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

[Nhat Pham]

On Tue, Jul 7, 2026 at 11:25 AM Yosry Ahmed <yosry@xxxxxxxxxx> wrote:
>
> On Tue, Jul 7, 2026 at 2:38 AM Zenghui Yu <zenghui.yu@xxxxxxxxx> wrote:
>
> We were discussing a way for userspace to explicitly trigger a flush
> before, which would come in handy for testing. However, we decided not
> to expose flushing as a concept to userspace.
>
> Unfortunately I think the only way to "fix" the test is to allocate
> more memory, enough to trigger a flush on most interesting setups.
> Perhaps we should scale the amount of memory with the number of CPUs
> so that we don't have to keep playing whack-a-mole.

I don't have a good idea for writeback, but for zswap out, would
MADV_PAGEOUT work here?