From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Peter Wu <peter@lekensteyn.nl>, Jonathan Corbet <corbet@lwn.net>,
Tom Zanussi <zanussi@kernel.org>,
Shuah Khan <shuahkhan@gmail.com>, bpf <bpf@vger.kernel.org>
Subject: [PATCH 12/12 v2] tracing: Have the document reflect that the trace file keeps tracing enabled
Date: Thu, 19 Mar 2020 19:22:31 -0400 [thread overview]
Message-ID: <20200319232733.286726349@goodmis.org> (raw)
In-Reply-To: 20200319232219.446480829@goodmis.org
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(-)
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
next prev parent reply other threads:[~2020-03-19 23:27 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 23:22 [PATCH 00/12 v2] ring-buffer/tracing: Remove disabling of ring buffer while reading trace file Steven Rostedt
2020-03-19 23:22 ` [PATCH 01/12 v2] selftest/ftrace: Fix function trigger test to handle trace not disabling the tracer Steven Rostedt
2020-03-19 23:22 ` [PATCH 02/12 v2] tracing: Save off entry when peeking at next entry Steven Rostedt
2020-03-20 2:57 ` Masami Hiramatsu
2020-03-26 9:12 ` [tracing] cd8f62b481: BUG:sleeping_function_called_from_invalid_context_at_mm/slab.h kernel test robot
2020-03-26 9:12 ` kernel test robot
2020-04-01 14:07 ` Masami Hiramatsu
2020-04-01 14:07 ` Masami Hiramatsu
2020-04-01 14:21 ` Steven Rostedt
2020-04-01 14:21 ` Steven Rostedt
2020-04-01 15:04 ` Steven Rostedt
2020-04-01 15:04 ` Steven Rostedt
2020-04-02 7:19 ` Masami Hiramatsu
2020-04-02 7:19 ` Masami Hiramatsu
2020-04-02 18:14 ` Steven Rostedt
2020-04-02 18:14 ` Steven Rostedt
2020-04-03 6:47 ` Masami Hiramatsu
2020-04-03 6:47 ` Masami Hiramatsu
2020-04-03 13:16 ` Steven Rostedt
2020-04-03 13:16 ` Steven Rostedt
2020-03-19 23:22 ` [PATCH 03/12 v2] ring-buffer: Have ring_buffer_empty() not depend on tracing stopped Steven Rostedt
2020-03-19 23:22 ` [PATCH 04/12 v2] ring-buffer: Rename ring_buffer_read() to read_buffer_iter_advance() Steven Rostedt
2020-03-19 23:22 ` [PATCH 05/12 v2] ring-buffer: Add page_stamp to iterator for synchronization Steven Rostedt
2020-03-19 23:22 ` [PATCH 06/12 v2] ring-buffer: Have rb_iter_head_event() handle concurrent writer Steven Rostedt
2020-03-19 23:22 ` [PATCH 07/12 v2] ring-buffer: Do not die if rb_iter_peek() fails more than thrice Steven Rostedt
2020-03-19 23:22 ` [PATCH 08/12 v2] ring-buffer: Optimize rb_iter_head_event() Steven Rostedt
2020-03-19 23:22 ` [PATCH 09/12 v2] ring-buffer: Do not disable recording when there is an iterator Steven Rostedt
2020-03-19 23:22 ` [PATCH 10/12 v2] tracing: Do not disable tracing when reading the trace file Steven Rostedt
2020-03-19 23:22 ` [PATCH 11/12 v2] ring-buffer/tracing: Have iterator acknowledge dropped events Steven Rostedt
2020-03-19 23:22 ` Steven Rostedt [this message]
2020-03-21 19:13 ` [PATCH 00/12 v2] ring-buffer/tracing: Remove disabling of ring buffer while reading trace file David Laight
2020-03-22 18:07 ` Steven Rostedt
2020-03-27 1:46 ` Steven Rostedt
2020-03-27 10:07 ` David Laight
2020-03-27 14:30 ` Steven Rostedt
2020-03-27 14:56 ` David Laight
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