netdev - Re: [RFC bpf-next 0/7] bpf: netdev TX metadata

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Message-ID: <87pm5wgaws.fsf@toke.dk>
Date: Thu, 15 Jun 2023 14:36:19 +0200
From: Toke Høiland-Jørgensen <toke@...nel.org>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Stanislav Fomichev <sdf@...gle.com>, bpf <bpf@...r.kernel.org>, Alexei
 Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>,
 Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau
 <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, Yonghong Song
 <yhs@...com>, John Fastabend <john.fastabend@...il.com>, KP Singh
 <kpsingh@...nel.org>, Hao Luo <haoluo@...gle.com>, Jiri Olsa
 <jolsa@...nel.org>, Willem de Bruijn <willemb@...gle.com>, David Ahern
 <dsahern@...nel.org>, "Karlsson, Magnus" <magnus.karlsson@...el.com>,
 Björn Töpel <bjorn@...nel.org>, "Fijalkowski, Maciej"
 <maciej.fijalkowski@...el.com>, Network Development
 <netdev@...r.kernel.org>
Subject: Re: [RFC bpf-next 0/7] bpf: netdev TX metadata

Alexei Starovoitov <alexei.starovoitov@...il.com> writes:

> On Wed, Jun 14, 2023 at 5:00 AM Toke Høiland-Jørgensen <toke@...nel.org> wrote:
>>
>> >>
>> >> It's probably going to work if each driver has a separate set of tx
>> >> fentry points, something like:
>> >>   {veth,mlx5,etc}_devtx_submit()
>> >>   {veth,mlx5,etc}_devtx_complete()
>>
>> I really don't get the opposition to exposing proper APIs; as a
>> dataplane developer I want to attach a program to an interface. The
>> kernel's role is to provide a consistent interface for this, not to
>> require users to become driver developers just to get at the required
>> details.
>
> Consistent interface can appear only when there is a consistency
> across nic manufacturers.
> I'm suggesting to experiment in the most unstable way and
> if/when the consistency is discovered then generalize.

That would be fine for new experimental HW features, but we're talking
about timestamps here: a feature that is already supported by multiple
drivers and for which the stack has a working abstraction. There's no
reason why we can't have that for the XDP path as well.

-Toke