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Perform I/O Operations in Parallel; Description from POSIX standard; Inside I/O Completion Ports by Mark Russinovich; Description from .NET Framework Developer's Guide; Asynchronous I/O and The Asynchronous Disk I/O Explorer; IO::AIO is a Perl module offering an asynchronous interface for most I/O operations; ACE Proactor
The model captures the fact that read and write operations are much faster in a cache than in main memory, and that reading long contiguous blocks is faster than reading randomly using a disk read-and-write head. The running time of an algorithm in the external memory model is defined by the number of reads and writes to memory required. [3]
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.
An alternative method is via instruction-based I/O which requires that a CPU have specialized instructions for I/O. [1] Both input and output devices have a data processing rate that can vary greatly. [2] With some devices able to exchange data at very high speeds direct access to memory (DMA) without the continuous aid of a CPU is required. [2]
The first use of channel I/O was with the IBM 709 [2] vacuum tube mainframe in 1957, whose Model 766 Data Synchronizer was the first channel controller. The 709's transistorized successor, the IBM 7090, [3] had two to eight 6-bit channels (the 7607) and a channel multiplexor (the 7606) which could control up to eight channels.
Programmed input–output (also programmable input/output, programmed input/output, programmed I/O, PIO) is a method of data transmission, via input/output (I/O), between a central processing unit (CPU) and a peripheral device, [1] such as a Parallel ATA storage device. Each data item transfer is initiated by an instruction in the program ...
Parallel I/O, in the context of a computer, means the performance of multiple input/output operations at the same time, for instance simultaneously outputs to storage devices and display devices. [1] It is a fundamental feature of operating systems .
The position of I/O schedulers (center) within various layers of the Linux kernel's storage stack. [1] Input/output (I/O) scheduling is the method that computer operating systems use to decide in which order I/O operations will be submitted to storage volumes. I/O scheduling is sometimes called disk scheduling.