  Round Robin (RR) Algorithm is considered as optimal in time shared
environment because the static time is equally shared among the processes. If
the time quantum taken is static then it undergoes degradation of the CPU
performance and leads to so many context switches. In this paper, we have
proposed a new effective dynamic RR algorithm SMDRR (Subcontrary Mean Dynamic
Round Robin) based on dynamic time quantum where we use the subcontrary mean or
harmonic mean to find the time quantum. The idea of this approach is to make
the time quantum repeatedly adjusted according to the burst time of the
currently running processes. Our experimental analysis shows that SMDRR
performs better than RR algorithm in terms of reducing the number of context
switches, average turnaround time and average waiting time.
