Screw You Realtek
7 hours ago
- #homelab
- #kubernetes
- #troubleshooting
- Author uses Lenovo M75 boxes as cheap, reasonably powerful k8s nodes for light workloads, but they have problematic Realtek RTL8111/8168/8211/8411 NICs.
- To fix soft-hangs under network load, author switched from the in-kernel r8169 driver to the out-of-tree r8168 driver via dkms package, which initially resolved issues.
- After moving house, one node showed slow performance; iperf tests revealed severe bandwidth drops (3.45 Mbits/sec vs. 987 Mbits/sec) with jumbo frames (MTU 9000).
- Clamping MTU to 1500 restored line rate, and binary search pinpointed a weird threshold: performance failed at MSS 7373 but worked at 7371.
- Claude suggested reverting to the r8169 driver; after removing r8168-dkms and rebooting, jumbo frames worked at line rate, fixing the RX path issue.