Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem


a simple TaskYield question

Posted by htio on July 4, 2013

just wondering if a context switching took place right before the TaskYield function, when it returns from the context switching will it execute the TaskYield (which will force another context switch again?), if so the task might be switched away twice in some random occasion and how do we prevent this from happening ?

please advise.

RE: a simple TaskYield question

Posted by Richard on July 4, 2013
The task has no knowledge of what the scheduler is doing. As far as it is concerned it is just executing a sequential piece of code.

The scheduler's job is to maintain the context of each task exactly as it switches the tasks in and out. It would be time consuming and a logical error for the scheduler to look ahead at what a task will do in the future and then try to change it.

Therefore there is nothing you can do about it, but a preemptive context switch will only occur if there is a task of higher priority that becomes available, or the timeslice used by the current task expires and there is a task of equal priority that is in the ready state.


RE: a simple TaskYield question

Posted by htio on July 4, 2013
Hi, thanks for the reply, and yes i am having 2 task with the same priority and one with a TaskYield function in it, and i can see it sometimes skipped.

[ Back to the top ]    [ About FreeRTOS ]    [ Privacy ]    [ Sitemap ]    [ ]

Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

NXP tweet showing LPC5500 (ARMv8-M Cortex-M33) running FreeRTOS.

Version 10.1.1 of the FreeRTOS kernel is available for immediate download. MIT licensed.

View a recording of the "OTA Update Security and Reliability" webinar, presented by TI and AWS.


FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Espressif ESP32

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers


STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

OpenRTOS and SafeRTOS

Xilinx Microblaze and Zynq partner