The networking subsystem updates have landed in the Linux 5.19 kernel with big updates to core networking code as well as a lot of individual driver work this cycle both for wired and wireless networking.
There is a lot going on in the networking space as usual with Linux running on everything from consumer network switches up through massive networking equipment by hyperscalers. Linux 5.19 brings Big TCP support as a very exciting core innovation, pureLiFi’s device driver is merged for the new light-based networking, various new wired and wireless device support, never-ending work improving BPF, and other innovations.
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Linux 5.19 networking subsystem highlights include:
– Support for Big TCP to overcome current limits and reduce TCP/IP stack overhead with 200Gbit and 400Gbit being hit within data centers. Big TCP is about going past the current 64KB TSO/GRO packet limit size for IPv6 traffic by way of the IPv6 Jumbogram extension header. Enabling big TCP across both send/receive systems can lead to huge throughput improvements and lower latencies for high speed networking environments. This Big TCP support is prepared for the core network code as well as the VETH, MLX4, and MLX5 drivers in v5.19.
– Mainlining of pureLiFi’s wireless drivers that use LED lighting for wireless communication. The driver supports pureLiFi X / XL / XC devices.
– Silicon Labs’ WFX WiFi Linux driver promoted out of staging.
– Using per-CPU lists rather than per-socket lists for the SKB freeing deferral. In tests carried out by Google’s Eric Dumazet who has spearheaded many Linux networking optimizations there are impressive gains. Benchmarks in one case by Eric show going from 49685 Mbits to 71874 Mbits with this switch.
– Various BPF improvements from supporting the BPF link iterator to libbpf support for User Statistically-Defined Tracing (USDTs) to various speed-ups/optimizations.
– Continued Multi-Path TCP (MPTCP) enhancements. MPTCP work this cycle includes support for the MPTCP path manager in user-space, support for falling back to regular TCP in certain cases, and avoiding possible races in MPTCP-level window tracking to enhance throughput and better stability.
– The Qualcomm ath11k WiFi driver has added Wake-on-WLAN support for more chipsets, device recovery / firmware restart support, support for reading the country code from the SMBIOS on more hardware, enabling keep-alive during WoWLAN, and remain-on-channel support.
– Support for zero-copy transfer with TLS 1.2 crypto offload.
– Realtek 8852ce device support within the RTW89 WiFi driver.
– Other new hardware support includes the Sunplus SP7021 SoC, Rensas RZ/V2M, MediaTek MT7986 switches, WCN6750, and MediaTek T700 modems.
The full list of Linux 5.19 networking changes can be found on the kernel mailing list.