From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 09C4C6B0006 for ; Mon, 2 Jul 2018 07:29:09 -0400 (EDT) Received: by mail-ed1-f72.google.com with SMTP id n2-v6so5566208edr.5 for ; Mon, 02 Jul 2018 04:29:08 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id p21-v6si2274567edm.136.2018.07.02.04.29.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Jul 2018 04:29:07 -0700 (PDT) Date: Mon, 2 Jul 2018 13:29:06 +0200 From: Michal Hocko Subject: Re: [PATCH] mm: be more informative in OOM task list Message-ID: <20180702112906.GH19043@dhcp22.suse.cz> References: <7de14c6cac4a486c04149f37948e3a76028f3fa5.1530461087.git.rfreire@redhat.com> <20180702093043.GB19043@dhcp22.suse.cz> <1113748807.15224076.1530530533122.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1113748807.15224076.1530530533122.JavaMail.zimbra@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Rodrigo Freire Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org On Mon 02-07-18 07:22:13, Rodrigo Freire wrote: > Hello Michal, > > ----- Original Message ----- > > From: "Michal Hocko" > > To: "Rodrigo Freire" > > Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org > > Sent: Monday, July 2, 2018 6:30:43 AM > > Subject: Re: [PATCH] mm: be more informative in OOM task list > > > > On Sun 01-07-18 13:09:40, Rodrigo Freire wrote: > > > The default page memory unit of OOM task dump events might not be > > > intuitive for the non-initiated when debugging OOM events. Add > > > a small printk prior to the task dump informing that the memory > > > units are actually memory _pages_. > > > > Does this really help? I understand the the oom report might be not the > > easiest thing to grasp but wouldn't it be much better to actually add > > documentation with clarification of each part of it? > > That would be great: After a quick grep -ri for oom in Documentation, > I found several other files containing its own OOM behaviour modifier > configurations. But it indeed lacks a central and canonical Doc file > which documents the OOM Killer behavior and workflows. > > However, I still stand by my proposed patch: It is unobtrusive, infers > no performance issue and clarifying: I recently worked in a case (for > full disclosure: I am a far cry from a MM expert) where the sum of the > RSS pages made sense when interpreted as real kB pages. Reason: There > were processes sharing (a good amount of) memory regions, misleading > the interpretation and that misled not only me, but some other > colleagues a well: The pages was only sorted out after actually > inspecting the source code. > > This patch is user-friendly and can be a great time saver to others in > the community. Well, all other counters we print are in page units unless explicitly kB. So I am not sure we really need to do anything but document the output better. Maybe others will find it more important though. -- Michal Hocko SUSE Labs