On-the-fly circuit to measure the average working set size

Two economic methods (Markov chain method and filtering method) which estimate the average working set size of a program on the fly are presented. Both methods are simple enough to be implemented inside a VLSI processor chip with small space requirements, or outside the chip to probe the memory reference traffic. The on-the-fly circuit tools that can estimate the average working set size of a program without much loss of accuracy make unnecessary the problematic and expensive procedures (hardware monitoring or simulation) of collecting the reference traces. Such tools can be used in all studies that require program locality measurements, including the study of a program locality, the effectiveness study of locality improvement techniques, and the study of optimizing compiler´s effect on program locality. Since both methods require only one comparison and an increment of one or two counters per memory reference, they can be easily implemented as circuits to probe the reference traffic between the processor and the main memory