From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id A915F29C7 for ; Tue, 3 Jan 2017 09:15:13 +0100 (CET) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga103.jf.intel.com with ESMTP; 03 Jan 2017 00:15:08 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,451,1477983600"; d="scan'208";a="25475160" Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.67.162]) by orsmga002.jf.intel.com with ESMTP; 03 Jan 2017 00:15:07 -0800 Date: Tue, 3 Jan 2017 16:16:54 +0800 From: Yuanhan Liu To: "Charles (Chas) Williams" Cc: dev@dpdk.org, mtetsuyah@gmail.com Message-ID: <20170103081654.GB21228@yliu-dev.sh.intel.com> References: <1482959452-18486-1-git-send-email-ciwillia@brocade.com> <1482959452-18486-2-git-send-email-ciwillia@brocade.com> <20161229085238.GD21789@yliu-dev.sh.intel.com> <20161230031501.GE21789@yliu-dev.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Subject: Re: [dpdk-dev] [PATCH 2/2] vhost: start vhost servers once X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 03 Jan 2017 08:15:14 -0000 On Fri, Dec 30, 2016 at 04:26:27PM -0500, Charles (Chas) Williams wrote: > > > On 12/29/2016 10:15 PM, Yuanhan Liu wrote: > >On Thu, Dec 29, 2016 at 10:58:11AM -0500, Charles (Chas) Williams wrote: > >>On 12/29/2016 03:52 AM, Yuanhan Liu wrote: > >>>On Wed, Dec 28, 2016 at 04:10:52PM -0500, Charles (Chas) Williams wrote: > >>>>Start a vhost server once during devinit instead of during device start > >>>>and stop. Some vhost clients, QEMU, don't re-attaching to sockets when > >>>>the vhost server is stopped and later started. Preserve existing behavior > >>>>for vhost clients. > >>> > >>>I didn't quite get the idea what you are going to fix. > >> > >>The issue I am trying to fix is QEMU interaction when DPDK's vhost is > >>acting as a server to QEMU vhost clients. If you create a vhost server > >>device, it doesn't create the actual datagram socket until you call > >>.dev_start(). If you call .dev_stop() is also deletes those sockets. > >>For QEMU, this is a problem since QEMU doesn't know how to re-attach to > >>datagram sockets that have gone away. > > > >Thanks! And I'd appreciate it if you could have written the commit log > >this way firstly. > > > >>.dev_start()/.dev_stop() seems to roughly means link up and link down > >>so I understand why you might want to add/remove the datagram sockets. > >>However, in practice, this doesn't seem to make much sense for a DPDK > >>vhost server. > > > >Agree. > > > >>This doesn't seem like the right way to indicate link > >>status to vhost clients. > >> > >>It seems like it would just be easier to do this for both clients and > >>servers, but I don't know why it was done this way originally so I > >>choose to keep the client behavior. > > > >I don't think there are any differences between DPDK acting as client or > >server. To me, the right logic seems to be (for both DPDK as server and > >client). > > > >For register, > >- register the vhost socket at probe stage (either at rte_pmd_vhost_probe > > or at eth_dev_vhost_create). > >- start the vhost session right after the register when we haven't started > > it before. > > > >For unregister, > >- invoke rte_vhost_driver_unregister() at rte_pmd_vhost_remove(). > > OK. This will be much easier than what I submitted. Good. > > >For dev_start/stop, > >- set allow_queuing to 1/0 for start/stop, respectively. > > Unfortunately, I don't think this will work. new_device() doesn't happen > until a client connects. allow_queueing seems to be following the status > of the "wire" as it where. .dev_start()/.dev_stop() is the link of local > port connected to the wire (administratively up or down as it where). > > .dev_start() can happen before new_device() and attempting to RX for a > client that doesn't exist doesn't seem like a good idea. Right. > Perhaps another > flag that follows dev_started, but for the queues? I will comment it on your v3 patches. --yliu