[dpdk-dev] [PATCH v5 1/3] vhost: Add callback and private data for vhost PMD
yuanhan.liu at linux.intel.com
Thu Dec 24 04:51:05 CET 2015
On Wed, Dec 23, 2015 at 11:00:15PM +0100, Thomas Monjalon wrote:
> 2015-12-23 10:44, Yuanhan Liu:
> > On Tue, Dec 22, 2015 at 01:38:29AM -0800, Rich Lane wrote:
> > > On Mon, Dec 21, 2015 at 9:47 PM, Yuanhan Liu <yuanhan.liu at linux.intel.com>
> > > wrote:
> > >
> > > On Mon, Dec 21, 2015 at 08:47:28PM -0800, Rich Lane wrote:
> > > > The queue state change callback is the one new API that needs to be
> > > > added because
> > > > normal NICs don't have this behavior.
> > >
> > > Again I'd ask, will vring_state_changed() be enough, when above issues
> > > are resolved: vring_state_changed() will be invoked at new_device()/
> > > destroy_device(), and of course, ethtool change?
> > >
> > >
> > > It would be sufficient. It is not a great API though, because it requires the
> > > application to do the conversion from struct virtio_net to a DPDK port number,
> > > and from a virtqueue index to a DPDK queue id and direction. Also, the current
> > > implementation often makes this callback when the vring state has not actually
> > > changed (enabled -> enabled and disabled -> disabled).
> > >
> > > If you're asking about using vring_state_changed() _instead_ of the link status
> > > event and rte_eth_dev_socket_id(),
> > No, I like the idea of link status event and rte_eth_dev_socket_id();
> > I was just wondering why a new API is needed. Both Tetsuya and I
> > were thinking to leverage the link status event to represent the
> > queue stats change (triggered by vring_state_changed()) as well,
> > so that we don't need to introduce another eth event. However, I'd
> > agree that it's better if we could have a new dedicate event.
> > Thomas, here is some background for you. For vhost pmd and linux
> > virtio-net combo, the queue can be dynamically changed by ethtool,
> > therefore, the application wishes to have another eth event, say
> > RTE_ETH_EVENT_QUEUE_STATE_CHANGE, so that the application can
> > add/remove corresponding queue to the datapath when that happens.
> > What do you think of that?
> Yes it is an event. So I don't understand the question.
> What may be better than a specific rte_eth_event_type?
The alternative is a new set of callbacks, but judging that we already
have a set of callback for vhost libraray, and adding a new set to vhost
pmd doesn't seem elegant to me.
Therefore, I'd prefer a new eth event.
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