Section: New Results

Improving Parallel Executions by Increasing Task Granularity in Task-based Runtime Systems using Acyclic DAG Clustering

Participants : Bérenger Bramas, Alain Ketterlin.

Bérenger Bramas and Alain Ketterlin collaborate with the TONUS team in the development of a parallel solver for the resolution of conservative hyperbolic upwind kinetic of unstructured tokamaks [49]. In their methods, they must solve the transport equation on an unstructured mesh, which can be seen as having a wave propagating from neighbor-to-neighbor. The resulting computation can be represented using a direct acyclic graph (DAG) of operations, where each operation is a tiny task. Therefore, Bérenger Bramas and Alain Ketterlin contributed mainly on two aspects. First, they have proposed a highly optimized lock-free parallel implementation of the solution based on atomic instructions. Second, they have improved an existing algorithm from the literature to cluster a DAG of tasks with the aim of increasing the granularity of the tasks and to reduce the overhead of the parallelization consequently. This new approach has been accepted in a dedicated paper (accepted but not yet published).