On Wed, Mar 05, 2025 at 08:51:21AM +0700, John Naylor wrote: > That was my hunch too, but I wanted to be more sure, so I modified the > benchmark so it doesn't know the address of the next calculation until > it finishes the last calculation so we can hopefully see the latency > caused by indirection. It also does an additional calculation on > constant 20 bytes, like the WAL header. I also tweaked the length each > iteration so the branch predictor maybe has a harder time predicting > the constant 20 input. And to make it more challenging, I removed the > part that inlined all small inputs, so it inlines only constant > inputs:
Would you mind sharing this test? It sounds like you are running a workload with a mix of constant/inlined calls and function pointer calls to simulate typical usage for WAL, but I'm not 100% sure I'm understanding you correctly. > These are still a bit noisy, and close, but, it seems there is no > penalty in using the function pointer as long as the header > calculation is inlined. These results look promising. -- nathan
