From patchwork Tue Mar 22 21:47:37 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12789263 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7D6AC433F5 for ; Tue, 22 Mar 2022 21:47:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 498FA6B018A; Tue, 22 Mar 2022 17:47:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4493F6B018B; Tue, 22 Mar 2022 17:47:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 311BC6B018C; Tue, 22 Mar 2022 17:47:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 234A16B018A for ; Tue, 22 Mar 2022 17:47:41 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id F020020E55 for ; Tue, 22 Mar 2022 21:47:40 +0000 (UTC) X-FDA: 79273359480.04.15A0AB2 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf23.hostedemail.com (Postfix) with ESMTP id 4CF37140034 for ; Tue, 22 Mar 2022 21:47:40 +0000 (UTC) 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 ams.source.kernel.org (Postfix) with ESMTPS id 3BC60B81DB0; Tue, 22 Mar 2022 21:47:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDF5BC340EC; Tue, 22 Mar 2022 21:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985658; bh=PKBM4rTGgiS0BGv1YOa2LNcKh6Y8F4G0wabfTEppIwc=; h=Date:To:From:In-Reply-To:Subject:From; b=y63Q6xmI2dDwq+Pl3592Z/OD/jYEdT1Q/B+Qg/qpHt8tp0PJ9VDnVY1KS6D9pzIlX F2nLV6kdwug+d7/ZxMtsXD7Pf6NodpQ02lx51zPMPx6673fawzo55spDW4MJWF3yfx t65dC9zXN89PYZnSVf521Ltt4dfvKCqmTF+iGqN4= Date: Tue, 22 Mar 2022 14:47:37 -0700 To: ying.huang@intel.com,stable@vger.kernel.org,huntbag@linux.vnet.ibm.com,dave.hansen@linux.intel.com,baolin.wang@linux.alibaba.com,osalvador@suse.de,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 179/227] mm: only re-generate demotion targets when a numa node changes its N_CPU state Message-Id: <20220322214737.EDF5BC340EC@smtp.kernel.org> X-Rspam-User: X-Stat-Signature: ji1o1jnayioau73f9myij1i4demjkja6 Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=y63Q6xmI; spf=pass (imf23.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4CF37140034 X-HE-Tag: 1647985660-307607 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: Oscar Salvador Subject: mm: only re-generate demotion targets when a numa node changes its N_CPU state 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/ [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 --- 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~mm-only-re-generate-demotion-targets-when-a-numa-node-changes-its-n_cpu-state +++ a/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~mm-only-re-generate-demotion-targets-when-a-numa-node-changes-its-n_cpu-state +++ a/mm/migrate.c @@ -3209,7 +3209,7 @@ 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(); @@ -3273,51 +3273,24 @@ 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~mm-only-re-generate-demotion-targets-when-a-numa-node-changes-its-n_cpu-state +++ a/mm/vmstat.c @@ -28,6 +28,7 @@ #include #include #include +#include #include "internal.h" @@ -2049,7 +2050,12 @@ 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; } @@ -2072,6 +2078,8 @@ static int vmstat_cpu_dead(unsigned int return 0; node_clear_state(node, N_CPU); + set_migration_target_nodes(); + return 0; } @@ -2103,6 +2111,9 @@ 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);