Horton

Re: pgsql: Introduce pg_shmem_allocations_numa view

Christoph Berg <myon@debian.org>

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From: Christoph Berg <myon@debian.org>
To: Tomas Vondra <tomas@vondra.me>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Andres Freund <andres@anarazel.de>, Tomas Vondra <tomas.vondra@postgresql.org>, pgsql-hackers@lists.postgresql.org
Date: 2025-06-24T15:30:02Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Handle EPERM in pg_numa_init

  2. Add CHECK_FOR_INTERRUPTS into pg_numa_query_pages

  3. Silence valgrind about pg_numa_touch_mem_if_required

  4. Limit the size of numa_move_pages requests

  5. Introduce pg_shmem_allocations_numa view

Re: Tomas Vondra
> If it's a reliable fix, then I guess we can do it like this. But won't
> that be a performance penalty on everyone? Or does the system split the
> array into 16-element chunks anyway, so this makes no difference?

There's still the overhead of the syscall itself. But no idea how
costly it is to have this 16-step loop in user or kernel space.

We could claim that on 32-bit systems, shared_buffers would be smaller
anyway, so there the overhead isn't that big. And the step size should
be larger (if at all) on 64-bit.

> Anyway, maybe we should start by reporting this to the kernel people. Do
> you want me to do that, or shall one of you take care of that? I suppose
> that'd be better, as you already wrote a fix / know the code better.

Submitted: https://marc.info/?l=linux-mm&m=175077821909222&w=2

Christoph