nm_tx_pending is always true (ixgbe)

[ds-j-ot]

Regarding appneta/tcpreplay#560

Using tcpreplay with netmap (current master, ixgbe out-of-tree driver), nm_tx_pending always reports true even when all packets are sent.

This does not occur with igb.

[ds-j-ot]

The same problem occurs with other driver versions and also using --no-ext-drivers.

[ds-j-ot]

Any idea?

[vmaffione]

How do you tell that packets where transmitted and the transmission was notified to netmap? Can you report the values of ring->head, ring->cur, and ring->tail when this happens? What are the values immediately after opening the netmap port, before performing any operation? What happens if you call ioctl(NIOCTXSYNC) a second after the apparent stall happens?