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b=oBjyg0QaMLODFKrWIxK8jt4BilAkTDYlHHT2ZCphU/ZRw6tO7Yl3yv5aH9/0NfIj7 HFIgjXEq10jntLjReJ8P7mZalS1N8xQM+zEvzGDPN+RptWiAOlYjJq4cD7Tg39rrse vdDNj50iY6jJak5T/htNp9lU0xRsP12IwDYKgv2r5rsgRBEbMm8P2siQgy6zE+8Row C4O8+8qJ7H1E+ITBF2r0jMwtyBWp8DaZrLiLVKHqWgkK63I+hBv6VYCcGOB6Y+Ixjm HSeoLr79uYsJPhAuDV+xv0zlQMIvMmJTV5cMz17ACT8Pk5NIG/flgkZSqu5J/1QjGh mHMjBWr4lPZtg== From: SeongJae Park To: Nhat Pham Cc: SeongJae Park , akpm@linux-foundation.org, hannes@cmpxchg.org, yosry.ahmed@linux.dev, chengming.zhou@linux.dev, herbert@gondor.apana.org.au, linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/zswap: reduce the size of the compression buffer to a single page Date: Wed, 20 Aug 2025 15:46:59 -0700 Message-Id: <20250820224659.88528-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250820181547.3794167-1-nphamcs@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7D6A1160007 X-Stat-Signature: 9w15ooqmybu1juzoay5n4u7wwjxow8my X-Rspam-User: X-HE-Tag: 1755730023-781685 X-HE-Meta: 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 x34/r3Tq uvbNJD/3C+XEzxx6+Up/gA4sfBfTbHUkGbIZjh5+b+coTngLMEKBahhU9acvsC5ItZPJJLGWGLMSC2tM40KFZpspxNzuzU1Vn7Lig2p8Gzw+fMGVkYXts71FFR50LQtTqtcQJPx5vTT3rbuZuvQ7pwN/HlXBijQ8qc7vkRmz4GcIQtZXIyTqUXSJ/u3ep3FN2Fn1P/NJBjM5nOzDqGQurcMha7bB+NKE2b26HvSBl85kpog6WdYgrUKSd0qZKPPAd3Hsp8OjLm1doZAqxykwOUsljmv7ENKObi5fjTRQhfl0jnAKzsL5hE92HZIsmsuh/e1xdVB5AwnEM787x0TNiOH0MGId8Ma9JmIVXPDvHWu9ACTvULqOKEIwU1j7Vqq8GO0kvxW3TCYTgG9M= 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 Wed, 20 Aug 2025 11:15:47 -0700 Nhat Pham wrote: > Reduce the compression buffer size from 2 * PAGE_SIZE to only one page, > as the compression output (in the success case) should not exceed the > length of the input. > > In the past, Chengming tried to reduce the compression buffer size, but > ran into issues with the LZO algorithm (see [2]). Herbert Xu reported > that the issue has been fixed (see [3]). Now we should have the > guarantee that compressors' output should not exceed one page in the > success case, and the algorithm will just report failure otherwise. > > With this patch, we save one page per cpu (per compression algorithm). > > [1]: https://lore.kernel.org/linux-mm/20231213-zswap-dstmem-v4-1-f228b059dd89@bytedance.com/ This is not mentioned anywhere. Probably you added this as a reference for the past work from Chengming? > [2]: https://lore.kernel.org/lkml/0000000000000b05cd060d6b5511@google.com/ > [3]: https://lore.kernel.org/linux-mm/aKUmyl5gUFCdXGn-@gondor.apana.org.au/ > > Co-developed-by: Chengming Zhou > Signed-off-by: Chengming Zhou > Signed-off-by: Nhat Pham Acked-by: SeongJae Park [...] Thanks, SJ