[xdp-hints] Re: [PATCH bpf-next v4 3/4] net: stmmac: Add launch time support to XDP ZC

["Song, Yoong Siang" <yoong.siang.song@intel.com>]

On Wednesday, January 8, 2025 1:08 AM, Stanislav Fomichev <stfomichev@gmail.com> wrote:
>On 01/06, Song Yoong Siang wrote:
>> Enable launch time (Time-Based Scheduling) support to XDP zero copy via XDP
>> Tx metadata framework.
>>
>> This patch is tested with tools/testing/selftests/bpf/xdp_hw_metadata on
>> Intel Tiger Lake platform. Below are the test steps and result.
>>
>> Test Steps:
>> 1. Add mqprio qdisc:
>>    $ sudo tc qdisc add dev enp0s30f4 handle 8001: parent root mqprio num_tc
>>      4 map 0 1 2 3 3 3 3 3 3 3 3 3 3 3 3 3 queues 1@0 1@1 1@2 1@3 hw 0
>>
>> 2. Enable launch time hardware offload on hardware queue 1:
>>    $ sudo tc qdisc replace dev enp0s30f4 parent 8001:2 etf offload clockid
>>      CLOCK_TAI delta 500000
>>
>> 3. Add an ingress qdisc:
>>    $ sudo tc qdisc add dev enp0s30f4 ingress
>>
>> 4. Add a flower filter to route incoming packet with VLAN priority 1 into
>>    hardware queue 1:
>>    $ sudo tc filter add dev enp0s30f4 parent ffff: protocol 802.1Q flower
>>      vlan_prio 1 hw_tc 1
>>
>> 5. Enable VLAN tag stripping:
>>    $ sudo ethtool -K enp0s30f4 rxvlan on
>>
>> 6. Start xdp_hw_metadata selftest application:
>>    $ sudo ./xdp_hw_metadata enp0s30f4 -l 1000000000
>>
>> 7. Send an UDP packet with VLAN priority 1 to port 9091 of DUT.
>
>Tangential: I wonder whether we can add the setup steps to the
>xdp_hw_metadata tool? It is useful to have one command to run that
>takes care of all the details. Same way it already enables HW
>tstamping..
>
>Or, if not the full setup, some kind of detection we can signal to the
>user that some things might be missing?

Sure. I can try to add the setup steps into xdp_hw_metadata
by using ioctl() function. However, there are some device specific
command, like the number of queue, their priority,
how they route the incoming packet, etc. I will try to find out
a common way that can work for most of the devices,
at least work for both igc and stmmac.

Thanks & Regards
Siang