From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [for-next][PATCH 14/21] tracing: Have the document reflect that the trace file keeps tracing enabled
Date: Sun, 29 Mar 2020 14:43:06 -0400 [thread overview]
Message-ID: <20200329184317.504571083@goodmis.org> (raw)
In-Reply-To: 20200329184252.289087453@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 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:
--
2.25.1
next prev parent reply other threads:[~2020-03-29 18:43 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-29 18:42 [for-next][PATCH 00/21] tracing: Updates for v5.7 Steven Rostedt
2020-03-29 18:42 ` [for-next][PATCH 01/21] tracing: Use address-of operator on section symbols Steven Rostedt
2020-03-29 18:42 ` [for-next][PATCH 02/21] selftest/ftrace: Fix function trigger test to handle trace not disabling the tracer Steven Rostedt
2020-03-29 18:42 ` [for-next][PATCH 03/21] tracing: Save off entry when peeking at next entry Steven Rostedt
2020-03-29 18:42 ` [for-next][PATCH 04/21] ring-buffer: Have ring_buffer_empty() not depend on tracing stopped Steven Rostedt
2020-03-29 18:42 ` [for-next][PATCH 05/21] ring-buffer: Rename ring_buffer_read() to read_buffer_iter_advance() Steven Rostedt
2020-03-29 18:42 ` [for-next][PATCH 06/21] ring-buffer: Add page_stamp to iterator for synchronization Steven Rostedt
2020-03-29 18:42 ` [for-next][PATCH 07/21] ring-buffer: Have rb_iter_head_event() handle concurrent writer Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 08/21] ring-buffer: Do not die if rb_iter_peek() fails more than thrice Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 09/21] ring-buffer: Optimize rb_iter_head_event() Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 10/21] ring-buffer: Make resize disable per cpu buffer instead of total buffer Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 11/21] ring-buffer: Do not disable recording when there is an iterator Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 12/21] tracing: Do not disable tracing when reading the trace file Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 13/21] ring-buffer/tracing: Have iterator acknowledge dropped events Steven Rostedt
2020-03-29 18:43 ` Steven Rostedt [this message]
2020-03-29 18:43 ` [for-next][PATCH 15/21] ftrace/kprobe: Show the maxactive number on kprobe_events Steven Rostedt
2020-03-31 13:11 ` Sasha Levin
2020-03-29 18:43 ` [for-next][PATCH 16/21] ftrace: Make function trace pid filtering a bit more exact Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 17/21] ftrace: Create set_ftrace_notrace_pid to not trace tasks Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 18/21] tracing: Create set_event_notrace_pid " Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 19/21] selftests/ftrace: Add test to test new set_ftrace_notrace_pid file Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 20/21] selftests/ftrace: Add test to test new set_event_notrace_pid file Steven Rostedt
2020-03-29 18:43 ` [for-next][PATCH 21/21] tracing: Add documentation on set_ftrace_notrace_pid and set_event_notrace_pid Steven Rostedt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200329184317.504571083@goodmis.org \
--to=rostedt@goodmis.org \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.