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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 7EF88C28CBC for ; Wed, 6 May 2020 13:33:41 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4596B20752 for ; Wed, 6 May 2020 13:33:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4596B20752 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CA8038E0005; Wed, 6 May 2020 09:33:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C57BC8E0003; Wed, 6 May 2020 09:33:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B6D588E0005; Wed, 6 May 2020 09:33:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0213.hostedemail.com [216.40.44.213]) by kanga.kvack.org (Postfix) with ESMTP id 9E9878E0003 for ; Wed, 6 May 2020 09:33:40 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 497F5824C739 for ; Wed, 6 May 2020 13:33:40 +0000 (UTC) X-FDA: 76786386600.08.title32_2e41b388f20c X-HE-Tag: title32_2e41b388f20c X-Filterd-Recvd-Size: 2983 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Wed, 6 May 2020 13:33:39 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 7CAB5AED5; Wed, 6 May 2020 13:33:40 +0000 (UTC) Subject: Re: [PATCH] mm: vmstat: Use zeroed stats for unpopulated zones To: Michal Hocko , Sandipan Das Cc: akpm@linux-foundation.org, linux-mm@kvack.org, khlebnikov@yandex-team.ru, kirill@shutemov.name, aneesh.kumar@linux.ibm.com, srikar@linux.vnet.ibm.com References: <20200504070304.127361-1-sandipan@linux.ibm.com> <20200504102441.GM22838@dhcp22.suse.cz> From: Vlastimil Babka Message-ID: <959f15af-28a8-371b-c5c3-cd7489d2a7fb@suse.cz> Date: Wed, 6 May 2020 15:33:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200504102441.GM22838@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 5/4/20 12:26 PM, Michal Hocko wrote: > On Mon 04-05-20 12:33:04, Sandipan Das wrote: >> For unpopulated zones, the pagesets point to the common >> boot_pageset which can have non-zero vm_numa_stat counts. >> Because of this memory-less nodes end up having non-zero >> NUMA statistics. This can be observed on any architecture >> that supports memory-less NUMA nodes. >> >> E.g. >> >> $ numactl -H >> available: 2 nodes (0-1) >> node 0 cpus: 0 1 2 3 >> node 0 size: 0 MB >> node 0 free: 0 MB >> node 1 cpus: 4 5 6 7 >> node 1 size: 8131 MB >> node 1 free: 6980 MB >> node distances: >> node 0 1 >> 0: 10 40 >> 1: 40 10 >> >> $ numastat >> node0 node1 >> numa_hit 108 56495 >> numa_miss 0 0 >> numa_foreign 0 0 >> interleave_hit 0 4537 >> local_node 108 31547 >> other_node 0 24948 >> >> Hence, return zero explicitly for all the stats of an >> unpopulated zone. > > I hope I am not just confused but I would expect that at least > numa_foreign and other_node to be non zero. Hmm, checking zone_statistics(): NUMA_FOREIGN increment uses preferred zone, which is the first in zone in zonelist, so it will be a zone from node 1 even for allocations on cpu associated to node 0 - assuming node 0's unpopulated zones are not included in node 0's zonelist. NUMA_OTHER uses numa_node_id(), which would mean the node 0's cpus have node 1 in their numa_node_id() ? Is that correct? So the 108 comes from where exactly, some early allocations until all was initialized?