From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Lan, Tianyu" Subject: Re: live migration vs device assignment (motivation) Date: Thu, 10 Dec 2015 11:15:59 +0800 Message-ID: <5668EE6F.90200@intel.com> References: <1448372127-28115-1-git-send-email-tianyu.lan@intel.com> <20151207165039.GA20210@redhat.com> <56685631.50700@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: "Michael S. Tsirkin" , aik@ozlabs.ru, Alex Williamson , amit.shah@redhat.com, Anthony Liguori , Ard Biesheuvel , Blue Swirl , cornelia.huck@de.ibm.com, "Dong, Eddie" , "Jani, Nrupal" , Alexander Graf , kvm@vger.kernel.org, Paolo Bonzini , qemu-devel@nongnu.org, "Tantilov, Emil S" , Or Gerlitz , "Skidmore, Donald C" , "Rustad, Mark D" , kraxel@redhat.com, lcapitulino@redhat.com, quintela@redhat.com To: Alexander Duyck Return-path: Received: from mga03.intel.com ([134.134.136.65]:19137 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751856AbbLJDQN (ORCPT ); Wed, 9 Dec 2015 22:16:13 -0500 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 12/10/2015 1:14 AM, Alexander Duyck wrote: > On Wed, Dec 9, 2015 at 8:26 AM, Lan, Tianyu wrote: > >> For other kind of devices, it's hard to work. >> We are also adding migration support for QAT(QuickAssist Technology) device. >> >> QAT device user case introduction. >> Server, networking, big data, and storage applications use QuickAssist >> Technology to offload servers from handling compute-intensive operations, >> such as: >> 1) Symmetric cryptography functions including cipher operations and >> authentication operations >> 2) Public key functions including RSA, Diffie-Hellman, and elliptic curve >> cryptography >> 3) Compression and decompression functions including DEFLATE and LZS >> >> PCI hotplug will not work for such devices during migration and these >> operations will fail when unplug device. > > I assume the problem is that with a PCI hotplug event you are losing > the state information for the device, do I have that right? > > Looking over the QAT drivers it doesn't seem like any of them support > the suspend/resume PM calls. I would imagine it makes it difficult > for a system with a QAT card in it to be able to drop the system to a > low power state. You might want to try enabling suspend/resume > support for the devices on bare metal before you attempt to take on > migration as it would provide you with a good testing framework to see > what needs to be saved/restored within the device and in what order > before you attempt to do the same while migrating from one system to > another. Sure. The suspend/resume job is under way. Actually, we have enabled QAT work for migration internally. Doing more test and fixing bugs. > > - Alex >