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Add a sample monitor to showcase hybrid/timed automata. The stall monitor identifies tasks stalled for longer than a threshold and reacts when that happens. Reviewed-by: Nam Cao <namcao@linutronix.de> Link: https://lore.kernel.org/r/20260330111010.153663-7-gmonaco@redhat.com Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
44 lines
1.6 KiB
ReStructuredText
44 lines
1.6 KiB
ReStructuredText
Monitor stall
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=============
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- Name: stall - stalled task monitor
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- Type: per-task hybrid automaton
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- Author: Gabriele Monaco <gmonaco@redhat.com>
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Description
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-----------
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The stalled task (stall) monitor is a sample per-task timed monitor that checks
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if tasks are scheduled within a defined threshold after they are ready::
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v
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#==========================#
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+-----------------> H dequeued H
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| #==========================#
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| |
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sched_switch_wait | sched_wakeup;reset(clk)
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| v
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| +--------------------------+ <+
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| | enqueued | | sched_wakeup
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| | clk < threshold_jiffies | -+
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| +--------------------------+
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| | ^
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| sched_switch_in sched_switch_preempt;reset(clk)
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| v |
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| +--------------------------+
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+------------------ | running |
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+--------------------------+
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^ sched_switch_in |
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| sched_wakeup |
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+----------------------+
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The threshold can be configured as a parameter by either booting with the
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``stall.threshold_jiffies=<new value>`` argument or writing a new value to
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``/sys/module/stall/parameters/threshold_jiffies``.
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Specification
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-------------
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Graphviz Dot file in tools/verification/models/stall.dot
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