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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 61E40C433F5 for ; Thu, 7 Apr 2022 03:28:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4ED3F6B007E; Wed, 6 Apr 2022 23:24:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 49C8C6B0080; Wed, 6 Apr 2022 23:24:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 33CA56B0081; Wed, 6 Apr 2022 23:24:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.28]) by kanga.kvack.org (Postfix) with ESMTP id 1F5D86B007E for ; Wed, 6 Apr 2022 23:24:50 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D8FB22B39 for ; Thu, 7 Apr 2022 03:24:39 +0000 (UTC) X-FDA: 79328640678.10.CF58031 Received: from mail-vs1-f47.google.com (mail-vs1-f47.google.com [209.85.217.47]) by imf14.hostedemail.com (Postfix) with ESMTP id 5E2A8100003 for ; Thu, 7 Apr 2022 03:24:39 +0000 (UTC) Received: by mail-vs1-f47.google.com with SMTP id x15so2432985vsq.10 for ; Wed, 06 Apr 2022 20:24:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VXDoG2g2jwih4Ta9g6SsrLn0dnPRuy1eOEj+ZKrL1z0=; b=Z4BeYKfpWPYRzcHAxen+yREF0lc1qo4VdR5KzsT0cfZjxxnF1Z29F5RCDuxxSTp5uQ 3RyRHjpSt4YcVLD6TTcb7BEFmkw/QbX2ZMf489+9mEySejhjZGdwbnGGgplOd1jwH+fd wIp7/NnZ9iyfV5j9Mq+A9ogFhxQT2hNGFnmDCuJTTATa2JWvEosbVebQDLu/9M3mH2XW EfBL5zM1kvN0s/DNhKM51dS5e80jIrpf1M9D+zYru8BHaXbVc8fxuZLQSXaTtT8ag9FT omstZc/WVRk+I7i/H6VlTT7Kx7M5pC8YnQF+pdTgN4k7RfHsB1J9gKWIlL2GkN+9o5wL mgug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VXDoG2g2jwih4Ta9g6SsrLn0dnPRuy1eOEj+ZKrL1z0=; b=MsHOJnWfakAlgIVQDz+QtLNAXUYg+hJ0ZMhdWvlA4YscG1dGx+lXhE+dr1B1KlYbG3 9HOUbRJdYg1SjjhUDRrIBW2ZoywyUKpoMZMXSKf7ckGK+IZx1Kr0qfNBIXeESNo2ppmj Gg84bGj1CgeJC16D681gElND1WGACTSjqWTvwta0DYwnwMgTSO/LsOez7tubGzxxNB7v 4Gs3sR7zmv+WkqMHnwn/MHegk1nn+OSVkbbTLZBYF18SQp9reiZquUc4vjlPepjOGYz0 VPFO4VyWJ37gXJoz4GuWmGuusFWq7/wAs/J9B+lb4A5KlITgwcI7zTJPAXXAbPerOsM3 3MYw== X-Gm-Message-State: AOAM530fIjFXgPO7z2lYdT3xOojuibxoDMFAS9UnxXHKrXQrH+mCnLkZ PBH3Cn9csEy7kGLDuYT6yTCnEi8SSCYvuWsvaiIHtg== X-Google-Smtp-Source: ABdhPJwrQQIytIzXL/+SDkqLEJGG+5KzqTudCk9LM36GaMAN5lfZyghvmm3JxJvTyb4WWqBgS87nhXIBfGcmOQSDBs8= X-Received: by 2002:a05:6102:5cc:b0:320:9bd2:3823 with SMTP id v12-20020a05610205cc00b003209bd23823mr3900955vsf.81.1649301878415; Wed, 06 Apr 2022 20:24:38 -0700 (PDT) MIME-Version: 1.0 References: <20220407031525.2368067-1-yuzhao@google.com> In-Reply-To: <20220407031525.2368067-1-yuzhao@google.com> From: Yu Zhao Date: Wed, 6 Apr 2022 21:24:27 -0600 Message-ID: Subject: Re: [PATCH v10 00/14] Multi-Gen LRU Framework To: Stephen Rothwell , Linux-MM Cc: Andi Kleen , Andrew Morton , Aneesh Kumar , Barry Song <21cnbao@gmail.com>, Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Linus Torvalds , Matthew Wilcox , Mel Gorman , Michael Larabel , Michal Hocko , Mike Rapoport , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , Linux ARM , "open list:DOCUMENTATION" , linux-kernel , Kernel Page Reclaim v2 , "the arch/x86 maintainers" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 55tnj7ps6u97yejsjj4dwc1nxfrufm89 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Z4BeYKfp; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf14.hostedemail.com: domain of yuzhao@google.com designates 209.85.217.47 as permitted sender) smtp.mailfrom=yuzhao@google.com X-Rspamd-Queue-Id: 5E2A8100003 X-HE-Tag: 1649301879-412811 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: On Wed, Apr 6, 2022 at 9:15 PM Yu Zhao wrote: > > TLDR > ==== > The current page reclaim is too expensive in terms of CPU usage and it > often makes poor choices about what to evict. This patchset offers an > alternative solution that is performant, versatile and > straightforward. > Summery > ======= > The facts are: > 1. The independent lab results and the real-world applications > indicate substantial improvements; there are no known regressions. > 2. Thrashing prevention, working set estimation and proactive reclaim > work out of the box; there are no equivalent solutions. > 3. There is a lot of new code; nobody has demonstrated smaller changes > with similar effects. > > Our options, accordingly, are: > 1. Given the amount of evidence, the reported improvements will likely > materialize for a wide range of workloads. > 2. Gauging the interest from the past discussions [22][23][24], the > new features will likely be put to use for both personal computers > and data centers. > 3. Based on Google's track record, the new code will likely be well > maintained in the long term. It'd be more difficult if not > impossible to achieve similar effects on top of the current > active/inactive LRU. Hi Stephen, Can you please include this patchset in linux-next? Git repo for you to fetch: https://linux-mm.googlesource.com/mglru for-linux-next My goal is to get additional test coverage before I send a pull request for 5.19 to Linus. I've explored all avenues, but ultimately I've failed to rally substantial support from the MM stakeholders [1]. There are no pending technical issues against this patchset [2]. What is more concerning are the fundamental disagreements on priorities, methodologies, etc. that are not specific to this patchset and have been hindering our progress as a collective. (Cheers to the mutual dissatisfaction.) While we plan to discuss those issues during the LSFMM next month, it doesn't seem reasonable to leave this patchset hanging in the air, since it has reached its maturity a while ago and there are strong demands from downstream kernels as well as a large user base. Thus I sent that pull request to Linus a couple of weeks ago, implying that he would have to make the final decision soon. I hope this gives enough background about what's been going on with this patchset. If you decide to take it and it causes you any troubles, please feel free to yell at me. Thanks! [1] https://lore.kernel.org/r/20220104202227.2903605-1-yuzhao@google.com/ [2] https://lore.kernel.org/r/20220326010003.3155137-1-yuzhao@google.com/