Netowork interface deferred start - does it work?

[Jaromír Doleček <jaromir.dolecek%gmail.com@localhost>]

Hi,

I'm looking on some performance improvements for xennet(4) and
particularly xvif(4).

The drivers use the deferred start and there are lots of comments on
how important it is to batch requests, but actually it's really rare
that the start routine would ever be called with more than one mbuf in
the Tx queue.

It seems the softnet is triggered more or less immediately after
enqueueing each packet in most cases. Maybe this used to be different
when giant lock used to be held more, but not so much nowadays.

So, is it supposed to still work?

Jaromir