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Mon, 10 Mar 2025 22:02:50 -0700 (PDT) Received: from google.com ([2401:fa00:8f:203:cce8:82e2:587d:db6a]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-224109ddca2sm87480825ad.13.2025.03.10.22.02.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Mar 2025 22:02:50 -0700 (PDT) Date: Tue, 11 Mar 2025 14:02:42 +0900 From: Sergey Senozhatsky To: Nhat Pham Cc: Barry Song <21cnbao@gmail.com>, Qun-Wei Lin , Jens Axboe , Minchan Kim , 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 , 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 2/2] kcompressd: Add Kcompressd for accelerated zram compression Message-ID: References: <20250307120141.1566673-1-qun-wei.lin@mediatek.com> <20250307120141.1566673-3-qun-wei.lin@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: idspnfgs3qx6oyc9e34wtrha3sutm6wc X-Rspam-User: X-Rspamd-Queue-Id: CD5CA100006 X-Rspamd-Server: rspam01 X-HE-Tag: 1741669371-204473 X-HE-Meta: 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 0h9Whk/2 L189xgp7vJFQoCTcU0FyaRPu5udPa4B8bTMhtk/pBbrUmVSBBW1Ow/cv1/6DuGkDEgyTJcpZ20++LB2NJR4H6vyh7HTgQ7LP3LPO+n6L16zYNpPqjwqLoJiMNkr/RD7MRADHBmy7YSDyrQGnTJiLsjJAARLCu4/GRdLtQEBLEJIHXSY9/ymlvn2lxh0WYq6FInAsOz9vLr7hFrvNb4hbAtrSktyF2c8+uy10+rX+k8U480NOLO37qN1jz4pr3k5qTZBAfNWhEXXvMoLtNAhRk/3rugtxnc04vt0Nf/lReTp5HQQ5iWEknIHZYpCR82O+qGFVXbwFmmShi2tk+tg0289jdSlY7zNDsJLQaZfzGaoBxqr/BeBSip5ZM3sIgGOLJ6ebHDTHsarEXJdhTvhHUAWsxkZJx0af2UImFbVL8yHlhTSXpXP/bCTDQ6w== 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 (25/03/07 15:13), Nhat Pham wrote: > > > +config KCOMPRESSD > > > + tristate "Kcompressd: Accelerated zram compression" > > > + depends on ZRAM > > > + help > > > + Kcompressd creates multiple daemons to accelerate the compression of pages > > > + in zram, offloading this time-consuming task from the zram driver. > > > + > > > + This approach improves system efficiency by handling page compression separately, > > > + which was originally done by kswapd or direct reclaim. > > > > For direct reclaim, we were previously able to compress using multiple CPUs > > with multi-threading. > > After your patch, it seems that only a single thread/CPU is used for compression > > so it won't necessarily improve direct reclaim performance? > > > > Even for kswapd, we used to have multiple threads like [kswapd0], [kswapd1], > > and [kswapd2] for different nodes. Now, are we also limited to just one thread? > > I also wonder if this could be handled at the vmscan level instead of the zram > > level. then it might potentially help other sync devices or even zswap later. > > Agree. A shared solution would be much appreciated. We can keep the > kcompressd idea, but have it accept IO work from multiple sources > (zram, zswap, whatever) through a shared API. I guess it also need to take swapoff into consideration (especially if it takes I/O from multiple sources)?