Multilevel Balancing Domain Decomposition at Extreme Scales
In this paper we present a fully distributed, communicator aware, recursive, and interlevel overlapped message passing implementation of the multilevel balancing domain decomposition by constraints (MLBDDC) preconditioner. The implementation highly relies on subcommunicators in order to achieve the desired effect of coarse grain overlapping of computation and communication, and communication and communication among levels in the hierarchy (namely, interlevel overlapping) Essentially, the main communicator is split into as many nonoverlapping subsets of message passing interface (MPI) tasks (i.e. MPI subcommunicators) as levels in the hierarchy. Provided that specialized resources (cores and memory) are devoted to each level, a careful rescheduling and mapping of all the computations and communications in the algorithm lets a high degree of overlapping be exploited among levels. All subroutines and associated data structures are expressed recursively, and therefore MLBDDC preconditioners with an arbitrar.
SIAM J. Sci. Comput.