Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759892AbcCDJrV (ORCPT ); Fri, 4 Mar 2016 04:47:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33122 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759634AbcCDJrQ (ORCPT ); Fri, 4 Mar 2016 04:47:16 -0500 Date: Fri, 4 Mar 2016 11:47:09 +0200 From: "Michael S. Tsirkin" To: "Li, Liang Z" Cc: "Dr. David Alan Gilbert" , Roman Kagan , "ehabkost@redhat.com" , "kvm@vger.kernel.org" , "quintela@redhat.com" , "linux-kernel@vger.kernel.org" , "qemu-devel@nongnu.org" , "linux-mm@kvack.org" , "amit.shah@redhat.com" , "pbonzini@redhat.com" , "akpm@linux-foundation.org" , "virtualization@lists.linux-foundation.org" , "rth@twiddle.net" Subject: Re: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization Message-ID: <20160304114519-mutt-send-email-mst@redhat.com> References: <1457001868-15949-1-git-send-email-liang.z.li@intel.com> <20160303174615.GF2115@work-vm> <20160304075538.GC9100@rkaganb.sw.ru> <20160304083550.GE9100@rkaganb.sw.ru> <20160304090820.GA2149@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 641 Lines: 17 On Fri, Mar 04, 2016 at 09:12:12AM +0000, Li, Liang Z wrote: > > Although I wonder which is cheaper; that would be fairly expensive for the > > guest wouldn't it? And you'd somehow have to kick the guest before > > migration to do the ballooning - and how long would you wait for it to finish? > > About 5 seconds for an 8G guest, balloon to 1G. Get the free pages bitmap take about 20ms > for an 8G idle guest. > > Liang Where is the time spent though? allocating within guest? Or passing the info to host? If the former, we can use existing inflate/deflate vqs: Have guest put each free page on inflate vq, then on deflate vq. -- MST