AFXDP-rs

This module provides a Rust interface for AF_XDP built on libbpf-sys (https://github.com/alexforster/libbpf-sys).

AF_XDP:

The goals of this crate, in order, are:

Correctness
Performance
Ease of use

Current Status

The API works for my current use cases but I expect it will change to achieve higher performance and usability.

If you have knowledge of Rust FFI and general Rust unsafe things I would greatly appreciate some help auditing this crate as my experience in this area is limited.

Sample Programs

There are two sample programs in src/bin/:

l2fwd-1link: Receives frames on a single link/queue, swaps the MAC and writes back to the same link/queue. This is roughly like the kernel xdpsock_user.c sample program in l2fwd mode.

l2fwd-2link: Receives frames from two link/queue pairs (separate devices) and forwards the frames to the opposite link.

Performance

Test System:

Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GHz
Single X710 (4 physical 10G ports) (i40e)
Kernel: 5.4.2-300.fc31.x86_64
Kernel boot args: skew_tick=1 mitigations=off selinux=0 isolcpus=4-27 nohz_full=4-27 rcu_nobcs=4-27 default_hugepagesz=1G hugepagesz=1G hugepages=4

Traffic Generator:

Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz
Single X710 (4 physical 10G ports) (i40e)
Traffic goes from one port, through test system and to second port on the same X710
T-Rex traffic generator (https://trex-tgn.cisco.com/) (DPDK)
64-byte UDP packets

Scenario 1: l2fwd-2link on a single core running userspace and NAPI

Small amounts of packet loss starts at about 6.5M PPS unidirectional and 6.0M PPS bi-directionally (3M each direction).

Little effort has been put into optimizing this so I expect there are some easy performance wins.

AF_XDP Features

HUGE TLB: At present this crate always uses HUGETLB to map the memory. This may require the hugepages kernel boot argument (above) making it harder for others to play.
ZEROCOPY: At present this crate always passes the ZEROCOPY flag which only works with a small number of drivers
Only the chunked memory mode is supported
Need wakeup flag is required which implies Linux >= 5.4

To Do