From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33798) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UmxU5-000115-Nc for qemu-devel@nongnu.org; Wed, 12 Jun 2013 22:41:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UmxU4-0002B1-Pa for qemu-devel@nongnu.org; Wed, 12 Jun 2013 22:41:57 -0400 Received: from e28smtp06.in.ibm.com ([122.248.162.6]:36122) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UmxU3-00025f-Qt for qemu-devel@nongnu.org; Wed, 12 Jun 2013 22:41:56 -0400 Received: from /spool/local by e28smtp06.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 13 Jun 2013 08:04:50 +0530 Message-ID: <51B9314C.3060103@linux.vnet.ibm.com> Date: Thu, 13 Jun 2013 10:41:16 +0800 From: Wenchao Xia MIME-Version: 1.0 References: <51A7036A.3050407@ozlabs.ru> <51A7049F.6040207@redhat.com> <51A70B3D.90609@ozlabs.ru> <51A71705.6060009@kamp.de> <51A74D79.7040204@redhat.com> <2765FDFA-8050-4AA3-8621-7E9EA2C89F9C@kamp.de> <51A764FC.7080705@redhat.com> <51ADF122.70307@kamp.de> <51ADF637.7060804@redhat.com> <51ADFBCE.3080200@kamp.de> <51ADFC7A.7030009@redhat.com> <51AE035A.5070301@kamp.de> <51B2EB0A.7000704@linux.vnet.ibm.com> <51B2EBA2.5060401@ozlabs.ru> <51B3E58C.50301@linux.vnet.ibm.com> <1370746424.3766.473.camel@pasglop> <51B87F05.6060807@redhat.com> <1371046299.8250.201.camel@pasglop> <51B8D5BE.7080304@redhat.com> In-Reply-To: <51B8D5BE.7080304@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [Qemu-ppc] broken incoming migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Alexey Kardashevskiy , Peter Lieven , "qemu-devel@nongnu.org" , "qemu-ppc@nongnu.org" , David Gibson 于 2013-6-13 4:10, Paolo Bonzini 写道: > Il 12/06/2013 10:11, Benjamin Herrenschmidt ha scritto: >> On Wed, 2013-06-12 at 10:00 -0400, Paolo Bonzini wrote: >>> The only bug we have is not a performance bug related to compression; >>> it's that writing zero pages breaks overcommit. Let's fix that, and >>> only that. >> >> Right, do we have a way to madvise "throw away" these instead ? > > We already do that, but apparently that madvise is asynchronous. > >> Or do we >> have a way to track that the platform init code did write something >> there and only clear *those* pages ? > > No need for; since it's copy-on-write, not copy-on-read :) we can just > check for pages that are zero and not rewrite them with zeros. That's I think it is the right way to improve overcommit without breaking anything. > what Peter's patches do, I'll review them right away. > > Paolo > > -- Best Regards Wenchao Xia