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Comparative measures between FIFO and HEAP
Time is measured with a scope between two GPIO output changes.
- Target: STM32F4 Discovery board from ST, STM32F407VG running at 168MHz
- Compiler: GCC 4.9.3
- Optimization: -O3
- Scope: RIGOL MSO1104Z 100MHz 4 channels oscilloscope.
From StartOS to AUTOSTART task: A GPIO output is switched on just before StartOS, A second GPIO output is switched on at start of the AUTOSTART task
- HEAP: 5.80µs
- FIFO/HEAP: 5.76µs
- FIFO: 5.48µs
Similar to the previous one but with 10 auto-start Tasks with lower priority than the AUTOSTART Task.
- HEAP: 13.44µs
- FIFO/HEAP: 10.76µs
- FIFO: 9.52µs
An autostart task activates a lower or equal priority task. No preemption occurs. A GPIO output is switched on just before ActivateTask, A second GPIO output is switched on just after ActivateTask.
- HEAP: 2.70µs
- FIFO/HEAP: 2.52µs
- FIFO: 2.40µs
An autostart task activates a higher priority task. A preemption occurs. A GPIO output is switched on just before ActivateTask, A second GPIO output is switched on at start of the activated task.
- HEAP: 5.04µs
- FIFO/HEAP: 4.78µs
- FIFO: 4.30µs
A higher priority AUTOSTART task sets an event to a lower priority AUTOSTART extended task. the extended task is READY but has not yet run, so it is not waiting for an event. A GPIO output is switched on just before SetEvent, A second GPIO output is switched on just after SetEvent.
- HEAP: 1.76µs
- FIFO/HEAP: 1.73µs
- FIFO: 1.68µs
A higher priority task sets an event to a lower priority extended task. the extended task is WAITING. No preemption occurs. A GPIO output is switched on just before SetEvent, A second GPIO output is switched on just after SetEvent.
- HEAP: 2.88µs
- FIFO/HEAP: 2.84µs
- FIFO: 2.60µs
A lower priority task sets an event to a higher priority extended task. the extended task is WAITING. A preemption occurs. A GPIO output is switched on just before SetEvent, A second GPIO output is switched on juste after the WaitEvent.
- HEAP: 4.60µs
- FIFO/HEAP: 4.68µs
- FIFO: 4.02µs