From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751550Ab1HYNrl (ORCPT ); Thu, 25 Aug 2011 09:47:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16466 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750858Ab1HYNrf (ORCPT ); Thu, 25 Aug 2011 09:47:35 -0400 Date: Thu, 25 Aug 2011 10:21:11 -0300 From: Marcelo Tosatti To: Avi Kivity Cc: Xiao Guangrong , LKML , KVM Subject: Re: [PATCH 11/11] KVM: MMU: improve write flooding detected Message-ID: <20110825132110.GA4384@amt.cnet> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E55D2A2.7050808@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.