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From: David Ahern <dsahern@gmail.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: "Toke Høiland-Jørgensen" <toke@redhat.com>,
	"Alexei Starovoitov" <alexei.starovoitov@gmail.com>,
	"Hangbin Liu" <liuhangbin@gmail.com>, bpf <bpf@vger.kernel.org>,
	"Network Development" <netdev@vger.kernel.org>,
	"Jiri Benc" <jbenc@redhat.com>,
	"Eelco Chaudron" <echaudro@redhat.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Lorenzo Bianconi" <lorenzo.bianconi@redhat.com>,
	"Andrii Nakryiko" <andrii.nakryiko@gmail.com>
Subject: Re: [PATCHv11 bpf-next 2/5] xdp: add a new helper for dev map multicast support
Date: Tue, 15 Sep 2020 10:12:09 -0600
Message-ID: <3b498f73-0a0c-bd25-d1a1-b1098ed403e2@gmail.com> (raw)
In-Reply-To: <20200911095820.304d9877@carbon>

On 9/11/20 1:58 AM, Jesper Dangaard Brouer wrote:
> On Thu, 10 Sep 2020 12:35:33 -0600
> David Ahern <dsahern@gmail.com> wrote:
> 
>> On 9/10/20 11:50 AM, Jesper Dangaard Brouer wrote:
>>> Maybe we should change the devmap-prog approach, and run this on the
>>> xdp_frame's (in bq_xmit_all() to be precise) .  Hangbin's patchset
>>> clearly shows that we need this "layer" between running the xdp_prog and
>>> the devmap-prog.   
>>
>> I would prefer to leave it in dev_map_enqueue.
>>
>> The main premise at the moment is that the program attached to the
>> DEVMAP entry is an ACL specific to that dev. If the program is going to
>> drop the packet, then no sense queueing it.
>>
>> I also expect a follow on feature will be useful to allow the DEVMAP
>> program to do another REDIRECT (e.g., potentially after modifying). It
>> is not handled at the moment as it needs thought - e.g., limiting the
>> number of iterative redirects. If such a feature does happen, then no
>> sense queueing it to the current device.
> 
> It makes a lot of sense to do queuing before redirecting again.  The
> (hidden) bulking we do at XDP redirect is the primary reason for the
> performance boost. We all remember performance difference between
> non-map version of redirect (which Toke fixed via always having the
> bulking available in net_device->xdp_bulkq).
> 
> In a simple micro-benchmark I bet it will look better running the
> devmap-prog right after the xdp_prog (which is what we have today). But
> I claim this is the wrong approach, as soon as (1) traffic is more
> intermixed, and (2) devmap-prog gets bigger and becomes more specific
> to the egress-device (e.g. BPF update constants per egress-device).
> When this happens performance suffers, as I-cache and data-access to
> each egress-device gets pushed out of cache. (Hint VPP/fd.io approach)
> 
> Queuing xdp_frames up for your devmap-prog makes sense, as these share
> common properties.  With intermix traffic the first xdp_prog will sort
> packets into egress-devices, and then the devmap-prog can operate on
> these.  The best illustration[1] of this sorting I saw in a Netflix
> blogpost[2] about FreeBSD, section "RSS Assisted LRO" (not directly
> related, but illustration was good).
> 
> 
> [1] https://miro.medium.com/max/700/1%2alTGL1_D6hTMEMa7EDV8yZA.png
> [2] https://netflixtechblog.com/serving-100-gbps-from-an-open-connect-appliance-cdb51dda3b99
> 

I understand the theory and testing will need to bear that out. There is
a bit of distance (code wise) between where the program is run now and
where you want to put it - the conversion from xdp_buff
to xdp_frame, the enqueue, and what it means to do a redirect to another
device in bq_xmit_all.

More importantly though for a redirect is the current xdp_ok_fwd_dev
check in __xdp_enqueue which for a redirect could be doing the wrong
checks for the wrong device.

  reply index

Thread overview: 127+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15  8:54 [RFC PATCH bpf-next 0/2] xdp: add " 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
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
2020-08-26 13:19           ` [PATCHv9 bpf-next 0/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-08-26 13:19             ` [PATCHv9 bpf-next 1/5] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-08-28 21:56               ` Daniel Borkmann
2020-09-03  9:15                 ` Hangbin Liu
2020-08-26 13:19             ` [PATCHv9 bpf-next 2/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-08-28 22:05               ` Daniel Borkmann
2020-08-26 13:20             ` [PATCHv9 bpf-next 3/5] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-08-26 13:20             ` [PATCHv9 bpf-next 4/5] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-08-26 13:20             ` [PATCHv9 bpf-next 5/5] selftests/bpf: Add verifier tests for bpf arg ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-03 10:26             ` [PATCHv10 bpf-next 0/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-03 10:26               ` [PATCHv10 bpf-next 1/5] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-04 14:26                 ` Daniel Borkmann
2020-09-03 10:26               ` [PATCHv10 bpf-next 2/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-04 14:22                 ` Daniel Borkmann
2020-09-03 10:26               ` [PATCHv10 bpf-next 3/5] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-09-03 10:27               ` [PATCHv10 bpf-next 4/5] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-09-03 10:27               ` [PATCHv10 bpf-next 5/5] selftests/bpf: Add verifier tests for bpf arg ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-07  8:27               ` [PATCHv11 bpf-next 0/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 1/5] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 2/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-09 21:52                   ` Alexei Starovoitov
2020-09-10  2:35                     ` Hangbin Liu
2020-09-10  3:30                       ` David Ahern
2020-09-10  5:35                         ` Alexei Starovoitov
2020-09-10  9:44                           ` Toke Høiland-Jørgensen
2020-09-10 15:39                             ` Alexei Starovoitov
2020-09-10 17:50                             ` Jesper Dangaard Brouer
2020-09-10 18:35                               ` David Ahern
2020-09-11  7:58                                 ` Jesper Dangaard Brouer
2020-09-15 16:12                                   ` David Ahern [this message]
2020-09-07  8:27                 ` [PATCHv11 bpf-next 3/5] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 4/5] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 5/5] selftests/bpf: Add verifier tests for bpf arg ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu

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