From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 10EA710A62CB for ; Thu, 26 Mar 2026 13:13:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2C27F6B0005; Thu, 26 Mar 2026 09:13:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 24C9A6B0088; Thu, 26 Mar 2026 09:13:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 114926B0089; Thu, 26 Mar 2026 09:13:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id EF5516B0005 for ; Thu, 26 Mar 2026 09:13:44 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 61C041B93E6 for ; Thu, 26 Mar 2026 13:13:44 +0000 (UTC) X-FDA: 84588256368.29.8776E50 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf04.hostedemail.com (Postfix) with ESMTP id 9A67740011 for ; Thu, 26 Mar 2026 13:13:42 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=tiC58gz+; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774530822; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ryA8TK5XxONxK0fS+I8EXaf02G4wxIszdifpgZVGWTw=; b=wuGEh0UBqafIcKxI433sGvF5VvXJ/WIFFAFwOgt1TysUuX4VMzX3/hS88kgEn06cAgGezP SPlWQC5QGoInLNaT+4PCHiirdLx9er1HfW8immJ7gq78P94kYgM51Iai0LSeJ/1Cesiypo v0hZs74vobCA0YOhvptkKColzM9llwA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774530822; a=rsa-sha256; cv=none; b=O4WiApcqHJLy0SxIrLaYeAfYa60J9zippX4MEOGzV7cyhXgABbHdOjmtup+eQaXbwSZ30Q L3gok3/IMITEt1/JeWE3jebRq2zo/UyaX+Y2GYSg8PQ74yY0kw8HBjOMZtE8uX+G/STaoC TeD46oMvD5Igioh7nHeu9c94sWmwL9g= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=tiC58gz+; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 1E1B460103; Thu, 26 Mar 2026 13:13:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6F88C19424; Thu, 26 Mar 2026 13:13:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774530821; bh=RppesdMGtLvcCeXRbqBSvK537/hNj9FmRtkPlUC+DG0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tiC58gz+NaUzy0dkhSAVFvJ0rieCKXkEj83kW8t5GOW4pYIMWHPH/bmZB5udX3CDn dhNHc7sPEWPELCAcZy1WbT2gnXyr1kzwNHf9I/CbMHk3qgOXJGwstWU//+3XnxYg3l VX4MSeLsUl21Ek1NQkrcozZPsMaJyRjNuqXorN7nTATkCVnHTSaV+nJr7aHVKfimFt EYWCM01LbEN42OeWXfNTwNiuEFe7z3vUHuoP5Edf2tchpJ3wttooo15PIYMOPt76qE Cqp9YfoAzYyiMwB3+8jDtE84GbrC46FbS6WeRVSd1iOtjJTHjz6h8VG1pa2fXjujRT TZjhROjZ5reSA== Date: Thu, 26 Mar 2026 13:13:33 +0000 From: "Lorenzo Stoakes (Oracle)" To: Kairui Song Cc: Michal Hocko , Andrew Morton , Shakeel Butt , lsf-pc@lists.linux-foundation.org, Johannes Weiner , David Hildenbrand , Qi Zheng , Chen Ridong , Emil Tsalapatis , Alexei Starovoitov , Axel Rasmussen , Yuanchu Xie , Wei Xu , Matthew Wilcox , Nhat Pham , Gregory Price , Barry Song <21cnbao@gmail.com>, David Stevens , Vernon Yang , David Rientjes , Kalesh Singh , wangzicheng , "T . J . Mercier" , Baolin Wang , Suren Baghdasaryan , Meta kernel team , bpf@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [LSF/MM/BPF TOPIC] Towards Unified and Extensible Memory Reclaim (reclaim_ext) Message-ID: <67f1588e-a094-413c-9746-9c28bdf6cc56@lucifer.local> References: <20260325210637.3704220-1-shakeel.butt@linux.dev> <20260325190547.abb7309fb63473b57b7a90a0@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: 9A67740011 X-Stat-Signature: op5phmxomggmdd8gw79sr5kn7obmgkc1 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1774530822-587791 X-HE-Meta: U2FsdGVkX1879iRq40UNetPEEEZunzTcyHTPLEC7BU+AWCYf0x2qioH86nJlgLnDtj1I5nMVtUh026yUZz46CD2xMqD7awqDjXKBuESPVt/MACwSX6yT6lriNtDsHo5E5KaPD80WcPljgULjWRXkhGD0Jse/VLzUVJvDtgTENpvBGijPQUfxqu9LD9h1BSv2XSfKrVZTzaZGxJmbErtNyb6YWu4FAV6IZsRauj2VxmaOsua9AO9PrBkeZCZGv1q/LR+VexFXqKlpAkiwlcPHdZ+432/niOyFECsoid1neaD2ITa/YObGb7C51m2/UttzTyvTdY4N+TUBWDtY973LM9Pox9u2X6HXkkeemH6ls/XaLI4+WKX1bfyDnU+/M2vo4Gkawp1j24js3hR2WXrWMB6NAZLbmnOZu6N0DCZKtArto5nCPMvIU2TuIzWjSSBmTkIWjo7Zyy4aPeZwMYhrIUIPc/kAOi9sX8SsLY6uQ9jkZX5RgoWf7KfxC/XzBwogTk3bFI3gLrOXifj973g1ljukab0TTHUO7Cvj7DAVxyMreX+KItcVsI54wOMcz/wMplZK+9prLKCRtK7NlHEvCdUEKd5E6SYd8Dl8ylye2/DS5VTbeHA/QAi+kG2rblM1E+t9KSDXv+bTjHnoFsZ9KZ9Akqw4+cILVO9SAKC87nLv452Un5mMnPMGRvT9Xl/ZidJz8xlVWcagXm+j1yd9FhwiXgmSBOdoYQvYr6UePNhkKn4s9tHDd/+FhzXVj5PoQvU6tSFINqPzUwV/hpoAOjrQcDnswKtdNW+jlXqNp3WtuUDzWA7+xQN27gEEHutOID6CNfZFdU9dnpmEpwpfqggLbQ8LkkTdXGLASy1Ew0IdBgNKxuXaYJa9p2h/17bPjF4m8k27Jw7TCXYuyNlFZ7ErwmrOWPEQ3GosaXp3P3T7pSsaAa4fsBcANKN3IkZP6oNRnQ9Yi3lfb5xh34P EzWHxPTI 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 26, 2026 at 08:37:06PM +0800, Kairui Song wrote: > On Thu, Mar 26, 2026 at 4:02 PM Lorenzo Stoakes (Oracle) wrote: > > > > On Thu, Mar 26, 2026 at 08:03:34AM +0100, Michal Hocko wrote: > > > On Wed 25-03-26 19:05:47, Andrew Morton wrote: > > > > On Wed, 25 Mar 2026 14:06:37 -0700 Shakeel Butt wrote: > > > > > > > > > We should unify both algorithms into a single code path. > > > > > > > > I'm here to ask the questions which others fear will sound dumb. > > > > > > Not dumb at all and recently discussed here https://lore.kernel.org/all/CAMgjq7AkYOtUL2HuZjBu5dJw=RTL7W2L1+zVv=SCOyHKYwc3AA@mail.gmail.com/T/#u > > > > > > > Is it indeed the plan to maintain both implementations? I thought the > > > > long-term ambition was to knock MGLRU into shape and to drop the legacy LRU? > > > > > > Yes, but MGLRU is not there yet and with development pace last year or > > > so we are not much closer than at the time MGLRU has been merged > > > unfortunatelly. > > > > I'm quite concerned about maintainership, as it seems the MGLRU maintainers have > > not been all that active, and the MGLRU to me at least is currently a black box. > > > > I'm not the only one who's raised this (see [0]). > > > > That'd very much have to be resolved and the community reassured that MGLRU is > > _actively_ maintained before we could even contemplate it replacing the > > 'classic' reclaim approach IMO. > > > > I hope that Kairu, Barry, Zicheng and others who are interested int it resolve > > this, however! > > Hi everyone, > > Right, I think we are starting to make good progress on improving > MGLRU recently. For the last few years we already have some commits > stashed downstream to enable that on our fleet, most of my effort in > upstream is spent on other parts like SWAP, really looking forward to > making MGLRU better upstreamly. > > Yesterday I was still discussing with CachyOS folks about their usage > while working on that series for MGLRU cleanup and dirty flush > optimization, and got some nice feedback later from their chat server > that MGLRU's TTL resolved their thrashing issue very well. With > classic LRU they needed a le9 patch downtreamly. > > For many other typical workloads under stress, MGLRU performs > significantly better too (e.g. database, build kernel could be more > than twice as fast), it would be a huge loss to leave it unmaintained. > > Barry also provided some really helpful ideas about MGLRU like > readahead handling. We are also seeing other vendors and people > contributing to MGLRU like Leno and Baolin recently. Things are > looking promising. Guys, can I please make a plea then for you guys to AT LEAST become reviewers in MAINTAINERS please: MEMORY MANAGEMENT - MGLRU (MULTI-GEN LRU) M: Andrew Morton Well Andrew is Andrew :) M: Axel Rasmussen git log mm/vmscan.c has 0 results. Axel has however engaged in discussion on https://lore.kernel.org/linux-mm/20260318-mglru-reclaim-v1-0-2c46f9eb0508@tencent.com/ recently for example, but not much in 2025 afaict. M: Yuanchu Xie git log mm/vmscan.c shows 1 result from August 13th 2024. Yuanchu has engaged in some MGLRU discussion also recently, here and there. R: Wei Xu git log mm/vmscan.c shows 2 results from October 2024. Wei doesn't look to have engaged in discussion on MGLRU recently. L: linux-mm@kvack.org S: Maintained W: http://www.linux-mm.org T: git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm F: Documentation/admin-guide/mm/multigen_lru.rst F: Documentation/mm/multigen_lru.rst F: include/linux/mm_inline.h F: include/linux/mmzone.h F: mm/swap.c F: mm/vmscan.c F: mm/workingset.c It doesn't really feel like MGLRU is currently maintained at all, quite honestly. So I think we need people to step up here. Thanks, Lorenzo