From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54137) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adv3A-0000ME-CR for qemu-devel@nongnu.org; Thu, 10 Mar 2016 02:30:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1adv37-000273-5w for qemu-devel@nongnu.org; Thu, 10 Mar 2016 02:30:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48644) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adv37-00026y-0R for qemu-devel@nongnu.org; Thu, 10 Mar 2016 02:30:21 -0500 Date: Thu, 10 Mar 2016 13:00:00 +0530 From: Amit Shah 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 In-Reply-To: <1457593292-30686-1-git-send-email-jitendra.kolhe@hpe.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC kernel 0/2]A PV solution for KVM live migration optimization List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jitendra Kolhe Cc: ehabkost@redhat.com, kvm@vger.kernel.org, quintela@redhat.com, qemu-devel@nongnu.org, liang.z.li@intel.com, dgilbert@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, mohan_parthasarathy@hpe.com, simhan@hpe.com, pbonzini@redhat.com, akpm@linux-foundation.org, virtualization@lists.linux-foundation.org, rth@twiddle.net 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 th= e balloon. > >> > >> We were also tying to address similar problem, without actually need= ing 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. >=20 > Hi, >=20 > Thanks for your response. The scope of this patch series doesn=E2=80=99= t seem to take care=20 > of ballooned out pages. To balloon out a guest ram page the guest ballo= on driver does=20 > a alloc_page() and then return the guest pfn to Qemu, so ballooned out = pages will not=20 > be seen as free ram pages by the guest. > Thus we will still end up scanning (for zero page) for ballooned out pa= ges during=20 > 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 th= e 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