From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752042Ab1HYOH2 (ORCPT ); Thu, 25 Aug 2011 10:07:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32997 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751919Ab1HYOHY (ORCPT ); Thu, 25 Aug 2011 10:07:24 -0400 Message-ID: <4E565704.5080007@redhat.com> Date: Thu, 25 Aug 2011 17:07:00 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0 MIME-Version: 1.0 To: Marcelo Tosatti CC: Xiao Guangrong , LKML , KVM Subject: Re: [PATCH 11/11] KVM: MMU: improve write flooding detected References: <4E4A1257.5080204@cn.fujitsu.com> <20110823080024.GA2297@amt.cnet> <4E53872B.3070407@cn.fujitsu.com> <20110823123818.GB4261@amt.cnet> <4E53D620.9030304@cn.fujitsu.com> <20110823190939.GA10220@amt.cnet> <4E540AB4.6060905@cn.fujitsu.com> <20110824200540.GA19804@amt.cnet> <20110825020424.GA2542@amt.cnet> <4E55D2A2.7050808@redhat.com> <20110825132110.GA4384@amt.cnet> <4E5656E6.1090204@redhat.com> In-Reply-To: <4E5656E6.1090204@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/25/2011 05:06 PM, Avi Kivity wrote: > On 08/25/2011 04:21 PM, Marcelo Tosatti wrote: >> On Thu, Aug 25, 2011 at 07:42:10AM +0300, Avi Kivity wrote: >> > On 08/25/2011 05:04 AM, Marcelo Tosatti wrote: >> > >> >> > >> It could increase the flood count independently of the >> accessed bit of >> > >> the spte being updated, zapping after 3 attempts as it is now. >> > >> >> > >> But additionally reset the flood count if the gpte appears to >> be valid >> > >> (points to an existant gfn if the present bit is set, or if >> its zeroed). >> > > >> > >Well not zero, as thats a common pattern for non ptes. >> > > >> > >> > On 32-bit with 4GB RAM, practically anything is a valid gpte. >> >> The following could be required to consider a valid gpte, for write >> flood detection purposes: >> >> - Must be present. >> - PageCacheDisable must be unset. >> - PageWriteThrough must be unset. >> > > Unless the guest is using PAT. > And not swapping. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.