Improving the scalability of SAMBA bus architecture

SAMBA bus (Lu and Koh, 2003) is a high performance bus architecture that can deliver multiple transactions in one bus cycle under single-winner bus arbitration. The bus architecture displays several advantages such as, high bandwidth, low latency, and low performance penalty from arbitration delay, all of which make it more scalable than traditional buses. However, its scalability may be limited by the bus access logic delay. As a module is connected to the bus through its interface unit, which is connected in series on the bus, the bus logic delay increases linearly as the bus size increases. In this paper, we propose to increase the scalability of SAMBA buses through two methods: control signal lookahead and module clustering. The control signal lookahead technique can determine the bus access control signal in advance, thereby reducing the effective delay of each interface unit. Module clustering, on the other hand, can reduce the number of interface units attached to a bus. Experimental results show that combining these two methods can effectively reduce the bus logic delay, and thus increase the scalability of SAMBA buses.