Regularity: A New Important Player in the Game of High-Performance Simulations in Manycore Era

摘要

The recent emergence of manycore processors with wide SIMD mechanisms brings a new important player, namely regularity, into the game of high-performance simulations to let it join other key players, parallelism and locality. Since the SIMD mechanism requires a set of operands onto which a particular operation is performed for its efficient work, a simulation code must be mainly composed of loops to access data sets and to perform arithmetic operations on them in a regular fashion in order to exploit the computation power of the mechanism. However, this requirement does not always mean that the simulation code must operate on very regular data structures, e.g., a simple structured Cartesian grid, but allows us to work on more flexible ones, such as unstructured grids and sets of objects, with some irregularity in general providing we can find small-scale regularity in them and represent it as a set of loops working on the majority regular part of the data set. This paper discusses the issues shown above with an example of our particle-in-cell (PIC) plasma simulation.