The present invention relates to the technical field of performance management for IT systems. More particularly, the present invention relates to a technology of performing monitoring on demand for a complex IT system. According to one aspect of the present invention, there is provided a method of system monitoring that includes: monitoring a performance parameter of a client of the system, determining, based on the performance parameter of the client, whether to monitor a service endpoint directly called by the client, locating the service endpoint to be monitored in response to a determination to monitor the service endpoint directly called by the client, and monitoring a performance parameter of the service endpoint.