Circuit Level Design of a Hardware Hash Unit for use in Modern Microprocessors

Modern microprocessors contain several Special Function Units (SFUs) such as specialized arithmetic units, cryptographic processors, etc. In recent times, applications such as cloud computing, web-based search engines, and network applications are widely used, and place new demands on the microprocessor. Hashing is a key algorithm that is extensively used in such applications. Hashing is typically performed in software. Thus, implementing a hardware-based hash unit on a modern microprocessor would potentially increase performance significantly. In this paper, we present the circuit design for a hardware hash unit (HU) for modern microprocessors, using a 45nm technology. Our proposed hardware hash unit is based on the use of a CAM to implement each bin of the hash function. We simulate the HU circuit and compare it with a traditional CAM design. We demonstrate an average power reduction of 5.48x using the HU over the traditional CAM. Also, we show that the HU can operate at a maximum frequency of 1.39 GHz (after accounting for process, voltage and temperature (PVT) variations and accounting for wiring parasitics). Furthermore, we present the delay, power and area trade-offs of the HU design with varying hash table sizes.