From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [RFC PATCH 0/3] directed yield for Pause Loop Exiting Date: Mon, 13 Dec 2010 12:02:51 -0500 Message-ID: <4D0651BB.9040609@redhat.com> References: <20101202144129.4357fe00@annuminas.surriel.com> <20101210050344.GR3158@balbir.in.ibm.com> <4D0328CC.1020809@redhat.com> <20101211135727.GU3158@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Avi Kivity , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Srivatsa Vaddagiri , Peter Zijlstra , Ingo Molnar , Anthony Liguori To: balbir@linux.vnet.ibm.com Return-path: In-Reply-To: <20101211135727.GU3158@balbir.in.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 12/11/2010 08:57 AM, Balbir Singh wrote: > If the vpcu holding the lock runs more and capped, the timeslice > transfer is a heuristic that will not help. That indicates you really need the cap to be per guest, and not per VCPU. Having one VCPU spin on a lock (and achieve nothing), because the other one cannot give up the lock due to hitting its CPU cap could lead to showstoppingly bad performance. -- All rights reversed