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02.
06.
2017
A C++ based MPI-enabled Tasking Framework to Efficiently Parallelize Fast Multipode Methods for Molecular Dynamics
David Haensel
Forschungszentrum Jülich
Modern molecular dynamic simulations steadily shift the scaling
bottleneck from computation towards communication.
The main bottleneck of such simulations are long-range interactions that
cannot be computed from local information only.
Any algorithm computing the equivalent of such long-range pairwise
interactions needs global information by design which leads to global
communication.
Especially for strong scaling with only a few particles per core such
Coulomb solvers are already communication/synchronization-bound.
To tackle these issues we are developing a parallel Fast Multipole
Method (FMM) in modern C++.
To reduce parallelization overhead, e.g. synchronization points or load
imbalance, algorithm-aware strategies have to be applied.
Such measures will improve performance, especially for a tasking
approach with dependency resolving and work scheduling.
Implementing those specific strategies in a scheduler and dependency
resolver of a third party library could be quite challenging.
Also, relying solely on universal dynamic scheduling implementations
could affect performance unfavorably.
The current C++ language standard (C++11) offers several robust features
for parallel intranode programming.
With the help of those standardized C++ features, we added a tasking
layer to our FMM library.
In this talk we want to present, which C++11 features are most suited
for tasking and how we apply and tailor such schemes for our purposes.
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