[xdp-hints] Re: [PATCH bpf-next v3 3/3] selftests/bpf: add Launch Time request to xdp_hw_metadata

[Song, Yoong Siang]

On Monday, December 4, 2023 11:00 PM, Willem de Bruijn wrote:
>Jesper Dangaard Brouer wrote:
>>
>>
>> On 12/3/23 17:51, Song Yoong Siang wrote:
>> > This patch is tested with stmmac on Intel Tiger Lake platform. Refer to
>> > result below, the delta between pre-determined launch time and actual HW
>> > transmit complete time is around 24 us.
>>
>> Is there any NIC setup (e.g. ethtool/qdisc) requirements to enable HW
>> for this feature?
>
>Judging from how we currently use this with FQ and ETF, no.
>
>See for instance tools/testing/selftests/net/so_txtime.sh

For stmmac, we need to enable per queue launch time support
by using tc qdisc etf offload command.
I believe igc also using the same way.
I will add into documentation to make it clear that
XDP_TXMD_FLAGS_LAUNCH_TIME only used to pass the
launch time value, not enable launch time feature.