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From: Toshiaki Makita <toshiaki.makita1@gmail.com>
To: William Tu <u9012063@gmail.com>
Cc: 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>,
	John Fastabend <john.fastabend@gmail.com>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Jiri Pirko <jiri@resnulli.us>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>
Subject: Re: [RFC PATCH bpf-next 00/14] xdp_flow: Flow offload to XDP
Date: Fri, 16 Aug 2019 10:38:45 +0900
Message-ID: <fbbfa7da-1a14-5edc-cc0d-7f6e5d97384a@gmail.com> (raw)
In-Reply-To: <CALDO+SYC4sPw-7iDkFMCD=kf2UnTW2qc0m6Kgz41zLmNNxQ+Ww@mail.gmail.com>

On 2019/08/16 0:46, William Tu wrote:
> On Tue, Aug 13, 2019 at 5:07 AM Toshiaki Makita
> <toshiaki.makita1@gmail.com> wrote:
>>
>> This is a rough PoC for an idea to offload TC flower to XDP.
>>
>>
>> * Motivation
>>
>> The purpose is to speed up software TC flower by using XDP.
>>
>> I chose TC flower because my current interest is in OVS. OVS uses TC to
>> offload flow tables to hardware, so if TC can offload flows to XDP, OVS
>> also can be offloaded to XDP.
>>
>> When TC flower filter is offloaded to XDP, the received packets are
>> handled by XDP first, and if their protocol or something is not
>> supported by the eBPF program, the program returns XDP_PASS and packets
>> are passed to upper layer TC.
>>
>> The packet processing flow will be like this when this mechanism,
>> xdp_flow, is used with OVS.
>>
>>   +-------------+
>>   | openvswitch |
>>   |    kmod     |
>>   +-------------+
>>          ^
>>          | if not match in filters (flow key or action not supported by TC)
>>   +-------------+
>>   |  TC flower  |
>>   +-------------+
>>          ^
>>          | if not match in flow tables (flow key or action not supported by XDP)
>>   +-------------+
>>   |  XDP prog   |
>>   +-------------+
>>          ^
>>          | incoming packets
>>
> I like this idea, some comments about the OVS AF_XDP work.
> 
> Another way when using OVS AF_XDP is to serve as slow path of TC flow
> HW offload.
> For example:
> 
>   Userspace OVS datapath (The one used by OVS-DPDK)
>       ^
>        |
>    +------------------------------+
>    |  OVS AF_XDP netdev |
>    +------------------------------+
>           ^
>           | if not supported or not match in flow tables
>    +---------------------+
>    |  TC HW flower  |
>    +---------------------+
>           ^
>           | incoming packets
> 
> So in this case it's either TC HW flower offload, or the userspace PMD OVS.
> Both cases should be pretty fast.
> 
> I think xdp_flow can also be used by OVS AF_XDP netdev, sitting between
> TC HW flower and OVS AF_XDP netdev.
> Before the XDP program sending packet to AF_XDP socket, the
> xdp_flow can execute first, and if not match, then send to AF_XDP.
> So in your patch set, implement s.t like
>    bpf_redirect_map(&xsks_map, index, 0);

Thanks, the concept sounds good but this is probably difficult as long as
this is a TC offload, which is emulating TC.
If I changed the direction and implement offload in ovs-vswitchd, it would
be possible. I'll remember this optimization.

> Another thing is that at each layer we are doing its own packet parsing.
>  From your graph, first parse at XDP program, then at TC flow, then at
> openvswitch kmod.
> I wonder if we can reuse some parsing result.

That would be nice if possible...
Currently I don't have any ideas to do that. Someday XDP may support more
metadata for this or HW-offload like checksum. Then we can store the information
and upper layers may be able to use that.

Toshiaki Makita

      reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-13 12:05 Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 01/14] xdp_flow: Add skeleton of XDP based TC offload driver Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 02/14] xdp_flow: Add skeleton bpf program for XDP Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 03/14] bpf: Add API to get program from id Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 04/14] xdp_flow: Attach bpf prog to XDP in kernel after UMH loaded program Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 05/14] xdp_flow: Prepare flow tables in bpf Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 06/14] xdp_flow: Add flow entry insertion/deletion logic in UMH Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 07/14] xdp_flow: Add flow handling and basic actions in bpf prog Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 08/14] xdp_flow: Implement flow replacement/deletion logic in xdp_flow kmod Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 09/14] xdp_flow: Add netdev feature for enabling TC flower offload to XDP Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 10/14] xdp_flow: Implement redirect action Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 11/14] xdp_flow: Implement vlan_push action Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 12/14] bpf, selftest: Add test for xdp_flow Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 13/14] i40e: prefetch xdp->data before running XDP prog Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 14/14] bpf, hashtab: Compare keys in long Toshiaki Makita
2019-08-14  1:44 ` [RFC PATCH bpf-next 00/14] xdp_flow: Flow offload to XDP Alexei Starovoitov
2019-08-14  7:33   ` Toshiaki Makita
2019-08-15 10:59     ` Toshiaki Makita
2019-08-14 17:07 ` Stanislav Fomichev
2019-08-15 10:26   ` Toshiaki Makita
2019-08-15 15:21     ` Stanislav Fomichev
2019-08-15 19:22       ` Jakub Kicinski
2019-08-16  1:28         ` Toshiaki Makita
2019-08-16 18:52           ` Jakub Kicinski
2019-08-17 14:01             ` Toshiaki Makita
2019-08-16 15:59         ` Stanislav Fomichev
2019-08-16 16:20           ` Stanislav Fomichev
2019-08-16  1:09       ` Toshiaki Makita
2019-08-16 15:35         ` Stanislav Fomichev
2019-08-17 14:10           ` Toshiaki Makita
2019-08-15 15:46 ` William Tu
2019-08-16  1:38   ` Toshiaki Makita [this message]

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