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Unformatted text preview: usion that it has exclusive use of the processor, even though many other programs are typically running on the system. If we were to use a debugger to single step the execution of our program, we would observe a series of program counter (PC) values that corresponded exclusively to instructions contained in our program’s executable object ﬁle or in shared objects linked into our program dynamically at run time. This sequence of PC values is known as a logical control ﬂow. Consider a system that runs three processes, as shown in Figure 8.10. The single physical control ﬂow of the processor is partitioned into three logical ﬂows, one for each process. Each vertical line represents a portion of the logical ﬂow for a process. In the example, process A runs for a while, followed by B, which runs to completion. Then C runs for awhile, followed by A, which runs to completion. Finally, C is able to run to completion. The key point in Figure 8.10 is that processes take turns using the processor. Each process...
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- Spring '10
- The American