[xdp-hints] Re: [PATCH bpf-next v7 4/5] igc: Refactor empty packet insertion into a reusable function

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

On Tuesday, February 4, 2025 8:36 PM, Fijalkowski, Maciej <maciej.fijalkowski@intel.com> wrote:
>On Tue, Feb 04, 2025 at 12:07:21PM +0100, Song, Yoong Siang wrote:

[...]

>>
>> "insert an empty packet" is a launch time trick to send a packet in
>> next Qbv cycle. The design is, the driver will still sending the
>> packet, even the empty packet insertion trick is fail (unable to
>> allocate). The intention of this patch set is to enable launch time
>> on XDP zero-copy data path, so I try not to change the original
>> behavior of launch time.
>>
>> btw, do you think driver should drop the packet if something went
>> wrong with the launch time, like launch time offload not enabled,
>> launch time over horizon, empty packet insertion fail, etc?
>> If yes, then maybe i can submit another patch to change the behavior
>> of launch time and we can continue to discuss there.
>
>That's rather a question to you since I am no TSN expert here :P
>the alloc skbs failures would rather be a minor thing but anyways it
>didn't look correct from a first glance to silently ignore this behavior
>if rest of the logic relies on this. I won't be insisting on any changes
>here but it's something you could consider to change maybe.

I got plan to refactor the launch time configuration, but that requires
more discussion, so I prefer to submit another separate patch for it.
I will keep the launch time configuration the original way, so that
this patch set have least impact to non XDP path.

>
>The real question is in 5/5, regarding the cleaning of these empty descs
>from ZC path.
>

Sure, I replied to your comments in 5/5. Let's continue the discussion there.

Thanks & Regards
Siang