System performance views
Every system performance characteristic belongs to one of two system performance views:
The performance views are complementary, i.e. metrics from both views are required to understand and improve a system's performance.
External system performance views
External system performance views are a system's performance characteristics as observed and measured from outside the tested system.
External system performance figures show the aggregated performance efforts of a system.
External system performance metrics are also measurements of system's service delivery limits. Examples of external view performance characteristics are response times, response variations, different capacity metrics, availability, stability, and many more.
External system performance characteristics show user esperienced performance, but doesn't explain the system's service delivery limits.
Internal system performance views
Internal system performance views are system's performance characteristics as observed and measured from inside the tested system.
Internal system performance figures show the performance of a system's components.
Performance characteristics of a system's components are measurements of what limits the system's external performance. Internal system performance measurements are made to find internal sources of deviations from performance requirements such as capacity bottlenecks.
Internal performance metrics are measurements of system resource usage and other factors that explain the external performance metrics. Examples of Internal system performance characteristics are CPU load, memory usage, queue lengths, and many more.
Internal system performance characteristics show the cause a system's service delivery limits, but doesn't explain the user esperienced performance.