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 1DD33C433F5 for ; Wed, 9 Mar 2022 14:47:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231279AbiCIOsB (ORCPT ); Wed, 9 Mar 2022 09:48:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233654AbiCIOrt (ORCPT ); Wed, 9 Mar 2022 09:47:49 -0500 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A960A13C9FB for ; Wed, 9 Mar 2022 06:46:50 -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-out2.suse.de (Postfix) with ESMTPS id 671EB1F381; Wed, 9 Mar 2022 14:46:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1646837209; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=ko7UOZvVKUXeiv6HhhhZ5IMQe0H3yOujOeV0ooUJ54M=; b=OfRFZdI3Vj0WLzQsfTQ/Ffc+ahVN8bazNvCmRdVxPvt3MIoi6CtjHvrG8Vo1H41TKw1SsJ +/psPQTvw4hXxcaa4n4eeNgZck807NU+lhTE6XT3vlik5aQE1CFgEg7SdKKZVjr7+SzWEc MmmlFwuakKfQ/p4/kI0O2TdiAqMgu/k= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1646837209; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=ko7UOZvVKUXeiv6HhhhZ5IMQe0H3yOujOeV0ooUJ54M=; b=4LgUg0m6byxdYAHOckGC3J8NMvUGvM212nZ+Oh8Pn/7trz+1CVsU0I9UqZy9FqwzUp3bJY hI09ZBuSKWgyIIBg== 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 E839F13D79; Wed, 9 Mar 2022 14:46:48 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id dzPdNdi9KGLaSAAAMHmgww (envelope-from ); Wed, 09 Mar 2022 14:46:48 +0000 From: Oscar Salvador To: Andrew Morton Cc: Dave Hansen , "Huang, Ying" , Abhishek Goel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador Subject: [PATCH] mm: Only re-generate demotion targets when a numa node changes its N_CPU state Date: Wed, 9 Mar 2022 15:46:44 +0100 Message-Id: <20220309144644.4278-1-osalvador@suse.de> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Abhishek reported that after patch [1], hotplug operations are taking ~double the expected time. [2] The reason behind is that the CPU callbacks that migrate_on_reclaim_init() sets always call set_migration_target_nodes() whenever a CPU is brought up/down. But we only care about numa nodes going from having cpus to become cpuless, and vice versa, as that influences the demotion_target order. We do already have two CPU callbacks (vmstat_cpu_online() and vmstat_cpu_dead()) that check exactly that, so get rid of the CPU callbacks in migrate_on_reclaim_init() and only call set_migration_target_nodes() from vmstat_cpu_{dead,online}() whenever a numa node change its N_CPU state. [1] https://lore.kernel.org/linux-mm/20210721063926.3024591-2-ying.huang@intel.com/ [2] https://lore.kernel.org/linux-mm/eb438ddd-2919-73d4-bd9f-b7eecdd9577a@linux.vnet.ibm.com/ Reported-by: Abhishek Goel Signed-off-by: Oscar Salvador --- I think there is further room for improvement like should we call in to set_migration_target_nodes() when demotion is disabled via sysctl? I will have a look into that, but let us go with this quick fix for now. Also, I am not really strong about the Fixes tag, but it can be added if you think it makes sense. --- include/linux/migrate.h | 5 +++++ mm/migrate.c | 36 +----------------------------------- mm/vmstat.c | 10 +++++++++- 3 files changed, 15 insertions(+), 36 deletions(-) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index db96e10eb8da..c64fe2923fb0 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -48,6 +48,11 @@ int folio_migrate_mapping(struct address_space *mapping, struct folio *newfolio, struct folio *folio, int extra_count); extern bool numa_demotion_enabled; +#ifdef CONFIG_HOTPLUG_CPU +extern void set_migration_target_nodes(void); +#else +static inline void set_migration_target_nodes() {} +#endif #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; } -- 2.34.1