Gannet: a functional task description language for a service-based SoC architecture

There is a growing demand for solutions allowing to design complex systems-on-chip (SoC) at high abstraction levels. The Gannet project proposes a functional programming approach for high-abstraction design of very large SoCs. Gannet is a distributed service-based SoC architecture, i.e. a network of services offered by hardware or software cores. The functionality of the system is defined by a functional task description language. The Gannet system performs tasks by executing task description programs. Thus Gannet not only provides a novel high abstraction-level SoC design concept, but effectively offers an alternative to the ubiquitous Von Neumann architecture. In this paper we present the Gannet architecture and language and introduce the concept of language services, which dramatically improve the performance. 1 THE GANNET SERVICE-BASED SOC ARCHITECTURE There is a growing demand for solutions allowing to design complex systemson-chip (SoC) at high abstraction levels [1, 2]. The Gannet project aims to address this need by proposing a novel system-on-chip architecture using a functional language paradigm. We propose a distributed service-based system-on-chip architecture which performs tasks through the interaction of services offered by IP cores. The tasks are described in a functional task description language. The physical Gannet fabric 1(a) consists of a matrix of processing cores (tiles) connected through an on-chip network. The architecture is motivated by the growing complexity offered by the latest generation of IC manufacturing technologies. Following Moore’s law, the complexity of integrated circuits has grown steadily in the past decades, from ICs with a few components via increasingly performant microprocessors to ever more complex systems-on-chip[3, 4]. Tomorrow’s SoCs will be very big (billions of logic gates). The main issues with these very large SoCs are connectivity and design complexity [5]. Traditional bus-style interconnects are no longer a viable option: synchronisation of hundreds of processing cores over large distances is impossible; fixed point-to-point connections result in huge wire overheads. Packet-switched on-chip networks (NoCs) [6] provide a solution because they offer flexible connectivity and an efficient mechanism for managing wires. For very large SoCs, design reuse is essential [7]. Design reuse is facilitated by the concept of IP (Intellectual Property) cores. These are are highly complex, self-contained units offering a specific functionality, such as audio/video codecs, cryptography cores, TCP/IP packet filtering etc. They can be implemented as hardware logic circuits, as embedded microcontrollers running specific software, or combinations of both. Because of their self-contained nature, treating IP blocks as services is a logical abstraction. To achieve service-based behaviour, every tile of a Gannet SoC contains a special control unit (the service manager), which provides a serviceoriented interface between the IP core and the system. Designing a Gannet SoC reduces to instantiating the IP cores in the Gannet fabric and creating a task description (a program) in the Gannet functional language. NoC sw it ching node service m odule service m anager configurable service core local m em ory