From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> Now that reading the trace file does not temporarly stop tracing while it is open, update the document to reflect this fact. Link: http://lkml.kernel.org/r/20200317213417.209675068@xxxxxxxxxxx Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- Documentation/trace/ftrace.rst | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index 99a0890e20ec..86e76f2a40dc 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -125,10 +125,13 @@ of ftrace. Here is a list of some of the key files: trace: This file holds the output of the trace in a human - readable format (described below). Note, tracing is temporarily - disabled when the file is open for reading. Once all readers - are closed, tracing is re-enabled. Opening this file for + readable format (described below). Opening this file for writing with the O_TRUNC flag clears the ring buffer content. + Note, this file is not a consumer. If tracing is off + (no tracer running, or tracing_on is zero), it will produce + the same output each time it is read. When tracing is on, + it may produce inconsistent results as it tries to read + the entire buffer without consuming it. trace_pipe: @@ -142,9 +145,7 @@ of ftrace. Here is a list of some of the key files: will not be read again with a sequential read. The "trace" file is static, and if the tracer is not adding more data, it will display the same - information every time it is read. Unlike the - "trace" file, opening this file for reading will not - temporarily disable tracing. + information every time it is read. trace_options: -- 2.25.1
