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 33AD5C4707E for ; Tue, 5 Apr 2022 07:50:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233269AbiDEHwR (ORCPT ); Tue, 5 Apr 2022 03:52:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233067AbiDEHrY (ORCPT ); Tue, 5 Apr 2022 03:47:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 424AB9E9E8; Tue, 5 Apr 2022 00:43:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C5257616D7; Tue, 5 Apr 2022 07:43:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAB90C340EE; Tue, 5 Apr 2022 07:43:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649144615; bh=aX9aeIuXYr50nURfh1LmmIau+LRWouTMztlGYS+gtMg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yWLzw84XaLcrHMziX1hIWhxEAH50vTlXCB3xqGA4EnMUas/IQNzK0c6B0rHi3MP8U N0VOcuXjnjePjzC7ik45sE9VJho8ckFH2KMPtnMfn0uf/oAMSjqTbLHiEyvw0u2ZDL OO05ldh6Fya+23whetyIuPzV0tzlEUN5MOfyhKHQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oscar Salvador , Baolin Wang , Abhishek Goel , Dave Hansen , "Huang, Ying" , Andrew Morton , Linus Torvalds Subject: [PATCH 5.17 0109/1126] mm: only re-generate demotion targets when a numa node changes its N_CPU state Date: Tue, 5 Apr 2022 09:14:16 +0200 Message-Id: <20220405070410.770232844@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oscar Salvador commit 734c15700cdf9062ae98d8b131c6fe873dfad26d upstream. Abhishek reported that after patch [1], hotplug operations are taking roughly 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/ [osalvador@suse.de: add feedback from Huang Ying] Link: https://lkml.kernel.org/r/20220314150945.12694-1-osalvador@suse.de Link: https://lkml.kernel.org/r/20220310120749.23077-1-osalvador@suse.de Fixes: 884a6e5d1f93b ("mm/migrate: update node demotion order on hotplug events") Signed-off-by: Oscar Salvador Reviewed-by: Baolin Wang Tested-by: Baolin Wang Reported-by: Abhishek Goel Cc: Dave Hansen Cc: "Huang, Ying" Cc: Abhishek Goel Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/migrate.h | 8 ++++++++ mm/migrate.c | 47 ++++++++++------------------------------------- mm/vmstat.c | 13 ++++++++++++- 3 files changed, 30 insertions(+), 38 deletions(-) --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -48,7 +48,15 @@ int folio_migrate_mapping(struct address struct folio *newfolio, struct folio *folio, int extra_count); extern bool numa_demotion_enabled; +extern void migrate_on_reclaim_init(void); +#ifdef CONFIG_HOTPLUG_CPU +extern void set_migration_target_nodes(void); #else +static inline void set_migration_target_nodes(void) {} +#endif +#else + +static inline void set_migration_target_nodes(void) {} static inline void putback_movable_pages(struct list_head *l) {} static inline int migrate_pages(struct list_head *l, new_page_t new, --- a/mm/migrate.c +++ b/mm/migrate.c @@ -3190,7 +3190,7 @@ again: /* * 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(); @@ -3254,51 +3254,24 @@ static int __meminit migrate_on_reclaim_ 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) +void __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); + hotplug_memory_notifier(migrate_on_reclaim_callback, 100); /* - * 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. + * At this point, all numa nodes with memory/CPus have their state + * properly set, so we can build the demotion order now. + * Let us hold the cpu_hotplug lock just, as we could possibily have + * CPU hotplug events during boot. */ - 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; + cpus_read_lock(); + set_migration_target_nodes(); + cpus_read_unlock(); } -late_initcall(migrate_on_reclaim_init); #endif /* CONFIG_HOTPLUG_CPU */ bool numa_demotion_enabled = false; --- 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(v 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 return 0; node_clear_state(node, N_CPU); + set_migration_target_nodes(); + return 0; } @@ -2097,6 +2105,9 @@ void __init init_mm_internals(void) start_shepherd_timer(); #endif +#if defined(CONFIG_MIGRATION) && defined(CONFIG_HOTPLUG_CPU) + migrate_on_reclaim_init(); +#endif #ifdef CONFIG_PROC_FS proc_create_seq("buddyinfo", 0444, NULL, &fragmentation_op); proc_create_seq("pagetypeinfo", 0400, NULL, &pagetypeinfo_op);