Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752495Ab3F1Sos (ORCPT ); Fri, 28 Jun 2013 14:44:48 -0400 Received: from mail-qc0-f180.google.com ([209.85.216.180]:45594 "EHLO mail-qc0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751513Ab3F1Sop (ORCPT ); Fri, 28 Jun 2013 14:44:45 -0400 MIME-Version: 1.0 In-Reply-To: <20130627210445.GA22860@mtj.dyndns.org> References: <20130625000118.GT1918@mtj.dyndns.org> <20130626212047.GB4536@htj.dyndns.org> <20130627010427.GF4536@htj.dyndns.org> <20130627173809.GB5599@mtj.dyndns.org> <20130627210445.GA22860@mtj.dyndns.org> From: Tim Hockin Date: Fri, 28 Jun 2013 11:44:23 -0700 X-Google-Sender-Auth: 8b3PqwZGdjh3dHd3zgh5cdQGC2s Message-ID: Subject: Re: cgroup: status-quo and userland efforts To: Tejun Heo Cc: Li Zefan , Containers , Cgroups , bsingharora , "dhaval.giani" , Kay Sievers , jpoimboe , "Daniel P. Berrange" , lpoetter , workman-devel , "linux-kernel@vger.kernel.org" , dawnchen@google.com, Paul Turner Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2965 Lines: 64 On Thu, Jun 27, 2013 at 2:04 PM, Tejun Heo wrote: > Hello, > > On Thu, Jun 27, 2013 at 01:46:18PM -0700, Tim Hockin wrote: >> So what you're saying is that you don't care that this new thing is >> less capable than the old thing, despite it having real impact. > > Sort of. I'm saying, at least up until now, moving away from > orthogonal hierarchy support seems to be the right trade-off. It all > depends on how you measure how much things are simplified and how > heavy the "real impacts" are. It's not like these things can be > determined white and black. Given the current situation, I think it's > the right call. I totally understand where you're coming from - trying to get back to a stable feature set. But it sucks to be on the losing end of that battle - you're cutting things that REALLY matter to us, and without a really viable alternative. So we'll keep fighting. >> If controller C is enabled at level X but disabled at level X/Y, does >> that mean that X/Y uses the limits set in X? How about X/Y/Z? > > Y and Y/Z wouldn't make any difference. Tasks belonging to them would > behave as if they belong to X as far as C is concerened. OK, that *sounds* sane. It doesn't solve all our problems, but it alleviates some of them. >> So take away some of the flexibility that has minimal impact and >> maximum return. Splitting threads across cgroups - we use it, but we >> could get off that. Force all-or-nothing joining of an aggregate > > Please do so. Splitting threads is sort of important for some cgroups, like CPU. I wonder if pjt is paying attention to this thread. >> construct (a container vs N cgroups). >> >> But perform surgery with a scalpel, not a hatchet. > > As anything else, it's drawing a line in a continuous spectrum of > grey. Right now, given that maintaining multiple orthogonal > hierarchies while introducing a proper concept of resource container > involves addition of completely new constructs and complexity, I don't > think that's a good option. If there are problems which can't be > resolved / worked around in a reasonable manner, please bring them up > along with their contexts. Let's examine them and see whether there > are other ways to accomodate them. You're arguing that the abstraction you want is that of a "container" but that it's easier to remove options than to actually build a better API. I think this is wrong. Take the opportunity to define the RIGHT interface that you WANT - a container. Implement it in terms of cgroups (and maybe other stuff!). Make that API so compelling that people want to use it, and your war of attrition on direct cgroup madness will be won, but with net progress rather than regress. -- 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/