4. Real-Time Systems

Scheduling Theory — Quiz

Test your understanding of scheduling theory with 5 practice questions.

Practice Questions

Question 1

Under Earliest Deadline First (EDF) scheduling, a set of independent, preemptive, periodic tasks with deadlines equal to periods is guaranteed to be schedulable if the total processor utilization satisfies which condition?

Question 2

Given three periodic tasks with execution times and periods: Task 1 ($C_1=2\,$ms, $T_1=5\,$ms), Task 2 ($C_2=1\,$ms, $T_2=8\,$ms), and Task 3 ($C_3=2\,$ms, $T_3=10\,$ms), is this task set schedulable under Rate Monotonic Scheduling (RMS) according to the Liu & Layland utilization bound for $n=3$ ($U_{max}=3(2^{1/3}-1)\approx0.78$)?

Question 3

In a fixed-priority system, a task $i$ has $C_i=3\,$ms, $T_i=10\,$ms, and two higher-priority tasks with $(C_1=1\,$ms, $T_1=4\,$ms) and $(C_2=2\,$ms, $T_2=5\,$ms). Using the Response Time Analysis equation $R_i=C_i+\sum_{j\in hp(i)}\Bigl\lceil\frac{R_i}{T_j}\Bigr\rceil C_j$, what is the worst-case response time $R_i$?

Question 4

What is the primary advantage of the Priority Ceiling Protocol (PCP) over the Priority Inheritance Protocol (PIP) in managing shared resources?

Question 5

In real-time scheduling for mixed periodic and aperiodic tasks, what is the primary role of a Sporadic Server?