From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frederic Weisbecker Subject: Re: [PATCH 00/10] cgroups: Task counter subsystem v8 Date: Thu, 2 Feb 2012 15:50:02 +0100 Message-ID: <20120202145000.GC9071@somewhere.redhat.com> References: <1328067470-5980-1-git-send-email-fweisbec@gmail.com> <20120201163126.GA19837@google.com> <20120201184959.GH6731@somewhere.redhat.com> <20120201115107.93e11471.akpm@linux-foundation.org> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=aR5XioQHZtKMnK/RZnkLjRMnqXB3zhFLY+TjSSUJbpo=; b=aRakenWTu2hp3g1Ta4GSThQQoMBsrIj6xmuoc7yCO6+GUsRtc9FT02KkJKlzsrljeG 2x10OYjoG/PgtMOXHIP4GTcXeby0lbWJlx1QNNmE5MEO5uTAAwW62lICkUNYGBJWksPa TZ7026EV69aCcVtCwSSsAXwpxx/TU31uNp3Wg= Content-Disposition: inline In-Reply-To: <20120201115107.93e11471.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: Tejun Heo , Li Zefan , LKML , "Kirill A. Shutemov" , Paul Menage , Johannes Weiner , Aditya Kali , Oleg Nesterov , Tim Hockin , Containers , Glauber Costa , Cgroups , Daniel J Walsh , "Daniel P. Berrange" , KAMEZAWA Hiroyuki , Max Kellermann , Mandeep Singh Baines On Wed, Feb 01, 2012 at 11:51:07AM -0800, Andrew Morton wrote: > On Wed, 1 Feb 2012 19:50:01 +0100 > Frederic Weisbecker wrote: > > > On Wed, Feb 01, 2012 at 08:31:26AM -0800, Tejun Heo wrote: > > > On Wed, Feb 01, 2012 at 04:37:40AM +0100, Frederic Weisbecker wrote: > > > > Changes In this version: > > > > > > > > - Split 32/64 bits version of res_counter_write_u64() [1/10] > > > > Courtesy of Kirill A. Shutemov > > > > > > > > - Added Kirill's ack [8/10] > > > > > > > > - Added selftests [9/10], [10/10] > > > > > > > > Please consider for merging. At least two users want this feature: > > > > > > Has there been further discussion about this approach? IIRC, we > > > weren't sure whether this should be merged. > > > > The doubts I have noticed were: > > > > Q: Can't we rather focus on a global solution to fight forkbombs? > > > > If we can find a reliable solution that works in any case and that > > prevent from any forkbomb to impact the rest of the system then it > > may be an acceptable solution. But I'm not aware of such feature. > > > > Besides, another point in having this task counter is that we > > have a per container limit. Assuming all containers are running under > > the same user, we can protect against a container starving all others > > with a massive amount of processes close to the NR_PROC rlimit. > > > > Q: Can/should we implement a limitation on the number of "fork" as well? > > (as in https://lkml.org/lkml/2011/11/3/233 ) > > > > I'm still not sure about why such a thing is needed. Is it really something we > > want? Why can't the task counter be used instead? > > > > I need more details from the author of this patch. But I doubt we can merge > > both subsystems, they have pretty different semantics. > > What I struggle with is "is this feature useful enough to warrant > merging it"? The reason why I've been working on it is because we need this feature (at least) for LXC. Two people from our teams have jumped onto the discussion to express that they want this feature and why: https://lkml.org/lkml/2011/12/13/309 https://lkml.org/lkml/2011/12/13/364 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932179Ab2BBOuM (ORCPT ); Thu, 2 Feb 2012 09:50:12 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:49816 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932067Ab2BBOuJ (ORCPT ); Thu, 2 Feb 2012 09:50:09 -0500 Date: Thu, 2 Feb 2012 15:50:02 +0100 From: Frederic Weisbecker To: Andrew Morton Cc: Tejun Heo , Li Zefan , LKML , "Kirill A. Shutemov" , Paul Menage , Johannes Weiner , Aditya Kali , Oleg Nesterov , Tim Hockin , Containers , Glauber Costa , Cgroups , Daniel J Walsh , "Daniel P. Berrange" , KAMEZAWA Hiroyuki , Max Kellermann , Mandeep Singh Baines Subject: Re: [PATCH 00/10] cgroups: Task counter subsystem v8 Message-ID: <20120202145000.GC9071@somewhere.redhat.com> References: <1328067470-5980-1-git-send-email-fweisbec@gmail.com> <20120201163126.GA19837@google.com> <20120201184959.GH6731@somewhere.redhat.com> <20120201115107.93e11471.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120201115107.93e11471.akpm@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 01, 2012 at 11:51:07AM -0800, Andrew Morton wrote: > On Wed, 1 Feb 2012 19:50:01 +0100 > Frederic Weisbecker wrote: > > > On Wed, Feb 01, 2012 at 08:31:26AM -0800, Tejun Heo wrote: > > > On Wed, Feb 01, 2012 at 04:37:40AM +0100, Frederic Weisbecker wrote: > > > > Changes In this version: > > > > > > > > - Split 32/64 bits version of res_counter_write_u64() [1/10] > > > > Courtesy of Kirill A. Shutemov > > > > > > > > - Added Kirill's ack [8/10] > > > > > > > > - Added selftests [9/10], [10/10] > > > > > > > > Please consider for merging. At least two users want this feature: > > > > > > Has there been further discussion about this approach? IIRC, we > > > weren't sure whether this should be merged. > > > > The doubts I have noticed were: > > > > Q: Can't we rather focus on a global solution to fight forkbombs? > > > > If we can find a reliable solution that works in any case and that > > prevent from any forkbomb to impact the rest of the system then it > > may be an acceptable solution. But I'm not aware of such feature. > > > > Besides, another point in having this task counter is that we > > have a per container limit. Assuming all containers are running under > > the same user, we can protect against a container starving all others > > with a massive amount of processes close to the NR_PROC rlimit. > > > > Q: Can/should we implement a limitation on the number of "fork" as well? > > (as in https://lkml.org/lkml/2011/11/3/233 ) > > > > I'm still not sure about why such a thing is needed. Is it really something we > > want? Why can't the task counter be used instead? > > > > I need more details from the author of this patch. But I doubt we can merge > > both subsystems, they have pretty different semantics. > > What I struggle with is "is this feature useful enough to warrant > merging it"? The reason why I've been working on it is because we need this feature (at least) for LXC. Two people from our teams have jumped onto the discussion to express that they want this feature and why: https://lkml.org/lkml/2011/12/13/309 https://lkml.org/lkml/2011/12/13/364