Hi, On 2023-10-09 18:31:11 -0400, Robert Haas wrote: > On Mon, Oct 9, 2023 at 4:47 PM Andres Freund <and...@anarazel.de> wrote: > > I think we might be able to speed some of this up by pre-compute values so > > we > > can implement things like bytesleft / UsableBytesInPage with shifts. IIRC we > > already insist on power-of-two segment sizes, so instead of needing to > > divide > > by a runtime value, we should be able to shift by a runtime value (and the > > modulo should be a mask). > > Huh, is there a general technique for this when dividing by a > non-power-of-two?
There is, but I was just having a brainfart, forgetting that UsableBytesInPage isn't itself a power of two. The general technique is used by compilers, but doesn't iirc lend itself well to be done at runtime. Greetings, Andres Freund
