bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: William Tu <u9012063@gmail.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Toshiaki Makita <toshiaki.makita1@gmail.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>,
	"David S. Miller" <davem@davemloft.net>,
	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 B 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 09:38:55 -0800	[thread overview]
Message-ID: <CALDO+SZEU7yfZK_JTPKQm-8HR_HMUfNjdMMik862dJDBc8SGQA@mail.gmail.com> (raw)
In-Reply-To: <87wocqrz2v.fsf@toke.dk>

On Sun, Oct 27, 2019 at 8:24 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Toshiaki Makita <toshiaki.makita1@gmail.com> writes:
>
> > On 19/10/23 (水) 2:45:05, Toke Høiland-Jørgensen wrote:
> >> John Fastabend <john.fastabend@gmail.com> writes:
> >>
> >>> I think for sysadmins in general (not OVS) use case I would work
> >>> with Jesper and Toke. They seem to be working on this specific
> >>> problem.
> >>
> >> We're definitely thinking about how we can make "XDP magically speeds up
> >> my network stack" a reality, if that's what you mean. Not that we have
> >> arrived at anything specific yet...
> >>
> >> And yeah, I'd also be happy to discuss what it would take to make a
> >> native XDP implementation of the OVS datapath; including what (if
> >> anything) is missing from the current XDP feature set to make this
> >> feasible. I must admit that I'm not quite clear on why that wasn't the
> >> approach picked for the first attempt to speed up OVS using XDP...
> >
> > Here's some history from William Tu et al.
> > https://linuxplumbersconf.org/event/2/contributions/107/
> >
> > Although his aim was not to speed up OVS but to add kernel-independent
> > datapath, his experience shows full OVS support by eBPF is very
> > difficult.
>
> Yeah, I remember seeing that presentation; it still isn't clear to me
> what exactly the issue was with implementing the OVS datapath in eBPF.
> As far as I can tell from glancing through the paper, only lists program
> size and lack of loops as limitations; both of which have been lifted
> now.
>
Sorry it's not very clear in the presentation and paper.
Some of the limitations are resolved today, let me list my experiences.

This is from OVS's feature requirements:
What's missing in eBPF
- limited stack size (resolved now)
- limited program size (resolved now)
- dynamic loop support for OVS actions applied to packet
  (now bounded loop is supported)
- no connection tracking/alg support (people suggest to look cilium)
- no packet fragment/defragment support
- no wildcard table/map type support
I think it would be good to restart the project again using
existing eBPF features.

What's missing in XDP
- clone a packet: this is very basic feature for a switch to
  broadcast/multicast. I understand it's hard to implement.
  A workaround is to XDP_PASS and let tc do the clone. But slow.

Because of no packet cloning support, I didn't try implementing
OVS datapath in XDP.

> 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...

Right, the point of that project is not performance improvement.
But sort of to see how existing eBPF feature can be used to implement
all features needed by OVS datapath.

Regards,
William

  parent reply	other threads:[~2019-11-12 17:39 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
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 [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CALDO+SZEU7yfZK_JTPKQm-8HR_HMUfNjdMMik862dJDBc8SGQA@mail.gmail.com \
    --to=u9012063@gmail.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=fw@strlen.de \
    --cc=hawk@kernel.org \
    --cc=jakub.kicinski@netronome.com \
    --cc=jhs@mojatatu.com \
    --cc=jiri@resnulli.us \
    --cc=john.fastabend@gmail.com \
    --cc=kadlec@netfilter.org \
    --cc=kafai@fb.com \
    --cc=netdev@vger.kernel.org \
    --cc=pablo@netfilter.org \
    --cc=pshelar@ovn.org \
    --cc=sdf@fomichev.me \
    --cc=songliubraving@fb.com \
    --cc=toke@redhat.com \
    --cc=toshiaki.makita1@gmail.com \
    --cc=xiyou.wangcong@gmail.com \
    --cc=yhs@fb.com \
    --subject='Re: [RFC PATCH v2 bpf-next 00/15] xdp_flow: Flow offload to XDP' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).