Layered Architecture of Operating System




Layered Architecture of Operating System

This is an important architecture of operating system which is meant to overcome the disadvantages of early monolithic systems. In this approach, OS is split into various layers such that all the layers perform different functionalities.

Each layer can interact with the one just above it and the one just below it. Lowermost layer which directly deals with the bare hardware is mainly meant to perform the functionality of I/O communication and the uppermost layer which is directly connected with the application program acts as an interface between user and operating system.

This is highly advantageous structure because all the functionalities are on different layers and hence each layer can be tested and debugged separately.

The Microsoft Windows NT Operating System is a good example of the layered structure.


 

Layered Architecture of Operating System

Fig. Layered Architecture of Operating System

Advantages of Layered architecture:

  1. Dysfunction of one layer will not affect the entire operating system

  2. Easier testing and debugging due to isolation among the layers.

  3. Adding new functionalities or removing the obsolete ones is very easy.

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Disadvantages of Layered architecture:

  1. It is not always possible to divide the functionalities, many a times they are inter-related and can’t be separated.

  2. Sometimes, a large no. of functionalities is there and number of layers increase greatly. This might lead to degradation in performance of the system.

  3. No communication between non-adjacent layers.



Frequently Asked Questions

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Ans: It is the oldest architecture of the operating system. We know that all the core software components of the operating system are collectively known as the kernel. view more..
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Ans: there are 4 types of architectures of operating system: 1. Monolithic architecture 2. Layered architecture 3. Microkernel architecture 4. Hybrid architecture view more..
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Ans: We can broadly classify these services into following five categories: Process management Device management Inter-process Communication File management Error detection view more..
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Ans: This is an important architecture of operating system which is meant to overcome the disadvantages of early monolithic systems. view more..
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Ans: The basic ideology in this architecture is to keep the kernel as small as possible. We know that kernel is the core part of the operating system and hence it should be meant for handling the most important services only. view more..
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Ans: the idea was to combine the best functionalities of all old approaches and hence this design is termed as the hybrid structured operating system. view more..
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Ans: System Calls and Programs All the present-day operating systems support the following two modes of operation for the CPU: User mode Kernel mode view more..
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Ans: A batch system executes jobs, whereas a time-shared system has user programs, or tasks. Even on a single-user system such as Microsoft Windows, a user may be able to run several programs at one time: a word processor, a web browser, and an e-mail package. Even if the user can execute only one program at a time, the operating system may need to suppoft its own internal programmed activities, such as memory management. view more..
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Ans: Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. view more..
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Ans: Process scheduling selects processes from the queue and loads them into memory for execution. Process loads into the memory for CPU scheduling. The primary objective of the job scheduler is to provide a balanced mix of jobs, such as I/O bound and processor bound. ... Time-sharing operating systems have no long term scheduler. view more..
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Ans: Inter process communication (IPC) is a mechanism which allows processes to communicate each other and synchronize their actions. The communication between these processes can be seen as a method of co-operation between them. Processes can communicate with each other using these two ways: Shared Memory. Message passing. view more..
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Ans: Direct memory access (DMA) is a method that allows an input/output (I/O) device to send or receive data directly to or from the main memory, bypassing the CPU to speed up memory operations. The process is managed by a chip known as a DMA controller (DMAC) view more..
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Ans: An instruction cycle (sometimes called a fetch–decode–execute cycle) is the basic operational process of a computer. It is the process by which a computer retrieves a program instruction from its memory, determines what actions the instruction dictates, and carries out those actions. view more..
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Ans: System programs provide a convenient environment for program development and execution. Some of them are simply user interfaces to system calls; others are considerably more complex view more..
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Ans: After an operating system is generated, it must be made available for use by the hardware. But how does the hardware know where the kernel is or how to load that kernel? The procedure of starting a computer by loading the kernel is known as booting the system. view more..
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Ans: A system as large and complex as a modern operating system must be engineered carefully if it is to function properly and be modified easily. A common approach is to partition the task into small components rather than have one monolithic system. Each of these modules should be a well-defined portion of the system, with carefully defined inputs, outputs, and functions. view more..
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Ans: System calls provide an interface to the services made available by an operating system. These calls are generally available as routines written in C and C++, although certain low-level tasks (for example, tasks where hardware must be accessed directly), may need to be written using assembly-language instructions. view more..
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Ans: Before we can explore the details of how computer systems operate, we need a general knowledge of the structure of a computer system. In this section, we look at several parts of this structure to round out our background knowledge. view more..




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