| commit | e1b98f0b4be153cf6590c5b5b2f76b001af71c51 | [log] [tgz] |
|---|---|---|
| author | RichardBarry <richardbarry.c@gmail.com> | Fri Feb 28 12:40:11 2020 -0800 |
| committer | RichardBarry <richardbarry.c@gmail.com> | Fri Feb 28 12:40:11 2020 -0800 |
| tree | 36295854e4067c02adc9c8703592c0a3252c1e31 | |
| parent | 499e55a03c0b0bba7fb5665e761bde0c65803230 [diff] |
This change prevents tickless idle mode potentially sleeping for an extra tick in the corer case that a tick interrupt occurred between the scheduler being suspended and the expected idle time being checked for a second time (within the idle task) - as described by the sequence below. Th change updates eTaskConfirmSleepModeStatus() to specifically check if a tick is pending, and if so, abort entering sleep mode. + The idle task decides to enter sleep mode on the following line. ``` if( xExpectedIdleTime >= configEXPECTED_IDLE_TIME_BEFORE_SLEEP ) ``` + The scheduler is suspended, preventing any context switches. [Potentially a tick interrupt could occur here. That could happen if other tasks executing consumed a lot of time since the above code line executed. If a tick interrupt occurs here the interrupt will be entered but the interrupt will not do anything other than increment xPendedTicks.] + The expected idle time is checked again. No context switches can occur now so the code will execute until the scheduler is unsuspended. Assuming configEXPECTED_IDLE_TIME_BEFORE_SLEEP is set to a sensible value, a tick interrupt won't occur for some time. + portSUPPRESS_TICKS_AND_SLEEP() is called. + The default implementation of the tickless function calls eTaskConfirmSleep() - which prior to this change does not return eAbortSleep even though xPendedTicks is not 0, and after this change does return eAbortSleep.
This repository contains FreeRTOS kernel source/header files and kernel ports only. This repository is referenced as a submodule in FreeRTOS/FreeRTOS repository, which contains pre-configured demo application projects under FreeRTOS/Demo directory.
The easiest way to use FreeRTOS is to start with one of the pre-configured demo application projects. That way you will have the correct FreeRTOS source files included, and the correct include paths configured. Once a demo application is building and executing you can remove the demo application files, and start to add in your own application source files. See the FreeRTOS Kernel Quick Start Guide for detailed instructions and other useful links.
Additionally, for FreeRTOS kernel feature information refer to the Developer Documentation, and API Reference.
If you have any questions or need assistance troubleshooting your FreeRTOS project, we have an active community that can help on the FreeRTOS Community Support Forum.
To clone using HTTPS:
git clone https://github.com/FreeRTOS/FreeRTOS-Kernel.git
Using SSH:
git clone git@github.com:FreeRTOS/FreeRTOS-Kernel.git
The root of this repository contains the three files that are common to every port - list.c, queue.c and tasks.c. The kernel is contained within these three files. croutine.c implements the optional co-routine functionality - which is normally only used on very memory limited systems.
The ./portable directory contains the files that are specific to a particular microcontroller and/or compiler. See the readme file in the ./portable directory for more information.
The ./include directory contains the real time kernel header files.