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Mon, 08 Sep 2025 05:18:06 -0700 (PDT) Received: from google.com ([2401:fa00:8f:203:b900:780:53bb:571c]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-24c7bb4eb4asm155396755ad.140.2025.09.08.05.18.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Sep 2025 05:18:06 -0700 (PDT) Date: Mon, 8 Sep 2025 21:18:01 +0900 From: Sergey Senozhatsky To: Yosry Ahmed , Vitaly Wool Cc: Vlastimil Babka , hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Christoph Hellwig , Sergey Senozhatsky Subject: Re: [PATCH 0/3] mm: remove zpool Message-ID: References: <20250829162212.208258-1-hannes@cmpxchg.org> <20250904093325.2768507-1-vitaly.wool@konsulko.se> <7b1ca42d-1b89-44f4-bffb-e6b09f86fdc5@suse.cz> <1d42c513-cc83-4f08-a10c-cbd6206070f4@konsulko.se> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 6DB5040010 X-Stat-Signature: xkag68oegsqxkd3fkd5meoq64unydnsw X-Rspam-User: X-HE-Tag: 1757333888-407442 X-HE-Meta: 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 Bf+p5F+G mqZELOloCMvKRb7wy4cTYYV3IB3IgbVXtKrJiOeLV/B8gNFqTBpE7cGYPkcSwlwV+DCagG7UtoAcgxbqsosaV6oAKCtJ8Pofa0ezFKE72jMdl0W6E5RB3+RZBjy2IUg/7tYxMEFLDlYzpViXWJ8IqMPeb0NKynPTGYxM5CZZNTE8O6tQtj+b7F2//cwyice6M3bOOx5jyiRej82jSUKP5NXBfYmsxITkanRA7wnuXGhrqIfK0YN/ISwN3kWK+XsM5BPGxbxESL7bL1WrmnSU3wBL0MWBhilLli1s2aH5xYDcMb4o5KHjnyZTQQWAray8j8BW0/JtEUHqO5Vu2sRzZL7z6lyEfcQR/BYzZK6sEJXX6RVN6JeMvQImmJPHXf6I6wTin 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 (25/09/06 14:25), Sergey Senozhatsky wrote: > On (25/09/05 19:57), Yosry Ahmed wrote: > > I think Android uses zram+zsmalloc with 16K pages. Perhaps Sergey could > > confirm. > > I'm not working on android directly, > > I can confirm that android uses zram+zsmalloc. As of 16K pages, there > was a way to toggle 16k pages on android (via system settings), I don't > know if this is the default now. While I don't know what zsmalloc struggles Vitaly is referring to in particular, off the top of my head, zsmalloc does memcpy()'s for objects that span multiple pages, when zsmalloc kmap()'s both physical pages and memcpy()'s chunks of the object into a provided buffer. With 16K pages we can have rather larger compressed objects, so those memcpy() are likely more visible. Attacking this would be a good idea, I guess.