round robin

Good Morning\evening i have to write a code for round robin(example 5 processes) i have number of processes and each process has its CPUtime(10,6,2,4 and 8 respectively)

i could not know why the CPUtime for process 4 and 5 do not go to zero

numOfJobs=input('Enter the number of jobs to run =  ');
for i=1:numOfJobs
    job(i)=i;
end
 CPUtime=input('Enter the CPU time required by each job = ,[in vector form] ');
totalCPUtime= sum(CPUtime)
while (totalCPUtime ~= 0)
for i=1:numOfJobs

          if (CPUtime(i)== 0)

          break

          else
              CPUtime(i)=CPUtime(i)-1;

          end
              job(i)

end

totalCPUtime=totalCPUtime-1;
end

Answer 1

[Walter Roberson]

TotalCPUtime needs to be recomputed as sum(CPUtime). Your "for i" loop can end up decrementing more than one CPUtime entry, so your total does not get decremented by exactly 1 under most circumstances.

[Ayda]

why should the tolalCPUtime recomputed

[Walter Roberson]

Your present code initializes totalCPUtime as the sum of the CPUtime . You then change what could be several of the CPUtime (all the non-zero ones), but your code only decreases totalCPUtime by 1 rather than by 1 per CPUtime that was decreased.