dhamdhere system programming and operating systems pdf book

Problem 5: In partitioned resource allocation, a ‘resource partition’ is assigned to a program when its execution is to be initiated. The print server keeps track of the order in which various virtual printers were created during operation of the system, and arranges to map them on the real printer for printing the file. Problem 4: When a file is to be printed, a virtual printer is created for it and the file is sent to the virtual printer. However, it is not possible to position the magnetic tape cartridge that was in use at the time of preemption at same point as atĢ Solutions Manual: Operating Systems (second edition) by Dhamdhere It is easy to restore the CPU and memory to the situation when preemption occurred by loading back correct values in the CPU registers (this is discussed in Section 2.1.1) and in memory locations. To be able to resume execution of a program ‘as if preemption had not occurred’, the OS should be able to restore the situation in the program as at the time of preemption. However, disks are not preempted programs simply use different areas on a disk. Memory, CPU and disks are not position sensitive. A device is not positionsensitive if a position has to be explicitly specified in any command required to use it. Examples are sequential devices such as printers, tapes and cartridges, etc. Hence position-sensitive devices cannot be preempted. Preemption of a device and its use by another program interferes with its position.

Informally, we say a device is position-sensitive if its operation involves a notion of position and depends on the position it was in when last used.

Problem 3: Students should be able to answer this question based on their knowledge of computer architecture. Section 2.5.3.1 discusses priority based preemption of the CPU to achieve efficient use of a system. Similarly memory may be preempted by removing a program from memory so that another program can be loaded in memory and given an opportunity to execute. This way a program cannot dominate use of the CPU leading to poor service to other programs. Problem 2: Fairness in the use of CPU can be achieved by preempting the CPU. (b) A user expects a large part of a disk to be reserved for his exclusive use, which limits the number of users of the system, which in turn affects efficient use of the system.

A sure way to achieve it is not to have any other programs in the system, which affects efficient use of the system.

Problem 1: (a) A user expects ‘immediate’ response to his computational request. Operating Systems -A Concept-Based Approach Second Edition

Dhamdhere system programming and operating systems pdf book