9.2 ixgbe tx queue hang

[Rick Macklem]

Julian Elischer wrote:
----- Original Message -----
> I wrote (and snipped):
>> Other drivers (and ixgbe for the 82598 chip) can handle a packet that
>> is in more than 32 mbufs. (I think the 82598 handles 100, grep for
>> SCATTER
>> in *.h in sys/dev/ixgbe.)
>>
>
> the Xen backend can not handle mor ethan 32 segments in some versions 
> of Xen.
Btw, I just did a quick find/grep (so I may have missed some), but here
is the list of net devices that appear to support TSO, but limited to
32 transmit segments for at least some supported chips:

jme, fxp, age, sge, msk, als, ale, ixgbe/ix, nfe, e1000/em, re

Also, several of these call m_collapse() instead of m_defrag() when
the run into a transmit mbuf list with > 32 elements.
m_collapse() - Isn't likely to squeeze the 35 mbuf 64Kbyte NFS I/O
    message into 32 mbufs, so I don't think these ones will work
    at all for NFS with default 64K I/O size and TSO enabled.

rick