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Diffstat (limited to 'Documentation/trace/rv/monitor_wwnr.rst')
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diff --git a/Documentation/trace/rv/monitor_wwnr.rst b/Documentation/trace/rv/monitor_wwnr.rst new file mode 100644 index 000000000000..9f739030f826 --- /dev/null +++ b/Documentation/trace/rv/monitor_wwnr.rst @@ -0,0 +1,45 @@ +Monitor wwnr +============ + +- Name: wwrn - wakeup while not running +- Type: per-task deterministic automaton +- Author: Daniel Bristot de Oliveira <bristot@kernel.org> + +Description +----------- + +This is a per-task sample monitor, with the following +definition:: + + | + | + v + wakeup +-------------+ + +--------- | | + | | not_running | + +--------> | | <+ + +-------------+ | + | | + | switch_in | switch_out + v | + +-------------+ | + | running | -+ + +-------------+ + +This model is broken, the reason is that a task can be running +in the processor without being set as RUNNABLE. Think about a +task about to sleep:: + + 1: set_current_state(TASK_UNINTERRUPTIBLE); + 2: schedule(); + +And then imagine an IRQ happening in between the lines one and two, +waking the task up. BOOM, the wakeup will happen while the task is +running. + +- Why do we need this model, so? +- To test the reactors. + +Specification +------------- +Grapviz Dot file in tools/verification/models/wwnr.dot |