Operating System: Question Set – 24
What is memory compaction?
Memory compaction reduces external fragmentation by rearranging memory to merge disparate free blocks into a single, cohesive block.
What are the different types of memory addresses?
- Logical Address: Generated by the CPU; also called a virtual address.
- Physical Address: Actual address in the memory hardware.
- Relative Address: Address expressed relative to a base location.
- Effective Address: Computed address after applying indexing or offset
What are overlays in memory management?
In systems with limited random-access memory (RAM), overlays enable a program to load only the essential portions of its code and data into memory.
What is hierarchical paging?
Hierarchical paging divides the page table into multiple levels to reduce the memory overhead of large page tables. For example:
- First-level table points to second-level tables.
- Second-level tables contain actual page-to-frame mappings.
What is an inverted page table?
An inverted page table stores a single table for the entire system, with one entry per physical frame. It reduces memory usage for page tables in large systems but increases lookup time.
What is the difference between resident set and working set?
- Resident Set: The set of pages currently in physical memory for a process.
- Working Set: The subset of the resident set that the process actively uses.
What is a frame?
A frame is a fixed-sized block of physical memory into which a page is loaded in a paging system.
What is the purpose of a frame table?
All physical frames are tracked by a frame table, which also indicates which are allocated or free and whose process or page they belong to.
What is a backing store?
Secondary storage, such as a disk, is used as a backing store to hold swapped-out pages or processes that are too big to fit in physical memory.
How does demand segmentation differ from demand paging?
- Demand Paging: Loads individual pages into memory on access.
- Demand Segmentation: Loads entire segments on demand.
What are guard pages?
Memory pages known as “guard pages” are positioned around important memory areas to identify overflows and stop corruption by raising an exception when they are accessed.
What is memory interleaving?
Memory interleaving increases throughput in multi-core systems by dividing memory into modules that can be accessed concurrently.