Re: Draft for basic NUMA observability

Hi,

On 2025-04-08 09:35:37 -0400, Andres Freund wrote:
> On April 8, 2025 9:21:57 AM EDT, Tomas Vondra <tomas(at)vondra(dot)me> wrote:
> >On 4/8/25 15:06, Andres Freund wrote:
> >> On 2025-04-08 17:44:19 +0500, Kirill Reshke wrote:
> >> I think it's not right that something in src/port defines an SQL callable
> >> function. The set of headers for that pull in a lot of things.
> >>
> >> Since the file relies on things like GUCs, I suspect this should be in
> >> src/backend/port or such instead.
> >>
> >
> >Yeah, I think you're right, src/backend/port seems like a better place
> >for this. I'll look into moving that in the evening.
>
> On a second look I wonder if just the SQL function and perhaps the page size
> function should be moved. There are FE programs that could potentially
> benefit from num a awareness (e.g. pgbench).

I would move pg_numa_available() to something like
src/backend/storage/ipc/shmem.c.

I wonder if pg_numa_get_pagesize() should loose the _numa_ in the name, it's
not actually directly NUMA related? If it were pg_get_pagesize() it'd fit in
with shmem.c or such.

Or we could just make it work in FE code by making this part

Assert(IsUnderPostmaster);
Assert(huge_pages_status != HUGE_PAGES_UNKNOWN);

if (huge_pages_status == HUGE_PAGES_ON)
GetHugePageSize(&os_page_size, NULL);

#ifndef FRONTEND - we don't currently support using huge pages in FE programs
after all. But querying the page size might still be useful.

Regardless of all of that, I don't think the include of fmgr.h in pg_numa.h is
needed?

Greetings,

Andres Freund