wm(4) faster than vioif(4) in some cases

[Tobias Nygren <tnn%NetBSD.org@localhost>]

Hi,

I found out wm(4) emulation is much faster than paravirtualized vioif(4)
for a hardware virtualized NetBSD guest when using NFS.
I suspect this may be because there is no TX completion notification
which NFS needs for good performance. There is a comment in if_vioif.c:

/*
 * tx interrupt is actually disabled; this should be called upon
 * tx vq full and watchdog
 */

Does anyone know what needs to be done to enable tx interrupt?

Thanks,
-Tobias