3e25d441a5
The following commit adds a real time stats example demonstrating how to obtain task CPU usage statistics over a period of time, as opposed to the current run time stats in FreeRTOS which measures task CPU usage as a percentage of total system run time.
72 lines
2.4 KiB
Markdown
72 lines
2.4 KiB
Markdown
# FreeRTOS Real Time Stats Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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FreeRTOS provides the function `vTaskGetRunTimeStats()` to obtain CPU usage statistics of tasks. However, these statistics are with respect to the entire runtime of FreeRTOS (i.e. **run time stats**). Furthermore, statistics of `vTaskGetRunTimeStats()` are only valid whilst the timer for run time statistics has not overflowed.
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This example demonstrates how to get CPU usage statistics of tasks with respect to a specified duration (i.e. **real time stats**) rather than over the entire runtime of FreeRTOS. The `print_real_time_stats()` function of this example demonstrates how this can be achieved.
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## How to use example
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### Hardware Required
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This example should be able to run on any commonly available ESP32 development board.
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### Configure the project
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```
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make menuconfig
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```
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* Set serial port under Serial Flasher Options.
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* Enable FreeRTOS to collect run time stats under `Component Config->FreeRTOS`
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* The clock source of reference timer used for FreeRTOS statistics can be configured under `Component Config->FreeRTOS`
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### Build and Flash
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Build the project and flash it to the board, then run monitor tool to view serial output:
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```
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make -j4 flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example Output
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```
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Getting real time stats over 100 ticks
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| Task | Run Time | Percentage
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| stats | 1304 | 0%
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| IDLE0 | 206251 | 10%
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| IDLE1 | 464785 | 23%
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| spin2 | 225389 | 11%
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| spin0 | 227174 | 11%
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| spin4 | 225303 | 11%
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| spin1 | 207264 | 10%
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| spin3 | 225331 | 11%
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| spin5 | 225369 | 11%
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| Tmr Svc | 0 | 0%
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| esp_timer | 0 | 0%
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| ipc1 | 0 | 0%
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| ipc0 | 0 | 0%
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Real time stats obtained
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```
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- When compiled in dual core mode, the percentage is with respect to the combined run time of both CPUs. Thus, `50%` would indicate full utilization of a single CPU.
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- In single core mode, the percentage is with respect to a single CPU. Thus, `100%` would indicate full utilization of the CPU.
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The unit of `Run Time` is the period of the timer clock source used for FreeRTOS statistics.
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## Troubleshooting
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```
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Getting real time stats over 100 ticks
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Error getting real time stats
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```
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If the above is output when running the example, users should check the return value of `print_real_time_stats()` to determine the reason for failure.
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