Microkernels
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The document discusses different types of computer kernels. A micro kernel performs only essential operations like inter-process communication and virtual memory management in the kernel space, while non-essential operations like device drivers and file systems run in user space. This improves modularity but incurs greater overhead during context switches between kernel and user mode. While micro kernels have advantages like flexibility, reliability and portability, monolithic kernels have better performance since everything runs in the kernel space. Hybrid kernels aim to achieve benefits of both models.
Microkernels
- 2. What is kernel? Kernel is central components of OS, responsible for communication between hardware and software.
- 3. Kernel Responsible for • Inter process communication • Device drivers • Virtual memory management • Interrupt handling • I/O & device management • File system management • Address space • Interrupts • Network services
- 4. Type of kernels • Monolithic kernel • Microkernel • Hybrid kernel • Nano kernel • Exo kernel
- 5. Monolithic kernel Each application in its own hardware address space Managed by OS Kernel in its own hardware address space
- 6. Monolithic kernel • Kernel implemented as an only one process • Large program where all the functional components of the kernel have access to all of its internal data structures and routines • Execute all of their code in the same address space (kernel space) • Monolithic Kernel : Kernel Image = (Kernel Core + Kernel Services). When system boots up entire services are loaded and resides in memory
- 7. Micro kernel • kernel perform only the essential operations • Everything else should be performed in user space – Device drivers, networking, file system, user interface – improve maintainability and modularity • Micro kernel : Kernel Image = Kernel Core. Services are build into special modules which can be loaded and unloaded as per need.
- 9. Advantages of micro kernel • Extensibility • Flexibility • Portability • Reliability • Distributed system support
- 10. Strikes against Microkernel • Kernel user switches – Border crossing cost • Address space switches – Basis for PPC for cross protection domain calls • Thread switches • Memory effect – Locality loss
- 11. summary • Monolithic kernels – Advantages: performance – Disadvantages: difficult to debug and maintain • Micro kernels – Advantages: more reliable and secure – Disadvantages: more overhead • Hybrid Kernels – Advantages: benefits of monolithic and micro kernels – Disadvantages: same as monolithic kernels
- 12. Thank You