Re: Large writable variables

Hi,

On 2018-10-17 09:38:18 +1300, Gavin Flower wrote:
> On 17/10/2018 09:36, Tom Lane wrote:
> > Andres Freund <andres(at)anarazel(dot)de> writes:
> > > Attached is a patch that shrinks fmgr_builtins by 25%. That seems
> > > worthwhile, it's pretty frequently accessed, making it more dense is
> > > helpful. Unless somebody protests soon, I'm going to apply that...
> > Hah. I'm pretty sure that struct *was* set up with an eye to padding ...
> > on 32-bit machines. This does make it shorter on 64-bit, but also
> > makes the size not a power of 2, which might add a few cycles to
> > array indexing calculations. Might be worth checking whether that's
> > going to be an issue anywhere.
> >
> > What's the point of the extra const decoration on funcName? ISTM
> > the whole struct should be const, or not.

> Would it be useful to add dummy variable(s) to bring it up to a power of 2?

Err. Reread what we're talking about. The point was to reduce the size,
it's a power of two right now (32). We could of course also just do
nothing (re-add a dummy variable), which would, drumroll, do nothing.

Greetings,

Andres Freund