From: John Fastabend <john.fastabend@gmail.com>
To: Stanislav Fomichev <sdf@google.com>,
John Fastabend <john.fastabend@gmail.com>
Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
yhs@fb.com, kpsingh@kernel.org, haoluo@google.com,
jolsa@kernel.org, David Ahern <dsahern@gmail.com>,
Jakub Kicinski <kuba@kernel.org>,
Willem de Bruijn <willemb@google.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Anatoly Burakov <anatoly.burakov@intel.com>,
Alexander Lobakin <alexandr.lobakin@intel.com>,
Magnus Karlsson <magnus.karlsson@gmail.com>,
Maryam Tahhan <mtahhan@redhat.com>,
xdp-hints@xdp-project.net, netdev@vger.kernel.org
Subject: [xdp-hints] Re: [RFC bpf-next v2 04/14] veth: Support rx timestamp metadata for xdp
Date: Wed, 09 Nov 2022 17:35:21 -0800 [thread overview]
Message-ID: <636c555942433_13ef3820861@john.notmuch> (raw)
In-Reply-To: <CAKH8qBvS9C5Z2L2dT4Ze-dz7YBSpw52VF6iZK5phcU2k4azN5A@mail.gmail.com>
Stanislav Fomichev wrote:
> On Wed, Nov 9, 2022 at 4:26 PM John Fastabend <john.fastabend@gmail.com> wrote:
> >
> > Stanislav Fomichev wrote:
> > > xskxceiver conveniently setups up veth pairs so it seems logical
> > > to use veth as an example for some of the metadata handling.
> > >
> > > We timestamp skb right when we "receive" it, store its
> > > pointer in new veth_xdp_buff wrapper and generate BPF bytecode to
> > > reach it from the BPF program.
> > >
> > > This largely follows the idea of "store some queue context in
> > > the xdp_buff/xdp_frame so the metadata can be reached out
> > > from the BPF program".
> > >
> >
> > [...]
> >
> > > orig_data = xdp->data;
> > > orig_data_end = xdp->data_end;
> > > + vxbuf.skb = skb;
> > >
> > > act = bpf_prog_run_xdp(xdp_prog, xdp);
> > >
> > > @@ -942,6 +946,7 @@ static int veth_xdp_rcv(struct veth_rq *rq, int budget,
> > > struct sk_buff *skb = ptr;
> > >
> > > stats->xdp_bytes += skb->len;
> > > + __net_timestamp(skb);
> >
> > Just getting to reviewing in depth a bit more. But we hit veth with lots of
> > packets in some configurations I don't think we want to add a __net_timestamp
> > here when vast majority of use cases will have no need for timestamp on veth
> > device. I didn't do a benchmark but its not free.
> >
> > If there is a real use case for timestamping on veth we could do it through
> > a XDP program directly? Basically fallback for devices without hw timestamps.
> > Anyways I need the helper to support hardware without time stamping.
> >
> > Not sure if this was just part of the RFC to explore BPF programs or not.
>
> Initially I've done it mostly so I can have selftests on top of veth
> driver, but I'd still prefer to keep it to have working tests.
I can't think of a use for it though so its just extra cycles. There
is a helper to read the ktime.
> Any way I can make it configurable? Is there some ethtool "enable tx
> timestamping" option I can reuse?
There is a -T option for timestamping in ethtool. There are also the
socket controls for it. So you could spin up a socket and use it.
But that is a bit broken as well I think it would be better if the
timestamp came from the receiving physical nic?
I have some mlx nics here and a k8s cluster with lots of veth
devices so I could think a bit more. I'm just not sure why I would
want the veth to timestamp things off hand?
>
> > > skb = veth_xdp_rcv_skb(rq, skb, bq, stats);
> > > if (skb) {
> > > if (skb_shared(skb) || skb_unclone(skb, GFP_ATOMIC))
next prev parent reply other threads:[~2022-11-10 1:35 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-04 3:25 [xdp-hints] [RFC bpf-next v2 00/14] xdp: hints via kfuncs Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 01/14] bpf: Introduce bpf_patch Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 02/14] bpf: Support inlined/unrolled kfuncs for xdp metadata Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 03/14] veth: Introduce veth_xdp_buff wrapper for xdp_buff Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 04/14] veth: Support rx timestamp metadata for xdp Stanislav Fomichev
2022-11-09 11:21 ` [xdp-hints] " Toke Høiland-Jørgensen
2022-11-09 21:34 ` Stanislav Fomichev
2022-11-10 0:25 ` John Fastabend
2022-11-10 1:02 ` Stanislav Fomichev
2022-11-10 1:35 ` John Fastabend [this message]
2022-11-10 6:44 ` Stanislav Fomichev
2022-11-10 17:39 ` John Fastabend
2022-11-10 18:52 ` Stanislav Fomichev
2022-11-11 10:41 ` Jesper Dangaard Brouer
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 05/14] selftests/bpf: Verify xdp_metadata xdp->af_xdp path Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 06/14] xdp: Carry over xdp metadata into skb context Stanislav Fomichev
2022-11-07 22:01 ` [xdp-hints] " Martin KaFai Lau
2022-11-08 21:54 ` Stanislav Fomichev
2022-11-09 3:07 ` Martin KaFai Lau
2022-11-09 4:19 ` Martin KaFai Lau
2022-11-09 11:10 ` Toke Høiland-Jørgensen
2022-11-09 18:22 ` Martin KaFai Lau
2022-11-09 21:33 ` Stanislav Fomichev
2022-11-10 0:13 ` Martin KaFai Lau
2022-11-10 1:02 ` Stanislav Fomichev
2022-11-10 14:26 ` Toke Høiland-Jørgensen
2022-11-10 18:52 ` Stanislav Fomichev
2022-11-10 23:14 ` Toke Høiland-Jørgensen
2022-11-10 23:52 ` Stanislav Fomichev
2022-11-11 0:10 ` Toke Høiland-Jørgensen
2022-11-11 0:45 ` Martin KaFai Lau
2022-11-11 9:37 ` Toke Høiland-Jørgensen
2022-11-11 0:33 ` Martin KaFai Lau
2022-11-11 0:57 ` Stanislav Fomichev
2022-11-11 1:26 ` Martin KaFai Lau
2022-11-11 9:41 ` Toke Høiland-Jørgensen
2022-11-10 23:58 ` Martin KaFai Lau
2022-11-11 0:20 ` Stanislav Fomichev
2022-11-10 14:19 ` Toke Høiland-Jørgensen
2022-11-10 19:04 ` Martin KaFai Lau
2022-11-10 23:29 ` Toke Høiland-Jørgensen
2022-11-11 1:39 ` Martin KaFai Lau
2022-11-11 9:44 ` Toke Høiland-Jørgensen
2022-11-10 1:26 ` John Fastabend
2022-11-10 14:32 ` Toke Høiland-Jørgensen
2022-11-10 17:30 ` John Fastabend
2022-11-10 22:49 ` Toke Høiland-Jørgensen
2022-11-10 1:09 ` John Fastabend
2022-11-10 6:44 ` Stanislav Fomichev
2022-11-10 21:21 ` David Ahern
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 07/14] selftests/bpf: Verify xdp_metadata xdp->skb path Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 08/14] bpf: Helper to simplify calling kernel routines from unrolled kfuncs Stanislav Fomichev
2022-11-05 0:40 ` [xdp-hints] " Alexei Starovoitov
2022-11-05 2:18 ` Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 09/14] ice: Introduce ice_xdp_buff wrapper for xdp_buff Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 10/14] ice: Support rx timestamp metadata for xdp Stanislav Fomichev
2022-11-04 14:35 ` [xdp-hints] " Alexander Lobakin
2022-11-04 18:21 ` Stanislav Fomichev
2022-11-07 17:11 ` Alexander Lobakin
2022-11-07 19:10 ` Stanislav Fomichev
2022-12-15 11:54 ` Larysa Zaremba
2022-12-15 14:29 ` Toke Høiland-Jørgensen
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 11/14] mlx4: Introduce mlx4_xdp_buff wrapper for xdp_buff Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 12/14] mxl4: Support rx timestamp metadata for xdp Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 13/14] bnxt: Introduce bnxt_xdp_buff wrapper for xdp_buff Stanislav Fomichev
2022-11-04 3:25 ` [xdp-hints] [RFC bpf-next v2 14/14] bnxt: Support rx timestamp metadata for xdp Stanislav Fomichev
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