From: "Björn Töpel" <bjorn.topel@gmail.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
bpf <bpf@vger.kernel.org>,
"John Fastabend" <john.fastabend@gmail.com>,
"Björn Töpel" <bjorn.topel@intel.com>,
"Karlsson, Magnus" <magnus.karlsson@intel.com>,
Netdev <netdev@vger.kernel.org>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Fijalkowski, Maciej" <maciej.fijalkowski@intel.com>
Subject: Re: [RFC PATCH bpf-next 2/2] i40e: avoid xdp_do_redirect() call when "redirect_tail_call" is set
Date: Wed, 10 Jun 2020 13:12:37 +0200 [thread overview]
Message-ID: <CAJ+HfNiuag3MQ94K__vWfpS5wqTtzSs839t_cKQTpw1k_QZeYQ@mail.gmail.com> (raw)
In-Reply-To: <87r1uo81i5.fsf@toke.dk>
On Tue, 9 Jun 2020 at 21:47, Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Björn Töpel <bjorn.topel@gmail.com> writes:
>
> > From: Björn Töpel <bjorn.topel@intel.com>
> >
> > If an XDP program, where all the bpf_redirect_map() calls are tail
> > calls (as defined by the previous commit), the driver does not need to
> > explicitly call xdp_do_redirect().
> >
> > The driver checks the active XDP program, and notifies the BPF helper
> > indirectly via xdp_set_redirect_tailcall().
> >
> > This is just a naive, as-simple-as-possible implementation, calling
> > xdp_set_redirect_tailcall() for each packet.
>
> Do you really need the driver changes? The initial setup could be moved
> to bpf_prog_run_xdp(), and xdp_do_redirect() could be changed to an
> inline wrapper that just checks a flag and immediately returns 0 if the
> redirect action was already performed. Or am I missing some reason why
> this wouldn't work?
>
Indeed! That's a good idea!
Björn
> -Toke
>
next prev parent reply other threads:[~2020-06-10 11:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-09 17:26 [RFC PATCH bpf-next 0/2] bpf_redirect_map() tail call detection and xdp_do_redirect() avoidance Björn Töpel
2020-06-09 17:26 ` [RFC PATCH bpf-next 1/2] bpf, xdp: add naive bpf_redirect_map() tail call detection Björn Töpel
2020-06-09 17:26 ` [RFC PATCH bpf-next 2/2] i40e: avoid xdp_do_redirect() call when "redirect_tail_call" is set Björn Töpel
2020-06-09 19:47 ` Toke Høiland-Jørgensen
2020-06-10 11:12 ` Björn Töpel [this message]
2020-06-09 20:10 ` [RFC PATCH bpf-next 0/2] bpf_redirect_map() tail call detection and xdp_do_redirect() avoidance Toke Høiland-Jørgensen
2020-06-10 12:21 ` Jesper Dangaard Brouer
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