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| author | Kurt Kanzenbach <kurt@linutronix.de> | 2022-04-14 11:18:05 +0200 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-04-27 23:19:30 +0200 |
| commit | 4d1257bbc220603d9e5c5157552448c066111c71 (patch) | |
| tree | 774d96336313e932d9436e33a62ab6a410f0240a | |
| parent | tracing: Introduce trace clock tai (diff) | |
| download | linux-4d1257bbc220603d9e5c5157552448c066111c71.tar.xz linux-4d1257bbc220603d9e5c5157552448c066111c71.zip | |
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: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
| -rw-r--r-- | Documentation/trace/ftrace.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index 45b8c56af67a..b37dc19e4d40 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -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 |