path: root/Documentation/trace
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authorChase Douglas <chase.douglas@canonical.com>2010-04-23 14:02:39 -0400
committerSteven Rostedt <rostedt@goodmis.org>2010-04-27 16:51:49 -0400
commit07271aa42d13378e67ebd79ea9ca1c4a5e2ad46f (patch)
tree7698e567d269f140019bd2e275cd44aefd2826b9 /Documentation/trace
parenta838b2e634405fb89ddbf4fa9412acb33911911f (diff)
tracing: Add documentation for trace commands mod, traceon/traceoff
The mod command went in as commit 64e7c440618998fd69eee6ab490b042d12248021 The traceon/traceoff commands went in as commit 23b4ff3aa479c9e3bb23cb6b2d0a97878399784a Signed-off-by: Chase Douglas <chase.douglas@canonical.com> LKML-Reference: <1272045759-32018-1-git-send-email-chase.douglas@canonical.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
1 files changed, 44 insertions, 0 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 52011815c905..557c1edeccaf 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -155,6 +155,9 @@ of ftrace. Here is a list of some of the key files:
to be traced. Echoing names of functions into this file
will limit the trace to only those functions.
+ This interface also allows for commands to be used. See the
+ "Filter commands" section for more details.
This has an effect opposite to that of
@@ -1824,6 +1827,47 @@ this special filter via:
echo > set_graph_function
+Filter commands
+A few commands are supported by the set_ftrace_filter interface.
+Trace commands have the following format:
+The following commands are supported:
+- mod
+ This command enables function filtering per module. The
+ parameter defines the module. For example, if only the write*
+ functions in the ext3 module are desired, run:
+ echo 'write*:mod:ext3' > set_ftrace_filter
+ This command interacts with the filter in the same way as
+ filtering based on function names. Thus, adding more functions
+ in a different module is accomplished by appending (>>) to the
+ filter file. Remove specific module functions by prepending
+ '!':
+ echo '!writeback*:mod:ext3' >> set_ftrace_filter
+- traceon/traceoff
+ These commands turn tracing on and off when the specified
+ functions are hit. The parameter determines how many times the
+ tracing system is turned on and off. If unspecified, there is
+ no limit. For example, to disable tracing when a schedule bug
+ is hit the first 5 times, run:
+ echo '__schedule_bug:traceoff:5' > set_ftrace_filter
+ These commands are cumulative whether or not they are appended
+ to set_ftrace_filter. To remove a command, prepend it by '!'
+ and drop the parameter:
+ echo '!__schedule_bug:traceoff' > set_ftrace_filter