Re: [dpdk-dev] [PATCH v2] ethdev: add IPv4 checksum RSS offload type

["Zhang, AlvinX" <alvinx.zhang@intel.com>]

> > This patch defines new RSS offload type for IPv4 checksum, which is
> > required when users want to distribute packets based on the IPv4
> > checksum field.
> >
> > For example "flow create 0 ingress pattern eth / ipv4 / end actions
> > rss types ipv4-chksum end queues end / end", this flow causes all
> > matching packets to be distributed to queues on basis of IPv4
> > checksum.
> >
> > Signed-off-by: Alvin Zhang <alvinx.zhang@intel.com>
> 
> The patch LGTM now. I hope we'll have a PMD in the release cycle which
> supports it.
> 
> In fact it is a funny idea. Let's consider a TCP connection and routing change
> with one extra hop on the way while the connection is alive. Or a UDP stream in
> the same conditions. If so, TTL will different, checksum changes and connection
> packets may be delivered to a different Rx queue.
> May be sometimes it is not important and/or can't happen.
> 
> L4 checksum sounds better from this point of view since it covers IP addresses
> and transport ports and less bits to hash. The only concern is distribution fairness,
> but I keep the topic to those who understand corresponding math better.
> 
> > ---

We are preparing a PMD patch to support this feature, if ready, we will submit it ASAP.

Thanks,
Alvin