先决条件：操作系统中的 CPU 调度
不同的调度算法：
- 先到先得 CPU 调度：
最简单的调度算法，根据进程的到达时间进行调度。先来先服务调度算法指出，先请求 CPU 的进程首先分配 CPU。它是通过使用 FIFO 队列实现的。当一个进程进入就绪队列时，它的 PCB 被链接到队列的尾部。当 CPU 空闲时，它被分配给位于队列头部的进程。然后从队列中删除正在运行的进程。 FCFS 是一种非抢占式调度算法。 - 最短作业优先(抢占式)：
在抢占式最短作业优先调度中，作业在到达时被放入就绪队列，但是当突发时间较短的进程到达时，现有进程被抢占或从执行中移除，并且更短的作业首先执行。 - 最短作业优先(非抢占式)：
在非抢占式最短作业优先中，首先调度具有最短突发时间的进程。如果两个进程的中断时间相同，则使用 FCFS 来打破平局。 - 最长作业优先(抢先)：
它类似于 SJF 调度算法。但是，在这种调度算法中，我们优先考虑剩余突发时间最大的进程。 - 最长作业优先(非抢占式)：
它类似于 SJF 调度算法。但是，在这种调度算法中，我们优先考虑突发时间最长的进程。这本质上是非抢占式的，即当任何进程开始执行时，在完成执行之前不能被中断。 - 循环调度：
为了实现循环调度，我们将就绪队列保留为进程的 FIFO 队列。新进程被添加到就绪队列的尾部。 CPU 调度程序从就绪队列中挑选第一个进程，设置一个定时器在 1 次时间间隔后中断，并调度该进程。然后会发生两件事之一。该进程可能具有小于 1 次量子的 CPU 突发。在这种情况下，进程本身会主动释放 CPU。然后调度程序将继续到就绪队列中的下一个进程。否则，如果当前正在运行的进程的 CPU 突发大于 1 时间量程，则计时器将关闭并导致操作系统中断。将执行上下文切换，并将进程置于就绪队列的尾部。然后 CPU 调度程序将选择就绪队列中的下一个进程。 - 基于优先级的(抢占式)调度：
在抢占式优先级调度中，当一个进程到达就绪队列时，它的优先级会与就绪队列中其他进程的优先级以及此时 CPU 正在执行的进程的优先级进行比较时间。在所有可用进程中具有最高优先级的进程将获得下一个 CPU。在这个程序中，我们有两种选择，是将最高数字视为最高优先级，还是将最低数字视为最高优先级。 - 基于优先级的(非抢占式)调度：
在非抢占优先级调度中，进程根据分配给它们的优先级编号进行调度。一旦该过程被安排，它将运行直到完成。通常，优先级数字越低，进程的优先级越高。人们可能会对优先级数字感到困惑，因此在 GATE 中，会清楚地提到哪一个是最高优先级，哪一个是最低优先级。在这个程序中，我们有两种选择，是将最高数字视为最高优先级还是将最低数字视为最高优先级。 - 最高响应率下一个(HRRN)调度：
下一个最高响应比 (HRRN) 是最优化的调度算法之一。这是一种非抢占式算法，其中调度是基于称为响应比的额外参数完成的。为每个可用作业计算响应率，响应率最高的作业优先于其他作业。
考虑下表： 
下面是使用优先级队列实现上述算法：
FCFS
// C++ implementation of the FCFS algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
// Function to set starting Arrival Time
// Because arrival time gets updated
// when you push process in ready queue again
// in preemptive algorithms
void P_set()
{
start_AT = AT;
BT_left = BT;
}
// Function to set Response Time
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implement FCFS algorithm
priority_queue FCFS_run(priority_queue ready_queue,
queue* gantt)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
// Till ready queue is not empty
while (!ready_queue.empty()) {
// While clock is less than
// Arrival Time
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = ready_queue.top();
ready_queue.pop();
p.set_RT(clock);
while (p.BT_left > 0) {
p.temp_BT++;
p.BT_left--;
clock++;
}
p.set_CT(clock);
// Update the Gantt Chart
(*gantt).push(p);
p.temp_BT = 0;
// Update the completion time to
// the queue
completion_queue.push(p);
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display Completion Queue and
// all the time
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1
<< endl;
cout << "Average completion time :- " << temp1 / size
<< endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1
<< endl;
cout << "Average turnaround time :- " << temp1 / size
<< endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1
<< endl;
cout << "Average waiting time :- " << temp1 / size
<< endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1
<< endl;
cout << "Average response time :- " << temp1 / size
<< endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
// For 1st row of gantt chart
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length()
+ (spaces.front().p_no != -1)
+ 2 * spaces.front().temp_BT,
'-')
<< "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
// For process no. in 2nd row
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << (string(to_string(spaces.front().p_no).length()
+ (spaces.front().p_no != -1)
+ 2 * spaces.front().temp_BT,
'-'))
<< "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
//For 3rd row of gantt chart
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << (string(to_string(spaces.front().p_no).length()
+ (spaces.front().p_no != -1)
+ 2 * spaces.front().temp_BT - temp / 2 - prev,
' '))
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue;
priority_queue completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call for completion data
completion_queue = FCFS_run(ready_queue, &gantt);
// Display Completion Queue
disp(completion_queue, false);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| 1 | 0 | 4 | 4 | 4 | 0 | 0 |
| 2 | 1 | 2 | 6 | 5 | 3 | 3 |
| 3 | 2 | 3 | 9 | 7 | 4 | 4 |
| 4 | 3 | 5 | 14 | 11 | 6 | 6 |
| 5 | 4 | 1 | 15 | 11 | 10 | 10 |
| 6 | 5 | 4 | 19 | 14 | 10 | 10 |
| 7 | 6 | 6 | 25 | 19 | 13 | 13 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
Total completion time :- 92
Average completion time :- 13.1429
Total turnaround time :- 71
Average turnaround time :- 10.1429
Total waiting time :- 46
Average waiting time :- 6.57143
Total response time :- 46
Average response time :- 6.57143
Gantt Chart (IS indicates ideal state) :-
+----------+------+--------+------------+----+----------+--------------+
| P1 | P2 | P3 | P4 | P5 | P6 | P7 |
+----------+------+--------+------------+----+----------+--------------+
0 4 6 9 14 15 19 25 SJF-P
// C++ implementation of the SJF preemptive algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
process pop_index(priority_queue* main_queue, int index)
{
priority_queue rm_index;
int i;
process p;
switch (index) {
case 0:
p = (*main_queue).top();
(*main_queue).pop();
break;
default:
for (i = 0; i < index; i++) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
p = (*main_queue).top();
(*main_queue).pop();
while (!(*main_queue).empty()) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
(*main_queue) = rm_index;
break;
}
return p;
}
time_t min_BT(priority_queue main_queue, time_t clock)
{
time_t min = 0;
while (!main_queue.empty() && main_queue.top().AT <= clock) {
if (min == 0 || min > main_queue.top().BT_left)
min = main_queue.top().BT_left;
main_queue.pop();
}
return min;
}
int min_BT_index(priority_queue main_queue, time_t limit)
{
int index, i = 0;
time_t min = 0;
while (!main_queue.empty() && main_queue.top().AT <= limit) {
if (min == 0 || main_queue.top().BT_left < min) {
min = main_queue.top().BT_left;
index = i;
}
main_queue.pop();
i++;
}
return index;
}
// Function to implement SJF preemptive algorithm
priority_queue SJF_P_run(priority_queue ready_queue,
queue* gantt)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue, min_BT_index(ready_queue, clock));
if (p.AT == p.start_AT)
p.set_RT(clock);
while (p.BT_left > 0 && (ready_queue.empty()
|| clock < ready_queue.top().AT
|| p.BT_left <= min_BT(ready_queue, clock))) {
p.BT_left--;
p.temp_BT++;
clock++;
}
if (p.BT_left == 0) {
p.AT = p.start_AT;
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
else {
p.AT = clock;
p.CT = clock;
(*gantt).push(p);
p.temp_BT = 0;
ready_queue.push(p);
}
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display Completion Queue
// and all the time
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-')
<< "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT
- temp / 2 - prev,
' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialize Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call for completion data
completion_queue = SJF_P_run(ready_queue, &gantt);
// Display Completion Queue
disp(completion_queue, false);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| 1 | 0 | 4 | 7 | 7 | 3 | 0 |
| 2 | 1 | 2 | 3 | 2 | 0 | 0 |
| 3 | 2 | 3 | 10 | 8 | 5 | 5 |
| 4 | 3 | 5 | 19 | 16 | 11 | 11 |
| 5 | 4 | 1 | 5 | 1 | 0 | 0 |
| 6 | 5 | 4 | 14 | 9 | 5 | 5 |
| 7 | 6 | 6 | 25 | 19 | 13 | 13 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
Total completion time :- 83
Average completion time :- 11.8571
Total turnaround time :- 62
Average turnaround time :- 8.85714
Total waiting time :- 37
Average waiting time :- 5.28571
Total response time :- 34
Average response time :- 4.85714
Gantt Chart (IS indicates ideal state) :-
+----+------+----+----+------+--------+----------+------------+--------------+
| P1 | P2 | P1 | P5 | P1 | P3 | P6 | P4 | P7 |
+----+------+----+----+------+--------+----------+------------+--------------+
0 1 3 4 5 7 10 14 19 25 SJF-NP
// C++ implementation of the SJF(Non-preemptive) algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implementation pop_index()
process pop_index(priority_queue* main_queue, int index)
{
priority_queue rm_index;
int i;
process p;
switch (index) {
case 0:
p = (*main_queue).top();
(*main_queue).pop();
break;
default:
for (i = 0; i < index; i++) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
p = (*main_queue).top();
(*main_queue).pop();
while (!(*main_queue).empty()) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
(*main_queue) = rm_index;
break;
}
return p;
}
// Function to find index of process
//with minimum BT
int min_BT_index(priority_queue main_queue, time_t limit)
{
int index, i = 0;
time_t min = 0;
while (!main_queue.empty() && main_queue.top().AT <= limit) {
if (min == 0 || main_queue.top().BT_left < min) {
min = main_queue.top().BT_left;
index = i;
}
main_queue.pop();
i++;
}
return index;
}
// Function to implement SJF(Non-preemptive)
priority_queue SJF_NP_run(priority_queue ready_queue,
queue* gantt)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue,
min_BT_index(ready_queue, clock));
p.set_RT(clock);
while (p.BT_left > 0) {
p.temp_BT++;
p.BT_left--;
clock++;
}
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
//Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display the queue
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-')
<< "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT
- temp / 2 - prev,
' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call to find completion data
completion_queue = SJF_NP_run(ready_queue, &gantt);
// Display Completion Queue
disp(completion_queue, false);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| 1 | 0 | 4 | 4 | 4 | 0 | 0 |
| 2 | 1 | 2 | 7 | 6 | 4 | 4 |
| 3 | 2 | 3 | 10 | 8 | 5 | 5 |
| 4 | 3 | 5 | 19 | 16 | 11 | 11 |
| 5 | 4 | 1 | 5 | 1 | 0 | 0 |
| 6 | 5 | 4 | 14 | 9 | 5 | 5 |
| 7 | 6 | 6 | 25 | 19 | 13 | 13 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
Total completion time :- 84
Average completion time :- 12
Total turnaround time :- 63
Average turnaround time :- 9
Total waiting time :- 38
Average waiting time :- 5.42857
Total response time :- 38
Average response time :- 5.42857
Gantt Chart (IS indicates ideal state) :-
+----------+----+------+--------+----------+------------+--------------+
| P1 | P5 | P2 | P3 | P6 | P4 | P7 |
+----------+----+------+--------+----------+------------+--------------+
0 4 5 7 10 14 19 25 LJF-P
// C++ implementation of the LJF(Preemptive) algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implementation pop_index()
process pop_index(priority_queue* main_queue, int index)
{
priority_queue rm_index;
int i;
process p;
switch (index) {
case 0:
p = (*main_queue).top();
(*main_queue).pop();
break;
default:
for (i = 0; i < index; i++) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
p = (*main_queue).top();
(*main_queue).pop();
while (!(*main_queue).empty()) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
(*main_queue) = rm_index;
break;
}
return p;
}
// Function to implement maximum Burst Time
time_t max_BT(priority_queue main_queue, time_t limit)
{
time_t max = 0;
while (!main_queue.empty() && main_queue.top().AT <= limit) {
if (main_queue.top().BT_left > max)
max = main_queue.top().BT_left;
main_queue.pop();
}
return max;
}
// Function to implement maximum BT index w.r.t given clock limit
int max_BT_index(priority_queue main_queue, time_t limit)
{
int index, i = 0;
time_t max = 0;
while (!main_queue.empty() && main_queue.top().AT <= limit) {
if (main_queue.top().BT_left > max) {
max = main_queue.top().BT_left;
index = i;
}
main_queue.pop();
i++;
}
return index;
}
// Function to implement LJF(Preemptive) algorithm
priority_queue LJF_P_run(priority_queue ready_queue,
queue* gantt)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue, max_BT_index(ready_queue, clock));
if (p.AT == p.start_AT)
p.set_RT(clock);
while (p.BT_left > 0 && (ready_queue.empty()
|| clock < ready_queue.top().AT
|| p.BT_left >= max_BT(ready_queue, clock))) {
p.temp_BT++;
p.BT_left--;
clock++;
}
if (p.BT_left == 0) {
p.AT = p.start_AT;
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
else {
p.AT = clock;
p.CT = clock;
(*gantt).push(p);
p.temp_BT = 0;
ready_queue.push(p);
}
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display Completion Queue
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT - temp / 2 - prev, ' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call to find completion data
completion_queue = LJF_P_run(ready_queue, &gantt);
// Display Completion Queue
disp(completion_queue, false);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| 1 | 0 | 4 | 23 | 23 | 19 | 0 |
| 2 | 1 | 2 | 22 | 21 | 19 | 12 |
| 3 | 2 | 3 | 24 | 22 | 19 | 0 |
| 4 | 3 | 5 | 19 | 16 | 11 | 0 |
| 5 | 4 | 1 | 20 | 16 | 15 | 15 |
| 6 | 5 | 4 | 21 | 16 | 12 | 0 |
| 7 | 6 | 6 | 25 | 19 | 13 | 0 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
Total completion time :- 154
Average completion time :- 22
Total turnaround time :- 133
Average turnaround time :- 19
Total waiting time :- 108
Average waiting time :- 15.4286
Total response time :- 27
Average response time :- 3.85714
Gantt Chart (IS indicates ideal state) :-
+------+----+------+----+----------+----+------+----+----+----+----+------+----+----+----+----+----+----+
| P1 | P3 | P4 | P6 | P7 | P4 | P6 | P2 | P1 | P3 | P7 | P4 | P5 | P6 | P2 | P1 | P3 | P7 |
+------+----+------+----+----------+----+------+----+----+----+----+------+----+----+----+----+----+----+
0 2 3 5 6 10 11 13 14 15 16 17 19 20 21 22 23 24 25 LJF-NP
// C++ implementation of the LJF(Non-Preemptive) algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implement pop_index()
process pop_index(priority_queue* main_queue, int index)
{
priority_queue rm_index;
int i;
process p;
switch (index) {
case 0:
p = (*main_queue).top();
(*main_queue).pop();
break;
default:
for (i = 0; i < index; i++) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
p = (*main_queue).top();
(*main_queue).pop();
while (!(*main_queue).empty()) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
(*main_queue) = rm_index;
break;
}
return p;
}
// Function to find maximum Burst Time Index w.r.t clock limit
int max_BT_index(priority_queue main_queue, time_t limit)
{
int index, i = 0;
time_t max = 0;
while (!main_queue.empty() && main_queue.top().AT <= limit) {
if (main_queue.top().BT_left > max) {
max = main_queue.top().BT_left;
index = i;
}
main_queue.pop();
i++;
}
return index;
}
// Function to implement LJF(Non-Preemptive) Algorithm
priority_queue LJF_NP_run(priority_queue ready_queue,
queue* gantt)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.set_CT(clock);
(*gantt).push(p);
}
p = pop_index(&ready_queue, max_BT_index(ready_queue, clock));
p.set_RT(clock);
while (p.BT_left > 0) {
p.temp_BT++;
p.BT_left--;
clock++;
}
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display Completion queue
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-')
<< "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT
- temp / 2 - prev,
' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call to find completion data
completion_queue = LJF_NP_run(ready_queue, &gantt);
// Display Completion Queue
disp(completion_queue, false);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| 1 | 0 | 4 | 4 | 4 | 0 | 0 |
| 2 | 1 | 2 | 24 | 23 | 21 | 21 |
| 3 | 2 | 3 | 22 | 20 | 17 | 17 |
| 4 | 3 | 5 | 9 | 6 | 1 | 1 |
| 5 | 4 | 1 | 25 | 21 | 20 | 20 |
| 6 | 5 | 4 | 19 | 14 | 10 | 10 |
| 7 | 6 | 6 | 15 | 9 | 3 | 3 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
Total completion time :- 118
Average completion time :- 16.8571
Total turnaround time :- 97
Average turnaround time :- 13.8571
Total waiting time :- 72
Average waiting time :- 10.2857
Total response time :- 72
Average response time :- 10.2857
Gantt Chart (IS indicates ideal state) :-
+----------+------------+--------------+----------+--------+------+----+
| P1 | P4 | P7 | P6 | P3 | P2 | P5 |
+----------+------------+--------------+----------+--------+------+----+
0 4 9 15 19 22 24 25 RR
// C++ implementation of the Round Robin algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implement Round Robin algorithm
priority_queue RR_run(priority_queue ready_queue,
time_t Time_Slice,
queue* gantt)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = ready_queue.top();
ready_queue.pop();
if (p.AT == p.start_AT)
p.set_RT(clock);
while (p.BT_left > 0 && (p.temp_BT < Time_Slice
|| ready_queue.empty()
|| clock < ready_queue.top().AT)) {
p.temp_BT++;
p.BT_left--;
clock++;
}
if (p.BT_left == 0) {
p.AT = p.start_AT;
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
else {
p.AT = clock;
p.CT = clock;
(*gantt).push(p);
p.temp_BT = 0;
ready_queue.push(p);
}
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display Completion queue
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT - temp / 2 - prev, ' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
// Time quantum for round robin
int tq = 2;
ready_queue = set_sample_data();
// Function call to find completion data
completion_queue = RR_run(ready_queue, tq, &gantt);
// Display Completion Queue
disp(completion_queue, false);
cout << "\nTime Quantum for round robin :- " << tq << endl;
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| 1 | 0 | 4 | 8 | 8 | 4 | 0 |
| 2 | 1 | 2 | 4 | 3 | 1 | 1 |
| 3 | 2 | 3 | 16 | 14 | 11 | 2 |
| 4 | 3 | 5 | 23 | 20 | 15 | 5 |
| 5 | 4 | 1 | 11 | 7 | 6 | 6 |
| 6 | 5 | 4 | 20 | 15 | 11 | 6 |
| 7 | 6 | 6 | 25 | 19 | 13 | 7 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
Total completion time :- 107
Average completion time :- 15.2857
Total turnaround time :- 86
Average turnaround time :- 12.2857
Total waiting time :- 61
Average waiting time :- 8.71429
Total response time :- 27
Average response time :- 3.85714
Time Quantum for round robin :- 2
Gantt Chart (IS indicates ideal state) :-
+------+------+------+------+------+----+------+------+----+------+------+------+----+------+
| P1 | P2 | P3 | P1 | P4 | P5 | P6 | P7 | P3 | P4 | P6 | P7 | P4 | P7 |
+------+------+------+------+------+----+------+------+----+------+------+------+----+------+
0 2 4 6 8 10 11 13 15 16 18 20 22 23 25 PB-P
// C++ implementation of the Priority Based(Preemptive) algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implement pop_index()
process pop_index(priority_queue* main_queue,
int index)
{
priority_queue rm_index;
int i;
process p;
switch (index) {
case 0:
p = (*main_queue).top();
(*main_queue).pop();
break;
default:
for (i = 0; i < index; i++) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
p = (*main_queue).top();
(*main_queue).pop();
while (!(*main_queue).empty()) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
(*main_queue) = rm_index;
break;
}
return p;
}
// Function to implement maximum priority w.r.t
//priority and also 2nd argument has boolean
//variable because we need to specify
// True=highest number as highest priority
// False=lowest number as highest priority
int max_priority(priority_queue main_priority_queue,
int limit, bool high)
{
int max = -1;
if (high == 1) {
while (!main_priority_queue.empty()
&& main_priority_queue.top().AT <= limit) {
if (main_priority_queue.top().priority > max)
max = main_priority_queue.top().priority;
main_priority_queue.pop();
}
}
else {
while (!main_priority_queue.empty()
&& main_priority_queue.top().AT <= limit) {
if (max == -1 || main_priority_queue.top().priority < max)
max = main_priority_queue.top().priority;
main_priority_queue.pop();
}
}
return max;
}
// Function to implement maximum priority index
int max_priority_index(priority_queue main_queue, int limit, bool high)
{
int max = -1, i = 0, index = 0;
if (high == 1) {
while (!main_queue.empty() && main_queue.top().AT <= limit) {
if (main_queue.top().priority > max) {
max = main_queue.top().priority;
index = i;
}
main_queue.pop();
i++;
}
}
else {
while (!main_queue.empty()
&& main_queue.top().AT <= limit) {
if (max == -1 || main_queue.top().priority < max) {
max = main_queue.top().priority;
index = i;
}
main_queue.pop();
i++;
}
}
return index;
}
// Function to implement priority based Preemptive scheduling
priority_queue Priority_P_run(priority_queue ready_queue, queue* gantt, bool high)
{
int temp;
priority_queue completion_queue;
process p;
time_t clock = 0;
if (high == 1) {
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue,
max_priority_index(ready_queue, clock, high));
if (p.AT == p.start_AT)
p.set_RT(clock);
while (p.BT_left > 0
&& (ready_queue.empty()
|| clock < ready_queue.top().AT
|| p.priority >= max_priority(ready_queue, clock, high))) {
p.temp_BT++;
p.BT_left--;
clock++;
}
if (p.BT_left == 0) {
p.AT = p.start_AT;
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
else {
p.AT = clock;
p.CT = clock;
(*gantt).push(p);
p.temp_BT = 0;
ready_queue.push(p);
}
}
}
else {
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue,
max_priority_index(ready_queue,
clock, high));
if (p.AT == p.start_AT)
p.set_RT(clock);
temp = max_priority(ready_queue, clock, high);
while (p.BT_left > 0 && (ready_queue.empty()
|| clock < ready_queue.top().AT
|| p.priority <= max_priority(ready_queue, clock, high))) {
p.temp_BT++;
p.BT_left--;
clock++;
}
if (p.BT_left == 0) {
p.AT = p.start_AT;
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
else {
p.AT = clock;
p.CT = clock;
(*gantt).push(p);
p.temp_BT = 0;
ready_queue.push(p);
}
}
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display main queue
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-')
<< "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT - temp / 2 - prev, ' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call to find completion data
//3rd argument has true passed becuase we have set
//highest number = highest priority
completion_queue = Priority_P_run(ready_queue, &gantt, true);
// Display Completion Queue as true in
//2nd argument to display priority
disp(completion_queue, true);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+----------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time | Priority |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+----------+
| 1 | 0 | 4 | 25 | 25 | 21 | 0 | 2 |
| 2 | 1 | 2 | 22 | 21 | 19 | 0 | 4 |
| 3 | 2 | 3 | 21 | 19 | 16 | 0 | 6 |
| 4 | 3 | 5 | 12 | 9 | 4 | 0 | 10 |
| 5 | 4 | 1 | 19 | 15 | 14 | 14 | 8 |
| 6 | 5 | 4 | 9 | 4 | 0 | 0 | 12 |
| 7 | 6 | 6 | 18 | 12 | 6 | 6 | 9 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+----------+
Total completion time :- 126
Average completion time :- 18
Total turnaround time :- 105
Average turnaround time :- 15
Total waiting time :- 80
Average waiting time :- 11.4286
Total response time :- 20
Average response time :- 2.85714
Gantt Chart (IS indicates ideal state) :-
+----+----+----+------+----------+--------+--------------+----+------+----+--------+
| P1 | P2 | P3 | P4 | P6 | P4 | P7 | P5 | P3 | P2 | P1 |
+----+----+----+------+----------+--------+--------------+----+------+----+--------+
0 1 2 3 5 9 12 18 19 21 22 25 PB-NP
// C++ implementation of the Priority Based(Non-Preemptive) algorithm
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implement pop_index()
process pop_index(priority_queue* main_queue,
int index)
{
priority_queue rm_index;
int i;
process p;
switch (index) {
case 0:
p = (*main_queue).top();
(*main_queue).pop();
break;
default:
for (i = 0; i < index; i++) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
p = (*main_queue).top();
(*main_queue).pop();
while (!(*main_queue).empty()) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
(*main_queue) = rm_index;
break;
}
return p;
}
//Function to implement maximum priority w.r.t clock limit
// and 3rd parameter as bool because we need true = highest
//number as highest and false as lowest number as highest priority
int max_priority(priority_queue main_priority_queue,
int limit, bool high)
{
int max = -1;
if (high == 1) {
while (!main_priority_queue.empty()
&& main_priority_queue.top().AT <= limit) {
if (main_priority_queue.top().priority > max)
max = main_priority_queue.top().priority;
main_priority_queue.pop();
}
}
else {
while (!main_priority_queue.empty()
&& main_priority_queue.top().AT <= limit) {
if (max == -1 || main_priority_queue.top().priority < max)
max = main_priority_queue.top().priority;
main_priority_queue.pop();
}
}
return max;
}
// Function to implement maximum priority index
int max_priority_index(priority_queue main_queue, int limit, bool high)
{
int max = -1, i = 0, index = 0;
if (high == 1) {
while (!main_queue.empty() && main_queue.top().AT <= limit) {
if (main_queue.top().priority > max) {
max = main_queue.top().priority;
index = i;
}
main_queue.pop();
i++;
}
}
else {
while (!main_queue.empty()
&& main_queue.top().AT <= limit) {
if (max == -1 || main_queue.top().priority < max) {
max = main_queue.top().priority;
index = i;
}
main_queue.pop();
i++;
}
}
return index;
}
// Function to implement priority based Preemptive scheduling
priority_queue Priority_NP_run(priority_queue ready_queue,
queue* gantt, bool high)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
if (high == 1) {
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue,
max_priority_index(ready_queue,
clock, high));
p.set_RT(clock);
while (p.BT_left > 0) {
p.temp_BT++;
p.BT_left--;
clock++;
}
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
}
else {
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue,
max_priority_index(ready_queue,
clock, high));
p.set_RT(clock);
while (p.BT_left > 0) {
p.temp_BT++;
p.BT_left--;
clock++;
}
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display main queue
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-')
<< "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT - temp / 2 - prev, ' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call to find completion data
//and true is passed as 3rd argument because we
//are considering highest number as highest priority
completion_queue = Priority_NP_run(ready_queue, &gantt, true);
// Display Completion Queue
disp(completion_queue, true);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+----------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time | Priority |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+----------+
| 1 | 0 | 4 | 4 | 4 | 0 | 0 | 2 |
| 2 | 1 | 2 | 25 | 24 | 22 | 22 | 4 |
| 3 | 2 | 3 | 23 | 21 | 18 | 18 | 6 |
| 4 | 3 | 5 | 9 | 6 | 1 | 1 | 10 |
| 5 | 4 | 1 | 20 | 16 | 15 | 15 | 8 |
| 6 | 5 | 4 | 13 | 8 | 4 | 4 | 12 |
| 7 | 6 | 6 | 19 | 13 | 7 | 7 | 9 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+----------+
Total completion time :- 113
Average completion time :- 16.1429
Total turnaround time :- 92
Average turnaround time :- 13.1429
Total waiting time :- 67
Average waiting time :- 9.57143
Total response time :- 67
Average response time :- 9.57143
Gantt Chart (IS indicates ideal state) :-
+----------+------------+----------+--------------+----+--------+------+
| P1 | P4 | P6 | P7 | P5 | P3 | P2 |
+----------+------------+----------+--------------+----+--------+------+
0 4 9 13 19 20 23 25 HRRN
// C++ implementation of the HRRN Scheduling
#include
#include
#include
using namespace std;
class process {
public:
pid_t p_no = 0;
time_t start_AT = 0, AT = 0,
BT_left = 0, BT = 0, temp_BT = 0,
CT = 0, TAT = 0, WT = 0, RT = 0;
int priority = 0;
// Function for completion time
void set_CT(time_t time)
{
CT = time;
set_TAT();
set_WT();
}
// Function for Turn Around Time
void set_TAT()
{
TAT = CT - start_AT;
}
// Function for Waiting Time
void set_WT()
{
WT = TAT - BT;
}
void P_set()
{
start_AT = AT;
BT_left = BT;
}
void set_RT(time_t time)
{
RT = time - start_AT;
}
// Overload operator '<' w.r.t arrival
// time because arrival time is the
// first priority even greater than
// priority of process and priority_queue
// pops out the greatest value first
// so we need to replace '<' with '>' inorder
// to pop out smallest value
friend bool operator<(const process& a, const process& b)
{
return a.AT > b.AT;
}
};
// Function to implement pop_index()
process pop_index(priority_queue* main_queue,
int index)
{
priority_queue rm_index;
int i;
process p;
switch (index) {
case 0:
p = (*main_queue).top();
(*main_queue).pop();
break;
default:
for (i = 0; i < index; i++) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
p = (*main_queue).top();
(*main_queue).pop();
while (!(*main_queue).empty()) {
rm_index.push((*main_queue).top());
(*main_queue).pop();
}
(*main_queue) = rm_index;
break;
}
return p;
}
// Function to implement maximum Response Ratio
// index w.r.t clock limit for arrival time
int max_response_ratio_index(priority_queue ready_queue,
time_t limit)
{
int index, i = 0;
double response_ratio = 0, max = 0;
while (!ready_queue.empty()
&& ready_queue.top().AT <= limit) {
response_ratio = ((double)(limit - ready_queue.top().AT) + ready_queue.top().BT_left) / ready_queue.top().BT_left;
if (response_ratio > max) {
max = response_ratio;
index = i;
}
i++;
ready_queue.pop();
}
return index;
}
// Function to implement HRRN Scheduling
priority_queue HRRN_run(priority_queue ready_queue,
queue* gantt)
{
priority_queue completion_queue;
process p;
time_t clock = 0;
while (!ready_queue.empty()) {
while (clock < ready_queue.top().AT) {
p.temp_BT++;
clock++;
}
if (p.temp_BT > 0) {
p.p_no = -1;
p.CT = clock;
(*gantt).push(p);
}
p = pop_index(&ready_queue,
max_response_ratio_index(ready_queue,
clock));
p.set_RT(clock);
while (p.BT_left > 0) {
p.temp_BT++;
p.BT_left--;
clock++;
}
p.set_CT(clock);
(*gantt).push(p);
p.temp_BT = 0;
completion_queue.push(p);
}
return completion_queue;
}
// Set data on the basis of given table
priority_queue set_sample_data()
{
priority_queue ready_queue;
process temp;
temp.AT = 0;
temp.BT = 4;
temp.priority = 2;
temp.p_no = 1;
temp.P_set();
ready_queue.push(temp);
temp.AT = 1;
temp.BT = 2;
temp.priority = 4;
temp.p_no = 2;
temp.P_set();
ready_queue.push(temp);
temp.AT = 2;
temp.BT = 3;
temp.priority = 6;
temp.p_no = 3;
temp.P_set();
ready_queue.push(temp);
temp.AT = 3;
temp.BT = 5;
temp.priority = 10;
temp.p_no = 4;
temp.P_set();
ready_queue.push(temp);
temp.AT = 4;
temp.BT = 1;
temp.priority = 8;
temp.p_no = 5;
temp.P_set();
ready_queue.push(temp);
temp.AT = 5;
temp.BT = 4;
temp.priority = 12;
temp.p_no = 6;
temp.P_set();
ready_queue.push(temp);
temp.AT = 6;
temp.BT = 6;
temp.priority = 9;
temp.p_no = 7;
temp.P_set();
ready_queue.push(temp);
return ready_queue;
}
// Function to get total Waiting Time
double get_total_WT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().WT;
processes.pop();
}
return total;
}
// Function to get total Turn Around Time
double get_total_TAT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().TAT;
processes.pop();
}
return total;
}
// Function to get total Completion Time
double get_total_CT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().CT;
processes.pop();
}
return total;
}
// Function to get total Response Time
double get_total_RT(priority_queue processes)
{
double total = 0;
while (!processes.empty()) {
total += processes.top().RT;
processes.pop();
}
return total;
}
// Function to display main queue
void disp(priority_queue main_queue, bool high)
{
int i = 0, temp, size = main_queue.size();
priority_queue tempq = main_queue;
double temp1;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
cout << "| Process No. | Arrival Time ";
cout << "| Burst Time | Completion Time ";
cout << "| Turnaround Time | Waiting Time | Response Time |";
if (high == true)
cout << " Priority |" << endl;
else
cout << endl;
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+" << endl;
else
cout << endl;
while (!main_queue.empty()) {
temp = to_string(main_queue.top().p_no).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().p_no << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().start_AT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().start_AT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().BT).length();
cout << '|' << string(6 - temp / 2 - temp % 2, ' ')
<< main_queue.top().BT << string(6 - temp / 2, ' ');
temp = to_string(main_queue.top().CT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().CT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().TAT).length();
cout << '|' << string(8 - temp / 2 - temp % 2, ' ')
<< main_queue.top().TAT << string(9 - temp / 2, ' ');
temp = to_string(main_queue.top().WT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().WT << string(7 - temp / 2, ' ');
temp = to_string(main_queue.top().RT).length();
cout << '|' << string(7 - temp / 2 - temp % 2, ' ')
<< main_queue.top().RT << string(8 - temp / 2, ' ');
if (high == true) {
temp = to_string(main_queue.top().priority).length();
cout << '|' << string(5 - temp / 2 - temp % 2, ' ')
<< main_queue.top().priority << string(5 - temp / 2, ' ');
}
cout << "|\n";
main_queue.pop();
}
cout << "+-------------+--------------";
cout << "+------------+-----------------";
cout << "+-----------------+--------------+---------------+";
if (high == true)
cout << "----------+";
cout << endl;
temp1 = get_total_CT(tempq);
cout << "\nTotal completion time :- " << temp1 << endl;
cout << "Average completion time :- " << temp1 / size << endl;
temp1 = get_total_TAT(tempq);
cout << "\nTotal turnaround time :- " << temp1 << endl;
cout << "Average turnaround time :- " << temp1 / size << endl;
temp1 = get_total_WT(tempq);
cout << "\nTotal waiting time :- " << temp1 << endl;
cout << "Average waiting time :- " << temp1 / size << endl;
temp1 = get_total_RT(tempq);
cout << "\nTotal response time :- " << temp1 << endl;
cout << "Average response time :- " << temp1 / size << endl;
}
// Function to display Gantt Chart
void disp_gantt_chart(queue gantt)
{
int temp, prev = 0;
queue spaces = gantt;
cout << "\n\nGantt Chart (IS indicates ideal state) :- \n\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-') << "+";
spaces.pop();
}
cout << "\n|";
spaces = gantt;
while (!spaces.empty()) {
cout << string(spaces.front().temp_BT, ' ');
if (spaces.front().p_no == -1)
cout << "IS" << string(spaces.front().temp_BT, ' ') << '|';
else
cout << "P" << spaces.front().p_no
<< string(spaces.front().temp_BT, ' ') << '|';
spaces.pop();
}
spaces = gantt;
cout << "\n+";
while (!spaces.empty()) {
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT, '-')
<< "+";
spaces.pop();
}
spaces = gantt;
cout << "\n0";
while (!spaces.empty()) {
temp = to_string(spaces.front().CT).length();
cout << string(to_string(spaces.front().p_no).length() + (spaces.front().p_no != -1) + 2 * spaces.front().temp_BT - temp / 2 - prev, ' ')
<< spaces.front().CT;
prev = temp / 2 - temp % 2 == 0;
spaces.pop();
}
cout << "\n\n";
}
// Driver Code
int main()
{
// Initialise Ready and Completion Queue
priority_queue ready_queue, completion_queue;
// queue for Gantt Chart
queue gantt;
ready_queue = set_sample_data();
// Function call to find completion data
completion_queue = HRRN_run(ready_queue, &gantt);
// Display Completion Queue
disp(completion_queue, false);
// Display Gantt Chart
disp_gantt_chart(gantt);
return 0;
}
OUTPUT :-+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| Process No. | Arrival Time | Burst Time | Completion Time | Turnaround Time | Waiting Time | Response Time |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
| 1 | 0 | 4 | 4 | 4 | 0 | 0 |
| 2 | 1 | 2 | 6 | 5 | 3 | 3 |
| 3 | 2 | 3 | 10 | 8 | 5 | 5 |
| 4 | 3 | 5 | 15 | 12 | 7 | 7 |
| 5 | 4 | 1 | 7 | 3 | 2 | 2 |
| 6 | 5 | 4 | 19 | 14 | 10 | 10 |
| 7 | 6 | 6 | 25 | 19 | 13 | 13 |
+-------------+--------------+------------+-----------------+-----------------+--------------+---------------+
Total completion time :- 86
Average completion time :- 12.2857
Total turnaround time :- 65
Average turnaround time :- 9.28571
Total waiting time :- 40
Average waiting time :- 5.71429
Total response time :- 40
Average response time :- 5.71429
Gantt Chart (IS indicates ideal state) :-
+----------+------+----+--------+------------+----------+--------------+
| P1 | P2 | P5 | P3 | P4 | P6 | P7 |
+----------+------+----+--------+------------+----------+--------------+
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