ESP32 Main Task Size

[llewellyn]

In my main function if I start 4 tasks of 2048 heap size each. Does my main task size need to be 4 * 2048?

[kolban]

Howdy ... no sir.

Each task you create has its own stack size that YOU explicitly specify when you create a task. If you look at the API you are using to create a task, you will find that the stack size for THAT task that you are are creating is a parameter on the API. Since there are some tasks within ESP-IDF that are created outside of your control (i.e. the main task that gets the story running in the first place), it is the stack size for those ESP-IDF tasks that are specified in the make menuconfig.

[permal]

Edit: As per ESP_igrr's post below, the FreeRTOS documentation doesn't correspond the the IDF-version of FreeRTOS. Please refer to ESP_igrr's post for correct info.

Also worth noting is that the number you specify isn't the size in the traditional sense. It is, as is clearly documented here (see usStackDepth), the depth of the stack.

The number of words (not bytes!) to allocate for use as the task's stack. For example, if the stack is 16-bits wide and usStackDepth is 100, then 200 bytes will be allocated for use as the task's stack. As another example, if the stack is 32-bits wide and usStackDepth is 400 then 1600 bytes will be allocated for use as the task's stack.
The stack depth multiplied by the stack width must not exceed the maximum value that can be contained in a variable of type size_t.

In the case if the ESP32, the word size is four (32 bits, 4 bytes)

[ESP_igrr]

Actually, stack size is given in units StackType_t (even though FreeRTOS documentation says that it is given in words).
In the original xtensa port StackType_t was defined as uint8_t. This was preserved in ESP-IDF version of FreeRTOS as well:
https://github.com/espressif/esp-idf/bl ... .h#L50-L52
https://github.com/espressif/esp-idf/bl ... #L104-L108

[permal]

Oh, wow. That's a factor of four from what the manual says!

What other IDF-specific quirks are there that are not corresponding to the official documentation? Is there a list of such things? These kind of differences are rather valuable/important to know.

[llewellyn]

Thanx A lot everyone. This helps !!

[burkulesomesh43]

Howdy ... no sir.

Each task you create has its own stack size that YOU explicitly specify when you create a task. If you look at the API you are using to create a task, you will find that the stack size for THAT task that you are are creating is a parameter on the API. Since there are some tasks within ESP-IDF that are created outside of your control (i.e. the main task that gets the story running in the first place), it is the stack size for those ESP-IDF tasks that are specified in the make menuconfig.

How can we determine the main task stack size?
it is 3584 default.