote:
> Volkmar Glauche wrote:
>
> > On Mon, 3 Jan 2005, Carolyn L. Fort wrote:
> >
> >> I'm purchasing a Linux workstation that will be devoted to fMRI
> >> processing/analysis and we'll primarily be running SPM (though AFNI,
> >> FSL and other packages will be loaded as well). I'm wondering whether
> >> SPM performs better on a dual processor or if sufficient speed (between
> >> 2.8 - 3.2 GB) on a single processor will suffice.
> >
> >
> > Matlab (and therefore SPM) will not make explicit use of a 2nd processor,
> > but it is recommended if you want to use the workstation interactively
> > while an analysis is running.
>
> Having a High speed processor waiting for interactive command is a bit
> of a waste. I would prefer to take the penalty of sluggish workstation
> response by running two analysis process on dual processor.
>
> Alternative is to get a single processor and hyperthread it. But
> analysis speed can be slower, assuming that Data access (Ethernet/Hard
> Disk/Cache) is not a limitting factor. May be dual processors,
> hyperthread to 4 processors is a better proposition (3 analysis + 1
> workstation activity). Unfortunately you cannot hyperthread only one
> processor in a dual processors config.
>
> Cinly
>
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