Commutation of context

A commutation of ''' context ''' ( context switch ) in Informatique consists in safeguarding the state of a process or a light Processus and restoring the state of another process (light) so that multiple processes can share the resources of only one Processeur within the framework of a Operating system Multitâche.

A commutation of context can be more or less expensive in time processor following the operating system and the material architecture used.

The safeguarded context must at least include a notable portion of the state of the Processeur (general registers, registers of states, etc) like, for certain systems, the data necessary to the operating system to manage this process.

The commutation of context calls upon at least three stages. For example, by supposing that one wants to commutate the use of the processor by the P₁ process towards the P₂ process:

To safeguard the context of the P₁ process some share in memory (usually on the pile of P₁).
To find the context of P₂ in memory (usually on the pile of P₂).
To restore the context of P₂ in the processor, the last stage of the restoration consisting in taking again the execution of P₂ at its point of last execution.

Certain processors can safeguard and restore the context of the processor in-house, thus avoiding having to safeguard this context in Random access memory.

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