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 5F69AC433F5 for ; Mon, 3 Jan 2022 03:54:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5006E6B0072; Sun, 2 Jan 2022 22:54:40 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4955D6B0073; Sun, 2 Jan 2022 22:54:40 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 375C46B0074; Sun, 2 Jan 2022 22:54:40 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0225.hostedemail.com [216.40.44.225]) by kanga.kvack.org (Postfix) with ESMTP id 256EA6B0072 for ; Sun, 2 Jan 2022 22:54:40 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C6481180DD56D for ; Mon, 3 Jan 2022 03:54:39 +0000 (UTC) X-FDA: 78987609078.19.ACA6E67 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf08.hostedemail.com (Postfix) with ESMTP id C15B5160005 for ; Mon, 3 Jan 2022 03:54:26 +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 3984B1FB; Sun, 2 Jan 2022 19:54:38 -0800 (PST) Received: from [10.163.71.229] (unknown [10.163.71.229]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B9BC33F66F; Sun, 2 Jan 2022 19:54:35 -0800 (PST) Subject: Re: [RFC] mm/migration: Add trace events for THP migrations To: Matthew Wilcox Cc: linux-mm@kvack.org, Steven Rostedt , Ingo Molnar , Andrew Morton , Zi Yan , Naoya Horiguchi , John Hubbard , linux-kernel@vger.kernel.org References: <1640328398-20698-1-git-send-email-anshuman.khandual@arm.com> From: Anshuman Khandual Message-ID: <96524032-cf0f-42df-975a-00a0ea6ba227@arm.com> Date: Mon, 3 Jan 2022 09:24:38 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: C15B5160005 X-Stat-Signature: 3csxsna6ntguu1rofsuyxqcoj6igw8q1 Authentication-Results: imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com; dmarc=pass (policy=none) header.from=arm.com X-HE-Tag: 1641182066-36414 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: Hello Matthew, On 12/24/21 8:18 PM, Matthew Wilcox wrote: > On Fri, Dec 24, 2021 at 12:16:38PM +0530, Anshuman Khandual wrote: >> This adds two trace events for PMD based THP migration without split. These >> events closely follow the implementation details like setting and removing >> of PMD migration entries, which are essential operations for THP migration. > > Why are you printing the address of a struct page? What useful > information does this supply? Same question for the struct mm. > And the pmdp, for that matter. Just to make individual trace records comprehensive enough to capture which (and where) the PMD entries went through migration entry state. But is there any particular concern here capturing mm, page and pmdp ? > > You haven't said _why_ you want these tracepoints. So it's impossible > to suggest what you _should_ be doing, because what you _are_ doing > is obviously wrong. Just for debug purpose. To see which (and where) PMD entries are being migrated as is without a split, via PMD migration entries. Wondering if you are suggesting just to capture addr, pmdval and just drop others ? > >> + TP_printk("mm=%p, address=%lx, pmdp=%p, page=%p pmdval=%lx", >> + __entry->mm, >> + __entry->address, >> + __entry->pmdp, >> + __entry->page, >> + __entry->pmdval) >> +); > - Anshuman