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What is file backed memory?
A file-backed section reflects the contents of an actual file on disk; in other words, it is a memory-mapped file. Any access to memory locations within a given file-backed section corresponds to accesses to locations in the associated file.
What do you mean by mapping files into memory?
File mapping is the process of mapping the disk sectors of a file into the virtual memory space of a process. Once mapped, your app accesses the file as if it were entirely resident in memory.
How does file mapping work?
File mapping allows the process to use both random input and output (I/O) and sequential I/O. It also allows the process to work efficiently with a large data file, such as a database, without having to map the whole file into memory. Multiple processes can also use memory-mapped files to share data.
Who performs memory mapping?
The above system call returns 0 on success or -1 on error. The system call munmap, performs the unmapping of the already memory mapped region. The fields addr indicates the starting address of the mapping and the length indicates the size in bytes of the mapping to be unmapped.
How do I use memory-mapped files?
To work with a memory-mapped file, you must create a view of the entire memory-mapped file or a part of it. You can also create multiple views to the same part of the memory-mapped file, thereby creating concurrent memory. For two views to remain concurrent, they have to be created from the same memory-mapped file.
Which is an example of a memory mapped file?
The following example consists of three separate processes (console applications) that write Boolean values to a memory-mapped file. The following sequence of actions occur: Process A creates the memory-mapped file and writes a value to it.
What is a non persisted memory mapped file?
Non-persisted files are memory-mapped files that are not associated with a file on a disk. When the last process has finished working with the file, the data is lost and the file is reclaimed by garbage collection.
Can a managed code access a memory mapped file?
You can use managed code to access memory-mapped files in the same way that native Windows functions access memory-mapped files, as described in Managing Memory-Mapped Files. There are two types of memory-mapped files:
Memory-mapped files can be shared across multiple processes. Processes can map to the same memory-mapped file by using a common name that is assigned by the process that created the file. To work with a memory-mapped file, you must create a view of the entire memory-mapped file or a part of it.