Why a lower priority task created before higher priority task get executed always? I have turned off time slicing.

Why not if it’s the highest prio ready task at this point of time ?

What do you mean by executed always? Do you mean only the lower priority task ever executes (executes all the time) and the higher priority task never executes? Or do you mean the lower priority task executes before the high priority task but both low and high do execute? If the second case pleas…

The first case, higher priority never executes.

What happens when a high priority task enters Ready state? Since it is having the highest priority, it should preempt the lower priority task, right?

Exactly. But if the higher prio task never executes as reported something else if wrong. Do you check the return values of xTaskCreate and did you define configASSERT and enabled stack overflow checking as recommended ?

I just tried this demo , which creates two application tasks, a send task and a receive task. I set the priority of the timer task to 0, the send task to 1, and the receive task to 2 - and turned off time slicing. By putting a break point at the start of each task I could see, as expected as it was…

I placed print statements in both the tasks.

Are you sure that your print function is thread safe and nothing else went wrong ? Any chance to use a debugger and use appropriate breakpoints ? BTW which MCU or port do you use ?

I used GUI flash tool. I am using NXP’s FRDM K64F series MCU

[image] ReticentFella: t If two tasks are created back to back with tasks having different priority, if lower priority is created first but the scheduler is started only after creating tasks, then why the lower priority task is running initially.

Task Priority?

Kernel

ReticentFella (Reticent Fella) January 7, 2022, 12:05pm 17

What does one exactly mean by thread safety?

Topic		Replies	Views
Tasks not running on priority base Kernel	5	1580	January 14, 2020
A single task doesn't run with a priority other than 0 Kernel	6	988	June 29, 2020
Problems with Task Priorities Kernel	2	211	June 4, 2009
Issue with two task with different priority Kernel	4	671	September 7, 2020
Tasks not running in priority order Kernel	7	277	April 14, 2025

Task Priority?

Related topics