Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 71485c45 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
Browse files

tracing: Fix formatting of trace README file 



Fix the formatting of the README file in the trace debugfs to fit in
an 80 character window.

Also add a comment about the event trigger counter with regards to
traceon and traceoff.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 26f25564

kernel/trace/trace.c

+64 −52
Original line number Diff line number Diff line
@@ -3519,91 +3519,103 @@ static const char readme_msg[] = 
	"  instances\t\t- Make sub-buffers with: mkdir instances/foo\n"

	"\t\t\t  Remove sub-buffer with rmdir\n"

	"  trace_options\t\t- Set format or modify how tracing happens\n"

	"\t\t\t  Disable an option by adding a suffix 'no' to the option name\n"

	"\t\t\t  Disable an option by adding a suffix 'no' to the\n"

	"\t\t\t  option name\n"

#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"

	"             example: echo :mod:ext3 > set_ftrace_filter\n"

	"            triggers: a command to perform when function is hit\n"

	"              Format: <function>:<trigger>[:count]\n"

	"             trigger: traceon, traceoff\n"

	"                      enable_event:<system>:<event>\n"

	"                      disable_event:<system>:<event>\n"

	"  set_ftrace_filter\t- echo function name in here to only trace these\n"

	"\t\t\t  functions\n"

	"\t     accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"

	"\t     modules: Can select a group via module\n"

	"\t      Format: :mod:<module-name>\n"

	"\t     example: echo :mod:ext3 > set_ftrace_filter\n"

	"\t    triggers: a command to perform when function is hit\n"

	"\t      Format: <function>:<trigger>[:count]\n"

	"\t     trigger: traceon, traceoff\n"

	"\t\t      enable_event:<system>:<event>\n"

	"\t\t      disable_event:<system>:<event>\n"

#ifdef CONFIG_STACKTRACE

	"                      stacktrace\n"

	"\t\t      stacktrace\n"

#endif

#ifdef CONFIG_TRACER_SNAPSHOT

	"                      snapshot\n"

	"\t\t      snapshot\n"

#endif

	"             example: echo do_fault:traceoff > set_ftrace_filter\n"

	"                      echo do_trap:traceoff:3 > set_ftrace_filter\n"

	"             The first one will disable tracing every time do_fault is hit\n"

	"             The second will disable tracing at most 3 times when do_trap is hit\n"

	"               The first time do trap is hit and it disables tracing, the counter\n"

	"               will decrement to 2. If tracing is already disabled, the counter\n"

	"               will not decrement. It only decrements when the trigger did work\n"

	"             To remove trigger without count:\n"

	"               echo '!<function>:<trigger> > set_ftrace_filter\n"

	"             To remove trigger with a count:\n"

	"               echo '!<function>:<trigger>:0 > set_ftrace_filter\n"

	"\t     example: echo do_fault:traceoff > set_ftrace_filter\n"

	"\t              echo do_trap:traceoff:3 > set_ftrace_filter\n"

	"\t     The first one will disable tracing every time do_fault is hit\n"

	"\t     The second will disable tracing at most 3 times when do_trap is hit\n"

	"\t       The first time do trap is hit and it disables tracing, the\n"

	"\t       counter will decrement to 2. If tracing is already disabled,\n"

	"\t       the counter will not decrement. It only decrements when the\n"

	"\t       trigger did work\n"

	"\t     To remove trigger without count:\n"

	"\t       echo '!<function>:<trigger> > set_ftrace_filter\n"

	"\t     To remove trigger with a count:\n"

	"\t       echo '!<function>:<trigger>:0 > set_ftrace_filter\n"

	"  set_ftrace_notrace\t- echo function name in here to never trace.\n"

	"            accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"

	"            modules: Can select a group via module command :mod:\n"

	"            Does not accept triggers\n"

	"\t    accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"

	"\t    modules: Can select a group via module command :mod:\n"

	"\t    Does not accept triggers\n"

#endif /* CONFIG_DYNAMIC_FTRACE */

#ifdef CONFIG_FUNCTION_TRACER

	"  set_ftrace_pid\t- Write pid(s) to only function trace those pids (function)\n"

	"  set_ftrace_pid\t- Write pid(s) to only function trace those pids\n"

	"\t\t    (function)\n"

#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	"  set_graph_function\t- Trace the nested calls of a function (function_graph)\n"

	"  max_graph_depth\t- Trace a limited depth of nested calls (0 is unlimited)\n"

#endif

#ifdef CONFIG_TRACER_SNAPSHOT

	"\n  snapshot\t\t- Like 'trace' but shows the content of the static snapshot buffer\n"

	"\t\t\t  Read the contents for more information\n"

	"\n  snapshot\t\t- Like 'trace' but shows the content of the static\n"

	"\t\t\t  snapshot buffer. Read the contents for more\n"

	"\t\t\t  information\n"

#endif

#ifdef CONFIG_STACK_TRACER

	"  stack_trace\t\t- Shows the max stack trace when active\n"

	"  stack_max_size\t- Shows current max stack size that was traced\n"

	"\t\t\t  Write into this file to reset the max size (trigger a new trace)\n"

	"\t\t\t  Write into this file to reset the max size (trigger a\n"

	"\t\t\t  new trace)\n"

#ifdef CONFIG_DYNAMIC_FTRACE

	"  stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace traces\n"

	"  stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace\n"

	"\t\t\t  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"

	"      enable\t\t- Write 0/1 to enable/disable tracing of all <system>\n"

	"\t\t\t  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"

	"  events/<system>/<event>/\t- Directory containing control files for\n"

	"\t\t\t  <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"

	"\t    Format: <trigger>[:count][if <filter>]\n"

	"\t   trigger: traceon, traceoff\n"

	"\t            enable_event:<system>:<event>\n"

	"\t            disable_event:<system>:<event>\n"

#ifdef CONFIG_STACKTRACE

	"                    stacktrace\n"

	"\t\t    stacktrace\n"

#endif

#ifdef CONFIG_TRACER_SNAPSHOT

	"                    snapshot\n"

	"\t\t    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"

	"\t   example: echo traceoff > events/block/block_unplug/trigger\n"

	"\t            echo traceoff:3 > events/block/block_unplug/trigger\n"

	"\t            echo 'enable_event:kmem:kmalloc:3 if nr_rq > 1' > \\\n"

	"\t                  events/block/block_unplug/trigger\n"

	"\t   The first disables tracing every time block_unplug is hit.\n"

	"\t   The second disables tracing the first 3 times block_unplug is hit.\n"

	"\t   The third enables the kmalloc event the first 3 times block_unplug\n"

	"\t     is hit and has value of greater than 1 for the 'nr_rq' event field.\n"

	"\t   Like function triggers, the counter is only decremented if it\n"

	"\t    enabled or disabled tracing.\n"

	"\t   To remove a trigger without a count:\n"

	"\t     echo '!<trigger> > <system>/<event>/trigger\n"

	"\t   To remove a trigger with a count:\n"

	"\t     echo '!<trigger>:0 > <system>/<event>/trigger\n"

	"\t   Filters can be ignored when removing a trigger.\n"

;



static ssize_t