Kernels and its types
- 2. What is Kernel? • A core component of Operating System without which OS can't work. • Kernel is the nervous system of OS. • It is the central core of Operating System. • It controls everything in OS including I/O Management, Process Management and so on. • It is a bridge between applications and the actual data processing done at the hardware level. • It acts as an interface between the user applications and the hardware.
- 4. Responsibilities of Kernel 1. Central Processing Unit The Kernel takes responsibility for deciding at anytime which of the many running programs should be allocated to the processors. 2. Random Access Memory Random Access memory is used to store both program instructions and data. Often multiple programs will want access to memory, frequently demanding more memory than the computer has available. The Kernel is responsible for deciding which memory each process can use, and determining what to do when not enough memory is available. 3. Input/output Devices The Kernel allocates requests from applications to perform I/O to an appropirate device and provides convenient methods for using the device.
- 5. 4. Memory Management The Kernel has full access to the system's memory and must allow processes to safely access this memory as they require it. 5.Device Management A Kernel must maintain a list of available devices. This list may be known in advance configured by the user or detected by the operating system at run time (normally called plug and play)
- 6. Features provided by Kernel 1) Scheduling of Process (Dispatching) 2) Interprocess Communication 3) Process Synchronization 4) Context Switching 5) Manipulation of Process Control Blocks 6) Interrupt Handling 7) Process Creation and Destruction 8) Process Suspension and Resumption
- 7. Monolithic Kernel Monolithic Kernels run every basic system services like process and memory management, interrupt handling and I/O Communication, file system etc in Kernel space. They are used by Unix, Linux like Operating systems. Since there is less software involved it is faster. Every component of the Operating system is contained in the kernel and can directly communicate with each other simply by using function calls. The Kernel typically executes with unrestricted access to the computer system. This approach provides rich and powerful hardware access.
- 9. Advantages of Monolithic Kernel 1) Smaller in Source and Compiled forms 2) Less code generally means fewer bugs and security problems is also less. 3) System calls are used to do operations in monolithic kernel 4) Execution is fast 5) It has all the things in kernel itself so we don't need any extra mechanism for handling of I/O and Process at the time of application making
- 10. Disadvantages of Monolithic Kernel 1) Coding in kernel space is hard, since you cannot use common libraries 2) Debugging is harder, rebooting the computer is often needed 3) Bugs in one part of kernel produce strong side effects 4) Kernels often become very huge and difficult to maintain. 5) Not portable one -Monolithic kernels must be rewritten for each new architecture that the OS is to be used on.
- 11. Micro Kernel In a microkernel, the kernel provides basic functionality that allows the execution of servers and separate programs . The Kernel is broken into separate processes known as servers. Some of the servers run in user space and some in kernel space. All servers are kept separate and run in different address spaces. The communication in microkernels is done via message passing. The servers communicate through Interprocess Communication(IPC). Servers invoke "services" from each other by sending messages. It is also possible to dynamically switch among operating systems and to have more than one active simultaneously.
- 14. Advantages of Micro Kernel 1) Easier to maintain than Monolithic Kernel 2) Crash resistant (If one server fails, other servers can still work efficiently). 3) Portable 4) Smaller in size 5) Contains smaller amount of code. It increases stability and security.
- 15. Hybrid Kernel Hybrid Kernel-Combination of Monolithic Kernels and Micro Kernels. It has qualities of both monolithic as well as micro kernels but it cannot be classfied as a monolithic or micro kernel exclusively It combines the best of both monolithic kernel and micro kernel +Speed and simple design of a monolithic kernel +Modularity and stability of a micro kernel
- 17. THANK YOU