From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f48.google.com (mail-qg0-f48.google.com [209.85.192.48]) by kanga.kvack.org (Postfix) with ESMTP id DD2036B0005 for ; Thu, 10 Mar 2016 02:30:21 -0500 (EST) Received: by mail-qg0-f48.google.com with SMTP id y89so63563332qge.2 for ; Wed, 09 Mar 2016 23:30:21 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id n197si2473427qhc.23.2016.03.09.23.30.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Mar 2016 23:30:21 -0800 (PST) Date: Thu, 10 Mar 2016 13:00:00 +0530 From: Amit Shah Subject: Re: [Qemu-devel] [RFC kernel 0/2]A PV solution for KVM live migration optimization Message-ID: <20160310073000.GA4678@grmbl.mre> References: <1457593292-30686-1-git-send-email-jitendra.kolhe@hpe.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1457593292-30686-1-git-send-email-jitendra.kolhe@hpe.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jitendra Kolhe Cc: liang.z.li@intel.com, dgilbert@redhat.com, ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com, quintela@redhat.com, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, linux-mm@kvack.org, pbonzini@redhat.com, akpm@linux-foundation.org, virtualization@lists.linux-foundation.org, rth@twiddle.net, mohan_parthasarathy@hpe.com, simhan@hpe.com On (Thu) 10 Mar 2016 [12:31:32], Jitendra Kolhe wrote: > On 3/8/2016 4:44 PM, Amit Shah wrote: > >>>> Hi, > >>>> An interesting solution; I know a few different people have been looking at > >>>> how to speed up ballooned VM migration. > >>>> > >>> > >>> Ooh, different solutions for the same purpose, and both based on the balloon. > >> > >> We were also tying to address similar problem, without actually needing to modify > >> the guest driver. Please find patch details under mail with subject. > >> migration: skip sending ram pages released by virtio-balloon driver > > > > The scope of this patch series seems to be wider: don't send free > > pages to a dest at all, vs. don't send pages that are ballooned out. > > Hi, > > Thanks for your response. The scope of this patch series doesna??t seem to take care > of ballooned out pages. To balloon out a guest ram page the guest balloon driver does > a alloc_page() and then return the guest pfn to Qemu, so ballooned out pages will not > be seen as free ram pages by the guest. > Thus we will still end up scanning (for zero page) for ballooned out pages during > migration. It would be ideal if we could have both solutions. Yes, of course it would be nice to have both solutions. My response was to the line: > >>> Ooh, different solutions for the same purpose, and both based on the balloon. which sounded misleading to me for a couple of reasons: 1, as you describe, pages being considered by this patchset and yours are different; and 2, as I mentioned in the other mail, this patchset doesn't really depend on the balloon, and I believe it should not. Amit -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org