Re: [RFC PATCH v3] mm/vmpressure: scale window size based on machine memory

Michal Hocko
2026-03-06T15:52:50Z

On Wed 04-03-26 22:30:38, Benjamin Lee McQueen wrote:
> the vmpressure window size has been fixed at 512 pages
> (SWAP_CLUSTER_MAX * 16), ever since the file's inception. a TODO in
> the file notes that the vmpressure window size should be scaled
> similarly to vmstat's scaling, via machine size.
>
> the problem with fixed window size on large memory systems:

Thank you for this much more detail insight into your thinking. This is
a good start. I am still missing an overall motivation though. Are you
trying to address a theoretical concern (the said TODO) or do you have
any practical workload that generates bogus vmpressure events. Also
please note that vmpressure is a legacy notification interface only
available in cgroup v1. PSI (via memory.pressure or global
/proc/pressure/) is a new/preferred method to measure memory pressure.
See more Documentation/accounting/psi.rst
--
Michal Hocko
SUSE Labs