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Kernel timeouts have always been a 32 bit integer despite the existence of generation macros, and existing code has been inconsistent about using them. Upcoming commits are going to make the timeout arguments opaque, so fix things up to be rigorously correct. Changes include: + Adding a K_TIMEOUT_EQ() macro for code that needs to compare timeout values for equality (e.g. with K_FOREVER or K_NO_WAIT). + Adding a k_msleep() synonym for k_sleep() which can continue to take integral arguments as k_sleep() moves away to timeout arguments. + Pervasively using the K_MSEC(), K_SECONDS(), et. al. macros to generate timeout arguments. + Removing the usage of K_NO_WAIT as the final argument to K_THREAD_DEFINE(). This is just a count of milliseconds and we need to use a zero. This patch include no logic changes and should not affect generated code at all. Signed-off-by: Andy Ross <andrew.j.ross@intel.com> |
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.. _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 ] Exit QEMU by pressing :kbd:`CTRL+A` :kbd:`x`.