leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

tracing: Add documentation for trace clock tai

Browse Source 
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>
This commit is contained in:
Kurt Kanzenbach 2022-04-14 11:18:05 +02:00 committed by Steven Rostedt (Google)
parent c575afe21c
commit 4d1257bbc2
1 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
Documentation/trace/ftrace.rst
View File

@ -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