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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33C43C433EF for ; Thu, 25 Nov 2021 05:50:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A06576B0074; Thu, 25 Nov 2021 00:49:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9B6686B0075; Thu, 25 Nov 2021 00:49:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8A4986B007B; Thu, 25 Nov 2021 00:49:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0030.hostedemail.com [216.40.44.30]) by kanga.kvack.org (Postfix) with ESMTP id 7B0346B0074 for ; Thu, 25 Nov 2021 00:49:52 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 2E6048DF6B for ; Thu, 25 Nov 2021 05:49:42 +0000 (UTC) X-FDA: 78846375720.17.8FE958C Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com [115.124.30.57]) by imf13.hostedemail.com (Postfix) with ESMTP id 9586F1046280 for ; Thu, 25 Nov 2021 05:49:37 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0UyDytYc_1637819376; Received: from 30.21.164.78(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0UyDytYc_1637819376) by smtp.aliyun-inc.com(127.0.0.1); Thu, 25 Nov 2021 13:49:37 +0800 Message-ID: <141bdfc6-f898-3cc3-f692-726c5f6cb74d@linux.alibaba.com> Date: Thu, 25 Nov 2021 13:50:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH 2/3] mm: migrate: Correct the hugetlb migration stats To: Mike Kravetz , Andrew Morton Cc: ziy@nvidia.com, shy828301@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <71a4b6c22f208728fe8c78ad26375436c4ff9704.1636275127.git.baolin.wang@linux.alibaba.com> <20211115202146.473fff2404d7fb200dd48bd3@linux-foundation.org> <71816b8f-93e5-5a2a-e616-d52a1c4d354c@linux.alibaba.com> <3e6dcac6-c947-5f94-cd94-b59a8247dbcf@oracle.com> <7423472b-a6d4-4b37-0953-24b11aba2fad@oracle.com> From: Baolin Wang In-Reply-To: <7423472b-a6d4-4b37-0953-24b11aba2fad@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-Rspamd-Queue-Id: 9586F1046280 X-Stat-Signature: 86in99c8daza7zmamq5tnrrx17c1sym5 Authentication-Results: imf13.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf13.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.57 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com X-Rspamd-Server: rspam02 X-HE-Tag: 1637819377-888625 Content-Transfer-Encoding: quoted-printable 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 2021/11/25 3:05, Mike Kravetz wrote: > On 11/24/21 02:47, Baolin Wang wrote: >> >> >> On 2021/11/24 3:25, Mike Kravetz wrote: >>> On 11/15/21 22:03, Baolin Wang wrote: >>>> On 2021/11/16 12:21, Andrew Morton wrote: >>>>> On Sun,=C2=A0 7 Nov 2021 16:57:26 +0800 Baolin Wang wrote: >>>>> >>> I 'think' this is OK since the behavior is not really defined today.=C2= =A0 But, we >>> are changing user visible output. >> >> Actually we did not change the user visible output for a hugetlb migra= tion. Since we still return the number of hugetlb failed to migrate as be= fore (though previous hugetlb behavior is not reasonable), not the number= of hguetlb subpages. We just correct the hugetlb migration stats for the= hugetlb in kernel, like PGMIGRATE_SUCCESS/FAIL stats. >> >=20 > Yes, the values returned by move_pages() will not change. >=20 > The 'stats' in the kernel which are changing are user visible. Specifi= cally. > the fields pgmigrate_success and pgmigrate_fail in the file /proc/vmsta= t. > The values reported there for migrated hugetlb pages is changing as a r= esult > of this series. >=20 > In addition, if someone monitors the trace point at the end of migrate_= pages > they will start seeing different values. Right, agree. >=20 > As mentioned, these values are not currently documented for hugetlb pag= es so > I think it is OK to change. If someone thinks otherwise, please speak = up! >=20 > Making them be similar to what is reported for THP pages would be a goo= d > thing. OK. >>> >>> Perhaps we should go ahead and document the hugetlb behavior when mak= ing these >>> changes? >> >> Sure. How about adding below modification for hugetlb? >=20 > Yes, please do make the below changes as well. Thanks. Andrew, I am not sure you can help to fold below changes into your mm=20 branch, or you want me to resend this patch set with adding below=20 changes, or just send an incremental patch to add hugetlb documentation? diff --git a/Documentation/vm/page_migration.rst b/Documentation/vm/page_migration.rst index 08810f5..8c5cb81 100644 --- a/Documentation/vm/page_migration.rst +++ b/Documentation/vm/page_migration.rst @@ -263,15 +263,15 @@ Monitoring Migration The following events (counters) can be used to monitor page migration. 1. PGMIGRATE_SUCCESS: Normal page migration success. Each count means that a - page was migrated. If the page was a non-THP page, then this counter = is - increased by one. If the page was a THP, then this counter is increased by - the number of THP subpages. For example, migration of a single 2MB THP that - has 4KB-size base pages (subpages) will cause this counter to increase by - 512. + page was migrated. If the page was a non-THP and non-hugetlb page, th= en + this counter is increased by one. If the page was a THP or hugetlb, t= hen + this counter is increased by the number of THP or hugetlb subpages. + For example, migration of a single 2MB THP that has 4KB-size base pag= es + (subpages) will cause this counter to increase by 512. 2. PGMIGRATE_FAIL: Normal page migration failure. Same counting rules as for PGMIGRATE_SUCCESS, above: this will be increased by the number of subpages, - if it was a THP. + if it was a THP or hugetlb.