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The (h,k)-paging problem is a generalization of the model of paging problem: Let h,k be positive integers such that . We measure the performance of an algorithm with cache of size h ≤ k {\displaystyle h\leq k} relative to the theoretically optimal page replacement algorithm .
A paging system makes efficient decisions on which memory to relegate to secondary storage, leading to the best use of the installed RAM. In addition the operating system may provide services to programs that envision a larger memory, such as files that can grow beyond the limit of installed RAM.
Similarly, a page frame is the smallest fixed-length contiguous block of physical memory into which memory pages are mapped by the operating system. [1] [2] [3] A transfer of pages between main memory and an auxiliary store, such as a hard disk drive, is referred to as paging or swapping. [4]
A 68451 MMU, which could be used with the Motorola 68010. A memory management unit (MMU), sometimes called paged memory management unit (PMMU), [1] is a computer hardware unit that examines all memory references on the memory bus, translating these requests, known as virtual memory addresses, into physical addresses in main memory.
A page table is a data structure used by a virtual memory system in a computer to store mappings between virtual addresses and physical addresses. Virtual addresses are used by the program executed by the accessing process , while physical addresses are used by the hardware, or more specifically, by the random-access memory (RAM) subsystem.
In computing, protected mode, also called protected virtual address mode, [1] is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as segmentation, virtual memory, paging and safe multi-tasking designed to increase an operating system's control over application software.
Paging obviously benefits from temporal and spatial locality. A cache is a simple example of exploiting temporal locality, because it is a specially designed, faster but smaller memory area, generally used to keep recently referenced data and data near recently referenced data, which can lead to potential performance increases.
With software-managed TLBs, a TLB miss generates a TLB miss exception, and operating system code is responsible for walking the page tables and finding the appropriate page table entry. The operating system then loads the information from that page table entry into the TLB and restarts the program from the instruction that caused the TLB miss.