From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MGYSR-0006n4-9r for qemu-devel@nongnu.org; Tue, 16 Jun 2009 09:12:11 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MGYSM-0006jL-5n for qemu-devel@nongnu.org; Tue, 16 Jun 2009 09:12:10 -0400 Received: from [199.232.76.173] (port=40906 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MGYSL-0006jG-Vt for qemu-devel@nongnu.org; Tue, 16 Jun 2009 09:12:06 -0400 Received: from mx2.redhat.com ([66.187.237.31]:51397) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MGYSL-0000jA-FV for qemu-devel@nongnu.org; Tue, 16 Jun 2009 09:12:05 -0400 Message-ID: <4A379A2D.5000304@redhat.com> Date: Tue, 16 Jun 2009 16:12:13 +0300 From: Avi Kivity MIME-Version: 1.0 References: <4A36B025.2080602@us.ibm.com> <4A37618E.6040606@redhat.com> <4A379504.4080100@us.ibm.com> <4A3795F4.9080507@redhat.com> <4A3796B1.8060003@us.ibm.com> In-Reply-To: <4A3796B1.8060003@us.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: Live migration broken when under heavy IO List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: "qemu-devel@nongnu.org" , kvm-devel On 06/16/2009 03:57 PM, Anthony Liguori wrote: >>> >>> The tricky bit is that this has to happen at the device layer >>> because the opaques cannot be saved in a meaningful way. >>> >> >> Do you mean the device has to record all cancelled requests and >> replay them? I think we can do it at the block layer (though we have >> to avoid it for nested requests). > > In order to complete the requests, you have to call a callback and > pass an opaque with the results. The callback/opaque cannot be saved > in the block layer in a meaningful way. > You're right, of course. I guess we'll have to cancel any near term cancellation plans. We could change the opaque to be something pre-registered (e.g. the device state object, which we don't need to save/restore) and pass in addition an integer request tag. These would be migratable. The device would be responsible for saving tags and their associated information (perhaps through a common API). -- error compiling committee.c: too many arguments to function