RIOT/tests/sys/sched_round_robin/README.md

Round Robing Scheduling Test

This application is a simple test case for round-robin scheduling. Two threads are started with the same priority. The first thread is a busy loop and is started first. The second thread unlocks a mutex allowing the main thread to continue and exit.

Without Round Robin scheduling the busy loop thread would run indefinitely, with round-robin in eventually getting de-scheduled allowing the main thread to run and exit.

Usage

By default sched_round_robin is included:

make tests/sys_sched_round_robin flash term

...Board Initialisation...

Help: Press s to start test, r to print it is ready
s
START
main(): This is RIOT! (Version: ...)
starting threads
double locking mutex
mutex_thread yield
bad thread looping
unlock mutex
[SUCCESS]

It can be excluded from the build by setting the command-line argument NORR=1:

NORR=1 make tests/sys_sched_round_robin flash term

...Board Initialisation...

Help: Press s to start test, r to print it is ready
s
START
main(): This is RIOT! (Version: ...)
starting threads
double locking mutex
mutex_thread yield
bad thread looping

This will loop endlessly as the bad thread does not release the CPU, make test will timeout in that case.