To measure the impact of bandwidth limitation, the execution time is broken down into processing time, raw memory latency time, and bandwidth time, where bandwidth time accounts for stalled cycles due to contention in the memory system. The authors support their thesis by measuring the execution time breakdown of a set of SPEC92 benchmarks on simulations of MIPS-like processors. Processors with aggressive latency hiding show substantially higher fractions of bandwidth stalls in the execution time. The biggest benefit appears to come from small block sizes, whereas min-replacement has a small impact. Finally they point out that increasing the effective pin bandwidth does not necessarily reduce the execution time.
Some programs benefit from small block sizes, others with spatial locality from large ones.
As a consequence, the authors suggest that block size be put under program control. It was felt that one of the main contributions of the paper was the split of execution time into processing time , memory stall time , and bandwidth stall time . These numbers seem to suggest that the architecture isn't well balanced. In view of this, the bandwidth limitation does not come as a surprise. Someone mentioned that the raw pin-bandwidth of processors isn't fully utilized today due to protocol limitations.