From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [RFC] cgroup TODOs Date: Fri, 14 Sep 2012 13:15:02 +0200 Message-ID: <1347621302.7172.22.camel@twins> References: <20120913205827.GO7677@google.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <20120913205827.GO7677@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo Cc: containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Li Zefan , Michal Hocko , Glauber Costa , Paul Turner , Johannes Weiner , Thomas Graf , "Serge E. Hallyn" , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Neil Horman , "Aneesh Kumar K.V" On Thu, 2012-09-13 at 13:58 -0700, Tejun Heo wrote: > The cpu ones handle nesting correctly - parent's accounting includes > children's, parent's configuration affects children's unless > explicitly overridden, and children's limits nest inside parent's. The implementation has some issues with fixed point math limitations on deep hierarchies/large cpu count, but yes. Doing soft-float/bignum just isn't going to be popular I guess ;-) People also don't seem to understand that each extra cgroup carries a cost and that nested cgroups are more expensive still, even if the intermediate levels are mostly empty (libvirt is a good example of how not to do things). Anyway, I guess what I'm saying is that we need to work on the awareness of cost associated with all this cgroup nonsense, people seem to think its all good and free -- or not think at all, which, while depressing, seem the more likely option.