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A memory-mapped file is a segment of virtual memory [1] that has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource. This resource is typically a file that is physically present on disk, but can also be a device, shared memory object, or other resource that an operating system can reference through a file descriptor.
This class of status code indicates the client must take additional action to complete the request. Many of these status codes are used in URL redirection. [2]A user agent may carry out the additional action with no user interaction only if the method used in the second request is GET or HEAD.
In computing, a page fault is an exception that the memory management unit (MMU) raises when a process accesses a memory page without proper preparations. Accessing the page requires a mapping to be added to the process's virtual address space. Furthermore, the actual page contents may need to be loaded from a back-up, e.g. a disk.
A process can store data in memory-mapped files on memory-backed file systems, such as the tmpfs file system or file systems on a RAM drive, and map files into and out of the address space as needed. A set of processes may still depend upon the enhanced security features page-based isolation may bring to a multitasking environment.
POSIX also provides the mmap API for mapping files into memory; a mapping can be shared, allowing the file's contents to be used as shared memory. Linux distributions based on the 2.6 kernel and later offer /dev/shm as shared memory in the form of a RAM disk , more specifically as a world-writable directory (a directory in which every user of ...
Instead of using standard input and output as with an anonymous pipe, processes write to and read from a named pipe, as if it were a regular file. All POSIX systems, Windows, AmigaOS 2.0+ Shared memory: Multiple processes are given access to the same block of memory, which creates a shared buffer for the processes to communicate with each other.
Memory-mapped I/O is preferred in IA-32 and x86-64 based architectures because the instructions that perform port-based I/O are limited to one register: EAX, AX, and AL are the only registers that data can be moved into or out of, and either a byte-sized immediate value in the instruction or a value in register DX determines which port is the source or destination port of the transfer.
Generally, most applications intended to be on a standard web server work well with a shared web hosting service. On the other hand, shared hosting is cheaper than other types of hosting such as dedicated server hosting. Shared hosting usually has usage limits and hosting providers should have extensive reliability features in place.