ETH_RSS_IP only does not seem to balance traffic

[Yasuhiro Ohara]

Hi,

My system developper friend recently ran into a problem where
l3fwd does not appear to receive balanced traffic on Intel XL710,
but it is resolved when the attached patch is applied.

-            .rss_hf = ETH_RSS_IP,
+            .rss_hf = ETH_RSS_IP | ETH_RSS_TCP | ETH_RSS_UDP,

IIRC I ran into a similar problem 3 or 4 years back,
but didn't report then because I believed I was doing something silly.
But since my friend is an experienced engineer, I feel like
it may be better (for the community) to ask this in the list.

We are using dpdk-stable-18.11.6 and igb_uio.

What are we doing wrong?

If it is not a FAQ, I can test it again with more recent stable,
and will report the details.

Thanks.

Best,
Yasu