Consider the following simple schedule:
| job number | arrival time | running time | priority |
|---|---|---|---|
| 0 | 0 | 8 | 1 |
| 1 | 1 | 8 | 1 |
| 2 | 3 | 4 | 2 |
The flow of execution of functions calls is as follows:
scheduler_start_up(cores = 2, scheme = FCFS)
--> scheduler initialized
new_job(job_number = 0, time = 0, running_time = 8, priority = 1)
--> returns 0, indicating job(id=0) should run on core(id=0)
new_job(job_number = 1, time = 1, running_time = 8, priority = 1)
--> returns 1, indicating that job(id=1) should run on core(id=1).
new_job(job_number = 2, time = 3, running_time = 4, priority = 2)
--> returns -1, indicating that job(id=2) will not be scheduled at this time.
job_finished(core_id = 0, job_number = 0, time = 8)
--> returns 2, indicating job(id=2) should run next on core(id=0).
job_finished(core_id = 1, job_number = 1, time = 9)
--> returns -1, indicating that core(id=1) should remain idle.
job_finished(core_id = 0, job_number = 2, time = 12)
--> returns -1, indicating that core(id=0) should remain idle.
scheduler_average_waiting_time()
--> returns (5/3) == 1.67.
scheduler_average_turnaround_time()
--> returns (25/3) == 8.33.
scheduler_average_response_time()
--> returns (5/3) == 1.67.
scheduler_clean_up()
--> cleans up and frees all memory used by the scheduler
When the simulator is executed and the flow of execution is implemented correctly, you will see the following output:
Loaded 2 core(s) and 3 job(s) using First Come First Served (FCFS) scheduling...
=== [TIME 0] ===
A new job, job 0 (running time=8, priority=1), arrived. Job 0 is now running on core 0.
Queue: 0(0)
At the end of time unit 0...
Core 0: 0
Core 1: -
Queue: 0(0)
=== [TIME 1] ===
A new job, job 1 (running time=8, priority=1), arrived. Job 1 is now running on core 1.
Queue: 0(0) 1(1)
At the end of time unit 1...
Core 0: 00
Core 1: -1
Queue: 0(0) 1(1)
=== [TIME 2] ===
At the end of time unit 2...
Core 0: 000
Core 1: -11
Queue: 0(0) 1(1)
=== [TIME 3] ===
A new job, job 2 (running time=4, priority=2), arrived. Job 2 is set to idle (-1).
Queue: 0(0) 1(1) 2(-1)
At the end of time unit 3...
Core 0: 0000
Core 1: -111
Queue: 0(0) 1(1) 2(-1)
=== [TIME 4] ===
At the end of time unit 4...
Core 0: 00000
Core 1: -1111
Queue: 0(0) 1(1) 2(-1)
=== [TIME 5] ===
At the end of time unit 5...
Core 0: 000000
Core 1: -11111
Queue: 0(0) 1(1) 2(-1)
=== [TIME 6] ===
At the end of time unit 6...
Core 0: 0000000
Core 1: -111111
Queue: 0(0) 1(1) 2(-1)
=== [TIME 7] ===
At the end of time unit 7...
Core 0: 00000000
Core 1: -1111111
Queue: 0(0) 1(1) 2(-1)
=== [TIME 8] ===
Job 0, running on core 0, finished. Core 0 is now running job 2.
Queue: 1(1) 2(0)
At the end of time unit 8...
Core 0: 000000002
Core 1: -11111111
Queue: 1(1) 2(0)
=== [TIME 9] ===
Job 1, running on core 1, finished. Core 1 is now running job -1.
Queue: 2(0)
At the end of time unit 9...
Core 0: 0000000022
Core 1: -11111111-
Queue: 2(0)
=== [TIME 10] ===
At the end of time unit 10...
Core 0: 00000000222
Core 1: -11111111--
Queue: 2(0)
=== [TIME 11] ===
At the end of time unit 11...
Core 0: 000000002222
Core 1: -11111111---
Queue: 2(0)
=== [TIME 12] ===
Job 2, running on core 0, finished. Core 0 is now running job -1.
Queue:
FINAL TIMING DIAGRAM:
Core 0: 000000002222
Core 1: -11111111---
Average Waiting Time: 1.67
Average Turnaround Time: 8.33
Average Response Time: 1.67
==19777==
==19777== HEAP SUMMARY:
==19777== in use at exit: 0 bytes in 0 blocks
==19777== total heap usage: 16 allocs, 16 frees, 3,102 bytes allocated
==19777==
==19777== All heap blocks were freed -- no leaks are possible
==19777==
==19777== For counts of detected and suppressed errors, rerun with: -v
==19777== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 4 from 4)