Re: Fix bank selection logic in SLRU

On Tue, 10 Dec 2024 at 6:32 PM, Andrey M. Borodin <x4mmm@yandex-team.ru>
wrote:

>
>
> > On 10 Dec 2024, at 15:39, Yura Sokolov <y.sokolov@postgrespro.ru> wrote:
> >
> > It is not critical bug, since it doesn't hurt correctness just
> performance. In worst case only one bank will be used.
>
> Ugh... yeah. IMO the problem is that we do not have protection that
> rejects values that are not power of 2.
> If other values given system operates as if there are 2^(popcount(n)-1)
> banks. So if we just round down value to nearest power of 2 - we will help
> incorrectly configured systems to use proper amount of memory and keep
> performance of properly configured systems.


+1


>
> IMO doing modulo is not necessary. And hash function is pure waste of CPU
> cycles.


I agree

—
Dilip

>