Re: [PATCH 1/3] Add TX sending hardware timestamp.

[Willem de Bruijn]

On Wed, Dec 9, 2020 at 9:37 AM Erez Geva <erez.geva.ext@xxxxxxxxxxx> wrote:
>
> Configure and send TX sending hardware timestamp from
>  user space application to the socket layer,
>  to provide to the TC ETC Qdisc, and pass it to
>  the interface network driver.
>
>  - New flag for the SO_TXTIME socket option.
>  - New access auxiliary data header to pass the
>    TX sending hardware timestamp.
>  - Add the hardware timestamp to the socket cookie.
>  - Copy the TX sending hardware timestamp to the socket cookie.
>
> Signed-off-by: Erez Geva <erez.geva.ext@xxxxxxxxxxx>

Hardware offload of pacing is definitely useful.

I don't think this needs a new separate h/w variant of SO_TXTIME.

Indeed, we want pacing offload to work for existing applications.

It only requires that pacing qdiscs, both sch_etf and sch_fq,
optionally skip queuing in their .enqueue callback and instead allow
the skb to pass to the device driver as is, with skb->tstamp set. Only
to devices that advertise support for h/w pacing offload.