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Diffstat (limited to 'Documentation/trace/ftrace.rst')
| -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 |