Re: Draft for basic NUMA observability

On Mon, Feb 24, 2025 at 5:11 PM Bertrand Drouvot
<bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>
> Hi,
>
> On Mon, Feb 24, 2025 at 09:06:20AM -0500, Andres Freund wrote:
> > Does the issue with "new" backends seeing pages as not present exist both with
> > and without huge pages?
>
> That's a good point and from what I can see it's correct with huge pages being
> used (it means all processes see the same NUMA node assignment regardless of
> access patterns).

Hi Bertrand , please see that nearby thread. I've got quite the
opposite results. I need page-fault memory or I get invalid results
("-2"). What kernel version are you using ? (I've tried it on two
6.10.x series kernels , virtualized in both cases; one was EPYC [real
NUMA, but not VM so not real hardware]).

> That said, wouldn't that be too strong to impose a restriction that huge_pages
> must be enabled?
>
> Jakub, thanks for the new patch version! FWIW, I did not look closely to the
> code yet (just did the minor changes already shared to have valid result with non
> tiny shared buffer size). I'll look closely at the code for sure once we all agree
> on the design part of it.

Cool, I think we are pretty close actually, but others might have
different perspective.

-J.