tracing: Add trace_trigger kernel command line option

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Allow triggers to be enabled at kernel boot up. For example:

  trace_trigger="sched_switch.stacktrace if prev_state == 2"

The above will enable the stacktrace trigger on top of the sched_switch
event and only trigger if its prev_state is 2 (TASK_UNINTERRUPTIBLE). Then
at boot up, a stacktrace will trigger and be recorded in the tracing ring
buffer every time the sched_switch happens where the previous state is
TASK_INTERRUPTIBLE.

Another useful trigger would be "traceoff" which can stop tracing on an
event if a field of the event matches a certain value defined by the
filter ("if" statement).

Link: https://lore.kernel.org/linux-trace-kernel/20221020210056.0d8d0a5b@gandalf.local.home

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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Steven Rostedt (Google) 2022-10-20 21:00:56 -04:00

parent 8230f27b1c

commit a01fdc897f

2 changed files with 89 additions and 2 deletions

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19

Documentation/admin-guide/kernel-parameters.txt

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72

kernel/trace/trace_events.c

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