Impact: clean up

The traceon and traceoff function probes are confusing to developers
to what happens when a counter is not specified. This should help
clear things up.

 # echo "*:traceoff" > set_ftrace_filter
 # cat /debug/tracing/set_ftrace_filter

  #### all functions enabled ####
  do_fork:traceoff:unlimited
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up

Ingo Molnar did not like the _hook naming convention used by the
select function tracer. Luis Claudio R. Goncalves suggested using
the "_probe" extension. This patch implements the change of
calling the functions and variables "_hook" and replacing them
with "_probe".
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Ingo Molnar pointed out some coding style issues with the recent ftrace
updates. This patch cleans them up.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

This patch adds a pretty print version of traceon and traceoff
output for set_ftrace_filter.

  # echo 'sys_open:traceon:4' > set_ftrace_filter
  # cat set_ftrace_filter

 #### all functions enabled ####
 sys_open:traceon:count=4
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

This patch adds the new function selection commands traceon and
traceoff. traceon sets the function to enable the ring buffers
while traceoff disables the ring buffers.  You can pass in the
number of times you want the command to be executed when the function
is hit. It will only execute if the state of the buffers are not
already in that state.

Example:

 # echo do_fork:traceon:4

Will enable the ring buffers if they are disabled every time it
hits do_fork, up to 4 times.

 # echo sys_close:traceoff

This will disable the ring buffers every time (unlimited) when
sys_close is called.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: cleanup

To make it easy for ftrace plugin writers, as this was open coded in
the existing plugins
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: NFrédéric Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up

After reorganizing the functions in trace.c and trace_function.c,
they no longer need to be in global context. This patch makes the
functions and one variable into static.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: less likely to interleave function and stack traces

This patch does replaces the separate stack trace on function with
a record function and stack trace together. This will switch between
the function only recording to a function and stack recording.

Also some whitespace fix ups as well.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up of trace.c

The function tracer functions were put in trace.c because it needed
to share static variables that were in trace.c.  Since then, those
variables have become global for various reasons. This patch moves
the function tracer functions into trace_function.c where they belong.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: new feature to stack trace any function

Chris Mason asked about being able to pick and choose a function
and get a stack trace from it. This feature enables his request.

 # echo io_schedule > /debug/tracing/set_ftrace_filter
 # echo function > /debug/tracing/current_tracer
 # echo func_stack_trace > /debug/tracing/trace_options

Produces the following in /debug/tracing/trace:

       kjournald-702   [001]   135.673060: io_schedule <-sync_buffer
       kjournald-702   [002]   135.673671:
 <= sync_buffer
 <= __wait_on_bit
 <= out_of_line_wait_on_bit
 <= __wait_on_buffer
 <= sync_dirty_buffer
 <= journal_commit_transaction
 <= kjournald

Note, be careful about turning this on without filtering the functions.
You may find that you have a 10 second lag between typing and seeing
what you typed. This is why the stack trace for the function tracer
does not use the same stack_trace flag as the other tracers use.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

This patch factors out common code from multiple tracers into a
tracing_reset_online_cpus() function and converts the tracers to use it.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: extend the ->init() method with the ability to fail

This bring a way to know if the initialization of a tracer successed.
A tracer must return 0 on success and a traditional error (ie:
-ENOMEM) if it fails.

If a tracer fails to init, it is free to print a detailed warn. The
tracing api will not and switch to a new tracer will just return the
error from the init callback.

Note: this will be used for the return tracer.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: remove obsolete variable in trace_array structure

With the new start / stop method of ftrace, the ctrl variable
in the trace_array structure is now obsolete. Remove it.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Remove the ctrl_update tracer method

With the new quick start/stop method of tracing, the ctrl_update
method is out of date.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: change where tracing is started up and stopped

Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.

The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.

This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.

For example, the startup of a tracer may enable tracepoints, or enable
the function tracer.  The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called.  The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.

The tracing_enabled file will simply start or stop tracing.

This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling  tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.

This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.

Note: There were two methods to the struct tracer that were never
 used: The methods start and stop. These were to be used as a hook
 to the reading of the trace output, but ended up not being
 necessary. These two methods are now used to enable the start
 and stop of each tracer, in case the tracer needs to do more than
 just not write into the buffer. For example, the irqsoff tracer
 must stop recording max latencies when tracing is stopped.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

To avoid further confusion between the ftrace infrastructure and the
function tracer. This patch renames the "ftrace" function tracer
to "function".

Now in available_tracers, instead of "ftrace" there will be "function".

This makes more sense, since people will not know exactly what the
"ftrace" tracer does.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch ports ftrace over to the new ring buffer.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This is more of a clean up. Currently the function tracer initializes the
tracer with which ever CPU was last used for tracing. This value isn't
realy useful for function tracing, but at least it should be something other
than a random number.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The new work with converting the trace hooks over to markers broke the
command line recording of ftrace. This patch fixes it again.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

In cleaning up of the sched_switch code, the function trace recording
of task comms was removed. This patch adds back the recording of comms
for function trace. The output of ftrace now has the task comm instead
of <...>.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

now that we have a kbuild method for notrace, no need to pollute the
C code with the annotations.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

rename and uninline now() to ftrace_now().
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This is a simple trace that uses the ftrace infrastructure. It is
designed to be fast and small, and easy to use. It is useful to
record things that happen over a very short period of time, and
not to analyze the system in general.

 Updates:

  available_tracers
     "function" is added to this file.

  current_tracer
    To enable the function tracer:

      echo function > /debugfs/tracing/current_tracer

     To disable the tracer:

       echo disable > /debugfs/tracing/current_tracer

The output of the function_trace file is as follows

  "echo noverbose > /debugfs/tracing/iter_ctrl"

preemption latency trace v1.1.5 on 2.6.24-rc7-tst
Signed-off-by: NIngo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
 latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
    -----------------
    | task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
    -----------------

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
 swapper-0     0d.h. 1595128us+: set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
 swapper-0     0d.h. 1595131us+: _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)

Or with verbose turned on:

  "echo verbose > /debugfs/tracing/iter_ctrl"

preemption latency trace v1.1.5 on 2.6.24-rc7-tst
--------------------------------------------------------------------
 latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
    -----------------
    | task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
    -----------------

         swapper     0 0 9 00000000 00000000 [f3675f41] 1595.128ms (+0.003ms): set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
         swapper     0 0 9 00000000 00000001 [f3675f45] 1595.131ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
         swapper     0 0 9 00000000 00000002 [f3675f48] 1595.135ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)

The "trace" file is not affected by the verbose mode, but is by the symonly.

 echo "nosymonly" > /debugfs/tracing/iter_ctrl

tracer:
[   81.479967] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <ffffffff80337a4d> <-- _spin_unlock_irqrestore+0xe/0x5a <ffffffff8048cc8f>
[   81.479967] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <ffffffff8048ccbf> <-- sub_preempt_count+0xc/0x7a <ffffffff80233d7b>
[   81.479968] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <ffffffff80233d9f> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
[   81.479968] CPU 0: bash:3154 vfs_write+0x11d/0x155 <ffffffff8029a043> <-- dnotify_parent+0x12/0x78 <ffffffff802d54fb>
[   81.479968] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <ffffffff802d5516> <-- _spin_lock+0xe/0x70 <ffffffff8048c910>
[   81.479969] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <ffffffff8048c91d> <-- add_preempt_count+0xe/0x77 <ffffffff80233df7>
[   81.479969] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <ffffffff80233e27> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>

 echo "symonly" > /debugfs/tracing/iter_ctrl

tracer:
[   81.479913] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <-- _spin_unlock_irqrestore+0xe/0x5a
[   81.479913] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <-- sub_preempt_count+0xc/0x7a
[   81.479913] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <-- in_lock_functions+0x9/0x24
[   81.479914] CPU 0: bash:3154 vfs_write+0x11d/0x155 <-- dnotify_parent+0x12/0x78
[   81.479914] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <-- _spin_lock+0xe/0x70
[   81.479914] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <-- add_preempt_count+0xe/0x77
[   81.479914] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <-- in_lock_functions+0x9/0x24
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NArnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>