Test non-scattered jumbo frames

[Morten Brørup]

Hi DPDK DTS team,

Some Linux Ethernet drivers have the braindead idea that when configured for max packet length slightly above 1518, e.g. 1536, they will scatter packets into segments of 1024 byte, so even normal size packets get scattered. I would like ensure that DPDK PMDs don't do something remotely similar.

I have looked at the test plans for Scattered Packets (chapter 135) and Jumbo Frames (chapter 81).

Some applications do not use scattered packets, but still might support jumbo frames, so I would like to suggest two test cases to verify that PMDs don't generate scattered packets on RX, even for jumbo frames:

1. Using --mbuf-size=2048 --max-pkt-len=1600, received packets up to 1600 byte should not be scattered on RX.

2. Using --mbuf-size=16384 --max-pkt-len=9600, received packets up to 9600 byte should not be scattered on RX.


Med venlig hilsen / Kind regards,
-Morten Brørup