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Wed, 12 Mar 2025 20:09:26 -0700 (PDT) Received: from google.com ([2401:fa00:8f:203:ef7a:848f:3b9:98dc]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-301302a8995sm848639a91.1.2025.03.12.20.09.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Mar 2025 20:09:26 -0700 (PDT) Date: Thu, 13 Mar 2025 12:09:18 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Qun-Wei Lin , Jens Axboe , Sergey Senozhatsky , Vishal Verma , Dan Williams , Dave Jiang , Ira Weiny , Andrew Morton , Matthias Brugger , AngeloGioacchino Del Regno , Chris Li , Ryan Roberts , "Huang, Ying" , Kairui Song , Dan Schatzberg , Barry Song , Al Viro , 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 , Chinwen Chang , Andrew Yang , James Hsu Subject: Re: [PATCH 0/2] Improve Zram by separating compression context from kswapd Message-ID: <5gqqbq67th4xiufiw6j3ewih6htdepa4u5lfirdeffrui7hcdn@ly3re3vgez2g> References: <20250307120141.1566673-1-qun-wei.lin@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: DB100140007 X-Rspamd-Server: rspam05 X-Stat-Signature: bxji6i5kdy5d5oizp49q9k5do1tuhbz5 X-HE-Tag: 1741835367-921176 X-HE-Meta: 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 BaKQSqnx nnELKFaPY9pmMcYBmgbMV7Vbx6RvpEWWuAHhmi0IUyomGHis1nWnnE5JF0XBokdSR731eCz0n0EQ7psCHyUXettBvIg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (25/03/12 11:11), Minchan Kim wrote: > 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. The current conclusion is that kcompressd will sit above zram, because zram is not the only compressing swap backend we have.