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 BBB19CD68ED for ; Tue, 10 Oct 2023 06:10:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2730F8D00AA; Tue, 10 Oct 2023 02:10:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1FC178D006D; Tue, 10 Oct 2023 02:10:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 076208D00AA; Tue, 10 Oct 2023 02:10:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id E53F58D006D for ; Tue, 10 Oct 2023 02:10:28 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id A5E71C0175 for ; Tue, 10 Oct 2023 06:10:28 +0000 (UTC) X-FDA: 81328527336.19.6EE806A Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.93]) by imf01.hostedemail.com (Postfix) with ESMTP id 789AF4000B for ; Tue, 10 Oct 2023 06:10:25 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=Bqy5TxQo; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf01.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=ying.huang@intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1696918226; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tbj0iKcY1LjIe2ubOsxY+ZXnIVDS0wEWqOVWVN2FVTI=; b=D71IvUu5dwpYgEmt+WGAxkoNOkyz9DG1QZDGJ/IX8mfFEjFDUsil7+8fEUHEjSFsnlFcQ3 cnOKOWlhYGru3cgQk09oyPKQy2Ys8CLlGEbAA4+1X/a257o9RsJXkZyMsGhYnfwXMKLvdI il8ebS9qHJVP09uWlU/gl45+BEynppc= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=Bqy5TxQo; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf01.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=ying.huang@intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1696918226; a=rsa-sha256; cv=none; b=OsJoMyua5v5f38CAqlfnvd4SDAQ5gCI/AFoeqUJstqFlXCLnR307orNNrBzQ8Nh5xV5ISf CD+MI+cN9VJTUIfB1qUn6WfeTBcrkNX0aUIs81ylVZ6aN38QFDI5fBlcCY48YBuGUGPoPF s1J8rdqzLqqAkT4kEvYsy56KG/7xnxQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696918225; x=1728454225; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=TUsCoEHWVSmVfCipsR2h51CAEI1MELGWQx6Zwd1DQwM=; b=Bqy5TxQohaprNcnUCiiw1Ox4USD8uY3V2IOXKrV22qY11239c6w82xxm 96TfPz3vwijL6RRf40HmcW1UPghx46px5OT7fuWOShTkXv/pOK0OxiUpn /PCwsphRXB6JwCL3bhpX/vx25RO3KwHqjMBTqOpsHg1IYdE2X7+UrW+3z /PJgSxINptQFJFJGWI2OaZvFudHw6ovh33lzHKlm94WXsjq5VZkj+nDrS +rOE8F7yBgyLJk94j439aNMRGjxs1H3vEdaGupLLgN3ziVEO9dy6JBWkN gra0EKdwCoz2vuXFdJVQqOvJpTPRPXq2o+KQLjj9GpqwooDBoORWbTeqa Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10858"; a="381577432" X-IronPort-AV: E=Sophos;i="6.03,211,1694761200"; d="scan'208";a="381577432" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Oct 2023 23:10:21 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10858"; a="819100631" X-IronPort-AV: E=Sophos;i="6.03,211,1694761200"; d="scan'208";a="819100631" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Oct 2023 23:10:17 -0700 From: "Huang, Ying" To: Zi Yan Cc: , , Ryan Roberts , Andrew Morton , "Matthew Wilcox (Oracle)" , David Hildenbrand , "Yin, Fengwei" , Yu Zhao , Vlastimil Babka , Johannes Weiner , Baolin Wang , Kemeng Shi , Mel Gorman , "Rohan Puri" , Mcgrof Chamberlain , "Adam Manzanares" , John Hubbard Subject: Re: [RFC PATCH 0/4] Enable >0 order folio memory compaction References: <20230912162815.440749-1-zi.yan@sent.com> <87a5ssjmld.fsf@yhuang6-desk2.ccr.corp.intel.com> <14089E95-251E-43A4-AF32-C9773723C810@nvidia.com> Date: Tue, 10 Oct 2023 14:08:08 +0800 In-Reply-To: <14089E95-251E-43A4-AF32-C9773723C810@nvidia.com> (Zi Yan's message of "Mon, 09 Oct 2023 09:43:38 -0400") Message-ID: <87r0m3ggc7.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: 789AF4000B X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 9h81o53xs8j9zbx7f6fqcycy4pdzg7bf X-HE-Tag: 1696918225-783643 X-HE-Meta: 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 DbQuW4lU OcTDIWJ0yfZ6mRj/rtUSwSQX9kD1FhHIFTvE4eCWx0KVF8QReFm/0VXMxbPQtTuRPxhrmxunJcRXS0q/nUuu0vi2DMZ08MP8j/EJk3uICKCYIEQLjjMrrHlJlIpw8IpgXP/Rs5YvIMSGke+yCR+0nd1ymEkSci9/W5k2yyID52EmXTVVRpsWoY8Cc7ONuVtuh9JSkp83rxq9p+Pz6HbibSNlTvOpwxO8b4Mo7VxMzMCoEEJlnR0O2zHMemRmOtEeUD21/KA8xkFy36zdkCCEsFwiG/IAEj9LQjRKSmSGuHUciNkjEUialIFeCnZBWN79GNi2KwautEXNvPnZcGVQcboT0idMgqze3Gd8UHFA6tJvqFFA5ofGagWdIWjqe6CQUMcoEHhrPzaRKE939TGxSA+UXYKx+/myr/vq9kmAv+58unMYgHJNu2531w+ujS8XbBbpA 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: Something wrong with my mail box. Sorry, if you received duplicated mail. Zi Yan writes: > On 9 Oct 2023, at 3:12, Huang, Ying wrote: > >> Hi, Zi, >> >> Thanks for your patch! >> >> Zi Yan writes: >> >>> From: Zi Yan >>> >>> Hi all, >>> >>> This patchset enables >0 order folio memory compaction, which is one of >>> the prerequisitions for large folio support[1]. It is on top of >>> mm-everything-2023-09-11-22-56. >>> >>> Overview >>> === >>> >>> To support >0 order folio compaction, the patchset changes how free pages used >>> for migration are kept during compaction. >> >> migrate_pages() can split the large folio for allocation failure. So >> the minimal implementation could be >> >> - allow to migrate large folios in compaction >> - return -ENOMEM for order > 0 in compaction_alloc() >> >> The performance may be not desirable. But that may be a baseline for >> further optimization. > > I would imagine it might cause a regression since compaction might gradually > split high order folios in the system. I may not call it a pure regression, since large folio can be migrated during compaction with that, but it's possible that this hurts performance. Anyway, this can be a not-so-good minimal baseline. > But I can move Patch 4 first to make this the baseline and see how > system performance changes. Thanks! >> >> And, if we can measure the performance for each step of optimization, >> that will be even better. > > Do you have any benchmark in mind for the performance tests? vm-scalability? I remember Mel Gorman has done some tests for defragmentation before. But that's for order-0 pages. >>> Free pages used to be split into >>> order-0 pages that are post allocation processed (i.e., PageBuddy flag cleared, >>> page order stored in page->private is zeroed, and page reference is set to 1). >>> Now all free pages are kept in a MAX_ORDER+1 array of page lists based >>> on their order without post allocation process. When migrate_pages() asks for >>> a new page, one of the free pages, based on the requested page order, is >>> then processed and given out. >>> >>> >>> Optimizations >>> === >>> >>> 1. Free page split is added to increase migration success rate in case >>> a source page does not have a matched free page in the free page lists. >>> Free page merge is possible but not implemented, since existing >>> PFN-based buddy page merge algorithm requires the identification of >>> buddy pages, but free pages kept for memory compaction cannot have >>> PageBuddy set to avoid confusing other PFN scanners. >>> >>> 2. Sort source pages in ascending order before migration is added to >> >> Trivial. >> >> s/ascending/descending/ >> >>> reduce free page split. Otherwise, high order free pages might be >>> prematurely split, causing undesired high order folio migration failures. >>> >>> >>> TODOs >>> === >>> >>> 1. Refactor free page post allocation and free page preparation code so >>> that compaction_alloc() and compaction_free() can call functions instead >>> of hard coding. >>> >>> 2. One possible optimization is to allow migrate_pages() to continue >>> even if get_new_folio() returns a NULL. In general, that means there is >>> not enough memory. But in >0 order folio compaction case, that means >>> there is no suitable free page at source page order. It might be better >>> to skip that page and finish the rest of migration to achieve a better >>> compaction result. >> >> We can split the source folio if get_new_folio() returns NULL. So, do >> we really need this? > > It depends. The situation it can benefit is that when the system is going > to allocate a high order free page and trigger a compaction, it is possible to > get the high order free page by migrating a bunch of base pages instead of > splitting a existing high order folio. > >> >> In general, we may reconsider all further optimizations given splitting >> is available already. > > In my mind, split should be avoided as much as possible. If so, should we use "nosplit" logic in migrate_pages_batch() in some situation? > But it really depends > on the actual situation, e.g., how much effort and cost the compaction wants > to pay to get memory defragmented. If the system really wants to get a high > order free page at any cost, split can be used without any issue. But applications > might lose performance because existing large folios are split just to a > new one. Is it possible that splitting is desirable in some situation? For example, allocate some large DMA buffers at the cost of large anonymous folios? > Like I said in the email, there are tons of optimizations and policies for us > to explore. We can start with the bare minimum support (if no performance > regression is observed, we can even start with split all high folios like you > suggested) and add optimizations one by one. Sound good to me! Thanks! >> >>> 3. Another possible optimization is to enable free page merge. It is >>> possible that a to-be-migrated page causes free page split then fails to >>> migrate eventually. We would lose a high order free page without free >>> page merge function. But a way of identifying free pages for memory >>> compaction is needed to reuse existing PFN-based buddy page merge. >>> >>> 4. The implemented >0 order folio compaction algorithm is quite naive >>> and does not consider all possible situations. A better algorithm can >>> improve compaction success rate. >>> >>> >>> Feel free to give comments and ask questions. >>> >>> Thanks. >>> >>> >>> [1] https://lore.kernel.org/linux-mm/f8d47176-03a8-99bf-a813-b5942830fd73@arm.com/ >>> >>> Zi Yan (4): >>> mm/compaction: add support for >0 order folio memory compaction. >>> mm/compaction: optimize >0 order folio compaction with free page >>> split. >>> mm/compaction: optimize >0 order folio compaction by sorting source >>> pages. >>> mm/compaction: enable compacting >0 order folios. >>> >>> mm/compaction.c | 205 +++++++++++++++++++++++++++++++++++++++--------- >>> mm/internal.h | 7 +- >>> 2 files changed, 176 insertions(+), 36 deletions(-) -- Best Regards, Huang, Ying