From patchwork Fri Mar 3 19:58:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcelo Tosatti X-Patchwork-Id: 6094 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:5915:0:0:0:0:0 with SMTP id v21csp601741wrd; Fri, 3 Mar 2023 12:02:08 -0800 (PST) X-Google-Smtp-Source: AK7set8MW4otCvn1tamSNoCuYkq/mKtZ+fVv+1aDhSle599fZkl3PGRcr+Wofjmi7g71ZG1FHvUH X-Received: by 2002:a62:1c16:0:b0:5a8:ada1:cc6f with SMTP id c22-20020a621c16000000b005a8ada1cc6fmr2851740pfc.33.1677873728174; Fri, 03 Mar 2023 12:02:08 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1677873728; cv=none; d=google.com; s=arc-20160816; b=fFE280e3PamRdqBDN9JFIhuwDHpPIk2yhp41dqGLKn5k5gnmfJM2ZFWGaMEiMlxCSv ZbmINhF28pqt8jT/ypwb9fEwacxEf9LrC5rP2UiXnemMQmOSDLaJEBYXQfjqUohwb9n6 PujzQX8i/wJ9ftCPUKrXWXfy200uGxukfpVxTrGL7XKMtKAPlR/bFlDF9AK7R8zSdDNZ 1xYBYoVZfGi1kcRWxL1Fd9Wt7hxWqUva7N25rEeT/5dMkmTV1xsG71v3IBffdC6X59xu FoAoOGq+x5gu5KgT4rAImRRLbe6xenSeWjqpWLlEbsSWIYQO0DxX28cNgDE0Z+L4qwGI bu5A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:subject:cc:to:from:date:user-agent:message-id :dkim-signature; bh=y7Yi1l52AyC6VYyAHckMD0UPWhdM1o7McEseCbmGWHM=; b=b5f59tehu1S8zjSdDC6FTg2oguY9veNKaU6xGWURahO0JTsbUlIrAFKdcKBuSYa4f2 qTDG5U+chvyhgfVeK/CxhgaHDd0N+5owjevht6XBQPrMVHh/wDvSYPyXhve5TTDFYTyy mfWjL+SWq86722iWHnPJ7NQlieES0tpeQpyM/g2+ZV6OL/9dLoO/zqP4+mV89ZksGWoh zqDsdOZROtGaGCHKjeneAH/ei59EASxPO7mwe3SgQUbyQnjhzHRfvHln4Yu++4rxsujW ELScl+W7APFainNhMmbaTKuniM92vgneu13SRu0wbAwPaw8pjtgznSONU/ra83h/shts U8XA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=LADjygL3; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id k7-20020aa79727000000b0059d96ba730dsi2938255pfg.110.2023.03.03.12.01.53; Fri, 03 Mar 2023 12:02:08 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=LADjygL3; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231349AbjCCUB2 (ORCPT + 99 others); Fri, 3 Mar 2023 15:01:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231150AbjCCUB1 (ORCPT ); Fri, 3 Mar 2023 15:01:27 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74CCD60ABC for ; Fri, 3 Mar 2023 12:00:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1677873634; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc; bh=y7Yi1l52AyC6VYyAHckMD0UPWhdM1o7McEseCbmGWHM=; b=LADjygL3PdwurkuKBkxM9mxOH5ltPPyfTbRH9XBu8wdbboPDlVLsuGI+90+L9oHHV2TB6r DNmZhz2hUBcYTPqlXNACPrX4O/dSP3MCATC1raErEMa2hJbaLxuvZ7FfnXwbU3+Fk+eWz5 3Pqfz+H2SCKFmWCS45eijxKydPTCN5U= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-435-LoKFVJqMNxqE4wuiHRGJuQ-1; Fri, 03 Mar 2023 15:00:31 -0500 X-MC-Unique: LoKFVJqMNxqE4wuiHRGJuQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 911461C05AAD; Fri, 3 Mar 2023 20:00:30 +0000 (UTC) Received: from tpad.localdomain (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4CD802026D4B; Fri, 3 Mar 2023 20:00:30 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id 85CF4403EA219; Fri, 3 Mar 2023 17:00:12 -0300 (-03) Message-ID: <20230303195841.310844446@redhat.com> User-Agent: quilt/0.67 Date: Fri, 03 Mar 2023 16:58:41 -0300 From: Marcelo Tosatti To: Christoph Lameter Cc: Aaron Tomlin , Frederic Weisbecker , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Russell King , Huacai Chen , Heiko Carstens , x86@kernel.org Subject: [PATCH v3 00/11] fold per-CPU vmstats remotely X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1759378122339510993?= X-GMAIL-MSGID: =?utf-8?q?1759378122339510993?= This patch series addresses the following two problems: 1. A customer provided some evidence which indicates that the idle tick was stopped; albeit, CPU-specific vmstat counters still remained populated. Thus one can only assume quiet_vmstat() was not invoked on return to the idle loop. If I understand correctly, I suspect this divergence might erroneously prevent a reclaim attempt by kswapd. If the number of zone specific free pages are below their per-cpu drift value then zone_page_state_snapshot() is used to compute a more accurate view of the aforementioned statistic. Thus any task blocked on the NUMA node specific pfmemalloc_wait queue will be unable to make significant progress via direct reclaim unless it is killed after being woken up by kswapd (see throttle_direct_reclaim()) 2. With a SCHED_FIFO task that busy loops on a given CPU, and kworker for that CPU at SCHED_OTHER priority, queuing work to sync per-vmstats will either cause that work to never execute, or stalld (i.e. stall daemon) boosts kworker priority which causes a latency violation By having vmstat_shepherd flush the per-CPU counters to the global counters from remote CPUs. This is done using cmpxchg to manipulate the counters, both CPU locally (via the account functions), and remotely (via cpu_vm_stats_fold). Thanks to Aaron Tomlin for diagnosing issue 1 and writing the initial patch series. v3: - Removed unused drain_zone_pages and changes variable (David Hildenbrand) - Use xchg instead of cmpxchg in refresh_cpu_vm_stats (Peter Xu) - Add drain_all_pages to vmstat_refresh to make stats more accurate (Peter Xu) - Improve changelog of "mm/vmstat: switch counter modification to cmpxchg" (Peter Xu / David) - Improve changelog of "mm/vmstat: remove remote node draining" (David Hildenbrand) v2: - actually use LOCK CMPXCHG on counter mod/inc/dec functions (Christoph Lameter) - use try_cmpxchg for cmpxchg loops (Uros Bizjak / Matthew Wilcox) arch/arm64/include/asm/percpu.h | 16 ++ arch/loongarch/include/asm/percpu.h | 23 +++- arch/s390/include/asm/percpu.h | 5 arch/x86/include/asm/percpu.h | 39 +++---- include/asm-generic/percpu.h | 17 +++ include/linux/mmzone.h | 3 include/linux/percpu-defs.h | 2 kernel/fork.c | 2 kernel/scs.c | 2 mm/page_alloc.c | 23 ---- mm/vmstat.c | 424 +++++++++++++++++++++++++++++++++++++++++------------------------------------ 11 files changed, 307 insertions(+), 249 deletions(-)