Computer Architecture. Virtual Memory. What do we want?. Logical. Physical. Memory with infinite capacity. Virtual Memory Concept. Hide all physical aspects of memory from users. Memory is a logically unbounded virtual (logical) address space of 2 n bytes.
reference (used) bit
+less internal fragmentation, better memory utilization.
-large page table, high page fault handling overheads.
+small page table, small page fault handling overheads.
-more internal fragmentation, worse memory utilization.
1. Lock pages in physical memory using lock bits, or
2. Perform all I/O into and out of OS space.