The Networking Changes For Linux 5.17 Are Very Exciting

The Linux networking subsystem updates for the in-development 5.17 kernel are quite exciting as usual given how prolific Linux is from large servers in the cloud to running on enterprise networking gear down to Linux on small IoT hardware. Not only is there a lot of hardware driver action as usual but also some key performance/latency optimizations.

On the performance optimization front, there is a significant latency optimization for AF_UNIX sockets.

Another performance win is optimizing x86_64's csum_partial() function that is commonly used for computing TCP checksums.

There is also a big TCP performance optimization by way of deferring SKB freeing after the socket lock is released. See that earlier article for details on the exciting improvement. Or for its exciting impact:

There are many Intel WiFi "IWLWIFI" driver improvements including new Killer AX211 PCI IDs, 6GHz WiFi improvements, support for OCE scanning. TAS support, and more.

Meanwhile on the AMD side is Ethernet support for Yellow Carp, better known as "Rembrandt" APUs. This is for where the networking support is integrated into the SoC.

There is also support for the yet-to-be-released NVIDIA Spectrum-4 network ASIC.

Some of the other networking changes for Linux 5.17 include new BPF helpers, supporting BPF relocations in the kernel loader, preparing libbpf for its v1.0 release, saving some CPU cycles in the WiFi code by using coarse time in the airtime fairness code, supporting the Android AOSP Bluetooth Quality Report, Multi-Patch TCP (MPTCP) enhancements, support for Management Component Transport (MCTP) over Serial, different network offload improvements, Microsoft's cloud driver now has XDP support, and the new IWLMEI driver. Intel's IWLMEI driver is for interfacing between Intel's WiFi driver and its Active Management Technology devices.

There are also a plethora of changes to the many other Linux network drivers as laid out in this pull request for Linux 5.17.