Re: [PATCH 0/2] Improve Zram by separating compression context from kswapd

[Minchan Kim <minchan@kernel.org>]

Hi Qun-Wei

On Fri, Mar 07, 2025 at 08:01:02PM +0800, Qun-Wei Lin wrote:
> This patch series introduces a new mechanism called kcompressd to
> improve the efficiency of memory reclaiming in the operating system. The
> main goal is to separate the tasks of page scanning and page compression
> into distinct processes or threads, thereby reducing the load on the
> kswapd thread and enhancing overall system performance under high memory
> pressure conditions.
> 
> Problem:
>  In the current system, the kswapd thread is responsible for both
>  scanning the LRU pages and compressing pages into the ZRAM. This
>  combined responsibility can lead to significant performance bottlenecks,
>  especially under high memory pressure. The kswapd thread becomes a
>  single point of contention, causing delays in memory reclaiming and
>  overall system performance degradation.

Isn't it general problem if backend for swap is slow(but synchronous)?
I think zram need to support asynchrnous IO(can do introduce multiple
threads to compress batched pages) and doesn't declare it's
synchrnous device for the case.