From patchwork Thu Jul 15 05:51:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Huang, Ying" X-Patchwork-Id: 12379019 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48850C07E96 for ; Thu, 15 Jul 2021 05:52:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D7FB7611C0 for ; Thu, 15 Jul 2021 05:52:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D7FB7611C0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 379B96B010E; Thu, 15 Jul 2021 01:52:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3299C8D0065; Thu, 15 Jul 2021 01:52:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1F2276B0112; Thu, 15 Jul 2021 01:52:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id E8C696B010E for ; Thu, 15 Jul 2021 01:52:21 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id CD70C235BA for ; Thu, 15 Jul 2021 05:52:20 +0000 (UTC) X-FDA: 78363752040.09.821DC1D Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf14.hostedemail.com (Postfix) with ESMTP id 3A530600199F for ; Thu, 15 Jul 2021 05:52:18 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10045"; a="232300536" X-IronPort-AV: E=Sophos;i="5.84,240,1620716400"; d="scan'208";a="232300536" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2021 22:52:13 -0700 X-IronPort-AV: E=Sophos;i="5.84,240,1620716400"; d="scan'208";a="505591545" Received: from yhuang6-mobl1.sh.intel.com ([10.238.6.138]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2021 22:52:10 -0700 From: Huang Ying To: Andrew Morton , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Dave Hansen , yang.shi@linux.alibaba.com, rientjes@google.com, ying.huang@intel.com, dan.j.williams@intel.com, david@redhat.com, osalvador@suse.de, weixugc@google.com, Michal Hocko , Yang Shi , Zi Yan Subject: [PATCH -V10 0/9] Migrate Pages in lieu of discard Date: Thu, 15 Jul 2021 13:51:36 +0800 Message-Id: <20210715055145.195411-1-ying.huang@intel.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 3A530600199F X-Stat-Signature: crszu15ooikymzuu6onocsjxroot648g Authentication-Results: imf14.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none); spf=none (imf14.hostedemail.com: domain of ying.huang@intel.com has no SPF policy when checking 192.55.52.88) smtp.mailfrom=ying.huang@intel.com X-HE-Tag: 1626328337-629280 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: The full series is also available here: https://github.com/hying-caritas/linux/tree/automigrate-20210715 The changes since the last post are as follows, * Reduce code duplication via move common demotion condition code into can_demote_anon_pages() per Wei's comments. --- We're starting to see systems with more and more kinds of memory such as Intel's implementation of persistent memory. Let's say you have a system with some DRAM and some persistent memory. Today, once DRAM fills up, reclaim will start and some of the DRAM contents will be thrown out. Allocations will, at some point, start falling over to the slower persistent memory. That has two nasty properties. First, the newer allocations can end up in the slower persistent memory. Second, reclaimed data in DRAM are just discarded even if there are gobs of space in persistent memory that could be used. This set implements a solution to these problems. At the end of the reclaim process in shrink_page_list() just before the last page refcount is dropped, the page is migrated to persistent memory instead of being dropped. While I've talked about a DRAM/PMEM pairing, this approach would function in any environment where memory tiers exist. This is not perfect. It "strands" pages in slower memory and never brings them back to fast DRAM. Huang Ying has follow-on work which repurposes autonuma to promote hot pages back to DRAM. This is also all based on an upstream mechanism that allows persistent memory to be onlined and used as if it were volatile: http://lkml.kernel.org/r/20190124231441.37A4A305@viggo.jf.intel.com We have tested the patchset with the postgresql and pgbench. On a 2-socket server machine with DRAM and PMEM, the kernel with the patchset can improve the score of pgbench up to 22.1% compared with that of the DRAM only + disk case. This comes from the reduced disk read throughput (which reduces up to 70.8%). == Open Issues == * Memory policies and cpusets that, for instance, restrict allocations to DRAM can be demoted to PMEM whenever they opt in to this new mechanism. A cgroup-level API to opt-in or opt-out of these migrations will likely be required as a follow-on. * Could be more aggressive about where anon LRU scanning occurs since it no longer necessarily involves I/O. get_scan_count() for instance says: "If we have no swap space, do not bother scanning anon pages" -- Changes since (automigrate-20210625): * Reduce code duplication via move common demotion condition code into can_demote_anon_pages() per Wei's comments. Changes since (automigrate-20210618): * Squash the original 01/10 and 02/10 and move the RCU protection from the original 03/10 to the squashed 1/9. * Make the newly added migrate_pages() parameter optional per Oscar's comments. * Restore the original behavior of MADV_PAGEOUT per Zi's comments. * Guard next_demotion_node() with numa_demotion_enabled per Wei's comments. Changes since (automigrate-20210331): * Change the page allocation flags per Michal's comments. * Change the user interface to enable the feature. Changes since (automigrate-20210304): * Add ack/review tags * Remove duplicate synchronize_rcu() call Changes since (automigrate-20210122): * move from GFP_HIGHUSER -> GFP_HIGHUSER_MOVABLE since pages *are* movable. * Separate out helpers that check for being able to relaim anonymous pages versus being able to meaningfully scan the anon LRU. Changes since (automigrate-20200818): * Fall back to normal reclaim when demotion fails * Fix some compile issues, when page migration and NUMA are off Changes since (automigrate-20201007): * separate out checks for "can scan anon LRU" from "can actually swap anon pages right now". Previous series conflated them and may have been overly aggressive scanning LRU * add MR_DEMOTION to tracepoint header * remove unnecessary hugetlb page check Changes since (https://lwn.net/Articles/824830/): * Use higher-level migrate_pages() API approach from Yang Shi's earlier patches. * made sure to actually check node_reclaim_mode's new bit * disabled migration entirely before introducing RECLAIM_MIGRATE * Replace GFP_NOWAIT with explicit __GFP_KSWAPD_RECLAIM and comment why we want that. * Comment on effects of that keep multiple source nodes from sharing target nodes Cc: Dave Hansen Cc: Michal Hocko Cc: Yang Shi Cc: David Rientjes Cc: Dan Williams Cc: David Hildenbrand Cc: osalvador Cc: Wei Xu Cc: Zi Yan