Modern network processor systems require the ability to adapt their processing capabilities at runtime to changes in network traffic. Traditionally, network processor applications have been optimized for a single static workload scenario, but recently several approaches for run-time adaptation have been proposed. Comparing these approaches and developing novel run-time support algorithms is difficult due to the multicore system-on-a-chip nature of network processors. In this paper, we present a model for network processors that can aid in evaluating different run-time support systems. The model considers workload characteristics of applications and network traffic. We use a queuing network abstraction to model different runtime systems. We illustrate the effectiveness of this model by comparing the performance of two existing workload adaptation algorithms. Categories and Subject Descriptors