1. 1 ProActive performance evaluation with NAS benchmarks and optimization of OO SPMD Brian AmedroVladimir Bodnartchouk

2. 2 Outline TimIt : A profiling tool for ProActive OO SPMD model in ProActive Performance evaluation with NAS benchmarks Optimizing group communications

3. 3 TimIt : A profiling tool for ProActive A ProActive feature to time and analyze applications

4. 4 OO SPMD model A parallel programming model Flexibility and high level of abstraction Strongly used in NAS benchmarks implementations One To AllScatteringReduce operation

5. 5 NAS Parallel Benchmarks Designed by NASA to evaluate benefits of high performance systems Strongly based on CFD 5 benchmarks (kernels) to test different aspects of a system Easy to implement thanks to OOSPMD pattern Tests performed on Sun 1.5 with RMI for ProActive and PGI 6.0 compiler for MPI

6. 6 CG Kernel (Conjugate Gradient) Floating point operations Eigen value computation High number of unstructured communications 12000 calls 570 MB sent 1 min 32 65 % comms

7. 7 MG Kernel (Multi Grid) Floating point operations Solving Poisson problem Structured communications 600 calls 45 MB sent 1 min 32 80 % comms

8. 8 IS Kernel (Integer Sort) Keys ranking operations Bucket sort Large arrays in memory 65 calls 22 MB sent 4 min 32 60 % comms

9. 9 EP Kernel (Embarrassingly Parallel) Random numbers generation Almost no communications 6 calls 246 bytes sent 7 min 32 2 % comms

10. 10 FT Kernel (Fourier Transformation) Floating point operations Big messages : 8 MB per call 22 calls 180 MB sent 1 min 32 40 % comms

11. 11 Optimizing group communications Implement efficient group communication Minimize the TCP traffic Decrease the network congestion Use clustering techniques to choose the better algorithm to use

12. 12 Ring all-to-all algorithm Best for large size communications Takes n-1 steps step1 2 3

13. 13 Recursive doubling all-to-all algorithm Best for small size communications Takes log(n) steps step1 2

14. 14 Conclusion TimIt : easy and helpful profiling tool NAS benchmarks easy to implements with ProActive and OO SPMD pattern http://www-sop.inria.fr/oasis/proactive/nas Good performances expected with future Sun Java 6 and usage of Ibis RMI

15. 15 Questions ?

16. 16 MPI / ProActive MPIProActive Mpirundeployment MPI_Initactivities creation MPI_Finalize MPI_Comm_SizegetMyGroupSize MPI_Comm_rankgetMyRank MPI_*Sendmethod call (setter and getter) MPI_*Recv MPI_Barrierbarrier MPI_Bcastmethod call MPI_Scattermethod call with a scatter group as parameter MPI_Gatherresult of a group communication MPI_Reduceprogrammer's method Back