From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuanhan Liu Subject: Re: [PATCH 2/2] net/virtio: support GUEST ANNOUNCE Date: Tue, 5 Dec 2017 22:26:00 +0800 Message-ID: <20171205142600.GG9111@yliu-dev> References: <1511521440-57724-1-git-send-email-xiao.w.wang@intel.com> <1511521440-57724-3-git-send-email-xiao.w.wang@intel.com> <20171127124855.GB23415@yliu-home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "dev@dpdk.org" , "Bie, Tiwei" To: "Wang, Xiao W" Return-path: Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by dpdk.org (Postfix) with ESMTP id 712BA1D8E for ; Tue, 5 Dec 2017 15:26:05 +0100 (CET) Content-Disposition: inline In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Thu, Nov 30, 2017 at 02:41:12AM +0000, Wang, Xiao W wrote: > > > > -----Original Message----- > > From: Yuanhan Liu [mailto:yliu@fridaylinux.org] > > Sent: Monday, November 27, 2017 8:49 PM > > To: Wang, Xiao W > > Cc: dev@dpdk.org > > Subject: Re: [PATCH 2/2] net/virtio: support GUEST ANNOUNCE > > > > On Fri, Nov 24, 2017 at 03:04:00AM -0800, Xiao Wang wrote: > > > When live migration is done, for the backup VM, either the virtio > > > frontend or the vhost backend needs to send out gratuitous RARP packet > > > to announce its new network location. > > > > > > This patch enables VIRTIO_NET_F_GUEST_ANNOUNCE feature to support > > live > > > migration scenario where the vhost backend doesn't have the ability to > > > generate RARP packet. > > > > Yes, it's a feature good to have. > > > > > +static int > > > +virtio_dev_pause(struct rte_eth_dev *dev) > > > +{ > > > + struct virtio_hw *hw = dev->data->dev_private; > > > + > > > + if (hw->started == 0) > > > + return -1; > > > + hw->started = 0; > > > + /* > > > + * Prevent the worker thread from touching queues to avoid condition, > > > + * 1 ms should be enough for the ongoing Tx function to finish. > > > + */ > > > + rte_delay_ms(1); > > > + return 0; > > > +} > > > + > > > +static void > > > +virtio_dev_resume(struct rte_eth_dev *dev) > > > +{ > > > + struct virtio_hw *hw = dev->data->dev_private; > > > + > > > + hw->started = 1; > > > +} > > > > However, the implementation (stop first, pause for 1ms, duplicate another > > Tx function, resume) doesn't seem elegant. > > > > You probably could try something like DPDK vhost does: > > > > - set a flag when S_ANNOUCE is received > > - inject a pkt when such flag is set in the xmit function > > > > You then should be able to get rid of all of above stuffs. > > > > --yliu > > The difference is that the virtio port may just receive packet, without xmit. Thanks, I missed that. However, you really should not add a duplicate function. It adds more maintain effort. I think you probably could just invoke the tx_pkt_burst callback directly. You have stopped the device after all. What's the necessary to duplicate it? --yliu