[for-next][PATCH 1/3] tracing/README: Add event file usage to tracing mini-HOWTO

Steven Rostedt
2014-01-26T05:00:36Z

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From: Tom Zanussi <tom.zanussi@linux.intel.com>

It would be useful to have a cheat-sheet for everything under
tracing/events/ alongside the existing text describing the other files
in the tracing/ dir.

Add short descriptions of the directories and files under events/
along with examples, similar to the existing text for the other files
in tracing/.

Also clean up a few minor alignment problems noticed when adding the
new text.

Link: http://lkml.kernel.org/r/1389993104.3040.445.camel@empanada

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 37 ++++++++++++++++++++++++++++++++++---
1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 20c755e..2ced5e5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3523,9 +3523,9 @@ static const char readme_msg[] =
#ifdef CONFIG_DYNAMIC_FTRACE
"\n available_filter_functions - list of functions that can be filtered on\n"
" set_ftrace_filter\t- echo function name in here to only trace these functions\n"
- " accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
- " modules: Can select a group via module\n"
- " Format: :mod:<module-name>\n"
+ " accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+ " modules: Can select a group via module\n"
+ " Format: :mod:<module-name>\n"
" example: echo :mod:ext3 > set_ftrace_filter\n"
" triggers: a command to perform when function is hit\n"
" Format: <function>:<trigger>[:count]\n"
@@ -3573,6 +3573,37 @@ static const char readme_msg[] =
" stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace traces\n"
#endif
#endif /* CONFIG_STACK_TRACER */
+ " events/\t\t- Directory containing all trace event subsystems:\n"
+ " enable\t\t- Write 0/1 to enable/disable tracing of all events\n"
+ " events/<system>/\t- Directory containing all trace events for <system>:\n"
+ " enable\t\t- Write 0/1 to enable/disable tracing of all <system> events\n"
+ " filter\t\t- If set, only events passing filter are traced\n"
+ " events/<system>/<event>/\t- Directory containing control files for <event>:\n"
+ " enable\t\t- Write 0/1 to enable/disable tracing of <event>\n"
+ " filter\t\t- If set, only events passing filter are traced\n"
+ " trigger\t\t- If set, a command to perform when event is hit\n"
+ " Format: <trigger>[:count][if <filter>]\n"
+ " trigger: traceon, traceoff\n"
+ " enable_event:<system>:<event>\n"
+ " disable_event:<system>:<event>\n"
+#ifdef CONFIG_STACKTRACE
+ " stacktrace\n"
+#endif
+#ifdef CONFIG_TRACER_SNAPSHOT
+ " snapshot\n"
+#endif
+ " example: echo traceoff > events/block/block_unplug/trigger\n"
+ " echo traceoff:3 > events/block/block_unplug/trigger\n"
+ " echo 'enable_event:kmem:kmalloc:3 if nr_rq > 1' > events/block/block_unplug/trigger\n"
+ " The first disables tracing every time block_unplug is hit.\n"
+ " The second disables tracing the first 3 times block_unplug is hit.\n"
+ " The third enables the kmalloc event the first 3 times block_unplug\n"
+ " is hit and has value of greater than 1 for the 'nr_rq' event field.\n"
+ " To remove a trigger without a count:\n"
+ " echo '!<trigger> > <system>/<event>/trigger\n"
+ " To remove a trigger with a count:\n"
+ " echo '!<trigger>:0 > <system>/<event>/trigger\n"
+ " Filters can be ignored when removing a trigger.\n"
;

static ssize_t
--
1.8.4.3