Term Definition: Quality of Service (QoS)
Main Description

A Quality of Service (QoS) is limitation on some aspect of functionality of a system or system part. Also know as "performance requirement" or "nonfunctional requirement", a quality of service is often represented with a UML constraint or a SysML Requirement. Some QoS properties are:

  • Time
    • Worst case execution time
    • Average execution time
    • Blocking time
    • Period
    • Jitter
    • Minimum inter arrival time
    • read-time
    • write-time
  • Burst length
  • Event arrival pattern
  • Event arrival rate
  • Event arrival probability distribution function
  • Reliability
  • Error rate
  • Risk
  • Safety
  • Mean Time Between Failures (MTBF)
  • Defect rate
  • Cost
  • memory usage
  • resource usage
  • portability
  • maintainability
  • complexity
  • schedulability
  • availability
  • usability