From: "Toke Høiland-Jørgensen" <toke@redhat•com>
To: "Björn Töpel" <bjorn.topel@gmail•com>,
ast@kernel•org, daniel@iogearbox•net, netdev@vger•kernel.org,
bpf@vger•kernel.org
Cc: "Björn Töpel" <bjorn.topel@intel•com>,
magnus.karlsson@intel•com, maciej.fijalkowski@intel•com,
kuba@kernel•org, jonathan.lemon@gmail•com, maximmi@nvidia•com,
davem@davemloft•net, hawk@kernel•org, john.fastabend@gmail•com
Subject: Re: [RFC PATCH bpf-next] bpf, xdp: per-map bpf_redirect_map functions for XDP
Date: Fri, 29 Jan 2021 17:45:27 +0100 [thread overview]
Message-ID: <87im7fy9nc.fsf@toke.dk> (raw)
In-Reply-To: <20210129153215.190888-1-bjorn.topel@gmail.com>
Björn Töpel <bjorn.topel@gmail•com> writes:
> From: Björn Töpel <bjorn.topel@intel•com>
>
> Currently the bpf_redirect_map() implementation dispatches to the
> correct map-lookup function via a switch-statement. To avoid the
> dispatching, this change adds one bpf_redirect_map() implementation per
> map. Correct function is automatically selected by the BPF verifier.
>
> Signed-off-by: Björn Töpel <bjorn.topel@intel•com>
> ---
> Hi XDP-folks!
>
> This is another take on my bpf_redirect_xsk() patch [1]. I figured I
> send it as an RFC for some early input. My plan is to include it as
> part of the xdp_do_redirect() optimization of [1].
Assuming the maintainers are OK with the special-casing in the verifier,
this looks like a neat way to avoid the runtime overhead to me. The
macro hackery is not the prettiest; I wonder if the same effect could be
achieved by using inline functions? If not, at least a comment
explaining the reasoning (and that the verifier will substitute the
right function) might be nice? Mostly in relation to this bit:
> static const struct bpf_func_proto bpf_xdp_redirect_map_proto = {
> - .func = bpf_xdp_redirect_map,
> + .func = bpf_xdp_redirect_devmap,
Ah, if only we were writing the kernel in a language with proper macro
support... One can dream! :)
>> For AF_XDP rxdrop this yields +600Mpps. I'll do CPU/DEVMAP
>> measurements for the patch proper.
>>
>
> Kpps, not Mpps. :-P
Aww, too bad ;)
Still, nice!
-Toke
next parent reply other threads:[~2021-01-29 16:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210129153215.190888-1-bjorn.topel@gmail.com>
2021-01-29 16:45 ` Toke Høiland-Jørgensen [this message]
2021-02-01 6:27 ` [RFC PATCH bpf-next] bpf, xdp: per-map bpf_redirect_map functions for XDP Björn Töpel
2021-02-01 9:31 ` Jesper Dangaard Brouer
2021-02-01 9:49 ` Björn Töpel
[not found] ` <CAJ+HfNiFtRd-KKMB1t3Mi3MZ=C+u5TTM5YFnzJFfR4Ruzc7c9Q@mail.gmail.com>
2021-01-29 18:06 ` Jesper Dangaard Brouer
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