Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751708AbZFENRI (ORCPT ); Fri, 5 Jun 2009 09:17:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751468AbZFENRA (ORCPT ); Fri, 5 Jun 2009 09:17:00 -0400 Received: from mx2.redhat.com ([66.187.237.31]:46029 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751013AbZFENQ7 (ORCPT ); Fri, 5 Jun 2009 09:16:59 -0400 Message-ID: <4A291A2F.3090201@redhat.com> Date: Fri, 05 Jun 2009 16:14:23 +0300 From: Avi Kivity User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: balbir@linux.vnet.ibm.com CC: bharata@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, Dhaval Giani , Vaidyanathan Srinivasan , Gautham R Shenoy , Srivatsa Vaddagiri , Ingo Molnar , Peter Zijlstra , Pavel Emelyanov , kvm@vger.kernel.org, Linux Containers , Herbert Poetzl Subject: Re: [RFC] CPU hard limits References: <20090605030309.GA3872@in.ibm.com> <4A28921C.6010802@redhat.com> <661de9470906042137u603e2997n80c270bf7f6191ad@mail.gmail.com> <4A28A2AB.3060108@redhat.com> <20090605044946.GA11755@balbir.in.ibm.com> <20090605051050.GB11755@balbir.in.ibm.com> <4A28AB67.7040800@redhat.com> <20090605052755.GE11755@balbir.in.ibm.com> <20090605053159.GB3872@in.ibm.com> <4A28B4CE.4010004@redhat.com> <20090605093947.GJ11755@balbir.in.ibm.com> In-Reply-To: <20090605093947.GJ11755@balbir.in.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1979 Lines: 44 Balbir Singh wrote: >> That's the limit part. I'd like to be able to specify limits and >> guarantees on the same host and for the same groups; I don't think that >> works when you advance the bandwidth period. >> > > Yes, this feature needs to be configurable. But your use case for both > limits and guarantees is interesting. We spoke to Peter and he was > convinced only of the guarantee use case. Could you please help > elaborate your use case, so that we can incorporate it into RFC v2 we > send out. Peter is opposed to having hard limits and is convinced that > they are not generally useful, so far I seen you and Paul say it is > useful, any arguments you have or any +1 from you will help us. Peter > I am not back stabbing you :) > I am selling virtual private servers. A 10% cpu share costs $x/month, and I guarantee you'll get that 10%, or your money back. On the other hand, I want to limit cpu usage to that 10% (maybe a little more) so people don't buy 10% shares and use 100% on my underutilized servers. If they want 100%, let them pay for 100%. >> I think we need to treat guarantees as first-class goals, not something >> derived from limits (in fact I think guarantees are more useful as they >> can be used to provide SLAs). >> > > Even limits are useful for SLA's since your b/w available changes > quite drastically as we add or remove groups. There are other use > cases for limits as well SLAs are specified in terms of guarantees on a service, not on limits on others. If we could use limits to provide guarantees, that would be fine, but it doesn't quite work out. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- 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/