Chapter s Operating System 5.1.1 Resource allocation and related functions Preemption of system resources is used by the Os to enforce fairness in their use by programs, or to realize certain system level goals. A preempted program cannot execute unless the preempted resource unit, or some other resource unit pi the same resource class. is allocated to it once again. The shorter term preemption is used preemption of the CPU, and the full term resource preemption is used for preemption of other resources 资源抢占是能指强行释放资源。操作系统依靠对系统资源的抢 占确保程序对资源的平等利用,或实现一些系统级的目标。对 于资源被抢占的程序来说,除非把被抢占的资源单位或同一资 源类的其他资源单位重新分配给它,否则无法继续执行。我们 称抢占CPU为抢占,而称抢占其他资源为资源抢占。 5-17
Chapter 5 Operating System 计算机专业英语 5-17 Preemption of system resources is used by the OS to enforce fairness in their use by programs, or to realize certain system level goals. A preempted program cannot execute unless the preempted resource unit, or some other resource unit pi' the same resource class, is allocated to it once again. The shorter term preemption is used preemption of the CPU, and the full term resource preemption is used for preemption of other resources. 资源抢占是能指强行释放资源。操作系统依靠对系统资源的抢 占确保程序对资源的平等利用，或实现一些系统级的目标。对 于资源被抢占的程序来说，除非把被抢占的资源单位或同一资 源类的其他资源单位重新分配给它，否则无法继续执行。我们 称抢占CPU为抢占，而称抢占其他资源为资源抢占。 5.1.1 Resource allocation and related functions
Chapter s Operating System 5.1.1 Resource allocation and related functions CPU Sharing The CPU can be shared in a sequential manner only. Hence only one program can execute at any time. Other programs in the system have to wait their turn. It is often important to provide fair service to all programs in the system. Hence preemption is used to free the CPU so that it can be given to another program. Deciding which program should be given the CPU and for how long is a critical function. This function is called CPU Scheduling, or simply scheduling. Partitioning is a bad approach for CPU Sharing, allocation from a pool is the obvious approach to use. CPU共享 CPU只能串行共享因此它一次只能执行一个程序,其他程序必须依次等待。 通常情况下,系统会要求平等对待所有的程序,用抢占来释放CPU以执行 其他程序。因此决定该执行哪个程序并执行多长时间是一个十分重要的功 能,这一功能被称为CPU调度或简称调度。显然,资源分区不适用于CPU 共享,同此,从资源池中分配成为惟一的选择 什算机专业语 5-18
Chapter 5 Operating System 计算机专业英语 5-18 CPU sharing The CPU can be shared in a sequential manner only. Hence only one program can execute at any time. Other programs in the system have to wait their turn. It is often important to provide fair service to all programs in the system. Hence preemption is used to free the CPU so that it can be given to another program. Deciding which program should be given the CPU and for how long is a critical function. This function is called CPU Scheduling, or simply scheduling. Partitioning is a bad approach for CPU Sharing, allocation from a pool is the obvious approach to use. CPU共享 CPU只能串行共享,因此它一次只能执行一个程序，其他程序必须依次等待。 通常情况下，系统会要求平等对待所有的程序，用抢占来释放CPU以执行 其他程序。因此决定该执行哪个程序并执行多长时间是一个十分重要的功 能，这一功能被称为CPU调度或简称调度。显然，资源分区不适用于CPU 共享，同此，从资源池中分配成为惟一的选择。 5.1.1 Resource allocation and related functions
Chapter s Operating System 5.1.1 Resource allocation and related functions Memory sharing Like the CPU, the memory also cannot be shared concurrently. However, unlike the CPU, its availability can be increased by treating different parts of memory as different resources. Both the partitioning and the pool-based allocation approaches can be used to manage the memory resource. Memory preemption can also be used to increase the availability of memory to programs. Special terms are used for different memory preemption techniques, hence the term memory preemption" is rarely used in our discussions. 存储器共享 和CPU一样,存储器也不能并行共享。但与CPU不同的是,可以把存储器 的不同部份看作不同的资源,因此可以增加它的可用性。资源分区和基于 资源池的分配方式都适用于存储器资源管理。存储器抢占也可用于提高程 序对存储器的可用性,但由于对不同的存储器抢占技术都有专用术语,故 在本书很少使用“存储器抢占”的说法。 水《第和英语 5-19
Chapter 5 Operating System 计算机专业英语 5-19 Memory sharing Like the CPU, the memory also cannot be shared concurrently. However, unlike the CPU, its availability can be increased by treating different parts of memory as different resources. Both the partitioning and the pool-based allocation approaches can be used to manage the memory resource. Memory preemption can also be used to increase the availability of memory to programs. Special terms are used for different memory preemption techniques, hence the term “memory preemption” is rarely used in our discussions. 存储器共享 和 CPU一样，存储器也不能并行共享。但与CPU不同的是，可以把存储器 的不同部份看作不同的资源，因此可以增加它的可用性。资源分区和基于 资源池的分配方式都适用于存储器资源管理。存储器抢占也可用于提高程 序对存储器的可用性，但由于对不同的存储器抢占技术都有专用术语，故 在本书很少使用“存储器抢占”的说法。 5.1.1 Resource allocation and related functions
Chapter s Operating System 5.1.2 User interface related functions The purpose of a user interface is to provide for the use of os resources, primarily the CPU, for processing a users computational requirements. OS user interfaces typically use command languages. The user uses a command to set up an appropriate computational structure to fulfill a computational requirement 用户接口的目的是为用户提供使用操作系统资源(主要是CPU) 的接口来完成用户的计算请求。操作系统用户接口一般使命令 语言,用户通过命令建方合适的计算结构以满足计算要求。 《什第机专出美语 5-20
Chapter 5 Operating System 计算机专业英语 5-20 The purpose of a user interface is to provide for the use of OS resources, primarily the CPU, for processing a user's computational requirements. OS user interfaces typically use command languages. The user uses a command to set up an appropriate computational structure to fulfill a computational requirement. 用户接口的目的是为用户提供使用操作系统资源(主要是CPU) 的接口来完成用户的计算请求。操作系统用户接口一般使命令 语言，用户通过命令建方合适的计算结构以满足计算要求。 5.1.2 User interface related functions
Chapter s Operating System 5.1.2 User interface related functions A variety of computational structures can be defined by an os. A sample list of computational structures is as follows: 1. A single program 2. A sequence of single programs 3. A collection of programs 不同的计算结构可由操作系统决定。计算结构举例如下: 1.单一程序 2.单一程序的序列 3.程序集合 《什第机专出美语 5-21
Chapter 5 Operating System 计算机专业英语 5-21 A variety of computational structures can be defined by an OS. A sample list of computational structures is as follows: 1. A single program 2. A sequence of single programs 3. A collection of programs. 不同的计算结构可由操作系统决定。计算结构举例如下： 1. 单一程序 2. 单一程序的序列 3. 程序集合 5.1.2 User interface related functions