Microkernel architecture in OS

 

Microkernels:

 

A microkernel is a software program loaded in main memory to perform some of the functions of the operating system so that the size of OS can be reduced. Microkernel provides process scheduling, memory management and communication services. Initially, microkernel approach was used in MACH Operating System. Later on, as its popularity increased, this approach was used in Windows 2000.

 

 Microkernel architecture:

Fig: Microkernel architecture

 

In the microkernel architecture, essential and main operating system functions should be executed in the kernel mode. Remaining all i.e. less essential services and applications are built on microkernel and execute in user mode. In ordinary operating systems like layered operating systems, all the essential functions are executed in kernel mode only.

 

Microkernel is a minimal operating system that performs only the essential functions of an operating system. System processes perform all other operating system functions.

 

Benefits:

 

1.    Portability:  portability is the main feature of micro kernel. Microkernel can be suitable to any type of system. It also supports addition of new services.

 

2.    Flexibility:  microkernel architecture is flexible as existing features can be removed to produce a smaller and more efficient architecture.

 

3.    Uniform interfaces:  microkernel design imposes a uniform interface on requests made by a process.

 

4.    Extensibility:  the microkernel architecture can incorporate the new services as well as new hardware devices.

 

5.    Reliability:  as the size of software product increases, the reliability will decrease. Here, the microkernel reduces the size of operating system. So reliability will increase.

 

6.    Object Oriented: it supports object oriented OS.

 

Differences between Monolithic and Microkernel:

Monolithic Kernel	Microkernel
Kernel size is large.	Kernel size is small.
OS is complex to design.	OS is easy to design, implement and install.
Request may be serviced faster.	Request may be serviced slower compared to monolithic kernel.
All OS services are included in kernel.	Kernel provides only IPC and low level device management services.
No message passing and context switching is required while kernel is performing the job.	It requires message passing and context switching facilities.