about stencil.c

[fdkong]

Hi Jed,

I think there are two ways to improve the performance of the code. (1) Change G-S to Jacobi. (2) Continue chaining Jacobi to a block version.

Fande,

[jedbrown]

1. That is likely true (if it optimizes) -- demonstrate it.
2. Would a block version execute faster or merely do more flops?

What is the fastest you can make this execute? You might find the output of -ftree-vectorize -fopt-info-vec-missed (with recent gcc) interesting. Does vectorization matter in this case? Can you trust what the compiler is saying?