[gmx-developers] free energies on GPUs?
ileontyev at ucdavis.edu
Wed Feb 22 10:05:02 CET 2017
I am having hard time with accelerating free energy (FE) simulations on
my high end GPU. Not sure is it normal for my smaller systems or I am
doing something wrong.
The efficiency of GPU acceleration seems to decrease with the system
size, right? Typical sizes in FE simulations in water is 32x32x32 A^3
(~3.5K atoms) and in protein it is about 60x60x60A^3 (~25K atoms).
Requirement for larger MD box in FE simulation is rather rare.
For my system (with 11K atoms) I am getting on 8 cpus and with GTX 1080
gpu only up to 50% speedup. GPU utilization during simulation is only
1-2%. Does it sound right? (I am using current gmx ver-2016.2 and CUDA
driver 8.0; by request will attach log-files with all the details.)
BTW, regarding how much take perturbed interactions, in my case
simulation with "free_energy = no" running about TWICE faster.
> On 2/13/17, 1:32 AM, "gromacs.org_gmx-developers-bounces at maillist.sys.kth.se on behalf of Berk Hess" <gromacs.org_gmx-developers-bounces at maillist.sys.kth.se on behalf of hess at kth.se> wrote:
> That depends on what you mean with this.
> With free-energy all non-perturbed non-bonded interactions can run on
> the GPU. The perturbed ones currently can not. For a large system with a
> few perturbed atoms this is no issue. For smaller systems the
> free-energy kernel can be the limiting factor. I think there is a lot of
> gain to be had in making the extremely complex CPU free-energy kernel
> faster. Initially I thought SIMD would not help there. But since any
> perturbed i-particle will have perturbed interactions with all j's, this
> will help a lot.
> On 2017-02-13 01:08, Michael R Shirts wrote:
> > What?s the current state of free energy code on GPU?s, and what are the roadblocks?
> > Thanks!
> > ~~~~~~~~~~~~~~~~
> > Michael Shirts
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