Interaction List Compression in Large Parallel Particle Simulations on Multicore Systems

Many particle simulation codes use interaction lists to store interacting particles. Depending on the physical parameters of the simulations those interaction lists may occupy a large amount of physical memory, which may limit the number of particles of the simulation. This article discusses several methods that try to reduce the size of interaction lists while maintaining the number of particle interactions per second or even increase it. Different techniques are discussed for a parallel shared memory algorithm on multicore architectures. On those architectures, the memory bandwidth is shared by multiple cores. Since the interaction list is a large shared data structure, it cannot be stored in CPU caches and has to be streamed into the processor several times. A reduction of the size of the interaction list will therefore reduce the number of elements to be reloaded resulting in more efficient implementations.