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Unformatted text preview: CS4410 - Fall 2008 Assignment 1 Solution Q1. Give three examples of an explicit hardware mechanism that is motivated by specific OS services. Answer: Atomic operations for synchronization. Kernel/user mode, base/limit registers, protected instructions for various forms of protection. Interrupt vectors for handling interrupts. Traps and trap vectors for handling internal errors and system calls. Interrupts and memory-mapped communication for I/O Q2. Can a process transition from waiting for an I/O operation to the terminated state? Why or why not? Answer: No. A process waiting for I/O must first transition to the ready queue and then to the running state before it may terminate. Q3. What are the differences between user-level and kernel-level threads? Under what circumstances is one type better than the other? What is the essential cause of the difference in cost between a context switch for kernel-level threads and a switch that occurs between user-level threads? Answer: User-level threads are threads that the OS is not aware of. They exist entirely within a process, and are scheduled to run within that process's timeslices....
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- Fall '07
- Operating Systems