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