From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Li, Liang Z" Subject: RE: [RFC Design Doc]Speed up live migration by skipping free pages Date: Mon, 18 Apr 2016 11:08:31 +0000 Message-ID: References: <20160324012424.GB14956@linux-gk3p> <20160324090004.GA2230@work-vm> <20160324102354.GB2230@work-vm> <20160324165530-mutt-send-email-mst@redhat.com> <20160324175503-mutt-send-email-mst@redhat.com> <20160324181031-mutt-send-email-mst@redhat.com> <20160324174933.GA11662@work-vm> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Cc: Wei Yang , "qemu-devel@nongnu.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kenel.org" , "pbonzini@redhat.com" , "rth@twiddle.net" , "ehabkost@redhat.com" , "amit.shah@redhat.com" , "quintela@redhat.com" , "mohan_parthasarathy@hpe.com" , "jitendra.kolhe@hpe.com" , "simhan@hpe.com" , "rkagan@virtuozzo.com" , "riel@redhat.com" To: "Dr. David Alan Gilbert" , "Michael S. Tsirkin" Return-path: Received: from mga11.intel.com ([192.55.52.93]:1271 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753185AbcDRLIf convert rfc822-to-8bit (ORCPT ); Mon, 18 Apr 2016 07:08:35 -0400 In-Reply-To: <20160324174933.GA11662@work-vm> Content-Language: en-US Sender: kvm-owner@vger.kernel.org List-ID: Hi Dave, I am now working on how to benefit post-copy by skipping the free pages, and I remember you have said we should let the destination know the info of free pages so as to avoid request the free pages from the source. We have two solutions: a. send the migration dirty page bitmap to destination before post copy start, so the destination can decide whether to request the pages or place zero pages by checking the migration dirty page bitmap. The advantage is that we can avoid sending the free pages. the disadvantage is that we have to send extra data to destination. b. Check the page request on the source side, if it's not a dirty page, send a zero page header to the destination. What's your opinion about them? Liang From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37499) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1as72m-00032c-Es for qemu-devel@nongnu.org; Mon, 18 Apr 2016 07:08:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1as72h-0000ai-EA for qemu-devel@nongnu.org; Mon, 18 Apr 2016 07:08:40 -0400 Received: from mga04.intel.com ([192.55.52.120]:60446) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1as72h-0000ab-8I for qemu-devel@nongnu.org; Mon, 18 Apr 2016 07:08:35 -0400 From: "Li, Liang Z" Date: Mon, 18 Apr 2016 11:08:31 +0000 Message-ID: References: <20160324012424.GB14956@linux-gk3p> <20160324090004.GA2230@work-vm> <20160324102354.GB2230@work-vm> <20160324165530-mutt-send-email-mst@redhat.com> <20160324175503-mutt-send-email-mst@redhat.com> <20160324181031-mutt-send-email-mst@redhat.com> <20160324174933.GA11662@work-vm> In-Reply-To: <20160324174933.GA11662@work-vm> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [Qemu-devel] [RFC Design Doc]Speed up live migration by skipping free pages List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" , "Michael S. Tsirkin" Cc: Wei Yang , "qemu-devel@nongnu.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kenel.org" , "pbonzini@redhat.com" , "rth@twiddle.net" , "ehabkost@redhat.com" , "amit.shah@redhat.com" , "quintela@redhat.com" , "mohan_parthasarathy@hpe.com" , "jitendra.kolhe@hpe.com" , "simhan@hpe.com" , "rkagan@virtuozzo.com" , "riel@redhat.com" Hi Dave, I am now working on how to benefit post-copy by skipping the free pages,=20 and I remember you have said we should let the destination know the info of free pages so as to avoid request the free pages from the source.=20 We have two solutions: a. send the migration dirty page bitmap to destination before post copy start, so the destination can decide whether to request the pages or=20 place zero pages by checking the migration dirty page bitmap. The advantage is that we can avoid sending the free pages. the disadvantage is that we ha= ve=20 to send extra data to destination. b. Check the page request on the source side, if it's not a dirty page, sen= d a zero page header to the destination. What's your opinion about them? Liang