In active and programmable networks, packet processing could be accomplished in the router within the data path. For efficient resource allocation in such networks, the packet scheduling schemes should consider multiple resources such as CPU and memory in addition to the bandwidth to improve overall performance. The inherent unpredictability of processing times of active packets poses a significant challenge in CPU scheduling. It has been identified that unlike bandwidth scheduling, prior estimation of CPU requirements of a packet is very difficult since it is platform dependent and it also depends on processing load at the time of execution and operating system scheduling etc. This paper presents an adaptive solution for estimating the processing requirements of active flows efficiently and accurately. The estimation process has been used in our composite scheduling algorithm called CBCSWFQ to estimate processing requirement. The performances of the estimation process for our composi...