Sun Performance and Tuning: Java™ and the Internet, Second Edition

Virtual Memory Address Space Segments

All the RAM in a system is managed in terms of pages; these are used to hold the physical address space of a process. The kernel manages the virtual address space of a process by maintaining a complex set of data structures. Each process has a single-address space structure, with any number of segment data structures to map each contiguous segment of memory to a backing device, which holds the pages when they are not in RAM. The segment keeps track of the pages that are currently in memory, and from this information, the system can produce the PMEG or PTE data structures that each kind of MMU reads directly to do the virtual-to-physical translations. The machine-independent routines that do this are called ...