Using GAs to Characterize Workloads

Systems administrators are frequently faced with answering questions such as, "How will the throughput of the system be affected if the number of users increases by 50% and if the CPU is upgraded by adding a floating point processing unit?" System models (e.g., analytical, simulation) can be used to help answer such questions. As one example, a closed multi-class queueing network model may be constructed of the system. This model consists of a network of servers and a set of customer classes. Each customer class is defined by the number of customers (i.e., jobs) in the class and by the demands that each customer in the class places on each of the servers. If the underlying model and assumptions are accurate, it is possible to predict how changes to the system will affect performance. A typical assumption of queueing models is that the time spent at a server by a class is exponentially distributed. One workload characterization problem is the determination of the customer demands. Softw..