The Linux Network Stack
summary
Explains the Linux networking stack from NIC DMA into the sk_buff structure through softirqs and NAPI, including the NAPI hybrid interrupt behavior and per-CPU scaling mechanisms (XPS/XRPS) and how latency is traded for CPU. Describes concrete offloads (GSO/GRO, checksum offload, segmentation), target hardware such as 100 Gbit NICs and limits seen (hundreds of thousands of connections/sec), and recent usable components and patches like tc qdiscs, BPF hooks, nftables and zero-copy sendmsg.
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chapters (17)
- 0:00Intro
- 0:17Problems
- 2:02Agenda
- 3:13How Does a Packet Reach the Kernel?
- 7:19Interrupt
- 9:57Newer Ethernet Cards/Drivers
- 11:53RX Ring Network Card (Example)
- 13:44packet rx
- 17:44socket buffer
- 22:34IPv4 Architecture
- 25:19How Does a Packet Reach the Network Card?
- 28:28packet tx
- 29:57GSO, GRO
- 35:45Nonlinear skbs
- 36:42Scaling: RSS (Receive Side Scaling), RPS
- 39:10Scaling: XPS (Transmit Packet Steering)
- 39:22Byte Queue Limits (BQL)
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