IoT Operating Systems ISE Practice Questions (Page 3)

Questions 11–15

1. 11expert · hard

   An RTOS-based medical pump has a high-priority task that controls the motor and a lower-priority task that logs data to flash. The logging task occasionally takes a long time to complete, causing the motor task to miss its deadline. The developer suspects priority inversion. What is the most effective solution?

   • AIncrease the priority of the logging task to be higher than the motor task
   • BImplement priority inheritance on the mutex that protects the shared flash resource
   • CUse a semaphore instead of a mutex for the flash resource
   • DDisable interrupts during the logging operation
   Reveal Solution Discussion Select an answer first
2. 12application · medium

   A wearable fitness tracker uses an RTOS and must extend battery life. The device has an accelerometer that needs to sample at 100 Hz during activity, but can be turned off when the user is idle. The OS supports idle hooks and dynamic voltage and frequency scaling (DVFS). What should the developer configure to minimize power consumption?

   • AIncrease the accelerometer sampling rate to 200 Hz to finish processing faster
   • BKeep the CPU in active mode and rely on DVFS to reduce voltage to the minimum at all times
   • CUse the idle hook to enter a low-power sleep mode when no tasks are ready, and use DVFS to lower the CPU frequency during light processing
   • DDisable the idle hook and use a busy-wait loop to keep the CPU ready for interrupts
   Reveal Solution Discussion Select an answer first
4. 13foundation · easy

   What is dynamic voltage and frequency scaling (DVFS) used for in IoT operating systems?

   • ATo adjust CPU power consumption based on workload
   • BTo increase the accuracy of the system clock
   • CTo boost network throughput
   • DTo protect the CPU from overheating
   Reveal Solution Discussion Select an answer first
5. 14application · medium

   A battery-powered environmental sensor node spends most of its time idle, waking every 10 minutes to take a reading and transmit it over LoRaWAN. The device must last 5 years on a single coin cell. Which power-management strategy should the IoT OS implement to maximize battery life?

   • AEnter deep sleep mode between transmissions and wake on a timer or external interrupt
   • BKeep the CPU in active mode but reduce the clock frequency to the minimum
   • CDisable all interrupts and use a busy-wait loop for timing
   • DUse dynamic voltage and frequency scaling (DVFS) to adjust voltage during idle
   Reveal Solution Discussion Select an answer first
6. 15application · medium

   An IoT device runs an RTOS with 128 KB of RAM. The firmware must never allocate memory dynamically after initialization because heap fragmentation could cause unpredictable failures. The team needs to ensure that all tasks have the memory they need without runtime allocation. What should they implement?

   • AStatically allocate all task stacks and kernel objects at compile time
   • BUse a memory pool with fixed-size blocks allocated on demand
   • CConfigure the RTOS to use a first-fit heap allocator
   • DEnable virtual memory with paging to expand available RAM
   Reveal Solution Discussion Select an answer first