Defining performance requirements isan important part of system design

ance requirements, it means that they exist in the heads of stakeholders, but nobody bothered to write them down and make sure that everybody agrees on them. Exactly what is specified may vary significantly depending on the system and environment, but all requirements should be quantitative and measurable. Performance requirements are the main input for performance testing (where they are verified), as well as capacity planning and production monitoring. There are several classes of performance requirements. Most traditional are response time (how fast the system can handle individual requests) and throughput (how many requests the system can handle). All classes are vital: Good throughput with a long response time often is unacceptable, as is good response time with low throughput. Response time (in the case of interactive work) or