Re: Slow-tier Page Promotion discussion recap and open questions

Gregory Price
2025-01-06T17:02:54Z

On Sun, Dec 29, 2024 at 09:36:41PM -0800, David Rientjes wrote:
> On Thu, 26 Dec 2024, Karim Manaouil wrote:
>
> memory node will have a standard top-tier node to promote to *or* that we
> stash that promotion node information at the time of demotion

Not sure stashing this information generalizes the way you want, and
may require space in the folio/page struct that may not be available.

Things also get more complicated the further away from virtual memory
mappings you get, because associations become weaker (physical pages
backing file cache may have weak, ephemeral associations, for example).

We should consider the implications of limiting promotion to one or
more levels in a single proximity domain - and whether the "two step"
migration process is ultimately harmful or not.

Just trying to save ourselves from crawling down a rabbit hole.

~Gregory