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

Byungchul Park
2025-02-25T05:06:57Z

On Mon, Feb 10, 2025 at 10:47:58AM -0500, Gregory Price wrote:
> 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.

Could you share the plan or what you have been thinking about it?

We'd be happy to discuss this topic together, and furthermore, it'd be
even better to work on it together.

Byungchul

> ~Gregory