ETH_RSS_IP only does not seem to balance traffic

[Bruce Richardson]

On Thu, Jan 13, 2022 at 12:52:04AM +0900, Yasuhiro Ohara wrote:
> 
> 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.
> 
For XL710 NICs, I believe that ETH_RSS_IP load balances only IP frames that
do not have TCP or UDP headers also. Adding i40e driver maintainer on CC
to comment further.

/Bruce