-操作系统精髓与设计原理(第五版)+课后题答案1
CHAPTER 3
PROCESS DESCRIPTION AND
CONTROL
Review Questions
3.5 Swapping involves moving part or all of a process from main memory to
disk. When none of the processes in main memory is in the Ready state, the operating system swaps one of the blocked processes out onto disk into a suspend queue, so that another process may be brought into main memory to execute.
3.10 The user mode has restrictions on the instructions that can be executed
and the memory areas that can be accessed. This is to protect the operating system from damage or alteration. In kernel mode, the
operating system does not have these restrictions, so that it can perform its tasks. Problems
3.1 Creation and deletion of both user and system processes. The
processes in the system can execute concurrently for information sharing, computation speedup, modularity, and convenience.
Concurrent execution requires a mechanism for process creation and deletion. The required resources are given to the process when it is created, or allocated to it while it is running. When the process terminates, the OS needs to reclaim any reusable resources. Suspension and resumption of processes. In process scheduling, the
OS needs to change the process's state to waiting or ready state when it is waiting for some resources. When the required resources are
available, OS needs to change its state to running state to resume its execution. Provision of mechanism for process synchronization. Cooperating
processes may share data. Concurrent access to shared data may result in data inconsistency. OS has to provide mechanisms for processes synchronization to ensure the orderly execution of cooperating processes, so that data consistency is maintained. Provision of mechanism for process communication. The processes
executing under the OS may be either independent processes or
cooperating processes. Cooperating processes must have the means to communicate with each other. Provision of mechanisms for deadlock handling. In a
multiprogramming environment, several processes may compete for a finite number of resources. If a deadlock occurs, all waiting processes