PCI Express multi-root switch reconfiguration during system operation

Abstract

As the use of data continues to expand, reliance on enterprise datacenters have become more and more critical. Evaluation of modern day datacenter performance has showed that datacenter servers are severely underutilized, resulting in inefficient use of physical and software resources. In order to alleviate these concerns, datacenters must improve their resiliency, flexibility and scalability. CPU and memory virtualization are approaches that are becoming increasingly prevalent, but a major bottleneck still exists in I/O connectivity due to the physical constraints of I/O devices in a clustered system. One solution lies with the recently developed PCI Express multi-root partitionable switch. The partitionable switch is highly configurable and provides a means of altering the allocation of I/O devices amongst multiple hosts. This offers a range of unexplored possibilities to improve system flexibility. In the thesis, we investigate the feasibility of integrating and reconfiguring a PCI Express multi-root switch in a multi-host environment on a FreeBSD platform in a live system. We study modifications required of the PCI bus and system resources. We also detail the development of a device driver to handle dynamic reconfiguration of the switch and the system's PCI bus data structures.