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=-2.3 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 70B45C433E1 for ; Tue, 2 Jun 2020 05:31:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 38A6B206A2 for ; Tue, 2 Jun 2020 05:31:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38A6B206A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A0DBE28006D; Tue, 2 Jun 2020 01:31:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9BFB828004A; Tue, 2 Jun 2020 01:31:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F9E128006D; Tue, 2 Jun 2020 01:31:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0250.hostedemail.com [216.40.44.250]) by kanga.kvack.org (Postfix) with ESMTP id 78F4628004A for ; Tue, 2 Jun 2020 01:31:46 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 3C91C180AD804 for ; Tue, 2 Jun 2020 05:31:46 +0000 (UTC) X-FDA: 76883149812.15.knee24_83cc3262fff10 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id 1A1741814B0C1 for ; Tue, 2 Jun 2020 05:31:46 +0000 (UTC) X-HE-Tag: knee24_83cc3262fff10 X-Filterd-Recvd-Size: 2868 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Tue, 2 Jun 2020 05:31:45 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A0E511FB; Mon, 1 Jun 2020 22:31:44 -0700 (PDT) Received: from [192.168.0.129] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1DDDA3F52E; Mon, 1 Jun 2020 22:31:41 -0700 (PDT) Subject: Re: [PATCH] mm/vmstat: Add events for PMD based THP migration without split To: John Hubbard , Daniel Jordan Cc: linux-mm@kvack.org, hughd@google.com, Naoya Horiguchi , Zi Yan , Andrew Morton , linux-kernel@vger.kernel.org References: <1590118444-21601-1-git-send-email-anshuman.khandual@arm.com> <20200601165736.qw5kwwknxltk7bv6@ca-dmjordan1.us.oracle.com> <0a936ec7-f44f-1d72-915f-f5758d25fd72@nvidia.com> <1e71d815-5359-3ebe-5d2b-5a3b54b63b51@arm.com> <274be3bf-2206-5e98-8114-1d91fac472c9@nvidia.com> From: Anshuman Khandual Message-ID: Date: Tue, 2 Jun 2020 11:00:37 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <274be3bf-2206-5e98-8114-1d91fac472c9@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 1A1741814B0C1 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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 06/02/2020 10:18 AM, John Hubbard wrote: > On 2020-06-01 21:20, Anshuman Khandual wrote: > ... >>> also important: maybe this patch should also be tracking other causes >>> of THP PMD migration failure, in order to get a truer accounting of the >>> situation. > > I hope one of the experts here can weigh in on that... > >> Is there any other failure reasons which are only specific to THP migration. >> Else, adding stats about generic migration failure reasons will just blur >> the overall understanding about THP migration successes and failure cases >> that results in splitting. >> > > Thinking about that: we do have PGMIGRATE_SUCCESS and PGMIGRATE_FAIL, so I > suppose comparing those numbers with the new THP_PMD_MIGRATION_SUCCESS and > THP_PMD_MIGRATION_FAILURE events should cover it. That is right. > > However, the fact that this is under discussion hints at the need for a > bit of documentation help. What do you think about adding some notes about > all of this to, say, Documentation/vm/page_migration.rst ? Sure but probably bit later. Because I am also planning to add couple of trace events for THP migration, hence will update the documentation part for both VM stat and trace events together.