Re: Query on new ethtool RSS hashing options

On Sat, Mar 6, 2021 at 4:37 AM Jakub Kicinski [off-list ref] wrote:

On Fri, 5 Mar 2021 16:15:51 +0530 Sunil Kovvuri wrote:

quoted

Hi,

We have a requirement where in we want RSS hashing to be done on packet fields
which are not currently supported by the ethtool.

Current options:
ehtool -n <dev> rx-flow-hash
tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6 m|v|t|s|d|f|n|r

Specifically our requirement is to calculate hash with DSA tag (which
is inserted by switch) plus the TCP/UDP 4-tuple as input.

Can you share the format of the DSA tag? Is there a driver for it
upstream? Do we need to represent it in union ethtool_flow_union?

No, there is no driver for this tag in the kernel.
I have attached the tag format.
There are multiple DSA tag formats and representing them ethtool_flow
union would be difficult.
Hence wondering if it would be okay to add a more flexible way ie
offset and num_bytes from the start of packet.

Thanks,
Sunil.