Re: [PATCH 0/3] mm/zswap: Implement per-cgroup proactive writeback

[Nhat Pham]

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. However, this reactive approach makes writeback
> timing indeterminate and can disrupt latency-sensitive workloads when
> eviction happens to coincide with a critical execution window.

You can make the same argument about ordinary memory reclaim :) That's
why we have kswapd (asynchronous reclaim ahead of time) and proactive
reclaim solutions (memory.reclaim), which would all target zswap as
well.

>
> Furthermore, in certain scenarios, it is desirable to trigger writeback
> in advance to free up memory. For example, users may want to prepare for
> an upcoming memory-intensive workload by flushing cold memory to the
> backing storage when the system is relatively idle.

Would memory.reclaim not work here? Why are we treating zswap memory
footprint as special here, and spare file and anon?