Introduction to eBPF Qdisc and Use Cases
summary
eBPF qdisc implements enqueue/dequeue as BPF programs via BPF stru_ops, adding three kernel/BPF changes: automatic skb reference acquisition on the first arg, verifier support for returning (leaking) skb refs on dequeue, and direct enqueue of skbs into BPF collections via exclusive ownership nodes. A FIFO qdisc is built as a few BPF functions and runs correctly. Performance shows a 7.6% throughput gain over the older BPF design and parity with native qdisks; use cases show loss-aware EDT compensation and mq+netem global state working via BPF maps.
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