Re: NUMA shared memory interleaving

Hi,

On Wed, Apr 16, 2025 at 10:05:04AM -0400, Robert Haas wrote:
> On Wed, Apr 16, 2025 at 5:14 AM Jakub Wartak
> <jakub(dot)wartak(at)enterprisedb(dot)com> wrote:
> > Normal pgbench workloads tend to be not affected, as each backend
> > tends to touch just a small partition of shm (thanks to BAS
> > strategies). Some remaining questions are:
> > 1. How to name this GUC (numa or numa_shm_interleave) ? I prefer the
> > first option, as we could potentially in future add more optimizations
> > behind that GUC.
>
> I wonder whether the GUC needs to support interleaving between a
> designated set of nodes rather than only being able to do all nodes.
> For example, suppose someone is pinning the processes to a certain set
> of NUMA nodes; perhaps then they wouldn't want to use memory from
> other nodes.

+1. That could be used for instances consolidation on the same host. One could
ensure that numa nodes are not shared across instances (cpu and memory resource
isolation per instance). Bonus point, adding Direct I/O into the game would
ensure that the OS page cache is not shared too.

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com