FreeRTOS scheduler does not preempt on Linux target (IDFGH-13539)

[snake-4]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

IDF version.

v5.4-dev-2004-g8e4454b285

Espressif SoC revision.

Linux

Operating System used.

Linux

How did you build your project?

Command line with idf.py

If you are using Windows, please specify command line type.

None

Development Kit.

None

Power Supply used.

USB

What is the expected behavior?

Scheduler should preempt all tasks since the option is enabled by default in ESP-IDF.

What is the actual behavior?

The scheduler doesn't seem to preempt tasks with busy loops on the Linux target. This results in most components locking up the system.

Steps to reproduce.

• main/app_main.c

#include <freertos/FreeRTOS.h>
#include <freertos/timers.h>
#include <freertos/task.h>
#include <stdio.h>

static void timer_cb(TimerHandle_t) {
    puts("timer_cb called");
}

static void task_cb(void *) {
    for (;;) {}
}

void app_main(void) {
    xTimerStart(xTimerCreate("Timer", pdMS_TO_TICKS(500), pdTRUE, NULL, timer_cb), 0);
    vTaskDelay(pdMS_TO_TICKS(2000));

    xTaskCreate(task_cb, "Task", 1024, NULL, tskIDLE_PRIORITY, NULL);
    vTaskDelay(pdMS_TO_TICKS(2000));
}

• main/CMakeLists.txt

idf_component_register(SRCS "app_main.c")

• CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
set(COMPONENTS main)
include($ENV{IDF_PATH}/tools/cmake/project.cmake)
project(firmware)

Observe how the timer stops getting called after the task is created.

Debug Logs.

No response

More Information.

My previous bug report #14395 was likely caused by this issue.

[louielauanu]

Hi @snake-4,

I pasted your code and tried to reproduce the issue at my end using Linux target. I slightly modified the task_cb to make it print every second, and here is my output:

timer_cb called
timer_cb called
timer_cb called
timer_cb called
task executes
timer_cb called
timer_cb called
task executes
timer_cb called
timer_cb called
task executes
timer_cb called
timer_cb called
task executes
timer_cb called
timer_cb called
task executes
timer_cb called
timer_cb called
task executes

I see both task and time execute as expected. Do you mean that at your end timer output stops at some point? Can you share your log output?

Thanks,
Xiaoyu

[snake-4]

Sorry, this report might've been in error as I also noticed that it works fine. Maybe the behavior under GDB was different due to signal configuration.