Latency

Definition

The performance quality subfactor, latency, is the time that a business enterprise, application or component takes to execute specific tasks (e.g., system operations and use case paths) from end to end.

Measurement

Latency is typically measured in terms of:

• Actual time (e.g., milliseconds)
• Average time

Requirements

See latency requirements.

Mechanisms

Typical mechanisms for improving latency include:

• Faster processors.
• Faster networks.
• Improved algorithms.

Guidelines

The following guidelines have been found to be useful with regard to producing latency:

• The difference between hard realtime and soft realtime applications impacts latency:
  • Hard realtime systems:
    • Have very tight time frames (e.g., milliseconds).
    • Are typically hardware driven (e.g., process control or avionics).
    • Physics will not wait (i.e., the right answer too late is the wrong answer).
  • Soft realtime systems:
    • Have less restricted time frames (e.g., seconds).
    • Are typically human driven (e.g., eCommerce, information systems).
    • People will wait (although not forever).