Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755323AbZFEJlG (ORCPT ); Fri, 5 Jun 2009 05:41:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751892AbZFEJkx (ORCPT ); Fri, 5 Jun 2009 05:40:53 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:39611 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751146AbZFEJkw (ORCPT ); Fri, 5 Jun 2009 05:40:52 -0400 Date: Fri, 5 Jun 2009 17:24:55 +0800 From: Balbir Singh To: Bharata B Rao Cc: Avi Kivity , 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 Message-ID: <20090605092455.GG11755@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <4A27BBCA.5020606@redhat.com> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090605053159.GB3872@in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1796 Lines: 41 * Bharata B Rao [2009-06-05 11:01:59]: > On Fri, Jun 05, 2009 at 01:27:55PM +0800, Balbir Singh wrote: > > * Avi Kivity [2009-06-05 08:21:43]: > > > > > Balbir Singh wrote: > > >>> But then there is no other way to make a *guarantee*, guarantees come > > >>> at a cost of idling resources, no? Can you show me any other > > >>> combination that will provide the guarantee and without idling the > > >>> system for the specified guarantees? > > >>> > > >> > > >> OK, I see part of your concern, but I think we could do some > > >> optimizations during design. For example if all groups have reached > > >> their hard-limit and the system is idle, should we do start a new hard > > >> limit interval and restart, so that idleness can be removed. Would > > >> that be an acceptable design point? > > > > > > I think so. Given guarantees G1..Gn (0 <= Gi <= 1; sum(Gi) <= 1), and a > > > cpu hog running in each group, how would the algorithm divide resources? > > > > > > > As per the matrix calculation, but as soon as we reach an idle point, > > we redistribute the b/w and start a new quantum so to speak, where all > > groups are charged up to their hard limits. > > But could there be client models where you are required to strictly > adhere to the limit within the bandwidth and not provide more (by advancing > the bandwidth period) in the presence of idle cycles ? > Good point, I think so, so I think there is should be a good default and configurable for the other case. -- Balbir -- 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/