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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C293C433F5 for ; Tue, 8 Mar 2022 10:27:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345819AbiCHK2q (ORCPT ); Tue, 8 Mar 2022 05:28:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345660AbiCHK2m (ORCPT ); Tue, 8 Mar 2022 05:28:42 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59243634E for ; Tue, 8 Mar 2022 02:27:45 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 763A7210E9; Tue, 8 Mar 2022 10:27:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1646735264; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=N73gu50O85bYZ1Q0djNPPNKpF0IxOh/oir1CnV0OAZI=; b=wVqXgQCHNjsMMqYfWNZ8FNPqelZPjYRI6TDqOP3FZ+6WAilyLsjSdRbGw5bJv9P73sSomR 03JR26sz9mXaF4ICdVC3H8hQVmpBf478P6AengGarHoeoHKWOXCBf9G7c7VTaELtWuOkeR 1Y3N5yCyNA80qlArE551HnnbD6Iw6kQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1646735264; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=N73gu50O85bYZ1Q0djNPPNKpF0IxOh/oir1CnV0OAZI=; b=llsd9OIWA9yatRxOCyldL5u6WrQZg6CQN5MfDz/iv23GCywCJpJX1zlmiUyo4BuGd2YnVv 1vVZAXi3AcqSBvAQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id C15E213C84; Tue, 8 Mar 2022 10:27:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id ZhblK58vJ2KzRQAAMHmgww (envelope-from ); Tue, 08 Mar 2022 10:27:43 +0000 Date: Tue, 8 Mar 2022 11:27:42 +0100 From: Oscar Salvador To: "Huang, Ying" Cc: Abhishek Goel , Dave Hansen , Dave Hansen , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zi Yan , David Hildenbrand , Yang Shi , Andrew Morton Subject: Re: [PATCH -V11 2/9] mm/migrate: update node demotion order on hotplug events Message-ID: References: <20210721063926.3024591-1-ying.huang@intel.com> <20210721063926.3024591-2-ying.huang@intel.com> <4e8067e1-0574-c9d2-9d6c-d676d32071bd@linux.vnet.ibm.com> <87pmnb3ccr.fsf@yhuang6-desk2.ccr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87pmnb3ccr.fsf@yhuang6-desk2.ccr.corp.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 25, 2022 at 10:32:20AM +0800, Huang, Ying wrote: > -static int migration_online_cpu(unsigned int cpu) > +static int migration_cpu_hotplug(unsigned int cpu) > { > - set_migration_target_nodes(); > - return 0; > -} > + static int nr_cpu_node_saved; > + int nr_cpu_node; > + > + nr_cpu_node = num_node_state(N_CPU); > + if (nr_cpu_node != nr_cpu_node_saved) { > + set_migration_target_nodes(); > + nr_cpu_node_saved = nr_cpu_node; > + } > > -static int migration_offline_cpu(unsigned int cpu) > -{ > - set_migration_target_nodes(); > return 0; > } These callbacks feel like re-inveting the wheel. We do already have two functions that get called during cpu online/offline, and that sets/clears N_CPU on the node properly. And that is exactly what we want, so what about the following (only compile-tested): diff --git a/include/linux/migrate.h b/include/linux/migrate.h index db96e10eb8da..031af2bb71dc 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -48,6 +48,7 @@ int folio_migrate_mapping(struct address_space *mapping, struct folio *newfolio, struct folio *folio, int extra_count); extern bool numa_demotion_enabled; +extern void set_migration_target_nodes(void); #else static inline void putback_movable_pages(struct list_head *l) {} diff --git a/mm/migrate.c b/mm/migrate.c index c7da064b4781..7847e4de01d7 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -3190,7 +3190,7 @@ static void __set_migration_target_nodes(void) /* * For callers that do not hold get_online_mems() already. */ -static void set_migration_target_nodes(void) +void set_migration_target_nodes(void) { get_online_mems(); __set_migration_target_nodes(); @@ -3254,47 +3254,13 @@ static int __meminit migrate_on_reclaim_callback(struct notifier_block *self, return notifier_from_errno(0); } -/* - * 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; -} - static int __init migrate_on_reclaim_init(void) { - int ret; - node_demotion = kmalloc_array(nr_node_ids, sizeof(struct demotion_nodes), GFP_KERNEL); WARN_ON(!node_demotion); - ret = cpuhp_setup_state_nocalls(CPUHP_MM_DEMOTION_DEAD, "mm/demotion:offline", - NULL, 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); - ret = cpuhp_setup_state(CPUHP_AP_MM_DEMOTION_ONLINE, "mm/demotion:online", - migration_online_cpu, NULL); - WARN_ON(ret < 0); - hotplug_memory_notifier(migrate_on_reclaim_callback, 100); return 0; } diff --git a/mm/vmstat.c b/mm/vmstat.c index 4057372745d0..0529a83c8f89 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -28,6 +28,7 @@ #include #include #include +#include #include "internal.h" @@ -2043,7 +2044,12 @@ static void __init init_cpu_node_state(void) static int vmstat_cpu_online(unsigned int cpu) { refresh_zone_stat_thresholds(); - node_set_state(cpu_to_node(cpu), N_CPU); + + if (!node_state(cpu_to_node(cpu), N_CPU)) { + node_set_state(cpu_to_node(cpu), N_CPU); + set_migration_target_nodes(); + } + return 0; } @@ -2066,6 +2072,8 @@ static int vmstat_cpu_dead(unsigned int cpu) return 0; node_clear_state(node, N_CPU); + set_migration_target_nodes(); + return 0; } I think this is just easier and meets exactly the goal. We could go even further and move the work left in migrate_on_reclaim_init() to init_mm_internals(). (I __think__ we should be fine because there is no dependency there, e.g: notifier being set up somewhere later after init_mm_internals() has been called). -- Oscar Salvador SUSE Labs