From: Axel Kohlmeyer (akohlmey_at_gmail.com)
Date: Thu Apr 14 2011 - 14:23:50 CDT
On Thu, Apr 14, 2011 at 2:58 PM, Salvador H-V <chava09hv_at_gmail.com> wrote:
> Hi All,
> If I understood well, to perform serious calculation for high performance
> computing, people is using GPUs cards with double precision
> such as tesla and quadro GPUs.
that is not quite right. some methods and algorithms _have_ to have
double precision math support, some others can make do with a combination
where you do part of the computation in single, the rest in double and
other calculations work just fine in single precision. the gromacs MD
code has had an all-single precision option for ages and that is how you
run it the fastest.
> I was wondering if it is possible to use the gaming series of GPUs such as
> GeForce GTX250 and the new one GeForce GTX580 for such kind of simulations.
> I mean, if i use this GTX series for small systems with NAMD how realiable
> are the results?
just as reliable as if you compute forces with SSE vectorization support.
in the current implementation, you should not see a difference in the
computation between Tesla and Geforce.
> Are there any benchmark biomolecular simulation results between double and
> single precision GPUs?
any g200 or fermi class GPU supports (some) double precision.
the 20x0 tesla cards just have _more_ double precision units.
that only makes a difference if _all_ calculations are done in double,
but they usually are not, since even on Tesla, you have twice as
many single precision units available than double precision.
the differences of the tesla cards is:
- more memory
- ECC memory support (at a small performance penalty)
- more double precision support
- the cards are very tightly quality controlled
and warranted by nvidia. if you have a broken
one, you get it replaced instantly.
all of this is very beneficial if you set up a large cluster
with many gpus and a large variety of applications.
if you want to equip a single desktop with a couple of
high-end geforce GPUs and only want to use NAMD on it,
then you might not need the tesla features so much.
ECC support is a bit of a religious issue. you can have
errors on the geforce without noticing, but many people
use MD without a problem on them. if i was running
MD on a geforce, i would regularly run cuda_memtest
in order to confirm the card is still doing ok.
> Any help o suggestion (or point out to information), will be greatly
> Thanks a lot in advance,
> Salvador HV
-- Dr. Axel Kohlmeyer akohlmey_at_gmail.com http://goo.gl/1wk0 Institute for Computational Molecular Science Temple University, Philadelphia PA, USA.
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