From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932237Ab2DQMmC (ORCPT ); Tue, 17 Apr 2012 08:42:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2076 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932197Ab2DQMl7 (ORCPT ); Tue, 17 Apr 2012 08:41:59 -0400 Message-ID: <4F8D6503.4040800@redhat.com> Date: Tue, 17 Apr 2012 15:41:39 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1 MIME-Version: 1.0 To: Takuya Yoshikawa CC: Xiao Guangrong , kvm-ppc@vger.kernel.org, Marcelo Tosatti , Xiao Guangrong , LKML , KVM Subject: Re: [PATCH 00/13] KVM: MMU: fast page fault References: <4F742951.7080003@linux.vnet.ibm.com> <4F82E04E.6000900@redhat.com> <20120409175829.GB21894@amt.cnet> <4F8329D3.7000605@gmail.com> <20120409194614.GB23053@amt.cnet> <4F840DD2.3090101@redhat.com> <20120410204031.ffb5b976225ac9fe6dae474e@gmail.com> <4F842074.1050108@linux.vnet.ibm.com> <20120411211514.35db29c11460516e604059b6@gmail.com> <4F857B61.9080602@linux.vnet.ibm.com> <20120411231441.9d0984672dd252b806f99128@gmail.com> <20120413232528.c5ddbddb3cc0870d6e85a332@gmail.com> <4F8A95CB.9070104@redhat.com> <20120417004935.a9a39d951b3c24588e29edd2@gmail.com> <4F8D0D29.9050009@linux.vnet.ibm.com> <4F8D210C.8070505@redhat.com> <20120417213748.f3c4ae8d0056676fd33a47c5@gmail.com> In-Reply-To: <20120417213748.f3c4ae8d0056676fd33a47c5@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/17/2012 03:37 PM, Takuya Yoshikawa wrote: > On Tue, 17 Apr 2012 10:51:40 +0300 > Avi Kivity wrote: > > > That's true with the write protect everything approach we use now. But > > it's not true with range-based write protection, where you issue > > GET_DIRTY_LOG on a range of pages and only need to re-write-protect them. > > > > (the motivation for that is to decrease the time between GET_DIRTY_LOG > > and sending the page; as the time increases, the chances that the page > > got re-dirtied go up). > > Thank you for explaining this. > > I was planning to give the userspace more freedom. > > Since there are many known algorithms to predict hot memory pages, > the userspace will be able to tune the frequency of GET_DIRTY_LOG for such > parts not to get too many faults repeatedly, if we can restrict the range > of pages to protect. > > This is the fine-grained control. Do you want per-page control, or just range-based? -- error compiling committee.c: too many arguments to function