Implementation and Simulation of DBHPD and CBQ scheduling - A Comparative Study

In this paper we analyze the operation of two scheduling algorithms, class based queuing (CBQ) and delay bounded hybrid proportional delay (DBHPD). We compare results obtained from simulations and measurements in a reasonably equivalent setup and state that considerable differences can be observed in the results produced by these two methods. We also perform kernel profiling to investigate the resource overhead caused by these algorithms. Kernel profiling results support the observation that deviations between simulations and measurements are mainly caused by complex measurement and calculation procedures that generate extra delays in real implementations. As a conclusion we suggest criticism to be used when making judgements about algorithm performance based on simulation results.