Commit 4d1257bb authored by Kurt Kanzenbach's avatar Kurt Kanzenbach Committed by Steven Rostedt (Google)
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tracing: Add documentation for trace clock tai 

Add documentation for newly introduced trace clock "tai".
This clock corresponds to CLOCK_TAI.

Link: https://lkml.kernel.org/r/20220414091805.89667-4-kurt@linutronix.de



Signed-off-by: default avatarKurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent c575afe2

Documentation/trace/ftrace.rst

+12 −0
Original line number Diff line number Diff line
@@ -517,6 +517,18 @@ of ftrace. Here is a list of some of the key files: 
		processing should be able to handle them. See comments in the

		ktime_get_boot_fast_ns() function for more information.



	tai:

		This is the tai clock (CLOCK_TAI) and is derived from the wall-

		clock time. However, this clock does not experience

		discontinuities and backwards jumps caused by NTP inserting leap

		seconds. Since the clock access is designed for use in tracing,

		side effects are possible. The clock access may yield wrong

		readouts in case the internal TAI offset is updated e.g., caused

		by setting the system time or using adjtimex() with an offset.

		These effects are rare and post processing should be able to

		handle them. See comments in the ktime_get_tai_fast_ns()

		function for more information.



	To set a clock, simply echo the clock name into this file::



	  # echo global > trace_clock