Re: [PATCH 2/3] mm/zswap: Implement proactive writeback

[Yosry Ahmed]

On Mon, May 11, 2026 at 12:49 PM Nhat Pham <nphamcs@xxxxxxxxx> wrote:
>
> On Mon, May 11, 2026 at 3:52 AM Hao Jia <jiahao.kernel@xxxxxxxxx> wrote:
> >
> > From: Hao Jia <jiahao1@xxxxxxxxxxx>
> >
> > Zswap currently writes back pages to backing swap devices reactively,
> > triggered either by memory pressure via the shrinker or by the pool
> > reaching its size limit. This reactive approach offers no precise
> > control over when writeback happens, which can disturb latency-sensitive
> > workloads, and it cannot direct writeback at a specific memory cgroup.
> > However, there are scenarios where users might want to proactively
> > write back cold pages from zswap to the backing swap device, for
> > example, to free up memory for other applications or to prepare for
> > upcoming memory-intensive workloads.
> >
> > Therefore, implement a proactive writeback mechanism for zswap by
> > adding a new cgroup interface file memory.zswap.proactive_writeback
> > within the memory controller.
>
>
> We already have memory.reclaim, no? Would that not work to create
> headroom generally for your use case? Is there a reason why we are
> treating zswap memory as special here?

+1, why do we need to specifically proactively reclaim the compressed memory?

Also, if we do need to minimize the compressed memory and force higher
writeback rates, we can do so with memory.zswap.max, right?