Hi, I have coded in parallel using PETSc and Hypre. I found that going from 1 to 4 processors gives an almost 4 times increase. However from 4 to 8 processors only increase performance by 1.2-1.5 instead of 2.
Is the slowdown due to the size of the matrix being not large enough? Currently I am using 600x2160 to do the benchmark. Even when increase the matrix size to 900x3240 or 1200x2160, the performance increase is also not much. Is it possible to use -log_summary find out the error? I have attached the log file comparison for the 4 and 8 processors, I found that some event like VecScatterEnd, VecNorm and MatAssemblyBegin have much higher ratios. Does it indicate something? Another strange thing is that MatAssemblyBegin for the 4 pros has a much higher ratio than the 8pros. I thought there should be less communications for the 4 pros case, and so the ratio should be lower. Does it mean there's some communication problem at that time? Thank you very much. Regards -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: test4_600_29min.txt URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20080607/08482424/attachment.txt> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: test8_600_19min.txt URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20080607/08482424/attachment-0001.txt>
