Re: [PATCH] mm/vmpressure: scale window size based on machine memory and CPU count

[Lorenzo Stoakes]

On Mon, Mar 02, 2026 at 09:56:38AM +0100, Michal Hocko wrote:
> On Fri 27-02-26 16:15:55, Benjamin Lee McQueen wrote:
> > on systems of different sizes, the fixed 512 page window may not
> > be suitable and cause excessive false positive memory pressure
> > notifications.
>
> Please be more specific about the issue you are trying to have fixed.
> The above is way too generic. How much memory the system has, what do
> you consider false positive and why. What is the workload. Etc...
>
> > or should window size be capped to avoid excessive notification
> > delays on very large systems?
> >
> > v2: better commit msg, also tried to fix the whitespace.
>
> Also please refrain from sending new versions in a quick succession
> and wait for more feedback to come.
>
> Last but not lease if this is a more of an idea rather than something
> aimed to be merged make the fact explicit by RFC prefix to PATCH.
>
> There is much more you can read about the process in Documentation/process/
>

Agree on all points here.

I'm also concerned that by simply adding this conjectured approach without a
_lot_ of careful testing and examination of real-world cases you risk causing
issues/breaking real world user's assumptions. This is pretty sensitive code.

Definitely this kind of potentially invasive change should always be submitted
as an RFC to begin with.

> Thanks
> --
> Michal Hocko
> SUSE Labs

Cheers, Lorenzo