Linux 5.15 To Bring More Scalable + Reliable Open vSwitch

Linux 5.15 later this year will bring improvements to the kernel side of Open vSwitch, the open-source virtual multi-layer switch implementation that is commonly used in large virtualized environments.

Red Hat's work on per-CPU upcall dispatch handling for the Open vSwitch kernel code has made it into net-next this week, thereby effectively making it among the material now waiting around for the Linux 5.15 cycle.

The kernel code rework moves to an upcall mode using per-CPU dispatch instead of the existing per-vPort dispatch. Long story short, the performance within the Open vSwitch kernel module is more scalable with the number of Netlink sockets scaling to the number of CPUs available rather than the number of vPorts.

Besides greater scaling with today's large servers, the improved Open vSwitch code in net-next also addresses a packet reordering issue currently plaguing the code as well as a thundering herd issue.

The updated OVS code for the kernel is now in net-next. There is also updated OVS user-space patches for distributing upcalls to user-space threads.