Windows has supported Receive Side Scaling (RSS) for a very long time and most NIC hardware is designed to meet its requirements. This allows Windows to use the hardware to load-balance TCP flows across all CPUs and avoid locking in the stack.
My recent work has extended the Xen netif protocol so that backends can be coded to meet the requirements of Windows RSS. The first implementation that meets the requirements is Linux xen-netback and this has been verified to meet Microsoft Logo requirements in conjunction with the latest Xen Project PV frontend.
This talk will detail the protocol extension, discuss the Linux backend implementation and show how aggregate network performance now scales effectively with the number of vCPUs in the Windows guest.
