From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:49728) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RBQrz-0006Ot-Ko for qemu-devel@nongnu.org; Wed, 05 Oct 2011 08:46:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RBQry-0003aH-Ez for qemu-devel@nongnu.org; Wed, 05 Oct 2011 08:46:43 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:54632) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RBQry-0003a4-CY for qemu-devel@nongnu.org; Wed, 05 Oct 2011 08:46:42 -0400 Received: from d01relay01.pok.ibm.com (d01relay01.pok.ibm.com [9.56.227.233]) by e8.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p95CVTB9024110 for ; Wed, 5 Oct 2011 08:31:29 -0400 Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay01.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p95CkbBR166278 for ; Wed, 5 Oct 2011 08:46:39 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p95Cka53001640 for ; Wed, 5 Oct 2011 08:46:37 -0400 Message-ID: <4E8C51AA.8020200@us.ibm.com> Date: Wed, 05 Oct 2011 07:46:34 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <1316443309-23843-1-git-send-email-mdroth@linux.vnet.ibm.com> <4E88C7DB.9090105@linux.vnet.ibm.com> <20111002210802.GC8072@redhat.com> <4E89B0D4.3090203@us.ibm.com> <20111003133802.GD18920@redhat.com> <4E89BDCE.2010502@codemonkey.ws> <20111003144109.GE19689@redhat.com> <4E89CE20.6050706@codemonkey.ws> <20111005112837.GA6501@redhat.com> In-Reply-To: <20111005112837.GA6501@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC] New Migration Protocol using Visitor Interface List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: owasserm@redhat.com, Stefan Berger , Michael Roth , qemu-devel@nongnu.org, aliguori@linux.vnet.ibm.com On 10/05/2011 06:28 AM, Michael S. Tsirkin wrote: > On Mon, Oct 03, 2011 at 10:00:48AM -0500, Anthony Liguori wrote: >>> Yes, it's easy to quantify. I think the following gives us >>> the offset before and after, so the difference is the size >>> we seek, right? > > OK, Orit (Cc'd) did some research - this is a booting > while still in grub, size probably does not get much less than that. > windows is said to be much more aggressive in allocating memory. > > start offset: 9600673 > end offset: 9614933 > > So we get 15K out of 9M. So, let's do some napkin math. Assume that it works out that most of that 15k are 4 byte integers. If we assume an average name length of 6 characters, a string should be encoded in 8 bytes. That means for every 4 bytes, we add 8 bytes which means we're increasing by 200%. That means 45k. A 1gbit link can xmit at max, 128k in 1ms. So that extra 30k is going to cost ~250us in transmit time if we can get 1gbit. A the default rate limit, it should cost us right around 1ms. I guess it's liveable although with 30 network cards, I suspect it gets a heck of a lot worse. Regards, Anthony Liguori > By the way, most of the memory here is pretty much > all uniform I guess, because compressing it gets us: > gzip: 1934169 > bzip2 -9: 1462551 > > So even with aggressive compression, we probably won't be able to get > below 1.5M for memory, two orders of magnitude above device state. > > Sounds convincing? >