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 B13DAC61DA4 for ; Thu, 9 Feb 2023 15:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230007AbjBIPeG (ORCPT ); Thu, 9 Feb 2023 10:34:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229647AbjBIPeD (ORCPT ); Thu, 9 Feb 2023 10:34:03 -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 EC28947087 for ; Thu, 9 Feb 2023 07:33:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675956801; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=LGWVlVnJpdpZsY64OC4/IsULi3iGJlzsOgwi06Ffb5I=; b=OMwp7q2g3Dx2cqRDfgY5KaO/WyAGXlNOXbTW38puODzE3dYtaVxft27AR+bcs+6QqSpNoG YKC0exqqGahS7qaQOMjHTQI9W+gkGI81YEF18sppXRi260tC6NsElMJgaZE2ay+t5xTlzF h/kzPmmckhSn0pPSovfya6mlgNBQjBk= 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-205-LPxsHX8gOi6p7L8Li5eumw-1; Thu, 09 Feb 2023 10:33:18 -0500 X-MC-Unique: LPxsHX8gOi6p7L8Li5eumw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 902DD1C29D4F; Thu, 9 Feb 2023 15:33:16 +0000 (UTC) Received: from tpad.localdomain (ovpn-112-3.gru2.redhat.com [10.97.112.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 625EB40C83B6; Thu, 9 Feb 2023 15:33:16 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id 86BD4400E5701; Thu, 9 Feb 2023 12:32:51 -0300 (-03) Message-ID: <20230209153204.873999366@redhat.com> User-Agent: quilt/0.67 Date: Thu, 09 Feb 2023 12:01:59 -0300 From: Marcelo Tosatti To: Christoph Lameter Cc: Aaron Tomlin , Frederic Weisbecker , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Marcelo Tosatti Subject: [PATCH v2 09/11] mm/vmstat: use cmpxchg loop in cpu_vm_stats_fold References: <20230209150150.380060673@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In preparation to switch vmstat shepherd to flush per-CPU counters remotely, use a cmpxchg loop instead of a pair of read/write instructions. Signed-off-by: Marcelo Tosatti Index: linux-2.6/mm/vmstat.c =================================================================== --- linux-2.6.orig/mm/vmstat.c +++ linux-2.6/mm/vmstat.c @@ -885,7 +885,7 @@ static int refresh_cpu_vm_stats(void) } /* - * Fold the data for an offline cpu into the global array. + * Fold the data for a cpu into the global array. * There cannot be any access by the offline cpu and therefore * synchronization is simplified. */ @@ -906,8 +906,9 @@ void cpu_vm_stats_fold(int cpu) if (pzstats->vm_stat_diff[i]) { int v; - v = pzstats->vm_stat_diff[i]; - pzstats->vm_stat_diff[i] = 0; + do { + v = pzstats->vm_stat_diff[i]; + } while (!try_cmpxchg(&pzstats->vm_stat_diff[i], &v, 0)); atomic_long_add(v, &zone->vm_stat[i]); global_zone_diff[i] += v; } @@ -917,8 +918,9 @@ void cpu_vm_stats_fold(int cpu) if (pzstats->vm_numa_event[i]) { unsigned long v; - v = pzstats->vm_numa_event[i]; - pzstats->vm_numa_event[i] = 0; + do { + v = pzstats->vm_numa_event[i]; + } while (!try_cmpxchg(&pzstats->vm_numa_event[i], &v, 0)); zone_numa_event_add(v, zone, i); } } @@ -934,8 +936,9 @@ void cpu_vm_stats_fold(int cpu) if (p->vm_node_stat_diff[i]) { int v; - v = p->vm_node_stat_diff[i]; - p->vm_node_stat_diff[i] = 0; + do { + v = p->vm_node_stat_diff[i]; + } while (!try_cmpxchg(&p->vm_node_stat_diff[i], &v, 0)); atomic_long_add(v, &pgdat->vm_stat[i]); global_node_diff[i] += v; }