Re: Auto-tune shared_buffers to use available huge pages

On Fri, Jan 23, 2026 at 4:50 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Not expressing an opinion on whether we should do this, but
> there is a comment on GetHugePageSize() that you seem to have
> falsified without bothering to correct:

Thanks for the review, I've updated the comment.

I've also revised the approach a bit. Using the free huge pages for
auto-tuning was too restrictive, it prevents setup like running
multiple Postgres on the same instance, which would require splitting
the available huge pages.

I've replaced it with a shared_buffers_autotune_target GUC, which
controls the amount of shared memory to target. If the requested
shared memory is below the target size, shared_buffers will be
increased to (approximately) reach this target.

By setting shared_buffers_autotune_target to the amount of available
huge pages, shared_buffers will be auto-tuned to use the leftover
space.

Regards,
Anthonin Bonnefoy