Preliminary product line support in BitKeeper

Abstract

One of the challenges of implementing a product line process is finding the appropriate tools for automation. One of our larger customers was implementing a product line process by-hand in a labor intensive and fragile way. We collaborated with them to evolve our distributed version control system, BitKeeper, into a tool that could handle their performance and product line requirements. The resulting product line generated several complex CPUs (around a billion transistors each). In this paper, we describe their by-hand process for producing different variations of a computer processor; we'll provide some background on the distributed version control system they were using; we'll describe the architectural changes implemented in BitKeeper for supporting product line work flows; we'll describe some of the changes we did to increase performance and provide some benchmark results comparing BitKeeper to Git, and we'll describe the work flow resulting from using the new architecture to replace their by-hand process. In the final section we'll discuss the current limitations of the existing tool, and describe how we plan on evolving it to overcome those limitations.