Abstract:

A minimum communication cycle strategy for large-scale parallel computation of transient electromagnetic fields is presented to solve the communication complexity of the discontinuous Galerkin time domain method using unstructured grids in parallel computation.The topology of point-to-point communication between processors is mapped to a communication matrix.By using the non-interference feature of communication between non-associated processes when the communication buffer is not full,the non-interference processors communication sequence is sorted,the simultaneous communication in each roundtrip is recorded as the same communication cycle,and the communication matrix is refilled.The minimum communication cycle strategy recursively takes the remainder of each element for the initial communication matrix,and after each recursion,processors that communicate simultaneously in the communication cycle are obtained,excluding the corresponding elements of these processors from the next recursion until all elements of the initial communication matrix are sorted.Minimum communication cycle strategy can effectively reduce the total number of communication cycles in the parallel iterative computing process,reduce the time consumed by the communication processor,and thus improve the computational efficiency of the algorithm.Compared with traditional strategies,the number of communication cycles of the minimum communication cycle strategy is reduced to 3%,which significantly improves the parallel efficiency and reduces the computing time.At the same time,the parallel efficiency of 70.38% (tenfold expansion) is achieved when using this strategy for calculation with 8 000 core groups (8 000 processors,520 000 cores) on the light of the Sunway Taihu-Light supercomputer.

Key words: discontinuous Galerkin time domain, auxiliary differential equation, parallel algorithm