60136f00cb
While trying out the hello_world sample built for QEMU, I was expecting the sample app to exit and I'd return to a command prompt. Nope. You need to exit QEMU manually, so add that step to the sample instructions. Looking around, there are more uses of QEMU like this that could use this added step after running the sample app. Signed-off-by: David B. Kinder <david.b.kinder@intel.com>
66 lines
1.9 KiB
ReStructuredText
66 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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Exit QEMU by pressing :kbd:`CTRL+A` :kbd:`x`.
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