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From: "Eelco Chaudron" <echaudro@redhat.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: "Hangbin Liu" <liuhangbin@gmail.com>,
	bpf@vger.kernel.org, netdev@vger.kernel.org,
	"Jiri Benc" <jbenc@redhat.com>,
	"Jesper Dangaard Brouer" <brouer@redhat.com>,
	ast@kernel.org, "Daniel Borkmann" <daniel@iogearbox.net>,
	"Lorenzo Bianconi" <lorenzo.bianconi@redhat.com>
Subject: Re: [PATCHv4 bpf-next 0/2] xdp: add dev map multicast support
Date: Wed, 27 May 2020 12:32:47 +0200
Message-ID: <28D58684-578C-4DDF-B18D-70280B923590@redhat.com> (raw)
In-Reply-To: <87zh9t1xvh.fsf@toke.dk>



On 27 May 2020, at 12:21, Toke Høiland-Jørgensen wrote:

> Hangbin Liu <liuhangbin@gmail.com> writes:
>
>> Hi all,
>>
>> This patchset is for xdp multicast support, which has been discussed
>> before[0]. The goal is to be able to implement an OVS-like data plane 
>> in
>> XDP, i.e., a software switch that can forward XDP frames to multiple
>> ports.
>>
>> To achieve this, an application needs to specify a group of 
>> interfaces
>> to forward a packet to. It is also common to want to exclude one or 
>> more
>> physical interfaces from the forwarding operation - e.g., to forward 
>> a
>> packet to all interfaces in the multicast group except the interface 
>> it
>> arrived on. While this could be done simply by adding more groups, 
>> this
>> quickly leads to a combinatorial explosion in the number of groups an
>> application has to maintain.
>>
>> To avoid the combinatorial explosion, we propose to include the 
>> ability
>> to specify an "exclude group" as part of the forwarding operation. 
>> This
>> needs to be a group (instead of just a single port index), because a
>> physical interface can be part of a logical grouping, such as a bond
>> device.
>>
>> Thus, the logical forwarding operation becomes a "set difference"
>> operation, i.e. "forward to all ports in group A that are not also in
>> group B". This series implements such an operation using device maps 
>> to
>> represent the groups. This means that the XDP program specifies two
>> device maps, one containing the list of netdevs to redirect to, and 
>> the
>> other containing the exclude list.
>>
>> To achieve this, I re-implement a new helper bpf_redirect_map_multi()
>> to accept two maps, the forwarding map and exclude map. If user
>> don't want to use exclude map and just want simply stop redirecting 
>> back
>> to ingress device, they can use flag BPF_F_EXCLUDE_INGRESS.
>>
>> The example in patch 2 is functional, but not a lot of effort
>> has been made on performance optimisation. I did a simple test(pkt 
>> size 64)
>> with pktgen. Here is the test result with BPF_MAP_TYPE_DEVMAP_HASH
>> arrays:
>>
>> bpf_redirect_map() with 1 ingress, 1 egress:
>> generic path: ~1600k pps
>> native path: ~980k pps
>>
>> bpf_redirect_map_multi() with 1 ingress, 3 egress:
>> generic path: ~600k pps
>> native path: ~480k pps
>>
>> bpf_redirect_map_multi() with 1 ingress, 9 egress:
>> generic path: ~125k pps
>> native path: ~100k pps
>>
>> The bpf_redirect_map_multi() is slower than bpf_redirect_map() as we 
>> loop
>> the arrays and do clone skb/xdpf. The native path is slower than 
>> generic
>> path as we send skbs by pktgen. So the result looks reasonable.
>
> How are you running these tests? Still on virtual devices? We really
> need results from a physical setup in native mode to assess the impact
> on the native-XDP fast path. The numbers above don't tell much in this
> regard. I'd also like to see a before/after patch for straight
> bpf_redirect_map(), since you're messing with the fast path, and we 
> want
> to make sure it's not causing a performance regression for regular
> redirect.
>
> Finally, since the overhead seems to be quite substantial: A 
> comparison
> with a regular network stack bridge might make sense? After all we 
> also
> want to make sure it's a performance win over that :)

What about adding a test with only one egress port? So it compares 
better to bpf_redirect_map(), i.e. “bpf_redirect_map_multi() with 1 
ingress, 1 egress”.


  reply index

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15  8:54 [RFC PATCH " Hangbin Liu
2020-04-15  8:54 ` [RFC PATCH bpf-next 1/2] " Hangbin Liu
2020-04-20  9:52   ` Hangbin Liu
2020-04-15  8:54 ` [RFC PATCH bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-04-24  8:56 ` [RFC PATCHv2 bpf-next 0/2] xdp: add dev map multicast support Hangbin Liu
2020-04-24  8:56   ` [RFC PATCHv2 bpf-next 1/2] xdp: add a new helper for " Hangbin Liu
2020-04-24 14:19     ` Lorenzo Bianconi
2020-04-28 11:09       ` Eelco Chaudron
2020-05-06  9:35       ` Hangbin Liu
2020-04-24 14:34     ` Toke Høiland-Jørgensen
2020-05-06  9:14       ` Hangbin Liu
2020-05-06 10:00         ` Toke Høiland-Jørgensen
2020-05-08  8:53           ` Hangbin Liu
2020-05-08 14:58             ` Toke Høiland-Jørgensen
2020-05-18  8:45       ` Hangbin Liu
2020-05-19 10:15         ` Jesper Dangaard Brouer
2020-05-20  1:24           ` Hangbin Liu
2020-04-24  8:56   ` [RFC PATCHv2 bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-04-24 14:21     ` Lorenzo Bianconi
2020-05-23  6:05 ` [PATCHv3 bpf-next 0/2] xdp: add dev map multicast support Hangbin Liu
2020-05-23  6:05   ` [PATCHv3 bpf-next 1/2] xdp: add a new helper for " Hangbin Liu
2020-05-26  7:34     ` kbuild test robot
2020-05-23  6:05   ` [PATCHv3 bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-05-26 14:05 ` [PATCHv4 bpf-next 0/2] xdp: add dev map multicast support Hangbin Liu
2020-05-26 14:05   ` [PATCHv4 bpf-next 1/2] xdp: add a new helper for " Hangbin Liu
2020-05-27 10:29     ` Toke Høiland-Jørgensen
2020-06-10 10:18     ` Jesper Dangaard Brouer
2020-06-12  8:54       ` Hangbin Liu
2020-06-16  8:55         ` Jesper Dangaard Brouer
2020-06-16 10:11           ` Hangbin Liu
2020-06-16 14:38             ` Jesper Dangaard Brouer
2020-06-10 10:21     ` Jesper Dangaard Brouer
2020-06-10 10:29       ` Toke Høiland-Jørgensen
2020-06-16  9:04         ` Jesper Dangaard Brouer
2020-05-26 14:05   ` [PATCHv4 bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-05-27 10:21   ` [PATCHv4 bpf-next 0/2] xdp: add dev map multicast support Toke Høiland-Jørgensen
2020-05-27 10:32     ` Eelco Chaudron [this message]
2020-05-27 12:38     ` Hangbin Liu
2020-05-27 15:04       ` Toke Høiland-Jørgensen
2020-06-16  9:09         ` Jesper Dangaard Brouer
2020-06-16  9:47           ` Hangbin Liu
2020-06-03  2:40     ` Hangbin Liu
2020-06-03 11:05       ` Toke Høiland-Jørgensen
2020-06-04  4:09         ` Hangbin Liu
2020-06-04  9:44           ` Toke Høiland-Jørgensen
2020-06-04 12:12             ` Hangbin Liu
2020-06-04 12:37               ` Toke Høiland-Jørgensen
2020-06-04 14:41                 ` Hangbin Liu
2020-06-04 16:02                   ` Toke Høiland-Jørgensen
2020-06-05  6:26                     ` Hangbin Liu
2020-06-08 15:32                       ` Toke Høiland-Jørgensen
2020-06-09  3:03                         ` Hangbin Liu
2020-06-09 20:31                           ` Toke Høiland-Jørgensen
2020-06-10  2:35                             ` Hangbin Liu
2020-06-10 10:03                               ` Jesper Dangaard Brouer
2020-07-01  4:19   ` [PATCHv5 bpf-next 0/3] xdp: add a new helper for " Hangbin Liu
2020-07-01  4:19     ` [PATCHv5 bpf-next 1/3] " Hangbin Liu
2020-07-01  5:09       ` Andrii Nakryiko
2020-07-01  6:51         ` Hangbin Liu
2020-07-01 18:33       ` kernel test robot
2020-07-01  4:19     ` [PATCHv5 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-01  4:19     ` [PATCHv5 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-07-09  1:30     ` [PATCHv6 bpf-next 0/3] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-07-09  1:30       ` [PATCHv6 bpf-next 1/3] " Hangbin Liu
2020-07-09 16:33         ` David Ahern
2020-07-10  6:55           ` Hangbin Liu
2020-07-10 13:46             ` David Ahern
2020-07-11  0:26               ` Hangbin Liu
2020-07-11 16:09                 ` David Ahern
2020-07-09  1:30       ` [PATCHv6 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-09 22:40         ` Daniel Borkmann
2020-07-10  6:41           ` Hangbin Liu
2020-07-10 14:32             ` Daniel Borkmann
2020-07-11  0:21               ` Hangbin Liu
2020-07-09  1:30       ` [PATCHv6 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-07-09 22:37       ` [PATCHv6 bpf-next 0/3] xdp: add a new helper for dev map multicast support Daniel Borkmann
2020-07-10  7:36         ` Hangbin Liu
2020-07-10 15:02           ` Daniel Borkmann
2020-07-10 16:52             ` David Ahern
2020-07-14  6:32       ` [PATCHv7 " Hangbin Liu
2020-07-14  6:32         ` [PATCHv7 bpf-next 1/3] " Hangbin Liu
2020-07-14 21:52           ` Toke Høiland-Jørgensen
2020-07-15 12:25             ` Hangbin Liu
2020-07-14  6:32         ` [PATCHv7 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-14  6:32         ` [PATCHv7 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-07-14 12:29         ` [PATCHv7 bpf-next 0/3] xdp: add a new helper for dev map multicast support Toke Høiland-Jørgensen
2020-07-14 17:12           ` David Ahern
2020-07-14 21:53             ` Toke Høiland-Jørgensen
2020-07-15 12:31               ` Hangbin Liu
2020-07-15  3:45             ` Hangbin Liu
2020-07-15 13:08         ` [PATCHv8 " Hangbin Liu
2020-07-15 13:08           ` [PATCHv8 bpf-next 1/3] " Hangbin Liu
2020-07-15 13:08           ` [PATCHv8 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-15 13:08           ` [PATCHv8 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu

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