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The first-in, first-out (FIFO) page replacement algorithm is a low-overhead algorithm that requires little bookkeeping on the part of the operating system. The idea is obvious from the name – the operating system keeps track of all the pages in memory in a queue, with the most recent arrival at the back, and the oldest arrival in front.
In computer operating systems, memory paging (or swapping on some Unix-like systems) is a memory management scheme by which a computer stores and retrieves data from secondary storage [a] for use in main memory. [1] In this scheme, the operating system retrieves data from secondary storage in same-size blocks called pages.
In operating systems that are not single address space operating systems, address space or process ID information is necessary so the virtual memory management system knows what pages to associate to what process. Two processes may use two identical virtual addresses for different purposes.
It is the smallest unit of data for memory management in an operating system that uses virtual memory. 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]
Heterogeneous System Architecture (HSA) creates a unified virtual address space for CPUs, GPUs and DSPs, obsoleting the mapping tricks and data copying. x86-64, the 64-bit version of the x86 architecture, almost entirely removes segmentation in favor of the flat memory model used by almost all operating systems for the 386 or newer processors ...
The next eleven most significant bits (bits 52 through 62) are reserved for operating system use by both Intel and AMD's architecture specifications. Thus, from 64 bits in the page table entry, 12 low-order and 12 high-order bits have other uses, leaving 40 bits (bits 12 though 51) for the physical page number.
"Traditional" 4 KiB paging 4 MiB paging using PSE. Imagine the following scenario: An application program requests a 1 MiB memory block. In order to fulfill this request, an operating system that supports paging and that is running on older x86 CPUs will have to allocate 256 pages of 4 KiB each. An overhead of 1 KiB of memory is required for ...
The 5-level paging is enabled by setting bit 12 of the CR4 register (known as LA57). [1]: 16 This is only used when the processor is operating in 64 bit mode, and only may be modified when it is not. [1]: 16 If the bit is not set, or the 5-level paging feature is not supported, the processor uses the 4-level page table structure when operating ...