tracing: Allow stacktraces to be saved as histogram variables

Allow to save stacktraces into a histogram variable. This will be used by
synthetic events to allow a stacktrace from one event to be passed and
displayed by another event.

The special keyword "stacktrace" is to be used to trigger a stack
trace for the event that the histogram trigger is attached to.

  echo 'hist:keys=pid:st=stacktrace" > events/sched/sched_waking/trigger

Currently nothing can get access to the "$st" variable above that contains
the stack trace, but that will soon change.

Link: https://lkml.kernel.org/r/[email protected]

Cc: Masami Hiramatsu <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Tom Zanussi <[email protected]>
Cc: Ross Zwisler <[email protected]>
Cc: Ching-lin Yu <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

0 files changed, 0 insertions, 0 deletions