I/O accesses often have a large impact on overall system performance. Calculate the CPI of a machine using the performance characteristics above, assuming a non-virtualized system. Calculate the CPI again, this time using a virtualized system. How do these CPIs change if the system has half the I/O accesses? Explain why I/O bound applications have a smaller impact from
virtualization.

One of the biggest impediments to widespread use of virtual machines is the performance overhead incurred by running a virtual machine. The table below lists various performance parameters and application behavior.

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a. b. Base CPI 1.5 1.75 Priviliged 0/S Accesses per 10,000 Instructions 120 90 Performance Impact to Trap to the Guest O/S 15 cycles 20 cycles Performance Impact to Trap to VMM 175 cycles 140 cycles 1/0 Accesses per 10,000 Instructions 30 25 1/0 Access Time (Includes Time to Trap to Guest 0/S) 1100 cycles 1200 cycles