Virtual machines can lose performance from a number of events, such as the execution of privileged instructions, TLB misses, traps, and I/O. These events are usually handled in system code. Thus one way of estimating the slowdown when running under a VM is the percentage of application execution time in system versus user mode. For example, an application spending 10% of its execution in system mode might slow down by 60% when running on a VM.
a. What types of programs would be expected to have larger slowdowns when running under VMs?

Figure 5.31 Early performance of various system calls under native execution, pure virtualization, and paravirtualization.
b. If slowdowns were linear as a function of system time, given the slowdown above, how much slower would a program spending 30% of its execution in system time be expected to run?
c. What is the mean slowdown of the functions in Figure 5.31 under pure and para virtualization?
d. Which functions in Figure 5.31 have the smallest slowdowns? What do you think the cause of this could be?

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Native 2 Open/close Install sighandler Handle signal 164.00 2084.00 Fork exec sh 1451.00 2360.00