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 X-Spam-Level: X-Spam-Status: No, score=-10.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C0C6C433E6 for ; Tue, 2 Feb 2021 23:08:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3AE3964F6C for ; Tue, 2 Feb 2021 23:08:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3AE3964F6C Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=fb.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B10FD6B006C; Tue, 2 Feb 2021 18:08:04 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AC2926B006E; Tue, 2 Feb 2021 18:08:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 98C016B0070; Tue, 2 Feb 2021 18:08:04 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0021.hostedemail.com [216.40.44.21]) by kanga.kvack.org (Postfix) with ESMTP id 7E6E66B006C for ; Tue, 2 Feb 2021 18:08:04 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 4745C8249980 for ; Tue, 2 Feb 2021 23:08:04 +0000 (UTC) X-FDA: 77774867688.12.kite14_1c0afe0275ce Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 223A91805517B for ; Tue, 2 Feb 2021 23:08:04 +0000 (UTC) X-HE-Tag: kite14_1c0afe0275ce X-Filterd-Recvd-Size: 9974 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by imf08.hostedemail.com (Postfix) with ESMTP for ; Tue, 2 Feb 2021 23:08:02 +0000 (UTC) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 112N2gU1015608; Tue, 2 Feb 2021 15:08:00 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=date : from : to : cc : subject : message-id : references : content-type : in-reply-to : mime-version; s=facebook; bh=TrlPo0eFafeFIQd4fPweXXFigvYNrR/l1TowLCAzMco=; b=DCJffGsgDmJguBrses2VkFJP1x3+0ff7pDl3GvpLHXHRh4ESGWIFWoezd3RTJKU+gCrJ VQyA4aBF4jaXZo3gZWr7EQ4/tCZLtyLFcpLtPXmGu0bj8s2HQ9StpqqTq5EOy60s2Myr TN69Br7pimgxM9K30SLxqmAX3CxpjbwwP/4= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 36drdbx9xt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Tue, 02 Feb 2021 15:08:00 -0800 Received: from NAM02-SN1-obe.outbound.protection.outlook.com (100.104.31.183) by o365-in.thefacebook.com (100.104.36.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 2 Feb 2021 15:07:58 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=MS56heoHwRyVPrbKr/iUaCKv0iHZ5Mc+ZXj3OkHL97V/9a41Zy5LOgfNUiiPA2vIb3oDaZyIumMJwMTekMnUNzjASfFHSHU+mXa2/I1HJCdReptPrg4qx9OzHAhZh7mMgfgqjhDajjjU2DPo3ee97Jp5Xyj1+gav1xEaphLl3gbzjwf3kjpC5v72RnBeKINUoiKTTSUwhEB+xFQ+CrJpsQ4IJskTsSRmlv10HRAJeVVA9sIi8gHc10ov5Usx8BPSe8ib9UI15d2YUE8eVOBknFRQ8BQytNy0PjucreAmH+jj15A0syGvKN+ss2EFbn5dQC4WNpvyNS62ExeR84G9Iw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=TrlPo0eFafeFIQd4fPweXXFigvYNrR/l1TowLCAzMco=; b=P/KGT+oEuk3J2xvOhmcSUahR0mjirbNnAMvMzxZlmYvnXE1fPXqYnrWVOcFhwbJgRBM/Jox6yL3Pit5NKDJ0VvroemaDHKggrsVTrFRuDk+M/Jq4OvN2ixqJ9OOcixqlwA+y2JaY0UZCz1PllWt52obmziySqvmRzBBZJrgtM1un3VzrLlZxDYrAUjiuxdvPc03QcibALi6vZy4mtTVejuBMz0gPW2v9vqkOtbty7l5VBzK+WNsCnNT6GwDSDvp+dLeXosQR5vmssUncV8VmVjIqkqkAFiSrBIrA/tFg8iX/dGqO6Hx+JU5lQsDCiUZ8j2NBUlPjJtkuHJclYOMdHA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector2-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=TrlPo0eFafeFIQd4fPweXXFigvYNrR/l1TowLCAzMco=; b=kfvVAkpqqWcXbgwcr5uWlOcq1BZbqKTfKLuqWcZv0irSCmXiqqXDpkDOpNVtAhpiCnb40eBAGW00lS6nE/HtXGrrU6G24mE5Eclh8PAiCiCfe/qgh46z1psOWFJXvlcduPXzoZDahtmnb8YHttHVt44upFUxRyMtcz3/DNkuDK0= Authentication-Results: cmpxchg.org; dkim=none (message not signed) header.d=none;cmpxchg.org; dmarc=none action=none header.from=fb.com; Received: from BYAPR15MB4136.namprd15.prod.outlook.com (2603:10b6:a03:96::24) by BYAPR15MB2216.namprd15.prod.outlook.com (2603:10b6:a02:8b::29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3805.24; Tue, 2 Feb 2021 23:07:52 +0000 Received: from BYAPR15MB4136.namprd15.prod.outlook.com ([fe80::53a:b2c3:8b03:12d1]) by BYAPR15MB4136.namprd15.prod.outlook.com ([fe80::53a:b2c3:8b03:12d1%7]) with mapi id 15.20.3805.028; Tue, 2 Feb 2021 23:07:52 +0000 Date: Tue, 2 Feb 2021 15:07:47 -0800 From: Roman Gushchin To: Johannes Weiner CC: Andrew Morton , Tejun Heo , Michal Hocko , , , , Subject: Re: [PATCH 1/7] mm: memcontrol: fix cpuhotplug statistics flushing Message-ID: <20210202230747.GA1812008@carbon.dhcp.thefacebook.com> References: <20210202184746.119084-1-hannes@cmpxchg.org> <20210202184746.119084-2-hannes@cmpxchg.org> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210202184746.119084-2-hannes@cmpxchg.org> X-Originating-IP: [2620:10d:c090:400::5:7ae2] X-ClientProxiedBy: CO1PR15CA0108.namprd15.prod.outlook.com (2603:10b6:101:21::28) To BYAPR15MB4136.namprd15.prod.outlook.com (2603:10b6:a03:96::24) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from carbon.dhcp.thefacebook.com (2620:10d:c090:400::5:7ae2) by CO1PR15CA0108.namprd15.prod.outlook.com (2603:10b6:101:21::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3825.17 via Frontend Transport; Tue, 2 Feb 2021 23:07:51 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 13ca1b00-c001-403e-18d3-08d8c7cf5ddc X-MS-TrafficTypeDiagnostic: BYAPR15MB2216: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:7219; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR15MB4136.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFS:(136003)(396003)(346002)(376002)(366004)(39860400002)(7696005)(6506007)(52116002)(5660300002)(66556008)(66476007)(4744005)(478600001)(16526019)(33656002)(1076003)(316002)(66946007)(8936002)(4326008)(9686003)(6666004)(8676002)(186003)(86362001)(55016002)(6916009)(54906003)(2906002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?xgufFMk7g4pf3IoVYYduq+dXX0MmWYT+PaVhbM3rGjSJZkG6Ubru/4es0pJm?= =?us-ascii?Q?q1jRLN2dMHu9UMSZBMk+3LfS+f1ZhCy6FStSX3DNqiQkNBrPXGEBruq7B41V?= =?us-ascii?Q?BYgM5DBdRBEP/V0dlvoFZn+S5/R2WiJkHNhHpoRsoMrmkW9V2+/Y0Zb5lsfc?= =?us-ascii?Q?EnBh9gJk3GmHUhEc3AlkBQYhu1nEkHB9+hNEJ24c+Yy1sDc1A8ryJWuEZiD6?= =?us-ascii?Q?K5B0Ol49p0u55BOuJpnBADrdsyWcMN7LL+r81/QHu7oB2hYqdQEGDYkOCBhW?= =?us-ascii?Q?aWy99K1eO+XdjYNTPoBci3+a7LYg63p6quxnFcxzxUzBm/kTCdqlvgPnTCBj?= =?us-ascii?Q?HjbLEj4seuGMJpa7g4X7kJ8OcnoCEj7Rm0mC4fzrx3oBGWcJAdhfbE0ajvwz?= =?us-ascii?Q?2/jaQIh1pOHP6wJR9RtpIchNXqJzOKOGzM3gWblSUqZfdJwvRYVDAnWaVW2P?= =?us-ascii?Q?N+qFBQ7CKEbxZ6u843Tj/1NR5/WgWO7UzDl8xkistiI74koKuCQcOa4e19be?= =?us-ascii?Q?Mfhp8+tXmG06xEEP0zkKsg5hQuvLs/+Y9iH7aDM8RFdlAb0DrB5Bp1/rF0L6?= =?us-ascii?Q?Hmh1hxQMkFy/4bdwsgKiPL/DQ6zH+KD03mqqdzbOiPxQzwLmVlJ4UD8yT0f5?= =?us-ascii?Q?QSxqBzA3HSys4YBWRALu7TTrn+P5urznRU5e588mgcppBEAGEfjm81rgbz9h?= =?us-ascii?Q?bNK9UBGoQqEgDXjYS1gkBeQaPvxpfRKzCJsGPxFsKBSUuHCcyw3kyJY0R70L?= =?us-ascii?Q?d/AAfznaBHrsb9of6md2k4gpL8actPI4q4Z4QzFCqPUUzx8SV51hFgqVpFs6?= =?us-ascii?Q?AezWeqExe91sy6QtPY6uNIPWpZ7aKqVJoZSBn3Bg4M+yckfR0wj0dcM7ekSQ?= =?us-ascii?Q?4BL9+kdem8vs8ggvl4X2twGl84oG7NOptbIyK+GeyTS8P2hhBJCzbEq2TtzE?= =?us-ascii?Q?xf8BnVlcMpL1eu25ZDgBTz0fG5fHjJF0WcVa5/a+nLkh1BHH8ZbWBJM6iHSd?= =?us-ascii?Q?wCrtunxZu7nt7jFYwDXb3V6TAvmsp49VSRWk72ZC0IsEoaNrHioYgt0lC47w?= =?us-ascii?Q?IyVYCNoC6NuWPKJDiSu7Cy0buHPiNMhE3SRAsIGMBfY6uZwUW8c=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 13ca1b00-c001-403e-18d3-08d8c7cf5ddc X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4136.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Feb 2021 23:07:52.2746 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 8wtjIM1QcP5cL3ZvVDyXsgtig8FxgkZM+xbJGZqgKGByTNhlg53zqj6jBjGquvgF X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2216 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.737 definitions=2021-02-02_13:2021-02-02,2021-02-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 suspectscore=0 adultscore=0 impostorscore=0 mlxscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 bulkscore=0 phishscore=0 malwarescore=0 priorityscore=1501 mlxlogscore=889 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102020146 X-FB-Internal: deliver 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: On Tue, Feb 02, 2021 at 01:47:40PM -0500, Johannes Weiner wrote: > The memcg hotunplug callback erroneously flushes counts on the local > CPU, not the counts of the CPU going away; those counts will be lost. > > Flush the CPU that is actually going away. > > Also simplify the code a bit by using mod_memcg_state() and > count_memcg_events() instead of open-coding the upward flush - this is > comparable to how vmstat.c handles hotunplug flushing. To the whole series: it's really nice to have an accurate stats at non-leaf levels. Just as an illustration: if there are 32 CPUs and 1000 sub-cgroups (which is an absolutely realistic number, because often there are many dying generations of each cgroup), the error margin is 3.9GB. It makes all numbers pretty much random and all possible tests extremely flaky. > > Signed-off-by: Johannes Weiner To this patch: Reviewed-by: Roman Gushchin Thanks!