From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC] CPU hard limits Date: Thu, 04 Jun 2009 15:19:22 +0300 Message-ID: <4A27BBCA.5020606@redhat.com> References: <20090604053649.GA3701@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, Dhaval Giani , Balbir Singh , Vaidyanathan Srinivasan , Gautham R Shenoy , Srivatsa Vaddagiri , Ingo Molnar , Peter Zijlstra , Pavel Emelyanov , kvm@vger.kernel.org, Linux Containers , Herbert Poetzl To: bharata@linux.vnet.ibm.com Return-path: Received: from mx2.redhat.com ([66.187.237.31]:50293 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753279AbZFDMVV (ORCPT ); Thu, 4 Jun 2009 08:21:21 -0400 In-Reply-To: <20090604053649.GA3701@in.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: Bharata B Rao wrote: > 2. Need for hard limiting CPU resource > -------------------------------------- > - Pay-per-use: In enterprise systems that cater to multiple clients/customers > where a customer demands a certain share of CPU resources and pays only > that, CPU hard limits will be useful to hard limit the customer's job > to consume only the specified amount of CPU resource. > - In container based virtualization environments running multiple containers, > hard limits will be useful to ensure a container doesn't exceed its > CPU entitlement. > - Hard limits can be used to provide guarantees. > How can hard limits provide guarantees? Let's take an example where I have 1 group that I wish to guarantee a 20% share of the cpu, and anther 8 groups with no limits or guarantees. One way to achieve the guarantee is to hard limit each of the 8 other groups to 10%; the sum total of the limits is 80%, leaving 20% for the guarantee group. The downside is the arbitrary limit imposed on the other groups. Another way is to place the 8 groups in a container group, and limit that to 80%. But that doesn't work if I want to provide guarantees to several groups. -- error compiling committee.c: too many arguments to function