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[12/12,v2] tracing: Have the document reflect that the trace file keeps tracing enabled

Message ID 20200319232733.286726349@goodmis.org
State Not Applicable
Delegated to: BPF Maintainers
Headers show
Series ring-buffer/tracing: Remove disabling of ring buffer while reading trace file | expand

Commit Message

Steven Rostedt March 19, 2020, 11:22 p.m. UTC 
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

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>
---
 Documentation/trace/ftrace.rst | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
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Patch

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: