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 X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 3B27BC433E6 for ; Fri, 5 Mar 2021 00:00:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F26C65005 for ; Fri, 5 Mar 2021 00:00:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230427AbhCEAAq (ORCPT ); Thu, 4 Mar 2021 19:00:46 -0500 Received: from mga07.intel.com ([134.134.136.100]:37599 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230222AbhCEAAo (ORCPT ); Thu, 4 Mar 2021 19:00:44 -0500 IronPort-SDR: 1mtsrck22LZ6m/LBe6Dtj06Mf9eSw6uMgnYKXXLWufjVGN/DkCkmPUgO52RsUn4M0nAVNwhPWz rRjAaLQdJmJg== X-IronPort-AV: E=McAfee;i="6000,8403,9913"; a="251569434" X-IronPort-AV: E=Sophos;i="5.81,223,1610438400"; d="scan'208";a="251569434" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2021 16:00:41 -0800 IronPort-SDR: JCWsUtywXLMo2eI7nfavFq9FiMneXA9gz1RoA/iiV+cJziu8PX6aoWf0jG6UvMcWCfJJtGGMXv Q9kTJLS/IszQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,223,1610438400"; d="scan'208";a="369924207" Received: from viggo.jf.intel.com (HELO localhost.localdomain) ([10.54.77.144]) by orsmga006.jf.intel.com with ESMTP; 04 Mar 2021 16:00:41 -0800 Subject: [PATCH 00/10] [v6] Migrate Pages in lieu of discard To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.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 From: Dave Hansen Date: Thu, 04 Mar 2021 15:59:49 -0800 Message-Id: <20210304235949.7922C1C3@viggo.jf.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The full series is also available here: https://github.com/hansendc/linux/tree/automigrate-20210304 which also inclues some vm.zone_reclaim_mode sysctl ABI fixup prerequisites. The meat of this patch is in: [PATCH 05/10] mm/migrate: demote pages during reclaim Which also has the most changes since the last post. This version is mostly to address review comments from Yang Shi and Oscar Salvador. Review comments are documented in the individual patch changelogs. This also contains a few prerequisite patches that fix up an issue with the vm.zone_reclaim_mode sysctl ABI. 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. -- 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. Other things need to be built 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 == Open Issues == * For cpusets and memory policies that restrict allocations to PMEM, is it OK to demote to PMEM? Do we need a cgroup- level API to opt-in or opt-out of these migrations? * 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" -- Documentation/admin-guide/sysctl/vm.rst | 9 include/linux/migrate.h | 20 + include/linux/swap.h | 3 include/linux/vm_event_item.h | 2 include/trace/events/migrate.h | 3 include/uapi/linux/mempolicy.h | 1 mm/compaction.c | 3 mm/gup.c | 4 mm/internal.h | 5 mm/memory-failure.c | 4 mm/memory_hotplug.c | 4 mm/mempolicy.c | 8 mm/migrate.c | 369 +++++++++++++++++++++++++++++--- mm/page_alloc.c | 13 - mm/vmscan.c | 173 +++++++++++++-- mm/vmstat.c | 2 16 files changed, 560 insertions(+), 63 deletions(-) -- 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: Yang Shi Cc: David Rientjes Cc: Huang Ying Cc: Dan Williams Cc: David Hildenbrand Cc: osalvador Cc: Huang Ying