Re: cgroup/test_zswap failed with "zswpout does not increase after test program"

[Michal Koutný]

On Tue, Jul 07, 2026 at 02:49:56PM -0700, Yosry Ahmed <yosry@xxxxxxxxxx> wrote:
> I would honestly rather use more memory. I think there might be cases
> where the flusher is delayed. The flush being slightly delayed is not
> technically a bug that we want to see a failure for, but if a large
> stats change is not visible that's a user-noticeable behavior that we
> want a failure for.
> 
> WDYT?

There's already the (recent) page size-based scaling, so the idea with
nr_cpus scaling could make the selftest useful on wider range of setups
(even page size can be considered as a slight implementation detail
leak, thus the justification of nr_cpus dependency).

Also, I still think that internally the threshold should be changed to
the "harmonic" formula [1] but the selftest can go with the linear
dependency for more pronounced effects.

Thanks,
Michal

[1] https://lore.kernel.org/lkml/n6mhkjsxsami3qmczkdh57eep4lmcgbtyl7ox3ajzveke44yf6@m4bjevvsr47k/

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