03 - Scheduling

Question 1

PROCESS SCHEDULING
(FCFS) First-Come, First-Served

Answer 1

Processes are executed in the other they arrive in the ready queue

Question 2

PROCESS SCHEDULING
(SJF) Shortest Job First

Answer 2

Processes with the shortest execution time are executed first

Question 3

PROCESS SCHEDULING
(RR) Round Robin

Answer 3

Processes are executed in a cyclic manner
Each process is assigned a fixed time quantum

Question 4

PROCESS SCHEDULING
Priority Scheduling

Answer 4

Processes are assigned priorities, CPU is allocated to highest priority process

Question 5

PROCESS SCHEDULING
Multilevel Queue Scheduling/Multilevel Feedback Queue Scheduling

Answer 5

Processes are divide into queues based on characteristics such as priority or process type

Feedback Scheduling:
ability for processes to move between queues based on their behaviour

Question 6

CPU Bursts

Answer 6

Occur when a process performs a significant amount of computation without requiring much I/O or waiting time.

the process actively uses the CPU to execute instructions continuously.

Question 7

I/O bursts

Answer 7

Occur when a process requires input/output operations

the process spends most of its time waiting for I/O operations to complete, with brief bursts of CPU activity when processing data.

Question 8

Preemptive Scheduling vs Nonpreemptive Scheduling

Answer 8

Preemptive scheduling: The operating system can interrupt a program currently running to let another one run.

Non-preemptive scheduling:
lets a program complete its execution before switching to another one.

Question 9

Race Conditions

Answer 9

Occur when the outcome of a program depends on the timing/sequence of events
Multiple threads and processes compete for shared resources without proper synchronisation

Question 10

Scheduling Criteria

Answer 10

CPU utilisation – keep the CPU as busy as possible

Throughput – # of processes that complete their execution per time unit

Turnaround time – amount of time to execute a particular process

Waiting time – amount of time a process has been waiting in the ready queue

Response time – amount of time it takes from when a
request was submitted until the first response is produced.

Question 11

Processor affinity

Answer 11

When a thread has been running on one processor, the cache contents of that processor stores the memory accessed by that thread

benefit:
improved cache performance.

Question 12

NUMA - Non-Uniform Memory Access

Answer 12

Computer architecture where multiple processors (or nodes) have access to their own local memory as well as the shared memory.

benefit:
Improves memory access times for local memory.