Improved Group Based Time Quantum is a CPU Scheduling algorithm which is derived from Robin algorithm and is proved to be very efficient and gives much better result than any other Pre-Emptive Round Robin algorithm. In this algorithm every process is first sorted in ascending order of burst times and then equally divided into four groups. For each group the mean of the burst time is considered as the Time Quantum for that group. Time quantum is a major factor which decides efficiency of Round Robin algorithm. So taking the average ensures that each process gets considerate amount of time in each cycle. Also, if 90% of the processes’ burst time is exhausted then it is allowed to run to completion else it will be pre-empted if necessary. Compared to other algorithms like Round Robin, Dynamic Round Robin with Controlled Pre-emption, Group Based Time Quantum, and this algorithm has proved to be faster and more efficient and the tasks are scheduling with much lesser Average Waiting Time and Average Turnaround Time.
Referrences- Hadiza Musa Mijinyawa, Saleh E Abdullahi: Improved Group Based Time Quantum (IGBTQ) CPU.
https://ieeexplore.ieee.org/abstract/document/8333324
Psuedocode: PSEUDO CODE
- FILL Ready_Queue (RQ) with burst times.
- IF Ready_Queue is empty go to step 9.
- Copy burst times and store in RQ and then sort the processes available in ascending order.
- Group the sorted burst times into four equal parts and place the grouped processes in queues Q1, Q2, Q3, and Q4 respectively.
- For each group, take the mean of the burst times as its time quantum (i.e. calculate TQ1, TQ2, TQ3 and TQ4).
- For each process, assign its time quantum to be the value of the TQ calculated for its group.
- Now the process are run just like Round Robin scheduling apart from the face that each group has a different time quantum assigned to it.
- FOR each process IN RQ{ IF process[remaining_burst_time] ≤ process[initial_burst_time]*0.10 THEN COMPLETE process CALCULATE WT, TT }
- Calculate AWT, ATAT by adding individual burst time and turnaround time and the dividing them by the number of processes.
- END