Performance evaluation of multithreading in a Diameter Credit Control Application

Abstract: Moore's law states that the amount of computational power available at a given cost doubles every 18 months and indeed, for the past 20 years there has been a tremendous development in microprocessors. However, for the last few years, Moore's law has been subject for debate, since to manage heat issues, processor manufacturers have begun favoring multicore processors, which means parallel computation has become necessary to fully utilize the hardware. This also means that software has to be written with multiprocessing in mind to take full advantage of the hardware, and writing parallel software introduces a whole new set of problems. For the last couple of years, the demands on telecommunication systems have increased and to manage the increasing demands, multiprocessor servers have become a necessity. Applications must fully utilize the hardware and such an application is the Diameter Credit Control Application (DCCA). The DCCA uses the Diameter networking protocol and the DCCA's purpose is to provide a framework for real-time charging. This could, for instance, be to grant or deny a user's request of a specific network activity and to account for the eventual use of that network resource. This thesis investigates whether it is possible to develop a Diameter Credit Control Application that achieves linear scaling and the eventual pitfalls that exist when developing a scalable DCCA server. The assumption is based on the observation that the DCCA server's connections have little to nothing in common (i.e. little or no synchronization), and introducing more processors should therefore give linear scaling. To investigate whether a DCCA server's performance scales linearly, a prototype has been developed. Along with the development of the prototype, constant performance analysis was conducted to see what affected performance and server scalability in a multiprocessor DCCA environment. As the results show, quite a few factors besides synchronization and independent connections affected scalability of the DCCA prototype. The results show that the DCCA prototype did not always achieve linear scaling. However, even if it was not linear, certain design decisions gave considerable performance increase when more processors were introduced.