Hello, I'm testing ex34.c under the examples of KSP. It's a multigrid 3D poisson solver.
For 64^3 mesh, the time cost is 1s for 1 node with 12 cores; for 128^3 mesh, the time cost is 13s for 1 node with 12 cores, and the same for 2 nodes with 6 cores. For 256^3 mesh, I use 2 nodes with 12 cores, and time cost goes up to 726s. This doesn't seem right for I'm expecting O(N log(N)). I think it could be the memory bandwidth is not sufficient, and I need to do the bind-to-socket stuff. But I'm wondering what is the typical time cost for a 256^3 mesh, and then a 512^3 mesh? Please give me a rough idea. Thank you. Best, Hui
