From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: 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>
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: Tue, 12 Nov 2019 17:53:23 +0100 [thread overview]
Message-ID: <87blthox30.fsf@toke.dk> (raw)
In-Reply-To: <640418c3-54ba-cd62-304f-fd9f73f25a42@gmail.com>
Toshiaki Makita <toshiaki.makita1@gmail.com> writes:
>
> Hi Toke,
>
> Sorry for the delay.
>
> On 2019/10/31 21:12, Toke Høiland-Jørgensen wrote:
>> Toshiaki Makita <toshiaki.makita1@gmail.com> writes:
>>
>>> On 2019/10/28 0:21, Toke Høiland-Jørgensen wrote:
>>>> Toshiaki Makita <toshiaki.makita1@gmail.com> writes:
>>>>>> Yeah, you are right that it's something we're thinking about. I'm not
>>>>>> sure we'll actually have the bandwidth to implement a complete solution
>>>>>> ourselves, but we are very much interested in helping others do this,
>>>>>> including smoothing out any rough edges (or adding missing features) in
>>>>>> the core XDP feature set that is needed to achieve this :)
>>>>>
>>>>> I'm very interested in general usability solutions.
>>>>> I'd appreciate if you could join the discussion.
>>>>>
>>>>> Here the basic idea of my approach is to reuse HW-offload infrastructure
>>>>> in kernel.
>>>>> Typical networking features in kernel have offload mechanism (TC flower,
>>>>> nftables, bridge, routing, and so on).
>>>>> In general these are what users want to accelerate, so easy XDP use also
>>>>> should support these features IMO. With this idea, reusing existing
>>>>> HW-offload mechanism is a natural way to me. OVS uses TC to offload
>>>>> flows, then use TC for XDP as well...
>>>>
>>>> I agree that XDP should be able to accelerate existing kernel
>>>> functionality. However, this does not necessarily mean that the kernel
>>>> has to generate an XDP program and install it, like your patch does.
>>>> Rather, what we should be doing is exposing the functionality through
>>>> helpers so XDP can hook into the data structures already present in the
>>>> kernel and make decisions based on what is contained there. We already
>>>> have that for routing; L2 bridging, and some kind of connection
>>>> tracking, are obvious contenders for similar additions.
>>>
>>> Thanks, adding helpers itself should be good, but how does this let users
>>> start using XDP without having them write their own BPF code?
>>
>> It wouldn't in itself. But it would make it possible to write XDP
>> programs that could provide the same functionality; people would then
>> need to run those programs to actually opt-in to this.
>>
>> For some cases this would be a simple "on/off switch", e.g.,
>> "xdp-route-accel --load <dev>", which would install an XDP program that
>> uses the regular kernel routing table (and the same with bridging). We
>> are planning to collect such utilities in the xdp-tools repo - I am
>> currently working on a simple packet filter:
>> https://github.com/xdp-project/xdp-tools/tree/xdp-filter
>
> Let me confirm how this tool adds filter rules.
> Is this adding another commandline tool for firewall?
>
> If so, that is different from my goal.
> Introducing another commandline tool will require people to learn
> more.
>
> My proposal is to reuse kernel interface to minimize such need for
> learning.
I wasn't proposing that this particular tool should be a replacement for
the kernel packet filter; it's deliberately fairly limited in
functionality. My point was that we could create other such tools for
specific use cases which could be more or less drop-in (similar to how
nftables has a command line tool that is compatible with the iptables
syntax).
I'm all for exposing more of the existing kernel capabilities to XDP.
However, I think it's the wrong approach to do this by reimplementing
the functionality in eBPF program and replicating the state in maps;
instead, it's better to refactor the existing kernel functionality to it
can be called directly from an eBPF helper function. And then ship a
tool as part of xdp-tools that installs an XDP program to make use of
these helpers to accelerate the functionality.
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
-Toke
next prev parent reply other threads:[~2019-11-12 16:55 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 4:07 [RFC PATCH v2 bpf-next 00/15] xdp_flow: Flow offload to XDP 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 [this message]
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
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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