CPU Scheduling

A computer has two processors, \(M_1\) and \(M_2\). Four processes \(P_1, P_2, P_3, P_4\) with CPU bursts of 20, 16, 25, and 10 milliseconds, respectively, arrive at the same time and these are the only processes in the system. The scheduler uses non-preemptive priority scheduling, with priorities decided as follows:

• \(M_1\) uses priority of execution for the processes as, \(P_1 \gt P_3 \gt P_2 \gt P_4\), i.e., \(P_1\) and \(P_4\) have highest and lowest priorities, respectively.
• \(M_2\) uses priority of execution for the processes as, \(P_2 \gt P_3 \gt P_4 \gt P_1\), i.e., \(P_2\) and \(P_1\) have highest and lowest priorities, respectively.

A process \(P_i\) is scheduled to a processor \(M_k\), if the processor is free and no other process \(P_j\) is waiting with higher priority. At any given point of time, a process can be allocated to any one of the free processors without violating the execution priority rules. Ignore the context switch time. What will be the average waiting time of the processes in milliseconds?

Processes \(P1\), \(P2\), \(P3\), \(P4\) arrive in that order at times 0, 1, 2, and 8 milliseconds respectively, and have execution times of 10, 13, 6, and 9 milliseconds respectively. Shortest Remaining Time First (SRTF) algorithm is used as the CPU scheduling policy. Ignore context switching times.

Which ONE of the following correctly gives the average turnaround time of the four processes in milliseconds?

Consider a single processor system with four processes A, B, C, and D, represented as given below, where for each process the first value is its arrival time, and the second value is its CPU burst time.

A (0, 10), B (2, 6), C (4, 3), and D (6, 7).

Which one of the following options gives the average waiting times when preemptive Shortest Remaining Time First (SRTF) and Non-Preemptive Shortest Job First (NP-SJF) CPU scheduling algorithms are applied to the processes?