[virt-tools-list] vhostmd - virtio channel support

[Jim Fehlig]

On 06/07/2018 09:42 AM, Trapp, Michael wrote:
>    
> I fully understand the requirements regarding coding style and the way the changes should be split and discussed in detail,
> but may I ask you to provide some general feedback about the basic concept and if this an option at all before we start discussing the details.

vhostmd already supports 'vbd' and 'xenstore' as transports for the metric data. 
Adding another virtio-channel based transport is a great idea IMO.

WRT writing the data to the various channels, I suppose it is possible to do 
that even if there is no (immediate) recipient for the data? The vbd and 
xenstore transports don't have a protocol so to speak. The data is simply 
written to the disk or xenstore node regardless if there is someone to consume 
it. Can the virtio transport work the same? If so, that would alleviate the need 
for polling all the fds and the static list of epoll_event. In 
virtio_metrics_update() we could simply connect to all the channels, write the 
data, close them, and repeat on the next update period (which is every 5sec by 
default).

Regards,
Jim