I noticed a while ago that the new fast-path locking code uses integer division to figure out the fast-path locking group slot. To me, this seems a bit unnecessary as FastPathLockGroupsPerBackend is always a power-of-two value, so we can use bitwise-AND instead.
I don't think FAST_PATH_REL_GROUP() is in any particularly hot code paths, but still, having the divide in there isn't sitting well with me. Can we get rid of it? I've attached a patch for that. I also adjusted the method used to calculate FastPathLockGroupsPerBackend. Also, the Assert that was going on at the end of the loop in InitializeFastPathLocks() looked a little odd as it seems to be verifying something that the loop condition was checking already. I thought it was better to check that we end up with a power-of-two. Please see the attached patch. David
v1-0001-Eliminate-integer-divide-in-fastpath-locking-code.patch
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