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https://github.com/zephyrproject-rtos/zephyr
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Tick rate is becoming a platform tunable in the tickless world. Some apps were setting it due to requirements of drivers or subsystems (or sometimes for reasons that don't make much sense), but the dependency goes the other way around now: board/soc/arch level code is responsible for setting tick rates that work with their devices. A few tests still use hard-configured tick rates, as they have baked-in assumptions (like e.g. "a tick will be longer than a millisecond") that need to be addressed first. Signed-off-by: Andy Ross <andrew.j.ross@intel.com> |
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| CMakeLists.txt | ||
| prj_tickless.conf | ||
| prj.conf | ||
| README.rst | ||
| sample.yaml | ||
.. _dining-philosophers-sample: Dining Philosophers ################### Overview ******** An implementation of a solution to the Dining Philosophers problem (a classic multi-thread synchronization problem). This particular implementation demonstrates the usage of multiple preemptible and cooperative threads of differing priorities, as well as dynamic mutexes and thread sleeping. The philosopher always tries to get the lowest fork first (f1 then f2). When done, he will give back the forks in the reverse order (f2 then f1). If he gets two forks, he is EATING. Otherwise, he is THINKING. Transitional states are shown as well, such as STARVING when the philosopher is hungry but the forks are not available, and HOLDING ONE FORK when a philosopher is waiting for the second fork to be available. Each Philosopher will randomly alternate between the EATING and THINKING state. It is possible to run the demo in coop-only or preempt-only mode. To achieve this, set these values for CONFIG_NUM_COOP_PRIORITIES and CONFIG_NUM_PREEMPT_PRIORITIES in prj.conf: preempt-only: CONFIG_NUM_PREEMPT_PRIORITIES 6 CONFIG_NUM_COOP_PRIORITIES 0 coop-only: CONFIG_NUM_PREEMPT_PRIORITIES 0 CONFIG_NUM_COOP_PRIORITIES 6 In these cases, the philosopher threads will run with priorities 0 to 5 (preempt-only) and -7 to -2 (coop-only). Building and Running ******************** This project outputs to the console. It can be built and executed on QEMU as follows: .. zephyr-app-commands:: :zephyr-app: samples/philosophers :host-os: unix :board: qemu_x86 :goals: run :compact: Sample Output ============= .. code-block:: console Philosopher 0 [P: 3] HOLDING ONE FORK Philosopher 1 [P: 2] HOLDING ONE FORK Philosopher 2 [P: 1] EATING [ 1900 ms ] Philosopher 3 [P: 0] THINKING [ 2500 ms ] Philosopher 4 [C:-1] THINKING [ 2200 ms ] Philosopher 5 [C:-2] THINKING [ 1700 ms ]