Search results
Results from the WOW.Com Content Network
In computer science, a data buffer (or just buffer) is a region of memory used to store data temporarily while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device (such as a microphone) or just before it is sent to an output device (such as speakers); however, a buffer may be used when data is moved between processes ...
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.
I/O scheduling usually has to work with hard disk drives that have long access times for requests placed far away from the current position of the disk head (this operation is called a seek).
Without an IOMMU, the operating system would have to implement time-consuming bounce buffers (also known as double buffers [3]). Memory is protected from malicious devices that are attempting DMA attacks and faulty devices that are attempting errant memory transfers because a device cannot read or write to memory that has not been explicitly ...
Many operating system functions exist to implement asynchronous I/O at many levels. In fact, one of the main functions of all but the most rudimentary of operating systems is to perform at least some form of basic asynchronous I/O, though this may not be particularly apparent to the user or the programmer.
In computing, vectored I/O, also known as scatter/gather I/O, is a method of input and output by which a single procedure call sequentially reads data from multiple buffers and writes it to a single data stream (gather), or reads data from a data stream and writes it to multiple buffers (scatter), as defined in a vector of buffers.
Multiple processes are given access to the same block of memory, which creates a shared buffer for the processes to communicate with each other. All POSIX systems, Windows Message passing: Allows multiple programs to communicate using message queues and/or non-OS managed channels. Commonly used in concurrency models.
They are data structures that describe I/O requests, and can be equally well thought of as "I/O request descriptors" or similar. Rather than passing a large number of small arguments (such as buffer address, buffer size, I/O function type, etc.) to a driver, all of these parameters are passed via a single pointer to this persistent data structure.