Re: [PATCHv17 bpf-next 0/6] xdp: add a new helper for dev map multicast support

Hangbin Liu
2021-02-04T00:16:16Z

Hi Daniel, Alexei,

It has been one week after Maciej, Toke, John's review/ack. What should
I do to make a progress for this patch set?

Thanks
Hangbin
On Mon, Jan 25, 2021 at 08:45:10PM +0800, Hangbin Liu wrote:
> This patch 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 there
> may have multi interfaces you want to exclude.
>
> 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 1st patch is Jesper's run devmap xdp_prog later in bulking step.
> The 2st patch add a new bpf arg to allow NULL map pointer.
> The 3rd patch add the new bpf_redirect_map_multi() helper.
> The 4-6 patches are for usage sample and testing purpose.
>
> I did same perf tests with the following topo:
>
> --------------------- ---------------------
> | Host A (i40e 10G) | ---------- | eno1(i40e 10G) |
> --------------------- | |
> | Host B |
> --------------------- | |
> | Host C (i40e 10G) | ---------- | eno2(i40e 10G) |
> --------------------- vlan2 | -------- |
> | veth1 -- | veth0| |
> | -------- |
> --------------------|
> On Host A:
> # pktgen/pktgen_sample03_burst_single_flow.sh -i eno1 -d $dst_ip -m $dst_mac -s 64
>
> On Host B(Intel(R) Xeon(R) CPU E5-2690 v3 @ 2.60GHz, 128G Memory):
> Use xdp_redirect_map and xdp_redirect_map_multi in samples/bpf for testing.
> The veth0 in netns load dummy drop program. The forward_map max_entries in
> xdp_redirect_map_multi is modify to 4.
>
> Here is the perf result with 5.10 rc6:
>
> The are about +/- 0.1M deviation for native testing
> Version | Test | Generic | Native | Native + 2nd
> 5.10 rc6 | xdp_redirect_map i40e->i40e | 2.0M | 9.1M | 8.0M
> 5.10 rc6 | xdp_redirect_map i40e->veth | 1.7M | 11.0M | 9.7M
> 5.10 rc6 + patch1 | xdp_redirect_map i40e->i40e | 2.0M | 9.5M | 7.5M
> 5.10 rc6 + patch1 | xdp_redirect_map i40e->veth | 1.7M | 11.6M | 9.1M
> 5.10 rc6 + patch1-6 | xdp_redirect_map i40e->i40e | 2.0M | 9.5M | 7.5M
> 5.10 rc6 + patch1-6 | xdp_redirect_map i40e->veth | 1.7M | 11.6M | 9.1M
> 5.10 rc6 + patch1-6 | xdp_redirect_map_multi i40e->i40e | 1.7M | 7.8M | 6.4M
> 5.10 rc6 + patch1-6 | xdp_redirect_map_multi i40e->veth | 1.4M | 9.3M | 7.5M
> 5.10 rc6 + patch1-6 | xdp_redirect_map_multi i40e->i40e+veth | 1.0M | 3.2M | 2.7M
>
> Last but not least, thanks a lot to Toke, Jesper, Jiri and Eelco for
> suggestions and help on implementation.
>
> [0] https://xdp-project.net/#Handling-multicast
>
> v17:
> For patch 01:
> a) rename to_sent to to_send.
> b) clear bq dev_rx, xdp_prog and flush_node in __dev_flush().
>
> v16:
> refactor bq_xmit_all logic and remove error label for patch 01
>
> v15:
> Update bq_xmit_all() logic for patch 01.
> Add some comments and remove useless variable for patch 03.
> Use bpf_object__find_program_by_title() for patch 04 and 06.
>
> v14:
> No code update, just rebase the code on latest bpf-next
>
> v13:
> Pass in xdp_prog through __xdp_enqueue() for patch 01. Update related
> code in patch 03.
>
> v12:
> Add Jesper's xdp_prog patch, rebase my works on this and latest bpf-next
> Add 2nd xdp_prog test on the sample and selftests.
>
> v11:
> Fix bpf_redirect_map_multi() helper description typo.
> Add loop limit for devmap_get_next_obj() and dev_map_redirect_multi().
>
> v10:
> Rebase the code to latest bpf-next.
> Update helper bpf_xdp_redirect_map_multi()
> - No need to check map pointer as we will do the check in verifier.
>
> v9:
> Update helper bpf_xdp_redirect_map_multi()
> - Use ARG_CONST_MAP_PTR_OR_NULL for helper arg2
>
> v8:
> a) Update function dev_in_exclude_map():
> - remove duplicate ex_map map_type check in
> - lookup the element in dev map by obj dev index directly instead
> of looping all the map
>
> v7:
> a) Fix helper flag check
> b) Limit the *ex_map* to use DEVMAP_HASH only and update function
> dev_in_exclude_map() to get better performance.
>
> v6: converted helper return types from int to long
>
> v5:
> a) Check devmap_get_next_key() return value.
> b) Pass through flags to __bpf_tx_xdp_map() instead of bool value.
> c) In function dev_map_enqueue_multi(), consume xdpf for the last
> obj instead of the first on.
> d) Update helper description and code comments to explain that we
> use NULL target value to distinguish multicast and unicast
> forwarding.
> e) Update memory model, memory id and frame_sz in xdpf_clone().
> f) Split the tests from sample and add a bpf kernel selftest patch.
>
> v4: Fix bpf_xdp_redirect_map_multi_proto arg2_type typo
>
> v3: Based on Toke's suggestion, do the following update
> a) Update bpf_redirect_map_multi() description in bpf.h.
> b) Fix exclude_ifindex checking order in dev_in_exclude_map().
> c) Fix one more xdpf clone in dev_map_enqueue_multi().
> d) Go find next one in dev_map_enqueue_multi() if the interface is not
> able to forward instead of abort the whole loop.
> e) Remove READ_ONCE/WRITE_ONCE for ex_map.
>
> v2: Add new syscall bpf_xdp_redirect_map_multi() which could accept
> include/exclude maps directly.
>
> Hangbin Liu (5):
> bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL
> xdp: add a new helper for dev map multicast support
> sample/bpf: add xdp_redirect_map_multicast test
> selftests/bpf: Add verifier tests for bpf arg
> ARG_CONST_MAP_PTR_OR_NULL
> selftests/bpf: add xdp_redirect_multi test
>
> Jesper Dangaard Brouer (1):
> bpf: run devmap xdp_prog on flush instead of bulk enqueue
>
> include/linux/bpf.h | 21 ++
> include/linux/filter.h | 1 +
> include/net/xdp.h | 1 +
> include/uapi/linux/bpf.h | 28 ++
> kernel/bpf/devmap.c | 262 +++++++++++----
> kernel/bpf/verifier.c | 16 +-
> net/core/filter.c | 124 ++++++-
> net/core/xdp.c | 29 ++
> samples/bpf/Makefile | 3 +
> samples/bpf/xdp_redirect_map_multi_kern.c | 87 +++++
> samples/bpf/xdp_redirect_map_multi_user.c | 302 ++++++++++++++++++
> tools/include/uapi/linux/bpf.h | 28 ++
> tools/testing/selftests/bpf/Makefile | 3 +-
> .../bpf/progs/xdp_redirect_multi_kern.c | 111 +++++++
> tools/testing/selftests/bpf/test_verifier.c | 22 +-
> .../selftests/bpf/test_xdp_redirect_multi.sh | 208 ++++++++++++
> .../testing/selftests/bpf/verifier/map_ptr.c | 70 ++++
> .../selftests/bpf/xdp_redirect_multi.c | 252 +++++++++++++++
> 18 files changed, 1501 insertions(+), 67 deletions(-)
> create mode 100644 samples/bpf/xdp_redirect_map_multi_kern.c
> create mode 100644 samples/bpf/xdp_redirect_map_multi_user.c
> create mode 100644 tools/testing/selftests/bpf/progs/xdp_redirect_multi_kern.c
> create mode 100755 tools/testing/selftests/bpf/test_xdp_redirect_multi.sh
> create mode 100644 tools/testing/selftests/bpf/xdp_redirect_multi.c
>
> --
> 2.26.2
>