A Minimal Round-Trip Strategy Based on Graph Matching for Parallel DGTD Method With Local Time-Stepping

The load distribution in the local time stepping (LTS) method significantly impacts its computing efficiency. This letter proposes a minimal round-trip (MRT) strategy of the LTS method to balance the communication load of the discontinuous Galerkin time-domain (DGTD) method. By discovering the matching of the connected graph of computing nodes, independent communication with a similar load can be done in the same round trip to minimize waiting between nodes in nonblocking communication, thereby decreasing the communication time of the DGTD-LTS technique. The numerical results indicate that the MRT strategy reduces the communication time between processors by 50% and improves the parallel performance when the LTS method is implemented in the DGTD method. The parallel scale of the MRT approach may be increased to 16 000 nodes (1 040 000 cores) on the supercomputer, and the parallel efficiency is greater than 73.8%.