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