Calculating Waiting Time and Turnaround Time in (non-preemptive) FCFS queue

Question

I have 6 processes as follows:

-- P0 --
  arrival time = 0 
  burst time = 10  

-- P1 --
  arrival time = 110 
  burst time = 210  

-- P2 --
  arrival time         


        

Answer 1

For non-preemptive system,

waitingTime = startTime - arrivalTime

turnaroundTime = burstTime + waitingTime = finishTime- arrivalTime

startTime = Time at which the process started executing

finishTime = Time at which the process finished executing

You can keep track of the current time elapsed in the system(timeElapsed). Assign all processors to a process in the beginning, and execute until the shortest process is done executing. Then assign this processor which is free to the next process in the queue. Do this until the queue is empty and all processes are done executing. Also, whenever a process starts executing, recored its startTime, when finishes, record its finishTime (both same as timeElapsed). That way you can calculate what you need.

Answer 2

wt = tt - cpu tm.
Tt = cpu tm + wt.

Where wt is a waiting time and tt is turnaround time. Cpu time is also called burst time.