Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932234AbcCDKLN (ORCPT ); Fri, 4 Mar 2016 05:11:13 -0500 Received: from mga02.intel.com ([134.134.136.20]:60246 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758930AbcCDKLG convert rfc822-to-8bit (ORCPT ); Fri, 4 Mar 2016 05:11:06 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,535,1449561600"; d="scan'208";a="929491434" From: "Li, Liang Z" To: "Michael S. Tsirkin" 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 Thread-Topic: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization Thread-Index: AQHRdTqPjTxTnYWKZEWM4lf/HjT6rZ9HeJiAgADtUoCAAImCUP//gbqAgAAJEwCAAIakYP//hDSAgACKl8A= Date: Fri, 4 Mar 2016 10:11:00 +0000 Message-ID: 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> <20160304114519-mutt-send-email-mst@redhat.com> In-Reply-To: <20160304114519-mutt-send-email-mst@redhat.com> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiNmFkMzljYTMtMjFlMC00YTc5LWExMjMtMDNjODgyMTE3M2QwIiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX0lDIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE1LjkuNi42IiwiVHJ1c3RlZExhYmVsSGFzaCI6IkxGQkczUmJYeUZCQmpUU0FtOUhOZzhxQStyYXlDa3VROHFiOFVCSUFrMXc9In0= x-ctpclassification: CTP_IC x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1154 Lines: 29 > 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. > Maybe I am not clear enough. I mean if we inflate balloon before live migration, for a 8GB guest, it takes about 5 Seconds for the inflating operation to finish. For the PV solution, there is no need to inflate balloon before live migration, the only cost is to traversing the free_list to construct the free pages bitmap, and it takes about 20ms for a 8GB idle guest( less if there is less free pages), passing the free pages info to host will take about extra 3ms. Liang > -- > MST