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Date: Wed, 12 Mar 2025 11:11:54 -0700
From: Minchan Kim <minchan@kernel.org>
To: Qun-Wei Lin <qun-wei.lin@mediatek.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Jiang <dave.jiang@intel.com>, Ira Weiny <ira.weiny@intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>,
	Chris Li <chrisl@kernel.org>, Ryan Roberts <ryan.roberts@arm.com>,
	"Huang, Ying" <ying.huang@intel.com>,
	Kairui Song <kasong@tencent.com>,
	Dan Schatzberg <schatzberg.dan@gmail.com>,
	Barry Song <baohua@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
	linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	nvdimm@lists.linux.dev, linux-mm@kvack.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	Casper Li <casper.li@mediatek.com>,
	Chinwen Chang <chinwen.chang@mediatek.com>,
	Andrew Yang <andrew.yang@mediatek.com>,
	James Hsu <james.hsu@mediatek.com>
Subject: Re: [PATCH 0/2] Improve Zram by separating compression context from
 kswapd
Message-ID: <Z9HOavSkFf01K9xh@google.com>
References: <20250307120141.1566673-1-qun-wei.lin@mediatek.com>
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In-Reply-To: <20250307120141.1566673-1-qun-wei.lin@mediatek.com>

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.