2018-12-21 12:54:35 +08:00
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.. _cmsis_rtos_v2-sample:
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Dining Philosophers (CMSI RTOS V2 APIs)
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#######################################
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Overview
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********
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This sample implements a solution to the `Dining Philosophers problem
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<https://en.wikipedia.org/wiki/Dining_philosophers_problem>`_ (a classic
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multi-thread synchronization problem) using CMSIS RTOS V2 APIs. This particular
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implementation demonstrates the usage of multiple preemptible and cooperative
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threads of differing priorities, as well as mutex/semaphore and thread sleeping
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which uses CMSIS RTOS V2 API implementation in Zephyr.
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The philosopher always tries to get the lowest fork first (f1 then f2). When
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done, he will give back the forks in the reverse order (f2 then f1). If he
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gets two forks, he is EATING. Otherwise, he is THINKING. Transitional states
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are shown as well, such as STARVING when the philosopher is hungry but the
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forks are not available, and HOLDING ONE FORK when a philosopher is waiting
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for the second fork to be available.
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Each Philosopher will randomly alternate between the EATING and THINKING state.
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Building and Running
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********************
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This project outputs to the console. It can be built and executed
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on QEMU as follows:
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.. zephyr-app-commands::
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:zephyr-app: samples/philosophers
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:host-os: unix
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:board: qemu_x86
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:goals: run
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:compact:
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Sample Output
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=============
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.. code-block:: console
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Philosopher 0 [P: 8] HOLDING ONE FORK
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Philosopher 1 [P: 9] HOLDING ONE FORK
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Philosopher 2 [P: 10] EATING [ 575 ms ]
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Philosopher 3 [P: 11] THINKING [ 225 ms ]
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Philosopher 4 [P: 12] THINKING [ 425 ms ]
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Philosopher 5 [P: 13] THINKING [ 325 ms ]
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Demo Description
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----------------
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An implementation of a solution to the Dining Philosophers
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problem (a classic multi-thread synchronization problem) using
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|
|
|
CMSIS RTOS V2 APIs. This particular implementation demonstrates the
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|
|
|
usage of multiple preemptible threads of differing
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priorities, as well as semaphores and thread sleeping.
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2019-08-29 06:46:09 +08:00
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Exit QEMU by pressing :kbd:`CTRL+A` :kbd:`x`.
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