From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751825AbcGORP4 (ORCPT ); Fri, 15 Jul 2016 13:15:56 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:36055 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750851AbcGORPu (ORCPT ); Fri, 15 Jul 2016 13:15:50 -0400 Subject: Re: [PATCH 02/14] resource limits: aggregate task highwater marks to cgroup level To: Tejun Heo References: <1468578983-28229-1-git-send-email-toiwoton@gmail.com> <1468578983-28229-3-git-send-email-toiwoton@gmail.com> <20160715141058.GI3078@mtj.duckdns.org> Cc: linux-kernel@vger.kernel.org, Jonathan Corbet , Li Zefan , Johannes Weiner , Markus Elfring , "David S. Miller" , Nicolas Dichtel , "open list:DOCUMENTATION" , "open list:CONTROL GROUP (CGROUP)" From: Topi Miettinen Openpgp: id=A0F2EB0D8452DA908BEC8E911CF9ADDBD610E936 Message-ID: Date: Fri, 15 Jul 2016 17:15:41 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.1.0 MIME-Version: 1.0 In-Reply-To: <20160715141058.GI3078@mtj.duckdns.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/15/16 14:10, Tejun Heo wrote: > Hello, Topi. > > On Fri, Jul 15, 2016 at 01:35:49PM +0300, Topi Miettinen wrote: >> Collect resource usage highwater marks of a task to cgroup >> statistics when the task exits. > > I'm not sure how this makes sense. The limits are enforced and > collected per user or along the process hierarchy which can be very > different from cgroup organization. What does collecting high > watermarks from orthogonal structure, sometimes even combining > per-user numbers from different users, even mean? These are numbers > without clear semantics. There are clear semantics for the limits themselves, either they apply per task or per user. It makes sense to gather values according to these semantics. Then with systemd or other tools you can use the valuse to set the limits for a service regardless if the limit applies per task or per user and it works according to each limit's semantics. cgroups are used to aggregate values from a group of tasks, which still are related to one service. Because with systemd the services also are given a cgroup context, the values will completely make sense there too. It could be useful to introduce a new set of limits that apply only cgroup level. It would not remove the need to aggregate values from a group of tasks. -Topi > > Thanks. >