Messages in this thread | | | From | Ross Zwisler <> | Date | Thu, 8 Dec 2022 15:27:07 -0700 | Subject | Re: [PATCH v2] tracing: Add trace_trigger kernel command line option |
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On Thu, Oct 20, 2022 at 7:00 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > 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). > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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> +#ifdef CONFIG_HIST_TRIGGERS
Can you help me understand why this is only available if CONFIG_HIST_TRIGGERS is selected in the kernel config? AFAICT this code doesn't depend on the histogram code, and the run-time selection of triggers is usable without CONFIG_HIST_TRIGGERS.
Thanks!
> +static void trace_early_triggers(struct trace_event_file *file, const char *name) > +{ > + int ret; > + int i;
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