Optimizing Xen inter-domain data transfer

The delivery of data to computing ressources in a short time is a crucial issue for the effectiveness of High Performance Computing. We meet this issue when, for example, designing drivers for virtual machines. We developped two tools to speed up data transfers between Xen virtual machines. The first one is a circular buffer shared in user memory space between the two communicating domains and allowing transfers without copy. The second pins pages in memory and transfers their Machine Frame Number (MFN), significantly reducing the transfered data volume. This paper briefly unveils the architecture of our tools and compare them with TCP sockets and XenSocket, a circular buffer in kernel memory space.