K 10
svn:author
V 9
vmaffione
K 8
svn:date
V 27
2018-12-22T16:23:42.335741Z
K 7
svn:log
V 421
netmap: fix txsync check in netmap poll

To check if txsync can be skipped, it is necessary to look for
unseen TX space. However, this means comparing ring->cur
against ring->tail, rather than ring->head against ring->tail
(like nm_ring_empty() does).
This change also adds some more comments to explain the optimization
performed at the beginning of netmap_poll().

MFC after:	3 days
Sponsored by:	Sunny Valley Networks

END