From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: "Björn Töpel" <bjorn.topel@gmail.com>
Cc: Netdev <netdev@vger.kernel.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Björn Töpel" <bjorn.topel@intel.com>, bpf <bpf@vger.kernel.org>,
"Magnus Karlsson" <magnus.karlsson@gmail.com>,
"Karlsson, Magnus" <magnus.karlsson@intel.com>,
"Jonathan Lemon" <jonathan.lemon@gmail.com>,
"Edward Cree" <ecree@solarflare.com>,
"Andrii Nakryiko" <andrii.nakryiko@gmail.com>,
"Tariq Toukan" <tariqt@mellanox.com>,
"Saeed Mahameed" <saeedm@mellanox.com>,
"Maxim Mikityanskiy" <maximmi@mellanox.com>
Subject: Re: [PATCH bpf-next v2 2/6] xdp: introduce xdp_call
Date: Mon, 25 Nov 2019 16:56:52 +0100 [thread overview]
Message-ID: <87d0dg0x17.fsf@toke.dk> (raw)
In-Reply-To: <CAJ+HfNhFERV+xE7EUup-tu_nBTTqG=7L8bWm+W8h_Lzth4zuKQ@mail.gmail.com>
Björn Töpel <bjorn.topel@gmail.com> writes:
> On Mon, 25 Nov 2019 at 12:18, Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> Björn Töpel <bjorn.topel@gmail.com> writes:
>>
>> > From: Björn Töpel <bjorn.topel@intel.com>
>> >
>> > The xdp_call.h header wraps a more user-friendly API around the BPF
>> > dispatcher. A user adds a trampoline/XDP caller using the
>> > DEFINE_XDP_CALL macro, and updates the BPF dispatcher via
>> > xdp_call_update(). The actual dispatch is done via xdp_call().
>> >
>> > Note that xdp_call() is only supported for builtin drivers. Module
>> > builds will fallback to bpf_prog_run_xdp().
>>
>> I don't like this restriction. Distro kernels are not likely to start
>> shipping all the network drivers builtin, so they won't benefit from the
>> performance benefits from this dispatcher.
>>
>> What is the reason these dispatcher blocks have to reside in the driver?
>> Couldn't we just allocate one system-wide, and then simply change
>> bpf_prog_run_xdp() to make use of it transparently (from the driver
>> PoV)? That would also remove the need to modify every driver...
>>
>
> Good idea! I'll try that out. Thanks for the suggestion!
Awesome! I guess the table may need to be a bit bigger if it's
system-wide? But since you've already gone to all that trouble with the
binary search, I guess that shouldn't have too much of a performance
impact? Maybe the size could even be a config option so users/distros
can make their own size tradeoff?
-Toke
next prev parent reply other threads:[~2019-11-25 15:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-23 7:12 [PATCH bpf-next v2 0/6] Introduce the BPF dispatcher and xdp_call.h Björn Töpel
2019-11-23 7:12 ` [PATCH bpf-next v2 1/6] bpf: introduce BPF dispatcher Björn Töpel
2019-11-24 1:55 ` Alexei Starovoitov
2019-11-24 6:55 ` Björn Töpel
2019-11-24 17:08 ` Alexei Starovoitov
2019-11-24 17:16 ` Björn Töpel
2019-11-25 0:08 ` kbuild test robot
2019-11-25 10:53 ` Daniel Borkmann
2019-11-25 15:20 ` Björn Töpel
2019-11-23 7:12 ` [PATCH bpf-next v2 2/6] xdp: introduce xdp_call Björn Töpel
2019-11-24 1:59 ` Alexei Starovoitov
2019-11-24 6:56 ` Björn Töpel
2019-11-25 11:18 ` Toke Høiland-Jørgensen
2019-11-25 15:21 ` Björn Töpel
2019-11-25 15:56 ` Toke Høiland-Jørgensen [this message]
2019-11-26 7:43 ` Björn Töpel
2019-11-26 8:37 ` Toke Høiland-Jørgensen
2019-11-23 7:12 ` [PATCH bpf-next v2 3/6] i40e: start using xdp_call.h Björn Töpel
2019-11-23 7:12 ` [PATCH bpf-next v2 4/6] ixgbe: " Björn Töpel
2019-11-23 7:12 ` [PATCH bpf-next v2 5/6] net/mlx4_en: " Björn Töpel
2019-11-23 7:12 ` [PATCH bpf-next v2 6/6] net/mlx5e: Start " Björn Töpel
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