Re: igc: AF_PACKET and SO_TXTIME question

[Kurt Kanzenbach <kurt@linutronix.de>]

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Hi Ferenc,

On Fri Feb 16 2024, Ferenc Fejes wrote:
> We simply placed the ETF qdisc as the root qdisc and assumed that this
> would enable offload on all TX queues. Apparently this is not the case.
> According to the code, it was only enabled for queue 0. Another mistake
> we made is we used multiq qdisc with skbedit queue_mapping without
> bypass - which works since the tx action is executed.
> However, with qdisc baypass, the TX queue selection for the packets
> sent to the AF_PACKET socket looks like this
>
> tx_queue = cpu_id of task % num_tx_queues.
>
> With taskset, we were able to explicitly send packets to TX queue 0 in
> the bypass case, and that essentially solved the problem.
>
> So we switched to mqprio and enabled offloading on all queues and with
> that we always see the delayed packet transmission with launchtime
> enabled.

Glad it worked out. Thanks for sharing your solution!

Thanks,
Kurt

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