Short version of question: We have a Opteron 6272 cluster, an we have recently started bilding FX 9370 based small cluster. Problem is that we are not able to get desired speed, i.e scaling with number or processes is not optimal.
Full story: When we ran CPMD on Opteron 6272 as a single process, on a single node (hence without any parallel component) we got execution time of say 44 sec. when same thing was repeated on FX 9370 time to finish up job was ~27 sec. but as number of processes are increased (max=8) opteron 6272 scales up very nicely as compared to 9370 and at towards the end manages to just better the 9370 performance.
As processor is almost twice as fast (as given by single process performance), shouldn't i expect similar trend in parallel performance?
MPICH2 was compiled with ACML, and x86_open64 compilers from amd to avoid any bottleneck. preformance with intel compilers was also same.
Here is the link to Intel MPI benchmarking results. http://pastebin.com/keACK8Qz