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From: Toshiaki Makita <toshiaki.makita1@gmail.com>
To: "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>,
	"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>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	William Tu <u9012063@gmail.com>,
	Stanislav Fomichev <sdf@fomichev.me>
Subject: Re: [RFC PATCH v2 bpf-next 00/15] xdp_flow: Flow offload to XDP
Date: Fri, 22 Nov 2019 14:42:18 +0900	[thread overview]
Message-ID: <db38dee6-1db9-85f3-7a0c-0bcee13b12ea@gmail.com> (raw)
In-Reply-To: <87k17xcwoq.fsf@toke.dk>

On 2019/11/18 19:20, Toke Høiland-Jørgensen wrote:
> Toshiaki Makita <toshiaki.makita1@gmail.com> writes:
> 
> [... trimming the context a bit ...]
> 
>>>>> Take your example of TC rules: You were proposing a flow like this:
>>>>>
>>>>> Userspace TC rule -> kernel rule table -> eBPF map -> generated XDP
>>>>> program
>>>>>
>>>>> Whereas what I mean is that we could do this instead:
>>>>>
>>>>> Userspace TC rule -> kernel rule table
>>>>>
>>>>> and separately
>>>>>
>>>>> XDP program -> bpf helper -> lookup in kernel rule table
>>>>
>>>> Thanks, now I see what you mean.
>>>> You expect an XDP program like this, right?
>>>>
>>>> int xdp_tc(struct xdp_md *ctx)
>>>> {
>>>> 	int act = bpf_xdp_tc_filter(ctx);
>>>> 	return act;
>>>> }
>>>
>>> Yes, basically, except that the XDP program would need to parse the
>>> packet first, and bpf_xdp_tc_filter() would take a parameter struct with
>>> the parsed values. See the usage of bpf_fib_lookup() in
>>> bpf/samples/xdp_fwd_kern.c
>>>
>>>> But doesn't this way lose a chance to reduce/minimize the program to
>>>> only use necessary features for this device?
>>>
>>> Not necessarily. Since the BPF program does the packet parsing and fills
>>> in the TC filter lookup data structure, it can limit what features are
>>> used that way (e.g., if I only want to do IPv6, I just parse the v6
>>> header, ignore TCP/UDP, and drop everything that's not IPv6). The lookup
>>> helper could also have a flag argument to disable some of the lookup
>>> features.
>>
>> It's unclear to me how to configure that.
>> Use options when attaching the program? Something like
>> $ xdp_tc attach eth0 --only-with ipv6
>> But can users always determine their necessary features in advance?
> 
> That's what I'm doing with xdp-filter now. But the answer to your second
> question is likely to be 'probably not', so it would be good to not have
> to do this :)
> 
>> Frequent manual reconfiguration when TC rules frequently changes does
>> not sound nice. Or, add hook to kernel to listen any TC filter event
>> on some daemon and automatically reload the attached program?
> 
> Doesn't have to be a kernel hook; we could enhance the userspace tooling
> to do it. Say we integrate it into 'tc':
> 
> - Add a new command 'tc xdp_accel enable <iface> --features [ipv6,etc]'
> - When adding new rules, add the following logic:
>    - Check if XDP acceleration is enabled
>    - If it is, check whether the rule being added fits into the current
>      'feature set' loaded on that interface.
>      - If the rule needs more features, reload the XDP program to one
>        with the needed additional features.
>      - Or, alternatively, just warn the user and let them manually
>        replace it?

Ok, but there are other userspace tools to configure tc in wild.
python and golang have their own netlink library project.
OVS embeds TC netlink handling code in itself. There may be more tools like this.
I think at least we should have rtnl notification about TC and monitor it
from daemon, if we want to reload the program from userspace tools.

Toshiaki Makita

  reply	other threads:[~2019-11-22  5:42 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 [this message]
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
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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