Week 11
It is an old memory technique, through which the Operating system (OS) divides Main memory into a fixed portion. External fragmentation and Internal fragmentation are two main disadvantages of Fixed Portion
In variable Partitioning, space in main memory is allocated strictly according to the need of process, hence there is no case of internal fragmentation. There will be no unused space left in the partition. No restriction on Degree of Multiprogramming
"Relocation registers used to protect user processes from each other, and from changing operating-system code and data. – The base register contains the value of smallest physical address – The limit register contains a range of logical addresses – each logical address must be less than the limit register" (Google)
In computer operating systems, paging is a memory management scheme by which a computer stores and retrieves data from secondary storage for use in main memory (Wikipedia). Paging Solve the external fragmentation problem by using fixed-sized units in both physical and virtual memory
- When the system allocates a frame to any page, it translates this logical address into a physical address and creates an entry into the page table to be used throughout the execution of the program. When a process is to be executed, its corresponding pages are loaded into any available memory frames (tutorialspoint.com)
- Internal fragmentation
- Memory reference overhead
- Memory required to hold page tables can be large
- Multilevel Paging is a paging scheme which consist of two or more levels of page tables in a hierarchical manner. It is also known as hierarchica