From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Lan, Tianyu" Subject: Re: [Qemu-devel] live migration vs device assignment (motivation) Date: Tue, 29 Dec 2015 01:42:14 +0800 Message-ID: <56817476.8080607@intel.com> References: <20151207165039.GA20210@redhat.com> <56685631.50700@intel.com> <20151210101840.GA2570@work-vm> <566961C1.6030000@gmail.com> <20151210114114.GE2570@work-vm> <56698E68.5040207@intel.com> <566D9320.8000209@intel.com> <567CEA53.5030601@intel.com> <20151225140336-mutt-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Alexander Duyck , "Dr. David Alan Gilbert" , Yang Zhang , qemu-devel@nongnu.org, "Tantilov, Emil S" , kvm@vger.kernel.org, Ard Biesheuvel , aik@ozlabs.ru, "Skidmore, Donald C" , quintela@redhat.com, "Dong, Eddie" , "Jani, Nrupal" , Alexander Graf , Blue Swirl , cornelia.huck@de.ibm.com, Alex Williamson , kraxel@redhat.com, Anthony Liguori , amit.shah@redhat.com, Paolo Bonzini , "Rustad, Mark D" , lcapitulino@redhat.com, Or Gerlitz To: "Michael S. Tsirkin" Return-path: Received: from mga11.intel.com ([192.55.52.93]:12892 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750950AbbL1RmU (ORCPT ); Mon, 28 Dec 2015 12:42:20 -0500 In-Reply-To: <20151225140336-mutt-send-email-mst@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 12/25/2015 8:11 PM, Michael S. Tsirkin wrote: > As long as you keep up this vague talk about performance during > migration, without even bothering with any measurements, this patchset > will keep going nowhere. > I measured network service downtime for "keep device alive"(RFC patch V1 presented) and "put down and up network interface"(RFC patch V2 presented) during migration with some optimizations. The former is around 140ms and the later is around 240ms. My patchset relies on the maibox irq which doesn't work in the suspend state and so can't get downtime for suspend/resume cases. Will try to get the result later. > > > > There's Alex's patch that tracks memory changes during migration. It > needs some simple enhancements to be useful in production (e.g. add a > host/guest handshake to both enable tracking in guest and to detect the > support in host), then it can allow starting migration with an assigned > device, by invoking hot-unplug after most of memory have been migrated. > > Please implement this in qemu and measure the speed. Sure. Will do that. > I will not be surprised if destroying/creating netdev in linux > turns out to take too long, but before anyone bothered > checking, it does not make sense to discuss further enhancements.