From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758393Ab0LMRDR (ORCPT ); Mon, 13 Dec 2010 12:03:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42515 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758369Ab0LMRDQ (ORCPT ); Mon, 13 Dec 2010 12:03:16 -0500 Message-ID: <4D0651BB.9040609@redhat.com> Date: Mon, 13 Dec 2010 12:02:51 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.8) Gecko/20100806 Fedora/3.1.2-1.fc13 Lightning/1.0b2pre Thunderbird/3.1.2 MIME-Version: 1.0 To: balbir@linux.vnet.ibm.com CC: Avi Kivity , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Srivatsa Vaddagiri , Peter Zijlstra , Ingo Molnar , Anthony Liguori Subject: Re: [RFC PATCH 0/3] directed yield for Pause Loop Exiting References: <20101202144129.4357fe00@annuminas.surriel.com> <20101210050344.GR3158@balbir.in.ibm.com> <4D0328CC.1020809@redhat.com> <20101211135727.GU3158@balbir.in.ibm.com> In-Reply-To: <20101211135727.GU3158@balbir.in.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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