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From: William Tu <u9012063@gmail.com>
To: Toshiaki Makita <toshiaki.makita1@gmail.com>
Cc: "David Miller" <davem@davemloft.net>,
	"Toke Høiland-Jørgensen" <toke@redhat.com>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Martin KaFai Lau" <kafai@fb.com>,
	"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
	"Jakub Kicinski" <jakub.kicinski@netronome.com>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"Jamal Hadi Salim" <jhs@mojatatu.com>,
	"Cong Wang" <xiyou.wangcong@gmail.com>,
	"Jiri Pirko" <jiri@resnulli.us>,
	"Pablo Neira Ayuso" <pablo@netfilter.org>,
	"Jozsef Kadlecsik" <kadlec@netfilter.org>,
	"Florian Westphal" <fw@strlen.de>,
	"pravin shelar" <pshelar@ovn.org>,
	"Linux Kernel Network Developers" <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>, "Stanislav Fomichev" <sdf@fomichev.me>
Subject: Re: [RFC PATCH v2 bpf-next 00/15] xdp_flow: Flow offload to XDP
Date: Tue, 12 Nov 2019 09:50:17 -0800	[thread overview]
Message-ID: <CALDO+SaxbNpON+=3zA4r4k6BE7UhbGU1WovW8Owyi8-9J_Wbkw@mail.gmail.com> (raw)
In-Reply-To: <09817958-e331-63e9-efbf-05341623a006@gmail.com>

On Wed, Oct 30, 2019 at 5:32 PM Toshiaki Makita
<toshiaki.makita1@gmail.com> wrote:
>
> On 2019/10/28 4:17, David Miller wrote:
> > From: Toke Høiland-Jørgensen <toke@redhat.com>
> > Date: Sun, 27 Oct 2019 16:24:24 +0100
> >
> >> The results in the paper also shows somewhat disappointing performance
> >> for the eBPF implementation, but that is not too surprising given that
> >> it's implemented as a TC eBPF hook, not an XDP program. I seem to recall
> >> that this was also one of the things puzzling to me back when this was
> >> presented...
> >
> > Also, no attempt was made to dyanamically optimize the data structures
> > and code generated in response to features actually used.
> >
> > That's the big error.
> >
> > The full OVS key is huge, OVS is really quite a monster.
> >
> > But people don't use the entire key, nor do they use the totality of
> > the data paths.
> >
> > So just doing a 1-to-1 translation of the OVS datapath into BPF makes
> > absolutely no sense whatsoever and it is guaranteed to have worse
> > performance.

1-to-1 translation has nothing to do with performance.

eBPF/XDP is faster only when you can by-pass/shortcut some code.
If the number of features required are the same, then an eBPF
implementation should be less than or equal to a kernel module's
performance. "less than" because eBPF usually has some limitations
so you have to redesign the data structure.

It's possible that after redesigning your data structure to eBPF,
it becomes faster. But there is no such case in my experience.

Regards,
William

  reply	other threads:[~2019-11-12 17:50 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-18  4:07 Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 01/15] xdp_flow: Add skeleton of XDP based flow offload driver Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 02/15] xdp_flow: Add skeleton bpf program for XDP Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 03/15] bpf: Add API to get program from id Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 04/15] xdp: Export dev_check_xdp and dev_change_xdp Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 05/15] xdp_flow: Attach bpf prog to XDP in kernel after UMH loaded program Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 06/15] xdp_flow: Prepare flow tables in bpf Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 07/15] xdp_flow: Add flow entry insertion/deletion logic in UMH Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 08/15] xdp_flow: Add flow handling and basic actions in bpf prog Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 09/15] xdp_flow: Implement flow replacement/deletion logic in xdp_flow kmod Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 10/15] xdp_flow: Add netdev feature for enabling flow offload to XDP Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 11/15] xdp_flow: Implement redirect action Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 12/15] xdp_flow: Implement vlan_push action Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 13/15] bpf, selftest: Add test for xdp_flow Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 14/15] i40e: prefetch xdp->data before running XDP prog Toshiaki Makita
2019-10-18  4:07 ` [RFC PATCH v2 bpf-next 15/15] bpf, hashtab: Compare keys in long Toshiaki Makita
2019-10-18 15:22 ` [RFC PATCH v2 bpf-next 00/15] xdp_flow: Flow offload to XDP John Fastabend
2019-10-21  7:31   ` Toshiaki Makita
2019-10-22 16:54     ` John Fastabend
2019-10-22 17:45       ` Toke Høiland-Jørgensen
2019-10-24  4:27         ` John Fastabend
2019-10-24 10:13           ` Toke Høiland-Jørgensen
2019-10-27 13:19             ` Toshiaki Makita
2019-10-27 15:21               ` Toke Høiland-Jørgensen
2019-10-28  3:16                 ` David Ahern
2019-10-28  8:36                   ` Toke Høiland-Jørgensen
2019-10-28 10:08                     ` Jesper Dangaard Brouer
2019-10-28 19:07                       ` David Ahern
2019-10-28 19:05                     ` David Ahern
2019-10-31  0:18                 ` Toshiaki Makita
2019-10-31 12:12                   ` Toke Høiland-Jørgensen
2019-11-11  7:32                     ` Toshiaki Makita
2019-11-12 16:53                       ` Toke Høiland-Jørgensen
2019-11-14 10:11                         ` Toshiaki Makita
2019-11-14 12:41                           ` Toke Høiland-Jørgensen
2019-11-18  6:41                             ` Toshiaki Makita
2019-11-18 10:20                               ` Toke Høiland-Jørgensen
2019-11-22  5:42                                 ` Toshiaki Makita
2019-11-22 11:54                                   ` Toke Høiland-Jørgensen
2019-11-25 10:18                                     ` Toshiaki Makita
2019-11-25 13:03                                       ` Toke Høiland-Jørgensen
2019-11-18 10:28                               ` Toke Høiland-Jørgensen
2019-10-27 13:13         ` Toshiaki Makita
2019-10-27 15:24           ` Toke Høiland-Jørgensen
2019-10-27 19:17             ` David Miller
2019-10-31  0:32               ` Toshiaki Makita
2019-11-12 17:50                 ` William Tu [this message]
2019-11-14 10:06                   ` Toshiaki Makita
2019-11-14 17:09                     ` William Tu
2019-11-15 13:16                       ` Toke Høiland-Jørgensen
2019-11-12 17:38             ` William Tu
2019-10-23 14:11       ` Jamal Hadi Salim
2019-10-24  4:38         ` John Fastabend
2019-10-24 17:05           ` Jamal Hadi Salim
2019-10-27 13:27         ` Toshiaki Makita
2019-10-27 13:06       ` Toshiaki Makita
2019-10-21 11:23 ` Björn Töpel
2019-10-21 11:47   ` Toshiaki Makita

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