GATE CS 1991 Q03-xi — Memory Management and Virtual Memory

We need to identify all the false statements among the given options:

• Statement A (True): Virtual memory is implemented by mapping the virtual address space to physical memory and secondary storage (swap space). Therefore, the maximum size of virtual memory is limited by the available secondary storage capacity (as well as the addressing limits of the processor).
• Statement B (False): Mutual exclusion in a critical section can be implemented using pure software solutions (such as Peterson's algorithm or Dekker's algorithm) without relying on hardware-supported atomic instructions like test-and-set.
• Statement C (False): Monitors are high-level synchronization constructs that automatically ensure mutual exclusion. However, they do not prevent deadlocks. For instance, if processes inside a monitor wait on condition variables in a circular dependency, a deadlock can still occur.
• Statement D (True): Thrashing occurs when a system spends more time paging than executing. This happens when the active working sets of running programs exceed the available physical frames. Any page-replacement policy, including LRU, can suffer from thrashing under such memory-starved conditions.
• Statement E (False): The best-fit memory allocation strategy chooses the smallest free block that is large enough. This often leaves behind tiny, unusable fragments of free memory, leading to severe external fragmentation.

Thus, the false statements are B, C, and E.