The ever increasing range of battery operated devices with often complex functionality is a major catalyst for driving the research in the field of low power system design. Battery technology advances at a slower pace and hence it is logical to find the ways to optimize power usage in the hardware architectures. Particularly stand alone embedded systems are being optimized for the energy efficiency during their design. The rapidly evolving field of pervasive computing is major patron for energy efficient devices or technologies. Many advanced systems such as mobile phones and Personal Digital Assistants (PDAs) have multiple processors for achieving the required computational speed or performance.