In my last post, I talked about the architecture of Hyper-V Virtual Switch (VMSWITCH), that powers some of the largest data centers in the world, including but not limited to Windows Azure. In this post I would talk about how it is able to meet the networking performance requirements of the demanding workloads that runs in these data centers.
VMSWITCH provides an extremely high performance packet processing pipeline by using various techniques such as lock free data path, using pre-allocated memory buffers, batch packet processing etc. In addition, it leverages the packet processing offloads provided by underlying physical NIC hardware. These offloads do some of the packet processing in NIC hardware, thereby reducing the overall CPU usage and providing a high performance networking. If you are unfamiliar with NIC offloads, you may want to first read about them here and here. (more…)