Editing Context switch (section)

== Steps ==
The state of the currently executing process must be saved so it can be restored when rescheduled for execution.

The process state includes all the registers that the process may be using, especially the [[program counter]], plus any other operating system specific data that may be necessary. This is usually stored in a data structure called a ''[[process control block]]'' (PCB) or ''switchframe''.

The PCB might be stored on a per-process [[stack (data structure)|stack]] in kernel memory (as opposed to the user-mode [[call stack]]), or there may be some specific operating system-defined data structure for this information. A [[handle (computing)|handle]] to the PCB is added to a queue of processes that are ready to run, often called the ''ready queue''.

Since the operating system has effectively suspended the execution of one process, it can then switch context by choosing a process from the ready queue and restoring its PCB. In doing so, the program counter from the PCB is loaded, and thus execution can continue in the chosen process. Process and thread priority can influence which process is chosen from the ready queue (i.e., it may be a [[priority queue]]).