Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754294Ab0DSBdW (ORCPT ); Sun, 18 Apr 2010 21:33:22 -0400 Received: from mga11.intel.com ([192.55.52.93]:34772 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751545Ab0DSBdU convert rfc822-to-8bit (ORCPT ); Sun, 18 Apr 2010 21:33:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,233,1270450800"; d="scan'208";a="790470489" From: "Zhang, Xiantao" To: "vatsa@in.ibm.com" , Peter Zijlstra CC: Avi Kivity , Srivatsa Vaddagiri , "kvm@vger.kernel.org" , Marcelo Tosatti , "Yang, Xiaowei" , "Dong, Eddie" , "Li, Xin" , Ingo Molnar , Mike Galbraith , Linux Kernel Mailing List Date: Mon, 19 Apr 2010 09:32:12 +0800 Subject: RE: VM performance issue in KVM guests. Thread-Topic: VM performance issue in KVM guests. Thread-Index: Acrcus1jW65uZu+eQe6RkvRYk4Yi9ACoxykQAACNDoA= Message-ID: References: <4BC0D125.9050108@redhat.com> <4BC2C07B.4040607@redhat.com> <4BC6CBE3.8020207@redhat.com> <1271338398.1674.13.camel@laptop> <20100415164313.GF9128@linux.vnet.ibm.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1276 Lines: 24 Srivatsa Vaddagiri wrote: > On Thu, Apr 15, 2010 at 03:33:18PM +0200, Peter Zijlstra wrote: >> On Thu, 2010-04-15 at 11:18 +0300, Avi Kivity wrote: >>> >>> Certainly that has even greater potential for Linux guests. Note >>> that we spin on mutexes now, so we need to prevent preemption while >>> the lock owner is running. >> >> either that, or disable spinning on (para) virt kernels. Para virt >> kernels could possibly extend the thing by also checking to see if >> the owner's vcpu is running. > > I suspect we will need a combination of both approaches, given that > we will not be able to avoid preempting guests in their critical > section always (too long critical sections or real-time tasks wanting > to preempt). Other idea is to gang-schedule VCPUs of the same guest > as much as possible? Gang-scheduling maybe the ideal solution to solve the issue, and has to change host's scheduler a lot to implement it, and it maybe hard to be upstream. So can we figure out an easy way(maybe not best) for this ? Xiantao -- 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/