21,198 research outputs found
Tackling Exascale Software Challenges in Molecular Dynamics Simulations with GROMACS
GROMACS is a widely used package for biomolecular simulation, and over the
last two decades it has evolved from small-scale efficiency to advanced
heterogeneous acceleration and multi-level parallelism targeting some of the
largest supercomputers in the world. Here, we describe some of the ways we have
been able to realize this through the use of parallelization on all levels,
combined with a constant focus on absolute performance. Release 4.6 of GROMACS
uses SIMD acceleration on a wide range of architectures, GPU offloading
acceleration, and both OpenMP and MPI parallelism within and between nodes,
respectively. The recent work on acceleration made it necessary to revisit the
fundamental algorithms of molecular simulation, including the concept of
neighborsearching, and we discuss the present and future challenges we see for
exascale simulation - in particular a very fine-grained task parallelism. We
also discuss the software management, code peer review and continuous
integration testing required for a project of this complexity.Comment: EASC 2014 conference proceedin
Efficient swap algorithms for molecular dynamics simulations of equilibrium supercooled liquids
It was recently demonstrated that a simple Monte Carlo (MC) algorithm
involving the swap of particle pairs dramatically accelerates the equilibrium
sampling of simulated supercooled liquids. We propose two numerical schemes
integrating the efficiency of particle swaps into equilibrium molecular
dynamics (MD) simulations. We first develop a hybrid MD/MC scheme combining
molecular dynamics with the original swap Monte Carlo. We implement this hybrid
method in LAMMPS, a software package employed by a large community of users.
Secondly, we define a continuous time version of the swap algorithm where both
the positions and diameters of the particles evolve via Hamilton's equations of
motion. For both algorithms, we discuss in detail various technical issues as
well as the optimisation of simulation parameters. We compare the numerical
efficiency of all available swap algorithms and discuss their relative merits.Comment: 16 pages, 13 figure
GPU-accelerated simulation of colloidal suspensions with direct hydrodynamic interactions
Solvent-mediated hydrodynamic interactions between colloidal particles can
significantly alter their dynamics. We discuss the implementation of Stokesian
dynamics in leading approximation for streaming processors as provided by the
compute unified device architecture (CUDA) of recent graphics processors
(GPUs). Thereby, the simulation of explicit solvent particles is avoided and
hydrodynamic interactions can easily be accounted for in already available,
highly accelerated molecular dynamics simulations. Special emphasis is put on
efficient memory access and numerical stability. The algorithm is applied to
the periodic sedimentation of a cluster of four suspended particles. Finally,
we investigate the runtime performance of generic memory access patterns of
complexity for various GPU algorithms relying on either hardware cache
or shared memory.Comment: to appear in a special issue of Eur. Phys. J. Special Topics on
"Computer Simulations on GPUs
Status and Future Perspectives for Lattice Gauge Theory Calculations to the Exascale and Beyond
In this and a set of companion whitepapers, the USQCD Collaboration lays out
a program of science and computing for lattice gauge theory. These whitepapers
describe how calculation using lattice QCD (and other gauge theories) can aid
the interpretation of ongoing and upcoming experiments in particle and nuclear
physics, as well as inspire new ones.Comment: 44 pages. 1 of USQCD whitepapers
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