Interrupts notify the processor of events such as device completion. Handling paths coordinate hardware events with scheduled application work.
Before you start
You should understand processes, threads, memory and basic file operations. Track ownership and state changes over time. For concurrent scenarios, write down at least two possible execution orders; the same instructions can behave differently when scheduling or resource availability changes.
The practical goal is to reason through this situation: A network device signals received data before an application eventually reads it. Read the walkthrough first, then try the interview exercise before opening its answer. The important part is explaining the decision and its consequences, rather than remembering a definition alone.
Step-by-step walkthrough
Step 1: Follow device completion
Hardware notification starts a kernel handling path.
Step 2: Track data availability
Kernel buffers can hold received bytes before application execution.
Step 3: Separate scheduling
The application must run and process input before the request completes.
Worked scenario
A network device signals received data before an application eventually reads it.
A network device reports packet arrival, the kernel makes bytes available and wakes relevant waiting work. The application may still wait for CPU scheduling, parse several frames and call a database. Device completion is one stage, not evidence that the full business request has finished.
Common mistake
An interrupt does not mean the application’s full request has completed.
Verify the behavior
Draw arrival, kernel, scheduling and application stages with their possible delays.
Interview exercise
Explain network input flow.
Answer and reasoning
Trace device arrival, kernel handling, buffer availability and application scheduling, distinguishing each ownership boundary.
Continue learning
Compare the scenario with the Operating Systems interview questions and test your understanding with the Operating Systems MCQs. For terminology and implementation details, consult the reference material.