An analysis of the information content of address reference streams

Abstract

We analyze the information content of several address reference streams. Our results indicate that a new scheme, based on Dynamic Huffman Coding [Vitt87], can encode a typical 32 bit address in four to seven bits. Unlike previous schemes used to estimate the information content of address words [HaDa771 ~arnm77], our scheme is completely on-line and does not rely on preeomputation of address transition probabilities. Our results imply that at least 83% of address bits in the traces we studied contain redundant information. Although our coding scheme is too complex and computationally expensive to implement in practice, it provides a lower bound on the bandwidth that can be achieved by practical compression schemes. Through use of these address compression techniques, the number of bus lines and 1/0 pins required to transmit address information between processor and memory can be ptly reduced.