Re: AW: 2CPU+1GPU vs 1CPU+2GPU

From: Axel Kohlmeyer (akohlmey_at_gmail.com)
Date: Tue Feb 14 2012 - 08:24:53 CST

2012/2/14 Marcel UJI (IMAP) <arzo_at_uji.es>:
> Yes I have found other sources with similar results (see
> http://www.cs.stanford.edu/people/ihaque/talks/resilience-2010.pdf), so I
> think I will finally go for those Tesla cards.

i think that is a bad choice.
please see my other post
and don't get scared too easily.

i know people that run a *lot* of desktop GPU
with GPU-MD codes that are by far more
demanding for the GPU, than NAMD.
a lot depends on how you operate the machine.

if you are still scared, don't get GPUs at all.
going for a compromise is almost always a
bad idea. keep in mind, that vendors prefer
to recommend expensive hardware, since
gives the more profit for less hassle. most
of these people don't know what they are
talking about.

please also check out the NAMD mailing
list archive for previous discussions on the
topic and experiences of other NAMD/GPU
users with different hardware.

axel.

> Thank you all for your help!
>
> Marcel
>
> Al 14/02/12 08:18, En/na Norman Geist ha escrit:
>
> Hi,
>
>
>
> I just wanted to add that I was pretty surprised when I first saw the ECC
> error counters on my Tesla C2050. Well in fact it’s the total of double bit
> and I never investigated their occurrence but I would only go without ECC
> with some belly aches because everything that doesn’t work or behave strange
> in your simulations, or even what works incredibly great can come due to
> artifacts of memory errors, that might sound a little overdone, but is
> possible. For what else, except of reliability, ECC has been developed. But
> I’m really not sure what influence those errors can really have, but with
> ecc you have one thing less to survey when problems occur.
>
>
>
> Best wishes
>
>
>
> Norman Geist.
>
>
>
> Von: owner-namd-l_at_ks.uiuc.edu [mailto:owner-namd-l_at_ks.uiuc.edu] Im Auftrag
> von Ajasja Ljubetic
> Gesendet: Montag, 13. Februar 2012 16:09
> Cc: Marcel UJI (IMAP); namd-l_at_ks.uiuc.edu
> Betreff: Re: namd-l: 2CPU+1GPU vs 1CPU+2GPU
>
>
>
> One final thing.  I've done some benchmarking with a AMD 6-core desktop and
> a GTX-570 and it ends up being about equal (slightly faster) than a 6-core
> xeon with an M2070.  You can buy a 3GB GTX580 for a fraction of the price of
> a M series card, and an AMD CPU (particularly the 3 GHz 6-core Thubans) will
> be close to half the price of the intel.  While I'm sure the intel chip is
> generally superior to the AMD one, it doesn't seem to be a factor when
> running NAMD.  So I would say buy two desktops and save yourself money and
> also gain performance.  I know there is the lack of ECC memory with the GTX
> series, but I'm really not convinced that is a big issue for MD (maybe
> someone on the list has a different opinion).
>
>
>
> I'm running my simulations on several  GTX 560 Ti for half a year now and it
> works great! So I would back up this advice.
>
>
>
> Best regards,
>
> Ajasja
>
>
>
> ~Aron
>
>
>
>
>
> On Mon, Feb 13, 2012 at 6:44 AM, Nicholas M Glykos <glykos_at_mbg.duth.gr>
> wrote:
>
>
>
> You will (hopefully) hear from Axel on this, but :
>
>
>> as it would give more speed for our NAMD based simulations
>
> Is this an assumption or the result of benchmarking the two hardware
> configurations with your intended system sizes ? For small (atom-wise)
> systems, you shouldn't expect much improvement by increasing the number of
> GPUs (and for tiny systems the 1CPU+2GPU may not scale at all).
>
> My twocents,
> Nicholas
>
>
> --
>
>
>            Nicholas M. Glykos, Department of Molecular Biology
>     and Genetics, Democritus University of Thrace, University Campus,
>  Dragana, 68100 Alexandroupolis, Greece, Tel/Fax (office) +302551030620,
>    Ext.77620, Tel (lab) +302551030615, http://utopia.duth.gr/~glykos/
>
>
>
> --
> Aron Broom M.Sc
> PhD Student
> Department of Chemistry
> University of Waterloo
>
>
>
>
> --
> Dr. Marcel Aguilella-Arzo
> Professor Titular d'Universitat, Física Aplicada
> Departament de Física
> Escola Superior de Tecnologia i Ciències Experimentals
> Universitat Jaume I
> Av. Sos Baynat, s/n
> 12071 Castelló de la Plana (Spain)
> +34 964 728 046
> arzo_at_fca.uji.es

-- 
Dr. Axel Kohlmeyer
akohlmey_at_gmail.com  http://goo.gl/1wk0
College of Science and Technology
Temple University, Philadelphia PA, USA.

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