From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753621Ab1BGLGG (ORCPT ); Mon, 7 Feb 2011 06:06:06 -0500 Received: from shutemov.name ([188.40.19.243]:36114 "EHLO shutemov.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753392Ab1BGLGE (ORCPT ); Mon, 7 Feb 2011 06:06:04 -0500 Date: Mon, 7 Feb 2011 13:06:03 +0200 From: "Kirill A. Shutemov" To: Jacob Pan Cc: Paul Menage , Li Zefan , containers@lists.linux-foundation.org, Arjan van de Ven , linux-kernel@vger.kernel.org, Matt Helsley , "Paul E. McKenney" Subject: Re: [PATCH, v3 2/2] cgroups: introduce timer slack subsystem Message-ID: <20110207110603.GB11712@shutemov.name> References: <1296679656-31163-1-git-send-email-kirill@shutemov.name> <1296679656-31163-3-git-send-email-kirill@shutemov.name> <20110202145605.6c9006fa@putvin> <20110203092229.GB1083@shutemov.name> <20110203095117.76a568fc@putvin> <20110203115743.1ef9a4c2@putvin> <20110204133439.GA7181@shutemov.name> <20110204092755.0bbfaa7a@putvin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110204092755.0bbfaa7a@putvin> User-Agent: Mutt/1.5.20 (2010-08-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 04, 2011 at 09:27:55AM -0800, Jacob Pan wrote: > On Fri, 4 Feb 2011 15:34:39 +0200 > "Kirill A. Shutemov" wrote: > > What's mean "original timer slack" if you are free to move a task > > between a lot of cgroups and process itself free to change it anytime? > > > > I need to manage tasks by a management software instead of letting the > task change timer_slack by itself. The goal is to make management > transparent and no modifications to the existing apps. Therefore, it is > desirable to automatically enforce timer_slack when the apps are in the > cgroup while automatically restore it when it is no longer under cgroup > management. Tasks are always under cgroup management. Root cgroup is still cgroup. > So the "original timer slack" can be the default 50us or whatever value > chosen by the task itself. But the app itself should not care or even be > aware of which cgroup it is in. > > So here are two optoins i can think of > 1. add a new variable called cg_timer_slack_ns to struct task_struct{} > cg_timer_slack_ns will be set by cgroup timer_slack subsystem, then we > can retain the original per task value in timer_slack_ns. > timer code will pick max(cg_timer_slack_ns, timer_slack_ns) if > cg_timer_slack_ns is set. > > 2. leave task_struct unchanged, add a current_timer_slack to the > cgroup. timer_slack cgroup does not modify per task timer_slack_ns. > similar to option #1, let timer code pick the timer_slack to use based > on whether the task is in timer_slack cgroup. > > Any thoughts? I think it's over-engineering. What about configuration like this: root_cgroup |--timer_slack.min_slack_ns = 0 |--timer_slack.max_slack_ns = ULONG_MAX |--50us | |--timer_slack.min_slack_ns = 50000 | |--timer_slack.max_slack_ns = 50000 |--500us |--timer_slack.min_slack_ns = 500000 |--timer_slack_max_slack_ns = ULONG_MAX If you want a task allow to drive its timer_slack, just leave it in root_cgroup. It you want to drive timer_slack of a task, move it between 50us and 500um based on your policy. -- Kirill A. Shutemov