RE: [net-next PATCH 0/3] Extend action skbedit to RX queue mapping

-----Original Message-----
From: Jakub Kicinski <kuba@kernel.org>
Sent: Wednesday, August 31, 2022 7:46 PM
To: Nambiar, Amritha <redacted>
Cc: netdev@vger.kernel.org; alexander.h.duyck@intel.com;
jhs@mojatatu.com; jiri@resnulli.us; xiyou.wangcong@gmail.com; Gomes,
Vinicius [off-list ref]; Samudrala, Sridhar
[off-list ref]
Subject: Re: [net-next PATCH 0/3] Extend action skbedit to RX queue mapping

On Tue, 30 Aug 2022 02:28:39 -0700 Amritha Nambiar wrote:

quoted

Based on the discussion on
https://lore.kernel.org/netdev/20220429171717.5b0b2a81@kernel.org/ (local),
the following series extends skbedit tc action to RX queue mapping.
Currently, skbedit action in tc allows overriding of transmit queue.
Extending this ability of skedit action supports the selection of receive
queue for incoming packets. Offloading this action is added for receive
side. Enabled ice driver to offload this type of filter into the
hardware for accepting packets to the device's receive queue.

Thinking about this again - is redirecting to a queue really the most
useful API to expose? Wouldn't users want to redirect to a set of
queues, i.e. RSS context?

Or in your case the redirect to a set of queues is done by assigning
a class?

We already support redirecting to a set of queues using the 'hw_tc' option
of tc-flower. From the man page of tc-flower:
"hw_tc TCID - Specify a hardware traffic class to pass matching packets on to.
 TCID is in the range 0 through 15."
We needed two levels of filtering via TC, the first level selects the set of
queues, and an additional level that selects a queue within the queue-set 
(from the first level). Hence redirecting to a queue as an action. The additional
advantage is that being a tc-action allows using other action controls on this,
action chaining via "pipe" with other tc actions, and continuing classification
via action control "continue" etc.

Either way we should start documenting things, so please find (/create)
some place under Documentation/networking where we can make notes for
posterity.

Agree. I'll update the man page for tc-skbedit action. I can add notes in
Documentation/networking as well.