From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B97E2C282CE for ; Tue, 4 Jun 2019 14:10:41 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 964DA2488E for ; Tue, 4 Jun 2019 14:10:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 964DA2488E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:53199 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hYA9A-0008Ms-Gk for qemu-devel@archiver.kernel.org; Tue, 04 Jun 2019 10:10:40 -0400 Received: from eggs.gnu.org ([209.51.188.92]:34238) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hYA8N-0007zt-Kd for qemu-devel@nongnu.org; Tue, 04 Jun 2019 10:09:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hYA8M-0001d1-Ny for qemu-devel@nongnu.org; Tue, 04 Jun 2019 10:09:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56992) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hYA8M-0001aO-It for qemu-devel@nongnu.org; Tue, 04 Jun 2019 10:09:50 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ECA103092667 for ; Tue, 4 Jun 2019 14:09:38 +0000 (UTC) Received: from localhost (ovpn-120-246.rdu2.redhat.com [10.10.120.246]) by smtp.corp.redhat.com (Postfix) with ESMTP id D7B431001947; Tue, 4 Jun 2019 14:09:31 +0000 (UTC) Date: Tue, 4 Jun 2019 11:09:30 -0300 From: Eduardo Habkost To: Jens Freimann Message-ID: <20190604140930.GA22103@habkost.net> References: <20190517125820.2885-1-jfreimann@redhat.com> <20190517125820.2885-4-jfreimann@redhat.com> <20190521094504.GB2915@work-vm> <20190530145645.tjwkgi4hae5yblsi@jenstp.localdomain> <20190531214748.GN22103@habkost.net> <20190603082456.vzpy256kj4o5e5wu@jenstp.localdomain> <20190603193648.GQ22103@habkost.net> <20190604134321.txlw7wjwe247g5ug@jenstp.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190604134321.txlw7wjwe247g5ug@jenstp.localdomain> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Tue, 04 Jun 2019 14:09:44 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pkrempa@redhat.com, berrange@redhat.com, mst@redhat.com, aadam@redhat.com, qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , laine@redhat.com, ailan@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Jun 04, 2019 at 03:43:21PM +0200, Jens Freimann wrote: > On Mon, Jun 03, 2019 at 04:36:48PM -0300, Eduardo Habkost wrote: > > On Mon, Jun 03, 2019 at 10:24:56AM +0200, Jens Freimann wrote: > > > On Fri, May 31, 2019 at 06:47:48PM -0300, Eduardo Habkost wrote: > > > > On Thu, May 30, 2019 at 04:56:45PM +0200, Jens Freimann wrote: > > > > > On Tue, May 28, 2019 at 11:04:15AM -0400, Michael S. Tsirkin wrote: > > > > > > On Tue, May 21, 2019 at 10:45:05AM +0100, Dr. David Alan Gilbert wrote: > > > > > > > * Jens Freimann (jfreimann@redhat.com) wrote: > > > Why is it bad to fully re-create the device in case of a failed migration? > > > > Bad or not, I thought the whole point of doing it inside QEMU was > > to do something libvirt wouldn't be able to do (namely, > > unplugging the device while not freeing resources). If we are > > doing something that management software is already capable of > > doing, what's the point? > > Event though management software seems to be capable of it, a failover > implementation has never happened. As Michael says network failover is > a mechanism (there's no good reason not to use a PT device if it is > available), not a policy. We are now trying to implement it in a > simple way, contained within QEMU. I don't think this is a strong enough reason to move complexity to QEMU. This might look like it's reducing complexity in the QEMU<->libvirt interface, but having QEMU unplugging/plugging devices automatically without libvirt involvement is actually complicating that interface. That said, I won't try to prevent this from being merged if the maintainers and libvirt developers agree on this interface. -- Eduardo