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    SubjectSCHED_FIFO & system()
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    Hello,
    I have some strange behavior in one of my systems.

    I have a real-time kernel thread under SCHED_FIFO which is running every
    10ms.
    It is blocking on a semaphore and released by a timer interrupt every 10ms.
    Generally this works really well.

    However, there is a module in the system that makes a / system() / call
    from c-code in user-space;

    system("run_my_script");

    By calling and running a bash script. Independent of how the actual
    script looks like the real time kernel thread does not get scheduled under
    the time of 80ms -- the time it takes for the system() call to finish.

    I can see when running a LTT session that the wake_up event occurs for
    the real time thread 10ms into the system call but nevertheless the real
    time kernel thread does not get scheduled.

    The thread that calls system("run_my_script") is configured as SCHED_OTHER.

    The Kernel is 2.6.21.


    Anybody who recognize this or similar situations?



    Cheers // Matias


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