Abstract: As rapid development of the high performance computers, more and more cores arc used and thus lead to more and more communication which debases the perfor-mance of parallel applications greatly. In the test of the performance of Dawning 5000A by a kind of Fast Fouler Transform (HFFT)，we found out that the huge overhead time of MPI_Alltoall is the bottleneck of HFFT. Thus, this paper aimed to test and analyze the leading Alltoall algorithm on Dawning 5000 and Deepcomp 7000 hoping to do a favor to further collective communication optimization. In this paper,the leading Alltoall algorithms such as 2D_Mesh, 3D_Mesh, Bruck, MPICH native, Pair, recursive doubling, Ring,LAM/MPI simple were recounted and tested with different message size and core numbers. The conclusion is that for short message MPICH native and 13ruck performs well on Dawning 5000A while the lower time consuming algorithms on Decpcomp 7000 arc LAM/MPI simple and Bruck; when the message size is medium and large, the best choice for Dawning 5000A is Ring while the optimal algorithm on Deepcomp 7000 is Pair.

Key words: Collective communication, Alltoall, Dawning 5000A, Performance test and analysis