Fande Kong <fdkong...@gmail.com> writes: > Hi All, > > I am trying to interpret the results from "make stream" on two compute > nodes, where each node has 48 cores. > > If my calculations are memory bandwidth limited, such as AMG, MatVec, > GMRES, etc..
There's a lot more to AMG setup than memory bandwidth (architecture matters a lot, even between different generation CPUs). MatMult and Krylov are almost pure bandwidth. > The best speedup I could get is 16.6938 if I start from one core?? The > speedup for function evaluations and Jacobian evaluations can be better > than16.6938? Residual and Jacobians can be faster, especially if your code is slow (poorly vectorized, branchy, or has a lot of arithmetic). Are you trying to understand perf on current hardware or make decisions about new hardware?