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However, the page file only expands when it has been filled, which, in its default configuration, is 150% of the total amount of physical memory. [16] Thus the total demand for page file-backed virtual memory must exceed 250% of the computer's physical memory before the page file will expand.
A page, memory page, or virtual page is a fixed-length contiguous block of virtual memory, described by a single entry in a page table.It is the smallest unit of data for memory management in an operating system that uses virtual memory.
If the virtual address is a valid page in a memory-mapped file or a paging file, a free page frame will be assigned and the page read in. In most cases, there will be an update to the page table, possibly followed by purging the Translation Lookaside Buffer (TLB), and the system restarts the instruction that causes the exception.
In computing, commit charge is a term used in Microsoft Windows operating systems to describe the total amount of virtual memory of all processes that must be backed by either physical memory or the page file. [1] Through the process of paging, the contents of this virtual memory may move between physical memory and the page file, but it cannot ...
PageDefrag is a program, developed by Sysinternals (now distributed by Microsoft), for Microsoft Windows that runs at start-up to defragment the virtual memory page file, the registry files and the Event Viewer's logs (files such as AppEvent.Evt, SysEvent.Evt, SecEvent.Evt and so on).
A similar mechanism is used for memory-mapped files, which are mapped to virtual memory and loaded to physical memory on demand. When physical memory is not full this is a simple operation; the page is written back into physical memory, the page table and TLB are updated, and the instruction is restarted.
The MMU detects the page fault, but the operating system's kernel handles the exception by making the required page accessible in the physical memory or denying an illegal memory access. Valid page faults are common and necessary to increase the amount of memory available to programs in any operating system that uses virtual memory, such as ...
By reducing the I/O activity caused by paging requests, virtual memory compression can produce overall performance improvements. The degree of performance improvement depends on a variety of factors, including the availability of any compression co-processors, spare bandwidth on the CPU, speed of the I/O channel, speed of the physical memory, and the compressibility of the physical memory ...