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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: Thu, 14 Nov 2019 19:11:36 +0900	[thread overview]
Message-ID: <c1b7ff64-6574-74c7-cd6b-5aa353ec80ce@gmail.com> (raw)
In-Reply-To: <87blthox30.fsf@toke.dk>

On 2019/11/13 1:53, Toke Høiland-Jørgensen wrote:
> 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

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;
}

But doesn't this way lose a chance to reduce/minimize the program
to only use necessary features for this device?

Toshiaki Makita

  reply	other threads:[~2019-11-14 10:11 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 [this message]
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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