From patchwork Thu Jul 15 05:51:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Huang, Ying" X-Patchwork-Id: 12379021 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 977BDC47E4D for ; Thu, 15 Jul 2021 05:52:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3487561362 for ; Thu, 15 Jul 2021 05:52:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3487561362 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 8A9C76B0110; Thu, 15 Jul 2021 01:52:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8592C6B0112; Thu, 15 Jul 2021 01:52:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6FC576B0114; Thu, 15 Jul 2021 01:52:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0115.hostedemail.com [216.40.44.115]) by kanga.kvack.org (Postfix) with ESMTP id 439E06B0110 for ; Thu, 15 Jul 2021 01:52:24 -0400 (EDT) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 24A29824805A for ; Thu, 15 Jul 2021 05:52:23 +0000 (UTC) X-FDA: 78363752166.31.B4EA5CB Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf24.hostedemail.com (Postfix) with ESMTP id 7E4D3B00009A for ; Thu, 15 Jul 2021 05:52:21 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10045"; a="232300552" X-IronPort-AV: E=Sophos;i="5.84,240,1620716400"; d="scan'208";a="232300552" 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 22:52:20 -0700 X-IronPort-AV: E=Sophos;i="5.84,240,1620716400"; d="scan'208";a="505591586" 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 22:52:17 -0700 From: Huang Ying To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dave Hansen , "Huang, Ying" , Yang Shi , Michal Hocko , Wei Xu , Zi Yan , osalvador , David Rientjes , Dan Williams , David Hildenbrand Subject: [PATCH -V10 2/9] mm/migrate: update node demotion order on hotplug events Date: Thu, 15 Jul 2021 13:51:38 +0800 Message-Id: <20210715055145.195411-3-ying.huang@intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210715055145.195411-1-ying.huang@intel.com> References: <20210715055145.195411-1-ying.huang@intel.com> MIME-Version: 1.0 Authentication-Results: imf24.hostedemail.com; dkim=none; spf=none (imf24.hostedemail.com: domain of ying.huang@intel.com has no SPF policy when checking 192.55.52.88) smtp.mailfrom=ying.huang@intel.com; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none) X-Stat-Signature: d5n5c9imoj1xqcgmw8rfx4gkgsd3nswn X-Rspamd-Queue-Id: 7E4D3B00009A X-Rspamd-Server: rspam01 X-HE-Tag: 1626328341-110027 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: From: Dave Hansen Reclaim-based migration is attempting to optimize data placement in memory based on the system topology. If the system changes, so must the migration ordering. The implementation is conceptually simple and entirely unoptimized. On any memory or CPU hotplug events, assume that a node was added or removed and recalculate all migration targets. This ensures that the node_demotion[] array is always ready to be used in case the new reclaim mode is enabled. This recalculation is far from optimal, most glaringly that it does not even attempt to figure out the hotplug event would have some *actual* effect on the demotion order. But, given the expected paucity of hotplug events, this should be fine. Signed-off-by: Dave Hansen Signed-off-by: "Huang, Ying" Reviewed-by: Yang Shi Cc: Michal Hocko Cc: Wei Xu Cc: Zi Yan Cc: osalvador Cc: David Rientjes Cc: Dan Williams Cc: David Hildenbrand --- Changes since 20210618: * moved RCU part to the prev patch in series. Changes since 20210302: * remove duplicate synchronize_rcu() --- mm/migrate.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 89 insertions(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index b7a40ab47648..a40c391f9ca7 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -49,6 +49,7 @@ #include #include #include +#include #include @@ -3057,6 +3058,7 @@ void migrate_vma_finalize(struct migrate_vma *migrate) EXPORT_SYMBOL(migrate_vma_finalize); #endif /* CONFIG_DEVICE_PRIVATE */ +#if defined(CONFIG_MEMORY_HOTPLUG) /* Disable reclaim-based migration. */ static void __disable_all_migrate_targets(void) { @@ -3191,10 +3193,96 @@ static void __set_migration_target_nodes(void) /* * For callers that do not hold get_online_mems() already. */ -__maybe_unused // <- temporay to prevent warnings during bisects static void set_migration_target_nodes(void) { get_online_mems(); __set_migration_target_nodes(); put_online_mems(); } + +/* + * React to hotplug events that might affect the migration targets + * like events that online or offline NUMA nodes. + * + * The ordering is also currently dependent on which nodes have + * CPUs. That means we need CPU on/offline notification too. + */ +static int migration_online_cpu(unsigned int cpu) +{ + set_migration_target_nodes(); + return 0; +} + +static int migration_offline_cpu(unsigned int cpu) +{ + set_migration_target_nodes(); + return 0; +} + +/* + * This leaves migrate-on-reclaim transiently disabled between + * the MEM_GOING_OFFLINE and MEM_OFFLINE events. This runs + * whether reclaim-based migration is enabled or not, which + * ensures that the user can turn reclaim-based migration at + * any time without needing to recalculate migration targets. + * + * These callbacks already hold get_online_mems(). That is why + * __set_migration_target_nodes() can be used as opposed to + * set_migration_target_nodes(). + */ +static int __meminit migrate_on_reclaim_callback(struct notifier_block *self, + unsigned long action, void *arg) +{ + switch (action) { + case MEM_GOING_OFFLINE: + /* + * Make sure there are not transient states where + * an offline node is a migration target. This + * will leave migration disabled until the offline + * completes and the MEM_OFFLINE case below runs. + */ + disable_all_migrate_targets(); + break; + case MEM_OFFLINE: + case MEM_ONLINE: + /* + * Recalculate the target nodes once the node + * reaches its final state (online or offline). + */ + __set_migration_target_nodes(); + break; + case MEM_CANCEL_OFFLINE: + /* + * MEM_GOING_OFFLINE disabled all the migration + * targets. Reenable them. + */ + __set_migration_target_nodes(); + break; + case MEM_GOING_ONLINE: + case MEM_CANCEL_ONLINE: + break; + } + + return notifier_from_errno(0); +} + +static int __init migrate_on_reclaim_init(void) +{ + int ret; + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "migrate on reclaim", + migration_online_cpu, + migration_offline_cpu); + /* + * In the unlikely case that this fails, the automatic + * migration targets may become suboptimal for nodes + * where N_CPU changes. With such a small impact in a + * rare case, do not bother trying to do anything special. + */ + WARN_ON(ret < 0); + + hotplug_memory_notifier(migrate_on_reclaim_callback, 100); + return 0; +} +late_initcall(migrate_on_reclaim_init); +#endif /* CONFIG_MEMORY_HOTPLUG */