From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Stanislav Fomichev <sdf@google.com>
Cc: bpf <bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
"Song Liu" <song@kernel.org>, "Yonghong Song" <yhs@fb.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"KP Singh" <kpsingh@kernel.org>, "Hao Luo" <haoluo@google.com>,
"Jiri Olsa" <jolsa@kernel.org>,
"Jakub Kicinski" <kuba@kernel.org>,
"Toke Høiland-Jørgensen" <toke@kernel.org>,
"Willem de Bruijn" <willemb@google.com>,
"David Ahern" <dsahern@kernel.org>,
"Karlsson, Magnus" <magnus.karlsson@intel.com>,
"Björn Töpel" <bjorn@kernel.org>,
"Fijalkowski, Maciej" <maciej.fijalkowski@intel.com>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"Network Development" <netdev@vger.kernel.org>,
xdp-hints@xdp-project.net
Subject: [xdp-hints] Re: [RFC bpf-next v3 09/14] net/mlx5e: Implement devtx kfuncs
Date: Tue, 11 Jul 2023 21:59:44 -0700 [thread overview]
Message-ID: <CAADnVQJnf=KJ17MJWujkj+oSxp7kNNK1k08PvH+Wx617yAtZ8Q@mail.gmail.com> (raw)
In-Reply-To: <ZK4eFox0DwbpyIJv@google.com>
On Tue, Jul 11, 2023 at 8:29 PM Stanislav Fomichev <sdf@google.com> wrote:
>
>
> This will slow things down, but not to the point where it's on par
> with doing sw checksum. At least in theory.
> We can't stay at skb when using AF_XDP. AF_XDP would benefit from having
> the offloads.
To clarify: yes, AF_XDP needs generalized HW offloads.
I just don't see how xdp tx offloads are moving a needle in that direction.
> I hope we can both agree that with an api like
> mlx5_l4_csum_offload(bool encap) we can't be 100% certain that the
> hw is gonna handle any packet layout? So how is that different
> from a generic api that also can't work in all cases?
If it's hw specific then yes.
Will [mlx5|...]_l4_csum_offload apply to other nics? I doubt.
> AF_XDP is a generic layer for low-level access and it provides generic
> descriptor format, so why suddenly we have this requirement where we have
> to do prog rewrite for every new nic?
>
> Current AF_XDP programs are pretty portable (obviously depend on
> a bunch of nic features), it seems like a good idea to try to preserve
> this property? (again, with an asterisk, where we should allow some
> differentiation, etc, etc)
Agree. AF_XDP needs a generic api that will allow user space
request HW to do TSO, csum offload, etc.
xdp tx and af_xdp are too different to pull under the same framework.
xdp progs will interact with the kernel via kfuncs.
af_xdp needs a different api to express packet geometry and offload requests.
The user space cannot do it with bpf programs.
In case of AF_XDP the bpf prog in the kernel is a filter only.
For the majority of the cases bpf prog is not necessary and shouldn't be
required to express HW offloads.
next prev parent reply other threads:[~2023-07-12 4:59 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-07 19:29 [xdp-hints] [RFC bpf-next v3 00/14] bpf: Netdev TX metadata Stanislav Fomichev
2023-07-07 19:29 ` [xdp-hints] [RFC bpf-next v3 01/14] bpf: Rename some xdp-metadata functions into dev-bound Stanislav Fomichev
2023-07-07 19:29 ` [xdp-hints] [RFC bpf-next v3 02/14] bpf: Make it easier to add new metadata kfunc Stanislav Fomichev
2023-07-07 19:29 ` [xdp-hints] [RFC bpf-next v3 03/14] xsk: Support XDP_TX_METADATA_LEN Stanislav Fomichev
2023-07-07 19:29 ` [xdp-hints] [RFC bpf-next v3 04/14] bpf: Implement devtx hook points Stanislav Fomichev
2023-07-07 19:29 ` [xdp-hints] [RFC bpf-next v3 05/14] bpf: Implement devtx timestamp kfunc Stanislav Fomichev
2023-07-07 19:29 ` [xdp-hints] [RFC bpf-next v3 06/14] net: veth: Implement devtx timestamp kfuncs Stanislav Fomichev
2023-07-07 19:29 ` [xdp-hints] [RFC bpf-next v3 07/14] bpf: Introduce tx checksum devtx kfuncs Stanislav Fomichev
2023-07-07 19:30 ` [xdp-hints] [RFC bpf-next v3 08/14] net: veth: Implement devtx tx checksum Stanislav Fomichev
2023-07-07 19:30 ` [xdp-hints] [RFC bpf-next v3 09/14] net/mlx5e: Implement devtx kfuncs Stanislav Fomichev
2023-07-11 22:56 ` [xdp-hints] " Alexei Starovoitov
2023-07-11 23:24 ` Stanislav Fomichev
2023-07-11 23:45 ` Alexei Starovoitov
2023-07-12 0:14 ` Stanislav Fomichev
2023-07-12 2:50 ` Alexei Starovoitov
2023-07-12 3:29 ` Stanislav Fomichev
2023-07-12 4:59 ` Alexei Starovoitov [this message]
2023-07-12 5:36 ` Stanislav Fomichev
2023-07-12 15:16 ` Willem de Bruijn
2023-07-12 16:28 ` Willem de Bruijn
2023-07-12 19:03 ` Alexei Starovoitov
2023-07-12 19:11 ` Willem de Bruijn
2023-07-12 19:42 ` Alexei Starovoitov
2023-07-12 20:09 ` Jakub Kicinski
2023-07-12 20:53 ` Stanislav Fomichev
2023-07-12 0:32 ` Jakub Kicinski
2023-07-12 2:37 ` Alexei Starovoitov
2023-07-12 3:07 ` Jakub Kicinski
2023-07-12 3:23 ` Alexei Starovoitov
2023-07-07 19:30 ` [xdp-hints] [RFC bpf-next v3 10/14] selftests/xsk: Support XDP_TX_METADATA_LEN Stanislav Fomichev
2023-07-07 19:30 ` [xdp-hints] [RFC bpf-next v3 11/14] selftests/bpf: Add helper to query current netns cookie Stanislav Fomichev
2023-07-07 19:30 ` [xdp-hints] [RFC bpf-next v3 12/14] selftests/bpf: Add csum helpers Stanislav Fomichev
2023-07-07 19:30 ` [xdp-hints] [RFC bpf-next v3 13/14] selftests/bpf: Extend xdp_metadata with devtx kfuncs Stanislav Fomichev
2023-07-07 19:30 ` [xdp-hints] [RFC bpf-next v3 14/14] selftests/bpf: Extend xdp_hw_metadata " Stanislav Fomichev
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