From: Jesper Dangaard Brouer <brouer@redhat.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: "Björn Töpel" <bjorn.topel@gmail.com>,
ast@kernel.org, daniel@iogearbox.net, bpf@vger.kernel.org,
john.fastabend@gmail.com, magnus.karlsson@intel.com,
netdev@vger.kernel.org, maciej.fijalkowski@intel.com,
bjorn.topel@intel.com, brouer@redhat.com
Subject: Re: [RFC PATCH bpf-next 0/2] bpf_redirect_map() tail call detection and xdp_do_redirect() avoidance
Date: Wed, 10 Jun 2020 14:21:10 +0200 [thread overview]
Message-ID: <20200610142110.25fa5a14@carbon> (raw)
In-Reply-To: <87o8ps80gc.fsf@toke.dk>
> Björn Töpel <bjorn.topel@gmail.com> writes:
>
> > Is this a good idea? I have only measured for AF_XDP redirects, but
> > all XDP_REDIRECT targets should benefit. For AF_XDP the rxdrop
> > scenario went from 21.5 to 23.2 Mpps on my machine.
Do remember that you are reporting saving 3.4 nanosec (from 21.5 to
23.2 Mpps). For comparison a function call cost around 1.2 ns, and I
think you have avoided two function calls xdp_do_redirect() and
dev_map_enqueue() (the rest should be inlined by compiler). Thus, that
alone account for 2.4 ns.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
prev parent reply other threads:[~2020-06-10 12:21 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
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 [this message]
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