Re: [LSF/MM/BPF TOPIC] Restricting or migrating unmovable kernel allocations from slow tier

Gregory Price
2025-02-10T15:48:04Z

On Mon, Feb 10, 2025 at 04:17:41PM +0900, Byungchul Park wrote:
> On Mon, Feb 10, 2025 at 01:00:02AM -0500, Gregory Price wrote:
> >
> > You can probably actually (maybe?) collect data on this today - but
> > you still have to contend with #2 and #3.
>
> Ah. You seem to mean those works should be serialized. Right? If it
> should be for some reason, then it could be sensible.
>

I'm suggesting that there isn't a strong reason (yet) to consider such a
complicated change. As Willy has said, it's a fairly fundamental change
for a single-reason (CXL), which does not bode well for its acceptance.

Honestly trying to save you some frustration. It would behoove you to
find stronger reasons (w/ data) or consider different solutions. Right
now there are stronger, simplers solutions to the ZONE_NORMAL capacity
issue (struct page resize, huge pages) for possible capacities.

I also think someone should actively ask whether `struct page` can be
hosted on remote memory without performance loss. I may look into this.

~Gregory