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Satisfying page faults may require freeing pages that will soon have to be re-read from disk. "Thrashing" is also used in contexts other than virtual memory systems; for example, to describe cache issues in computing or silly window syndrome in networking. A worst case might occur on VAX processors. A single MOVL crossing a page boundary could ...
A system with a smaller page size uses more pages, requiring a page table that occupies more space. For example, if a 2 32 virtual address space is mapped to 4 KiB (2 12 bytes) pages, the number of virtual pages is 2 20 = (2 32 / 2 12). However, if the page size is increased to 32 KiB (2 15 bytes), only 2 17 pages are required. A multi-level ...
The theoretically optimal page replacement algorithm (also known as OPT, clairvoyant replacement algorithm, or Bélády's optimal page replacement policy) [3] [4] [2] is an algorithm that works as follows: when a page needs to be swapped in, the operating system swaps out the page whose next use will occur farthest in the future. For example, a ...
Memory paging creates internal fragmentation because an entire page frame will be allocated whether or not that much storage is needed. [2] Due to the rules governing memory allocation, more computer memory is sometimes allocated than is needed. For example, memory can only be provided to programs in chunks (usually a multiple of 4 bytes), and ...
[1] [2] Once connected, a user can simply enter the commands to send a message to a pager connected to that network. For example, a PAGE command with the number of the device specifies the device to send the message to. The MESS command sets the text of the message to be sent to the text following it. The message is sent out by issuing the SEND ...
The page table is a key component of virtual address translation that is necessary to access data in memory. The page table is set up by the computer's operating system, and may be read and written during the virtual address translation process by the memory management unit or by low-level system software or firmware.
Last year, when Angela, a journalist in San Francisco, was Class Mom at her six-year-old son’s school, she attended a Parents Association meeting where something extraordinary happened: ...
In computer operating systems, demand paging (as opposed to anticipatory paging) is a method of virtual memory management. In a system that uses demand paging, the operating system copies a disk page into physical memory only when an attempt is made to access it and that page is not already in memory (i.e., if a page fault occurs).