Two level implementation

The concept of separating mechanism from policy is an important principle in operating system design. It refers to the division of responsibilities between the low-level mechanisms of an operating system and the high-level policies that govern their behavior. This separation allows for greater flexibility and modularity in the design of the operating system.

What is mechanism?

Mechanism refers to the low-level, technical components of an operating system that perform specific tasks or functions. These mechanisms are responsible for implementing the fundamental operations of the operating system, such as process scheduling, memory management, and file system access. They are typically implemented in the form of algorithms, data structures, and system calls.

What is policy?

Policy, on the other hand, refers to the high-level rules and strategies that determine how the operating system behaves in different situations. It encompasses decisions such as which processes should be given priority for execution, how memory should be allocated to different processes, and how files should be organized and accessed. Policies are usually defined by the operating system designers or system administrators and can be modified without affecting the underlying mechanisms.

Advantages of separating mechanism from policy:

1. Flexibility: By separating mechanism from policy, operating systems can be more easily customized to meet specific requirements. Changes to the policy can be made independently of the underlying mechanisms, allowing for greater flexibility and adaptability.

2. Modularity: The separation of mechanism and policy enables the operating system to be modular and easier to maintain. Modifications or upgrades to the policy can be made without affecting the underlying mechanisms, reducing the risk of introducing errors or disruptions.

3. Portability: Separating mechanism from policy promotes portability by isolating the low-level implementation details from the high-level policy decisions. This allows the operating system to be more easily adapted to different hardware platforms or architectures.

4. Enhanced security: The separation of mechanism and policy can improve system security by allowing for fine-grained control over access and permissions. Security policies can be defined independently of the underlying mechanisms, ensuring that changes to the policy do not compromise the integrity or functionality of the system.

In summary, the two level implementation in operating systems separates the low-level mechanisms from the high-level policies, providing advantages such as flexibility, modularity, portability, and enhanced security. This separation allows for easier customization, maintenance, and adaptation of the operating system to meet specific requirements and environments.