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Thu, 26 Feb 2026 20:31:46 -0800 (PST) Received: from Barrys-MBP.hub ([47.72.129.29]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2adfb5b1035sm57973225ad.7.2026.02.26.20.31.43 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 26 Feb 2026 20:31:46 -0800 (PST) From: Barry Song <21cnbao@gmail.com> To: willy@infradead.org Cc: axelrasmussen@google.com, linux-mm@kvack.org, lsf-pc@lists.linux-foundation.org, ryncsn@gmail.com, weixugc@google.com, yuanchu@google.com Subject: Re: [LSF/MM/BPF] Improving MGLRU Date: Fri, 27 Feb 2026 12:31:39 +0800 Message-Id: <20260227043139.95115-1-21cnbao@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E995F1C0004 X-Stat-Signature: o6cq74ongnufhzdn6bfsfhsx7dn175gw X-Rspam-User: X-HE-Tag: 1772166707-696904 X-HE-Meta: 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 dedxUC9j o7xozIBFnimzf6Ts= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >> MGLRU has been introduced in the mainline for years, but we still have two LRUs >> today. There are many reasons MGLRU is still not the only LRU implementation in >> the kernel. > To my mind, the biggest problem with MGLRU is that Google dumped it on us > and ran away. Commit 44958000bada claimed that it was now maintained and > added three people as maintainers. In the six months since that commit, > none of those three people have any commits in mm/! This is a shameful > state of affairs. > > I say rip it out. Hi Matthew, Can we keep it for now? Kairui, Zicheng, and I are working on it. >From what I’ve seen, it performs much better than the active/inactive approach after applying a few vendor hooks on Android, such as forced aging and avoiding direct activation of read-ahead folios during page faults, among others. To be honest, performance was worse than active/inactive without those hooks, which are still not in mainline. It just needs more work. MGLRU has many strong design aspects, including using more generations to differentiate cold from hot, the look-around mechanism to reduce scanning overhead by leveraging cache locality, and data structure designs that minimize lock holding. Best regards Barry