This exercise studies the impact of aggressive techniques to exploit instruction-level parallelism in the processor when used in the design of shared-memory multiprocessor systems. Consider two systems identical except for the processor. System A uses a processor with a simple single-issue in-order pipeline, while system B uses a processor with four-way issue, out-of-order execution, and a reorder buffer with 64 entries.
a. Following the convention of Figure 5.11, let us divide the execution time into instruction execution, cache access, memory access, and other stalls. How would you expect each of these components to differ between system A and system B?

b. Based on the discussion of the behavior of the On-Line Transaction Processing (OLTP) workload in Section 5.3, what is the important difference between the OLTP workload and other benchmarks that limits benefit from a more aggressive processor design?

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100% - O Other stalls O Memory access O L3 access I L2 access I Instruction execution 90% 80% - 70% - 60% 50% - 40% - 30% - 20% - 10% - 0% OLTP DSS AltaVista Figure 5.11 Percentage of execution time