UNIVERSITY OF HERTFORDSHIRE
		 COMPUTER SCIENCE RESEARCH COLLOQUIUM

			      presents

		 "Energy Efficiency and Branch Prediction"

			   Michael Hicks
	  (Algorithms Research Group, School of Computer Science,
		      University of Hertfordshire)


		      14 November 2007 Wednesday

			  Lecture Theatre E350
		       Hatfield, College Lane Campus
			       3 - 4 pm

	       Coffee/tea and biscuits will be available.

		    Everyone is Welcome to Attend



Abstract:

Energy efficiency in processor design has become increasingly important
in recent years. With more battery operated devices utilizing high
performance architectures, the energy requirements of the processor are
a continual problem for hardware designers. Each new generation of
embedded processor design includes more transistors and more complex
logic. This only serves to exacerbate the situation.

Dynamic Branch Prediction is a hardware method used to forecast the
direction (and target address) of control flow instructions. This is
required in modern pipelined and MII processor designs in order to
achieve the optimum throughput of instructions per cycle (performance).
However, the overhead for dynamic branch prediction logic is
considerable, and accounts for over 10% of a processor's global power
budget.

This colloquium will explore the significance of power consumption in
energy aware processors, and briefly discuss the sources and remedies
to these problems. The energy consumption of dynamic branch prediction
will be investigated, and previous approaches to increase its energy
efficiency will be demonstrated. The focus of the talk will be on the
'combined algorithm', developed by our group at the University of
Hertfordshire, which combines several hardware and software techniques
to reduce overall power consumption of a processor by up to 6%. This
power saving is achieved by decreasing the amount of energy consumed by
the dynamic branch predictor during a program's execution.

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Hertfordshire Computer Science Research Colloquium
http://homepages.feis.herts.ac.uk/~nehaniv/colloq