====== Latency ======

When a real-time system is said to have //latencies// or that it has a //latency// that needs to be debugged, the term //latency// means "a situation in which a task or an operation took too long to finish". In a real-time context, the time that it takes a system to perform a particular task (i.e. the latency of the task) is important as each task must be able to finish before its specified deadline.

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If an RT task does not complete within the specified time limit, it is as bad as if a task does not complete at all. This is why developers spend long amounts of time making sure that, even in the worst possible cases, a task can still complete before its deadline. This means that when evaluating the performance of a real-time system, the most important latency value to measure is the maximum latency.

In computing, the term //latency// is generally defined as "the time taken to perform a task". As explained above, the term //latency// often means something slightly different when discussing an RT system.  Having this second definition for the term //latency// can sometimes get a little confusing because the general definition of the term is also used when discussing real-time topics. So, it is important to remember that //latency// can mean slightly different things depending on how it is used.

More information:
  * [[realtime:documentation:howto:debugging:start|Latency debugging]]