Re: Path forward for Virtualized Swap?

[Johannes Weiner <hannes@cmpxchg.org>]

On Tue, Sep 22, 2026 at 05:23:31AM -1000, Chris Li wrote:
> In my experiment, 100% is already way above that bound, which is why
> I'm curious about your data point. How do you run and test your system
> at 100%? Please correct me if I am wrong, but it looks like you
> haven't.

You're conflating machine size with workingset residency.

Rik showed an example where the compressed set was twice as large as
the anon set, and it worked fine. And why is that surprising?

We know many applications have long tails of cold pages. Idle tmpfs
files and shmem segments. Things that get rarely used. memcache style
workloads have a small, hot index and a huge data segment with poor
access locality. Even if large parts of it are in compressed space
that's better than storage fetches.

Your "this will thrash after 7-10%" is an average based on common
workingsets that are actually hot. It doesn't mean there aren't cases
that benefit from much higher overcommit.

Why even get into this? Why even try to find some universal limit on
something that just costs memory anyway, when memory containment is
already a solved problem?