Remote DBA Plans
Remote DBA Service

The run queue and the sleep queue in UNIX
Oracle Tips by Burleson Consulting

The run queue and the sleep queue in UNIX

When a UNIX user process communicates with UNIX, the process is placed into a temporary “sleep” state until the system call is completed. This is known as the sleep queue, and it is where UNIX tasks wait while UNIX system calls are being serviced on their behalf. The process of a UNIX task sleeping and re-awakening is called context switching. Active UNIX processes will commonly have context switching as they change from active to waiting states.

All UNIX tasks enter the UNIX run queue whenever they require UNIX services. This is sometimes called the dispatch queue, and the run queue is a list of processes that is prioritized by UNIX according to the tasks dispatching priority, which is called the nice value and is determined by the priocntl system call in UNIX (Figure 2-2).