High bandwidth of networks demands high performance communication processors that integrate application processing, network processing, and system support functions into a single, low cost System-On-Chip (SOC) solution. However, conventional processors, when used in network related applications, are beset by the overhead of save/restore of register context, cache misses due to fetching interrupt handler from memory, and the possibility of NIC buffer overflow. Therefore, this paper analyzes the effectiveness of multithreading to service interrupts on an embedded processor from the perspective of a Network processor and a Communication processor. A Simulation environment enhanced with a multithreaded hardware execution model is used and our results reveal that multithreading for interrupts from a single NIC brings a fair improvement in performance of Network processors and little or no effect on Communication processors. However, our analysis also show that multithreading for interrupts has a lot of potential when applied to communication processors with multiple interrupt sources, such as Ethernet, ATM, USB, and HDLC. Index terms: Multithreading, UDP, IP, device driver, interrupt processing, communication processor. / Graduation date: 2003