![]() ![]() Physical memory is shared between processes the same way as computer power supply is shared, or CPU is shared. They could be solved differently, but virtual memory is the way today. Then OS takes care of actually reading bytes (in page-sized chunks) from disk and writing changes back, the process can just access the memory like any memory.Įvery modern multi-tasking general purpose operating system uses virtual memory, because the CPUs they run support it, and because it solves a big bunch of problems, for example memory fragmentation, transparently using swapping to disk, memory protection. Same page of memory can also be mapped to several places at once, for example with shared memory, so same data can be accessed by several processes at once (virtual address is probably different, so can't share pointer variables).Īnother special case of virtual memory use is mapping a regular file on disk to virtual memory (same thing which happens with swap file, but now controlled by normal application process). OS then needs to either map that virtual memory page to RAM (possibly needing to free some RAM first by swapping current data out to swap file, or terminating some application if out of all memory) and load the right data into it, or it can terminate the application (address was not in valid range, or is read-only but process tries to write). In other cases, if process accesses that page, there is a CPU exception, which transfers control to operating system. Only when virtual memory page is mapped to physical RAM page, is there something there. If the process accesses the page (read or write), it needs to be loaded to page in RAM first (see above). Swapped out to disk (might be a swap file), in order to free physical RAM pages (done automatically by the operating system).Mapped to physical memory, meaning some page-size area in computers RAM stores the contents, and they can be directly used by the process.If process writes to this kind of page, it needs to be given a page of physical memory (by OS, see below) so value can be stored. ![]() not stored physically (assumed to be all 0).Each valid page can be in 3 different states: This address space is divided into pages for easier management (example size 4 KB). In context of modern common operating systems, each process has its own virtual memory space, with overlapping virtual memory addresses. Usually, if you disable paging file, some applications may stop working, some system features may not work efficiently, and you may end up with some weird behaviors."Virtual memory" means there is a valid address space, which does not map to any particular physical memory or storage, hence virtual. While it's recommended to use one and a half times the available memory for the initial and three times the memory for the maximum size, make sure to test the changes and adjust the values if you're experiencing freezes, crashes, and other problems.Īlthough it's possible to disable virtual memory on Windows 10, even when you have a large amount of system memory, it's not recommended to disable this feature. If you no longer need to use the custom size for virtual memory, you can always revert the changes and allow Windows 10 to manage this feature using this command: wmic computersystem where name='%computername%' set AutomaticManagedPagefile=true Type the following command to restart your computer and press Enter: shutdown -r -t 00Īfter you complete the steps, the device will start using the new values for virtual memory, which, if done correctly, should help to improve system performance.Source: Windows Central (Image credit: Source: Windows Central)
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