Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752909Ab1BDNel (ORCPT ); Fri, 4 Feb 2011 08:34:41 -0500 Received: from shutemov.name ([188.40.19.243]:48379 "EHLO shutemov.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751525Ab1BDNek (ORCPT ); Fri, 4 Feb 2011 08:34:40 -0500 Date: Fri, 4 Feb 2011 15:34:39 +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: <20110204133439.GA7181@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110203115743.1ef9a4c2@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 Content-Length: 1883 Lines: 45 On Thu, Feb 03, 2011 at 11:57:43AM -0800, Jacob Pan wrote: > On Thu, 3 Feb 2011 10:12:51 -0800 > Paul Menage wrote: > > > On Thu, Feb 3, 2011 at 9:51 AM, Jacob Pan > > wrote: > > > > > > I think this logic defeats the purpose of having timer_slack > > > subsystem in the first place. IMHO, the original intention was to > > > have grouping effect of tasks in the cgroup. > > > > You can get the semantics you want by just setting min_slack_ns = > > max_slack_ns. > > > true. it will just make set fail when min = max. it is awkward and > counter intuitive when you want to change the group timer_slack. you > will have to move both min and max to clamp the value, where set > function can not be used. Interface is very similar to /sys/devices/system/cpu/cpuX/cpufreq. I think it's sane. If you want some extention, you can do it with userspace helper. > In addition, when a parent changes min = max, I don't see the current > code enforce new settings on the children. Am i missing something? I've missed it. I'll fix. > In my use case, i want to put some apps into a managed group where > relaxed slack value is used, but when time comes to move the app out of > that cgroup, we would like to resore the original timer slack. I see > having a current value per cgroup can be useful if we let timer code > pick whether to use task slack value or the cgroup slack value. > Or we have to cache the old value per task 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? -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/