Skip to main content

What is the purpose of the command interpreter? Why is it usually separate from the kernel? Would it be possible for the user to develop a new command interpreter using the system‐call interface provided by the operating system?

 What is the purpose of the command interpreter? Why is it usually separate from the kernel? Would it be possible for the user to develop a new command interpreter using the system‐call interface provided by the operating system?


Answer: It reads commands from the user or a file of commands and executes them, usually by turning them into one or more system calls. It is usually not part of the kernel since the command interpreter is subject to changes. A user should be able to develop a new command interpreter using the system‐call interface provided by the operating system. The command interpreter allows a user to create and manage processes and also determine ways by which they communicate (such as through pipes and files). As all of this functionality could be accessed by a user‐level program using the system calls, it should be possible for the user to develop a new command‐line interpreter.


Why is the separation of mechanism and policy desirable in an operating system?


Answer: Mechanism and policy must be separate to ensure that systems are easy to modify. No two system installations are the same, so each installation may want to tune the operating system to suit its needs. With mechanism and policy separate, the policy may be changed at will while the mechanism stays unchanged. This arrangement provides a more flexible system. 


What are the two models of interprocess communication? What are the strengths and weaknesses of the two approaches?


Answer: The two models of interprocess communication are the message-passing Model and the shared‐memory model.


In what ways is the modular kernel approach similar to the layered approach? In what ways does it differ from the layered approach?


Answer: The modular kernel approach requires subsystems to interact with each other through carefully constructed interfaces that are typically narrow (in terms of the functionality that is exposed to external modules). The layered kernel approach is similar in that respect. However, the layered kernel imposes a strict ordering of subsystems such that subsystems at the lower layers are not allowed to invoke operations corresponding to the upper‐layer subsystems. There are no such restrictions in the modular‐kernel approach, wherein modules are free to invoke each other without any constraints.


What is the main advantage for an operating‐system designer of using a virtual‐machine architecture? What is the main advantage for a user?


Answer: The system is easy to debug, and security problems are easy to solve. virtual machines also provide a good platform for operating system research since many different operating systems may run on one physical system.


What is the purpose of interrupts? What are the differences between a trap and an interrupt? Can traps be generated intentionally by a user program? If so, for what purpose?


Answer: An interrupt is a hardware‐generated change‐of‐flow within the system. An interrupt handler is summoned to deal with the cause of the interrupt; control is then returned to the interrupted context and instruction. A trap is a software‐generated interrupt. An interrupt can be used to signal the completion of an I/O to obviate the need for device polling. A trap can be used to call operating system routines or to catch arithmetic errors.

Labels:

Comments

Post a Comment

Popular posts from this blog

Defination of the essential properties of operating systems

Define the essential properties of the following types of operating sys-tems:  Batch  Interactive  Time sharing  Real time  Network  Parallel  Distributed  Clustered  Handheld ANSWERS: a. Batch processing:-   Jobs with similar needs are batched together and run through the computer as a group by an operator or automatic job sequencer. Performance is increased by attempting to keep CPU and I/O devices busy at all times through buffering, off-line operation, spooling, and multi-programming. Batch is good for executing large jobs that need little interaction; it can be submitted and picked up later. b. Interactive System:-   This system is composed of many short transactions where the results of the next transaction may be unpredictable. Response time needs to be short (seconds) since the user submits and waits for the result. c. Time sharing:-   This systems uses CPU scheduling and multipro-gramming to provide economical interactive use of a system. The CPU switches rapidl
Post a Comment
Read more

What is a Fair lock in multithreading?

  Photo by  João Jesus  from  Pexels In Java, there is a class ReentrantLock that is used for implementing Fair lock. This class accepts optional parameter fairness.  When fairness is set to true, the RenentrantLock will give access to the longest waiting thread.  The most popular use of Fair lock is in avoiding thread starvation.  Since longest waiting threads are always given priority in case of contention, no thread can starve.  The downside of Fair lock is the low throughput of the program.  Since low priority or slow threads are getting locks multiple times, it leads to slower execution of a program. The only exception to a Fair lock is tryLock() method of ReentrantLock.  This method does not honor the value of the fairness parameter.
Post a Comment
Read more

How do clustered systems differ from multiprocessor systems? What is required for two machines belonging to a cluster to cooperate to provide a highly available service?

 How do clustered systems differ from multiprocessor systems? What is required for two machines belonging to a cluster to cooperate to provide a highly available service? Answer: Clustered systems are typically constructed by combining multiple computers into a single system to perform a computational task distributed across the cluster. Multiprocessor systems on the other hand could be a single physical entity comprising of multiple CPUs. A clustered system is less tightly coupled than a multiprocessor system. Clustered systems communicate using messages, while processors in a multiprocessor system could communicate using shared memory. In order for two machines to provide a highly available service, the state on the two machines should be replicated and should be consistently updated. When one of the machines fails, the other could then take‐over the functionality of the failed machine. Some computer systems do not provide a privileged mode of operation in hardware. Is it possible t
Post a Comment
Read more