On Sat, 2 Nov 2024 at 01:50, Bertrand Drouvot <bertranddrouvot...@gmail.com> wrote: > > On Fri, Nov 01, 2024 at 09:47:05PM +1300, David Rowley wrote: > > I've attached what I thought a more optimal version might look like in > > case anyone thinks making it better is a good idea. > > > > Thanks for the proposal! > > I like the idea, I think that's worth to add a few comments, something like:
I'm happy if you want to pick this up and continue working on it. I'm mostly just keen to not leave the suboptimal version of the function in core as it is. One thing you might want to consider is if it's worth having a macro to help decide if you want to inline the function for smaller sizes and not inline for larger sizes. A macro that checks something like: if (__builtin_constant_p(len) && len <= 32) could call an inline version of the function for smaller sizes and do a function call for lager sizes. Compilers seem to have heuristics that result in behaviour like this for library functions such as memset and memcpy. Maybe some experimentation with godbolt.org would yield the crossover point in bytes where compilers switch tactics. I just feel that at the rate we receive small code change suggestions on the mailing lists, it's just a matter of time before someone will come along and suggest we use pg_memory_is_all_zeros() in PageIsVerifiedExtended() again. If we don't optimize that function, then there's a chance a committer might re-commit what's just been reverted. David
