From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932901Ab0D3RQV (ORCPT ); Fri, 30 Apr 2010 13:16:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30759 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932524Ab0D3RQA (ORCPT ); Fri, 30 Apr 2010 13:16:00 -0400 Message-ID: <4BDAA8B8.9030103@redhat.com> Date: Fri, 30 Apr 2010 12:54:00 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Xiao Guangrong CC: Marcelo Tosatti , KVM list , LKML Subject: Re: [PATCH 3/4] KVM MMU: allow shadow page become unsync at creating time References: <4BDA9C37.9070602@cn.fujitsu.com> <4BDA9C86.8080204@cn.fujitsu.com> <4BDA9CD0.6070501@cn.fujitsu.com> In-Reply-To: <4BDA9CD0.6070501@cn.fujitsu.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 04/30/2010 12:03 PM, Xiao Guangrong wrote: > Allow new shadow page become unsync when is created, then we no need > write-protect the 'sp->gfn', this idea is from Avi: > > |Another interesting case is to create new shadow pages in the unsync > |state. That can help when the guest starts a short lived process: we > |can avoid write protecting its pagetables completely > > Any idea how this improves performance? A kernel build has a lot of short lived processes, might see an improvement there. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.