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Tue, 26 Mar 2024 15:01:29 -0700 (PDT) MIME-Version: 1.0 References: <20240325235018.2028408-1-yosryahmed@google.com> <20240325235018.2028408-6-yosryahmed@google.com> In-Reply-To: <20240325235018.2028408-6-yosryahmed@google.com> From: Nhat Pham Date: Tue, 26 Mar 2024 15:01:18 -0700 Message-ID: Subject: Re: [RFC PATCH 5/9] mm: zswap: remove zswap_same_filled_pages_enabled To: Yosry Ahmed Cc: Andrew Morton , Johannes Weiner , Chengming Zhou , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6305740028 X-Stat-Signature: 7aqkuqbq81ra11k4hkbuo4erh8otmm13 X-HE-Tag: 1711490490-244577 X-HE-Meta: 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 pdVD0bRA yG8ZXiWoqVs8c8G//p7er10SfZu5jzXPtbY4hwSD6DEv/kyjM7kZNgXVNFtRAREd6ZEiPy1Gt6QCcGlQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.087022, 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 Mon, Mar 25, 2024 at 4:50=E2=80=AFPM Yosry Ahmed = wrote: > > There is no logical reason to refuse storing same-filled pages more > efficiently and opt for compression. Remove the userspace knob. > Agree. Absolutely no idea why we have this knob in the first place - if you have cycles to compress, you probably have some extra cycles to check same-filled page state? And that is the only cost I can think of - it wins on probably all other aspects: memory usage, "decompression", no need to write back these pages etc. Any actual zswap user who has data or counter-use case should chime in, but FWIW, my vote is: Reviewed-by: Nhat Pham