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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 A6A28C433E0 for ; Tue, 2 Jun 2020 03:20:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6D1622068D for ; Tue, 2 Jun 2020 03:20:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="GrIz+z5h" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D1622068D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BEC5180007; Mon, 1 Jun 2020 23:20:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B9D708E0006; Mon, 1 Jun 2020 23:20:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AB18C80007; Mon, 1 Jun 2020 23:20:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0150.hostedemail.com [216.40.44.150]) by kanga.kvack.org (Postfix) with ESMTP id 901548E0006 for ; Mon, 1 Jun 2020 23:20:12 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 4A0EA8248047 for ; Tue, 2 Jun 2020 03:20:12 +0000 (UTC) X-FDA: 76882818264.26.desk05_1b81ba586e3d Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin26.hostedemail.com (Postfix) with ESMTP id 2C2461804B668 for ; Tue, 2 Jun 2020 03:20:12 +0000 (UTC) X-HE-Tag: desk05_1b81ba586e3d X-Filterd-Recvd-Size: 4116 Received: from hqnvemgate25.nvidia.com (hqnvemgate25.nvidia.com [216.228.121.64]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Tue, 2 Jun 2020 03:20:11 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 01 Jun 2020 20:18:43 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 01 Jun 2020 20:20:10 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 01 Jun 2020 20:20:10 -0700 Received: from [10.2.56.10] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 2 Jun 2020 03:20:05 +0000 Subject: Re: [PATCH] mm/vmstat: Add events for PMD based THP migration without split To: Daniel Jordan , Anshuman Khandual CC: , , Naoya Horiguchi , Zi Yan , Andrew Morton , References: <1590118444-21601-1-git-send-email-anshuman.khandual@arm.com> <20200601165736.qw5kwwknxltk7bv6@ca-dmjordan1.us.oracle.com> X-Nvconfidentiality: public From: John Hubbard Message-ID: <0a936ec7-f44f-1d72-915f-f5758d25fd72@nvidia.com> Date: Mon, 1 Jun 2020 20:20:05 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.1 MIME-Version: 1.0 In-Reply-To: <20200601165736.qw5kwwknxltk7bv6@ca-dmjordan1.us.oracle.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1591067923; bh=D8A1hpMTIZ2k2DR5/UwfONmp0VIuvs4qyuES2Sn0xHI=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=GrIz+z5hstXvn5L/CafsZt24hH1k+QVqhtvYgU/lu9Ljg3nTrKtd77O17KQLDl4vN lmAZr7+feh4qJlTL5hsQbTUhjhWAdVEXovxBrznllPwBYYJ43uaLj2rcovQAIf61Zv JlMuR/pyceVvBuF3Y6GO+SQRZ0ZsYPc1wd7AWbgHkwoEfh7wXO8K0m3wiw+OscXAr7 KZRy9shP7jrQkVFCWAtaTR3wi82pXtw2GL4liNVN4JZ3midiN+fNVVydCo0VVq+Fyz /8sMNGI674n0h7BrlFtwLenM+HbDOd3k/5CUr7szqoVRehIdhFCrwH+XWz+UMR6jGf Ge+G+fFQ7q2Og== X-Rspamd-Queue-Id: 2C2461804B668 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 2020-06-01 09:57, Daniel Jordan wrote: > Hi Anshuman, > > On Fri, May 22, 2020 at 09:04:04AM +0530, Anshuman Khandual wrote: >> This adds the following two new VM events which will help in validating PMD >> based THP migration without split. Statistics reported through these events >> will help in performance debugging. >> >> 1. THP_PMD_MIGRATION_SUCCESS >> 2. THP_PMD_MIGRATION_FAILURE > > The names suggest a binary event similar to the existing > pgmigrate_success/fail, but FAILURE only tracks one kind of migration error, > and then only when the thp is successfully split, so shouldn't it be called > SPLIT instead? > So the full description of the situation, which we're trying to compress into a shorter name, is "THP pmd migration failure, due to successfully splitting the THP". From that, the beginning part is the real point here, while the last part is less important. In other words, the users of these events are people who are trying to quantify THP migrations, and these events are particularly relevant for that. The "THP migration failed" is more important here than the reason that it failed. Or so I believe so far. So I still think that the names are really quite good, but your point is 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. thanks, -- John Hubbard NVIDIA