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 2080EC433EF for ; Thu, 27 Jan 2022 17:26:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244564AbiA0R0w (ORCPT ); Thu, 27 Jan 2022 12:26:52 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:53646 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244550AbiA0R0q (ORCPT ); Thu, 27 Jan 2022 12:26:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643304406; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc; bh=xMKy2VRQz2HoWa5S4yciERZyfBqJoN3RtPJpKzUUi+Y=; b=FITpmQGFMqj9NIPRlgsw74A/zQIyKZZPPtfqw24+/xb8s7VCi6YTGue6DCPV1AK0ldfbyy TNV91/uO9LJOJxBDWeq2ABR4KcR/gngHUrNxfWw4yjYdotrVGjMkyys0ay8+ly7Trboznw 0AkYbF4tmebjqfRxmwnmuQ1A7VmGsis= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-561-ZHbryHjaOWOLOd3J6lc0XQ-1; Thu, 27 Jan 2022 12:26:43 -0500 X-MC-Unique: ZHbryHjaOWOLOd3J6lc0XQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AADBA81E4D3; Thu, 27 Jan 2022 17:26:41 +0000 (UTC) Received: from fuller.cnet (ovpn-112-4.gru2.redhat.com [10.97.112.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 729D274E99; Thu, 27 Jan 2022 17:26:29 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id A8915417131F; Thu, 27 Jan 2022 14:26:05 -0300 (-03) Message-ID: <20220127172552.585742698@fuller.cnet> User-Agent: quilt/0.66 Date: Thu, 27 Jan 2022 14:23:28 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org Cc: Nitesh Lal , Nicolas Saenz Julienne , Frederic Weisbecker , Christoph Lameter , Juri Lelli , Peter Zijlstra , Alex Belits , Peter Xu , Thomas Gleixner , Daniel Bristot de Oliveira , Marcelo Tosatti Subject: [patch v9 09/10] mm: vmstat: move need_update X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The logic to disable vmstat worker thread, when entering nohz full, does not cover all scenarios. For example, it is possible for the following to happen: References: <20220127172319.428529308@fuller.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Move need_update() function up in vmstat.c, needed by next patch. No code changes. Remove a duplicate comment while at it. Signed-off-by: Marcelo Tosatti --- mm/vmstat.c | 58 +++++++++++++++++++++++++++++----------------------------- 1 file changed, 29 insertions(+), 29 deletions(-) Index: linux-2.6/mm/vmstat.c =================================================================== --- linux-2.6.orig/mm/vmstat.c +++ linux-2.6/mm/vmstat.c @@ -1880,6 +1880,35 @@ static const struct seq_operations vmsta static DEFINE_PER_CPU(struct delayed_work, vmstat_work); int sysctl_stat_interval __read_mostly = HZ; +/* + * Check if the diffs for a certain cpu indicate that + * an update is needed. + */ +static bool need_update(int cpu) +{ + pg_data_t *last_pgdat = NULL; + struct zone *zone; + + for_each_populated_zone(zone) { + struct per_cpu_zonestat *pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu); + struct per_cpu_nodestat *n; + + /* + * The fast way of checking if there are any vmstat diffs. + */ + if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff))) + return true; + + if (last_pgdat == zone->zone_pgdat) + continue; + last_pgdat = zone->zone_pgdat; + n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu); + if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff))) + return true; + } + return false; +} + #ifdef CONFIG_PROC_FS static void refresh_vm_stats(struct work_struct *work) { @@ -1961,35 +1990,6 @@ static void vmstat_update(struct work_st } /* - * Check if the diffs for a certain cpu indicate that - * an update is needed. - */ -static bool need_update(int cpu) -{ - pg_data_t *last_pgdat = NULL; - struct zone *zone; - - for_each_populated_zone(zone) { - struct per_cpu_zonestat *pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu); - struct per_cpu_nodestat *n; - - /* - * The fast way of checking if there are any vmstat diffs. - */ - if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff))) - return true; - - if (last_pgdat == zone->zone_pgdat) - continue; - last_pgdat = zone->zone_pgdat; - n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu); - if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff))) - return true; - } - return false; -} - -/* * Switch off vmstat processing and then fold all the remaining differentials * until the diffs stay at zero. The function is used by NOHZ and can only be * invoked when tick processing is not active.