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Diffstat (limited to 'Documentation/trace/ftrace.rst')
| -rw-r--r-- | Documentation/trace/ftrace.rst | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index b3166c4a7867..60bceb018d6a 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 @@ -552,7 +564,7 @@ of ftrace. Here is a list of some of the key files: start:: - trace_fd = open("trace_marker", WR_ONLY); + trace_fd = open("trace_marker", O_WRONLY); Note: Writing into the trace_marker file can also initiate triggers that are written into /sys/kernel/tracing/events/ftrace/print/trigger @@ -3370,7 +3382,7 @@ one of the latency tracers, you will get the following results. Instances --------- -In the tracefs tracing directory is a directory called "instances". +In the tracefs tracing directory, there is a directory called "instances". This directory can have new directories created inside of it using mkdir, and removing directories with rmdir. The directory created with mkdir in this directory will already contain files and other |