1. A dynamic performance modeling and system resource controller system comprising: a performance monitor which continuously collects data about input traffic load and system output performance of a computer system being controlled and generates traffic measurements of throughput, X, and system measurements of concurrency, N, at throughput X; a traffic modeler which receives the generated traffic measurements, builds a traffic model and outputs traffic parameters; a Serial Parallel Queueing Network (SPQN) modeler which receives the generated system measurements and outputs SPQN model parameter: serial service time, A, parallel service time, B, dormant time, C, and number of parallel resources, M, wherein service time, S, is equal to A+B+C, parallelism, P, is equal to B/(A+B), and activity, V, is equal to (A+B)/S; a system model analyzer which receives the traffic parameters, the SPQN model parameters and control parameters and makes a performance prediction; and a resource controller which outputs the control parameters to the system model analyzer, the control parameters depending on control management concerned with resources allocated to various computer application services, the resource controller generating control settings for the computer system being controlled to achieve pre-specified system level objectives.