Command queue

In computer science, a command queue is a queue that determines when a command is executed, usually by order of priority or on a first-in first-out basis. Instead of waiting for each command to be executed before sending the next one, a program will put all its commands in the command queue, freeing it to perform other functions while the queue is processed by the operating system.

This delegation not only frees the program from handling the queue but can also help optimize execution. For instance, when handling multiple requests from several users, a network server's hard drive can reorder the requests in its queue using the elevator algorithm, which minimizes mechanical movement.

Examples

• Native Command Queuing (NCQ) in Serial ATA (SATA)
• Tagged Command Queuing (TCQ) in Parallel ATA and SCSI

See also

• Batch processing
• Burst mode (computing)
• Command pattern
• Job queue
• Job scheduler