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 54FB5C433E1 for ; Wed, 3 Jun 2020 04:37:37 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 20E4E2067B for ; Wed, 3 Jun 2020 04:37:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 20E4E2067B 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 98CAA80007; Wed, 3 Jun 2020 00:37:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 93CEF8E0006; Wed, 3 Jun 2020 00:37:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8517080007; Wed, 3 Jun 2020 00:37:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0082.hostedemail.com [216.40.44.82]) by kanga.kvack.org (Postfix) with ESMTP id 6C5218E0006 for ; Wed, 3 Jun 2020 00:37:36 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 261DF3CFB for ; Wed, 3 Jun 2020 04:37:36 +0000 (UTC) X-FDA: 76886642112.28.crush08_819df3a22602 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin28.hostedemail.com (Postfix) with ESMTP id 0E3856D6F for ; Wed, 3 Jun 2020 04:37:36 +0000 (UTC) X-HE-Tag: crush08_819df3a22602 X-Filterd-Recvd-Size: 3290 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Wed, 3 Jun 2020 04:37:35 +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 B630231B; Tue, 2 Jun 2020 21:37:34 -0700 (PDT) Received: from [10.163.77.218] (unknown [10.163.77.218]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E92843F305; Tue, 2 Jun 2020 21:37:31 -0700 (PDT) Subject: Re: [PATCH] mm/vmstat: Add events for PMD based THP migration without split To: Daniel Jordan , John Hubbard 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> <20200602145208.qucum52lwslhiqff@ca-dmjordan1.us.oracle.com> From: Anshuman Khandual Message-ID: Date: Wed, 3 Jun 2020 10:06:31 +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: <20200602145208.qucum52lwslhiqff@ca-dmjordan1.us.oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 0E3856D6F X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000015, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 06/02/2020 08:22 PM, Daniel Jordan wrote: > On Mon, Jun 01, 2020 at 09:48:09PM -0700, John Hubbard wrote: >> 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 ? > > Yes, that would be good. I understand the intent better now but still think > the 'failure' event could be misinterpreted as outright failure instead of > splitting followed by successfully moving the constituent pages. Does this look okay and sufficient ? --- a/Documentation/vm/page_migration.rst +++ b/Documentation/vm/page_migration.rst @@ -253,5 +253,20 @@ which are function pointers of struct address_space_operations. PG_isolated is alias with PG_reclaim flag so driver shouldn't use the flag for own purpose. +Quantifying Migration +===================== +Following events can be used to quantify page migration. + +- PGMIGRATE_SUCCESS +- PGMIGRATE_FAIL +- THP_MIGRATION_SUCCESS +- THP_MIGRATION_FAILURE + +THP_MIGRATION_FAILURE in particular represents an event when a THP could not be +migrated as a single entity following an allocation failure and ended up getting +split into constituent normal pages before being retried. This event, along with +PGMIGRATE_SUCCESS and PGMIGRATE_FAIL will help in quantifying and analyzing THP +migration events including both success and failure cases. + > > It might help to clarify in the changelog as well. > Sure, will update the commit message accordingly.