Adding a new packet scheduling algorithm in the kernel requires implementing a Qdisc kernel module - which could be cumbersome. Writing a custom scheduling algorithm which may not make sense for the rest of the community is frowned upon. On top of Qdiscs, different classifiers and rules can be applied to packets as well, which further complicates the combination of choices. Amery Hung and Cong Wang introduce eBPF Qdisc, a fully programmable Qdisc with eBPF.

Amery and Cong believe that the approach they are taking will provide developers not only a more flexible and safer way to implement packet schedulers, but also orchestrating packets in coordination with other networking components. In this talk, they first show that eBPF Qdisc is capable of realizing a sophisticated Qdisc by implementing fair queueing (fq) Qdisc. Then, they evaluate the performance of the fq against the existing fq in the Linux kernel. Finally, they will show how eBPF Qdisc can help developers implement Qdisc's with diverse functionalities through two use cases: 1) we build a more robust earliest departure time (EDT) rate limiter by coordinating with a fq Qdisc through eBPF maps and 2) show eBPF Qdisc as a flexible way to create network emulators.

cheers, jamal