Re: SLRU optimization - configurable buffer pool and partitioning the SLRU lock

Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> writes:
> Pushed that way, but we can discuss further wording improvements/changes
> if someone wants to propose any.

I just noticed that drongo is complaining about two lines added
by commit 53c2a97a9:

drongo | 2024-03-04 14:34:52 | ../pgsql/src/backend/access/transam/slru.c(436): warning C4047: '!=': 'SlruPageStatus *' differs in levels of indirection from 'int'
drongo | 2024-03-04 14:34:52 | ../pgsql/src/backend/access/transam/slru.c(717): warning C4047: '!=': 'SlruPageStatus *' differs in levels of indirection from 'int'

These lines are

Assert(&shared->page_status[slotno] != SLRU_PAGE_EMPTY);

Assert(&ctl->shared->page_status[slotno] != SLRU_PAGE_EMPTY);

These are comparing the address of something with an enum value,
which surely cannot be sane. Is the "&" operator incorrect?

It looks like SLRU_PAGE_EMPTY has (by chance, or deliberately)
the numeric value of zero, so I guess the majority of our BF
animals are understanding this as "address != NULL". But that
doesn't look like a useful test to be making.

regards, tom lane