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| author |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-03-17 17:32:33 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-03-27 16:39:02 -0400 |
| commit | 8a815e6b8b88bfbbaba7c484af0833551a825321 (patch) | |
| tree | 6a7f929ea43d4a5b8834c2fb67987b136ba261f3 /Documentation/trace | |
| parent | ring-buffer/tracing: Have iterator acknowledge dropped events (diff) | |
| download | linux-dev-8a815e6b8b88bfbbaba7c484af0833551a825321.tar.xz linux-dev-8a815e6b8b88bfbbaba7c484af0833551a825321.zip | |
tracing: Have the document reflect that the trace file keeps tracing enabled
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@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/ftrace.rst | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index c33950a35d65..00621731bf27 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: |