72046a8abc
In order to be able to document the build on Windows and UNIX systems, slight variations are required on the app commands that are used throughout the documentation system. This includes getting rid of the prompt symbol and providing commands for both UNIX and Windows operating systems. Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
65 lines
1.9 KiB
ReStructuredText
65 lines
1.9 KiB
ReStructuredText
.. _dining-philosophers-sample:
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Dining Philosophers
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###################
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Overview
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********
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An implementation of a solution to the Dining Philosophers problem (a classic
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multi-thread synchronization problem). This particular implementation
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demonstrates the usage of multiple preemptible and cooperative threads of
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differing priorities, as well as dynamic mutexes and thread sleeping.
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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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It is possible to run the demo in coop-only or preempt-only mode. To achieve
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this, set these values for CONFIG_NUM_COOP_PRIORITIES and
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CONFIG_NUM_PREEMPT_PRIORITIES in prj.conf:
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preempt-only:
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CONFIG_NUM_PREEMPT_PRIORITIES 6
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CONFIG_NUM_COOP_PRIORITIES 0
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coop-only:
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CONFIG_NUM_PREEMPT_PRIORITIES 0
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CONFIG_NUM_COOP_PRIORITIES 6
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In these cases, the philosopher threads will run with priorities 0 to 5
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(preempt-only) and -7 to -2 (coop-only).
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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: 3] HOLDING ONE FORK
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Philosopher 1 [P: 2] HOLDING ONE FORK
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Philosopher 2 [P: 1] EATING [ 1900 ms ]
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Philosopher 3 [P: 0] THINKING [ 2500 ms ]
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Philosopher 4 [C:-1] THINKING [ 2200 ms ]
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Philosopher 5 [C:-2] THINKING [ 1700 ms ]
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