Jesper Dangaard Brouer wrote:
>
>
> On 12/3/23 17:51, Song Yoong Siang wrote:
> > This patch enables Launch Time (Time-Based Scheduling) support to XDP zero
> > copy via XDP Tx metadata framework.
> >
> > Signed-off-by: Song Yoong Siang<yoong.siang.song@xxxxxxxxx>
> > ---
> > drivers/net/ethernet/stmicro/stmmac/stmmac.h | 2 ++
>
> As requested before, I think we need to see another driver implementing
> this.
>
> I propose driver igc and chip i225.
>
> The interesting thing for me is to see how the LaunchTime max 1 second
> into the future[1] is handled code wise. One suggestion is to add a
> section to Documentation/networking/xsk-tx-metadata.rst per driver that
> mentions/documents these different hardware limitations. It is natural
> that different types of hardware have limitations. This is a close-to
> hardware-level abstraction/API, and IMHO as long as we document the
> limitations we can expose this API without too many limitations for more
> capable hardware.
I would assume that the kfunc will fail when a value is passed that
cannot be programmed.
What is being implemented here already exists for qdiscs. The FQ
qdisc takes a horizon attribute and
"
when a packet is beyond the horizon
at enqueue() time:
- either drop the packet (default policy)
- or cap its delivery time to the horizon.
"
commit 39d010504e6b ("net_sched: sch_fq: add horizon attribute")
Having the admin manually configure this on the qdisc based on
off-line knowledge of the device is more fragile than if the device
would somehow signal its limit to the stack.
But I don't think we should add enforcement of that as a requirement
for this xdp extension of pacing.
