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tracing/README: Add event file usage to tracing mini-HOWTO

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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>
This commit is contained in:
Tom Zanussi 2014-01-17 15:11:44 -06:00 committed by Steven Rostedt
parent 92fdd98cf8
commit 26f255646e
1 changed files with 34 additions and 3 deletions
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37
kernel/trace/trace.c
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@ -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