Commit Graph

42 Commits

Author SHA1 Message Date
Thomas Gleixner 0199c4e68d locking: Convert __raw_spin* functions to arch_spin*
Name space cleanup. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
2009-12-14 23:55:32 +01:00
Thomas Gleixner edc35bd72e locking: Rename __RAW_SPIN_LOCK_UNLOCKED to __ARCH_SPIN_LOCK_UNLOCKED
Further name space cleanup. No functional change

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
2009-12-14 23:55:32 +01:00
Thomas Gleixner 445c89514b locking: Convert raw_spinlock to arch_spinlock
The raw_spin* namespace was taken by lockdep for the architecture
specific implementations. raw_spin_* would be the ideal name space for
the spinlocks which are not converted to sleeping locks in preempt-rt.

Linus suggested to convert the raw_ to arch_ locks and cleanup the
name space instead of using an artifical name like core_spin,
atomic_spin or whatever

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
2009-12-14 23:55:32 +01:00
Carsten Emde b5130b1e7d tracing: do not update tracing_max_latency when tracer is stopped
The state of the function pair tracing_stop()/tracing_start() is
correctly considered when tracer data are updated. However, the global
and externally accessible variable tracing_max_latency is always updated
- even when tracing is stopped.

The update should only occur, if tracing was not stopped.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12 21:45:17 -04:00
Carsten Emde 41dfba4367 tracing: remove unused local variables in tracer probe functions
When the nsecs_to_usecs() conversion in probe_wakeup_sched_switch() and
check_critical_timing() was moved to a later stage in order to avoid
unnecessary computing, it was overlooked to remove the original
variables, assignments and comments..

Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12 21:44:13 -04:00
Steven Rostedt 478142c39c tracing: do not grab lock in wakeup latency function tracing
The wakeup tracer, when enabled, has its own function tracer.
It only traces the functions on the CPU where the task it is following
is on. If a task is woken on one CPU but then migrates to another CPU
before it wakes up, the latency tracer will then start tracing functions
on the other CPU.

To find which CPU the task is on, the wakeup function tracer performs
a task_cpu(wakeup_task). But to make sure the task does not disappear
it grabs the wakeup_lock, which is also taken when the task wakes up.
By taking this lock, the function tracer does not need to worry about
the task being freed as it checks its cpu.

Jan Blunck found a problem with this approach on his 32 CPU box. When
a task is being traced by the wakeup tracer, all functions take this
lock. That means that on all 32 CPUs, each function call is taking
this one lock to see if the task is on that CPU. This lock has just
serialized all functions on all 32 CPUs. Needless to say, this caused
major issues on that box. It would even lockup.

This patch changes the wakeup latency to insert a probe on the migrate task
tracepoint. When a task changes its CPU that it will run on, the
probe will take note. Now the wakeup function tracer no longer needs
to take the lock. It only compares the current CPU with a variable that
holds the current CPU the task is on. We don't worry about races since
it is OK to add or miss a function trace.

Reported-by: Jan Blunck <jblunck@suse.de>
Tested-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-09 23:54:04 -04:00
Steven Rostedt 2f26ebd549 tracing: use timestamp to determine start of latency traces
Currently the latency tracers reset the ring buffer. Unfortunately
if a commit is in process (due to a trace event), this can corrupt
the ring buffer. When this happens, the ring buffer will detect
the corruption and then permanently disable the ring buffer.

The bug does not crash the system, but it does prevent further tracing
after the bug is hit.

Instead of reseting the trace buffers, the timestamp of the start of
the trace is used instead. The buffers will still contain the previous
data, but the output will not count any data that is before the
timestamp of the trace.

Note, this only affects the static trace output (trace) and not the
runtime trace output (trace_pipe). The runtime trace output does not
make sense for the latency tracers anyway.

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-04 18:44:22 -04:00
Steven Rostedt 9be24414aa tracing/wakeup: move access to wakeup_cpu into spinlock
The code had the following outside the lock:

        if (next != wakeup_task)
                return;

        pc = preempt_count();

        /* The task we are waiting for is waking up */
        data = wakeup_trace->data[wakeup_cpu];

On initialization, wakeup_task is NULL and wakeup_cpu -1. This code
is not under a lock. If wakeup_task is set on another CPU as that
task is waking up, we can see the wakeup_task before wakeup_cpu is
set. If we read wakeup_cpu while it is still -1 then we will have
a bad data pointer.

This patch moves the reading of wakeup_cpu within the protection of
the spinlock used to protect the writing of wakeup_cpu and wakeup_task.

[ Impact: remove possible race causing invalid pointer dereference ]

Reported-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-04-23 23:01:36 -04:00
Steven Rostedt ad8d75fff8 tracing/events: move trace point headers into include/trace/events
Impact: clean up

Create a sub directory in include/trace called events to keep the
trace point headers in their own separate directory. Only headers that
declare trace points should be defined in this directory.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-04-14 22:05:43 -04:00
Steven Rostedt 301fd748e2 tracing: remove CALLER_ADDR2 from wakeup tracer
Maneesh Soni was getting a crash when running the wakeup tracer.
We debugged it down to the recording of the function with the
CALLER_ADDR2 macro.  This is used to get the location of the caller
to schedule.

But the problem comes when schedule is called by assmebly. In the case
that Maneesh had, retint_careful would call schedule. But retint_careful
does not set up a proper frame pointer. CALLER_ADDR2 is defined as
__builtin_return_address(2). This produces the following assembly in
the wakeup tracer code.

   mov    0x0(%rbp),%rcx  <--- get the frame pointer of the caller
   mov    %r14d,%r8d
   mov    0xf2de8e(%rip),%rdi

   mov    0x8(%rcx),%rsi  <-- this is __builtin_return_address(1)
   mov    0x28(%rdi,%rax,8),%rbx

   mov    (%rcx),%rax  <-- get the frame pointer of the caller's caller
   mov    %r12,%rcx
   mov    0x8(%rax),%rdx <-- this is __builtin_return_address(2)

At the reading of 0x8(%rax) Maneesh's machine would take a fault.
The reason is that retint_careful did not set up the return address
and the content of %rax here was zero.

To verify this, I sent Maneesh a patch to create a frame pointer
in retint_careful. He ran the test again but this time he would take
the same type of fault from sysret_careful. The retint_careful was no
longer an issue, but there are other callers that still have issues.

Instead of adding frame pointers for all callers to schedule (in possibly
all archs), it is much safer to simply not use CALLER_ADDR2. This
loses out on knowing what called schedule, but the function tracer
will help there if needed.

Reported-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-07 13:58:54 +02:00
Steven Rostedt e9d25fe6ea tracing: have latency tracers set the latency format
The latency tracers (irqsoff, preemptoff, preemptirqsoff, and wakeup)
are pretty useless with the default output format. This patch makes them
automatically enable the latency format when they are selected. They
also record the state of the latency option, and if it was not enabled
when selected, they disable it on reset.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-04 22:15:30 -05:00
Frederic Weisbecker 6eaaa5d57e tracing/core: use appropriate waiting on trace_pipe
Impact: api and pipe waiting change

Currently, the waiting used in tracing_read_pipe() is done through a
100 msecs schedule_timeout() loop which periodically check if there
are traces on the buffer.

This can cause small latencies for programs which are reading the incoming
events.

This patch makes the reader waiting for the trace_wait waitqueue except
for few tracers such as the sched and functions tracers which might be
already hold the runqueue lock while waking up the reader.

This is performed through a new callback wait_pipe() on struct tracer.
If none is implemented on a specific tracer, the default waiting for
trace_wait queue is attached.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-18 01:40:20 +01:00
Wenji Huang 73d8b8bc4f tracing: fix typing mistake in hint message and comments
Impact: cleanup

Fix incorrect hint message in code and typos in comments.

Signed-off-by: Wenji Huang <wenji.huang@oracle.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-17 12:38:24 -05:00
Arnaldo Carvalho de Melo 7be421510b trace: Remove unused trace_array_cpu parameter
Impact: cleanup

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-05 14:35:47 +01:00
Arnaldo Carvalho de Melo b3a8c34886 trace_sched_wakeup: Remove unused variable
Impact: cleanup

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-29 14:31:03 +01:00
Steven Rostedt f8ec1062f5 wakeup-tracer: show scheduling data in output
Impact: better data for wakeup tracer

This patch adds the wakeup and schedule calls that are used by
the scheduler tracer to make the wakeup tracer more readable.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-22 10:27:39 +01:00
Steven Rostedt 3244351c31 trace: separate out rt tasks from wakeup tracer
Impact: add option to trace all tasks or just RT tasks

The current wakeup tracer only traces RT task wakeups. This is
fine for those interested in wake up timings of RT tasks, but
it is useless for those that are interested in the causes
of long wakeups for non RT tasks.

This patch creates a "wakeup_rt" to implement the tracing of just
RT tasks (as the current "wakeup" does). And makes "wakeup" now
trace all tasks as an average developer would expect.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-22 10:27:22 +01:00
Steven Rostedt 5bc4564b22 trace: do not disable wake up tracer on output of trace
Impact: fix to erased trace output

To try not to have the outputing of a trace interfere with the wakeup
tracer, it would disable tracing while the output was printing. But
if a trace had started when it was disabled, it can show a partial
trace. To try to solve this, on closing of the tracer, it would
clear the trace buffer.

The latency tracers (wakeup and irqsoff) have two buffers. One for
recording and one for holding the max trace that is printed. The
clearing of the trace above should only affect the recording buffer.
But for some reason it would move the erased trace to the print
buffer. Probably due to a race with the closing of the trace and
the saving ofhe max race.

The above is all pretty useless, and if the user does not want the
printing of the trace to be traced itself, then the user can manual
disable tracing. This patch removes all the code that tries to keep
the output of the tracer from modifying the trace.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-22 10:26:50 +01:00
Steven Rostedt 745b1626dd trace: set max latency variable to zero on default
Impact: trace max latencies on start of latency tracing

This patch sets the max latency to zero whenever one of the
irq variant tracers or the wakeup tracer is set to current tracer.

Most developers expect to see output when starting up a latency
tracer. But since the max_latency is already set to max, and
it takes a latency greater than max_latency to be recorded, there
is no trace. This is not the expected behavior and has even confused
myself.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-16 12:18:09 +01:00
Peter Zijlstra 468a15bb4c sched, trace: update trace_sched_wakeup()
Impact: extend the wakeup tracepoint with the info whether the wakeup was real

Add the information needed to distinguish 'real' wakeups from 'false'
wakeups.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-25 13:10:21 +01:00
Frederic Weisbecker 1c80025a49 tracing/ftrace: change the type of the init() callback
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: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-16 07:55:23 +01:00
Steven Rostedt c76f06945b ftrace: remove trace array ctrl
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: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-08 09:51:39 +01:00
Steven Rostedt bbf5b1a0ce ftrace: remove ctrl_update method
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: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-08 09:51:34 +01:00
Steven Rostedt 9036990d46 ftrace: restructure tracing start/stop infrastructure
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: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-06 07:51:03 +01:00
Steven Rostedt 182e9f5f70 ftrace: insert in the ftrace_preempt_disable()/enable() functions
Impact: use new, consolidated APIs in ftrace plugins

This patch replaces the schedule safe preempt disable code with the
ftrace_preempt_disable() and ftrace_preempt_enable() safe functions.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-04 10:09:49 +01:00
Steven Rostedt 606576ce81 ftrace: rename FTRACE to FUNCTION_TRACER
Due to confusion between the ftrace infrastructure and the gcc profiling
tracer "ftrace", this patch renames the config options from FTRACE to
FUNCTION_TRACER.  The other two names that are offspring from FTRACE
DYNAMIC_FTRACE and FTRACE_MCOUNT_RECORD will stay the same.

This patch was generated mostly by script, and partially by hand.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-20 18:27:03 +02:00
Steven Rostedt 38697053fa ftrace: preempt disable over interrupt disable
With the new ring buffer infrastructure in ftrace, I'm trying to make
ftrace a little more light weight.

This patch converts a lot of the local_irq_save/restore into
preempt_disable/enable.  The original preempt count in a lot of cases
has to be sent in as a parameter so that it can be recorded correctly.
Some places were recording it incorrectly before anyway.

This is also laying the ground work to make ftrace a little bit
more reentrant, and remove all locking. The function tracers must
still protect from reentrancy.

Note: All the function tracers must be careful when using preempt_disable.
  It must do the following:

  resched = need_resched();
  preempt_disable_notrace();
  [...]
  if (resched)
	preempt_enable_no_resched_notrace();
  else
	preempt_enable_notrace();

The reason is that if this function traces schedule() itself, the
preempt_enable_notrace() will cause a schedule, which will lead
us into a recursive failure.

If we needed to reschedule before calling preempt_disable, we
should have already scheduled. Since we did not, this is most
likely that we should not and are probably inside a schedule
function.

If resched was not set, we still need to catch the need resched
flag being set when preemption was off and the if case at the
end will catch that for us.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-14 10:39:09 +02:00
Steven Rostedt 3928a8a2d9 ftrace: make work with new ring buffer
This patch ports ftrace over to the new ring buffer.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-14 10:38:57 +02:00
Mathieu Desnoyers b07c3f193a ftrace: port to tracepoints
Porting the trace_mark() used by ftrace to tracepoints. (cleanup)

Changelog :
- Change error messages : marker -> tracepoint

[ mingo@elte.hu: conflict resolutions ]
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: 'Peter Zijlstra' <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-14 10:32:26 +02:00
Steven Rostedt e59494f441 ftrace: fix 4d3702b6 (post-v2.6.26): WARNING: at kernel/lockdep.c:2731 check_flags (ftrace)
On Wed, 16 Jul 2008, Vegard Nossum wrote:

> When booting 4d3702b6, I got this huge thing:
>
> Testing tracer wakeup: <4>------------[ cut here ]------------
> WARNING: at kernel/lockdep.c:2731 check_flags+0x123/0x160()
> Modules linked in:
> Pid: 1, comm: swapper Not tainted 2.6.26-crashing-02127-g4d3702b6 #30
>  [<c015c349>] warn_on_slowpath+0x59/0xb0
>  [<c01276c6>] ? ftrace_call+0x5/0x8
>  [<c012d800>] ? native_read_tsc+0x0/0x20
>  [<c0158de2>] ? sub_preempt_count+0x12/0xf0
>  [<c01814eb>] ? trace_hardirqs_off+0xb/0x10
>  [<c0182fbc>] ? __lock_acquire+0x2cc/0x1120
>  [<c01814eb>] ? trace_hardirqs_off+0xb/0x10
>  [<c01276af>] ? mcount_call+0x5/0xa
>  [<c017ff53>] check_flags+0x123/0x160
>  [<c0183e61>] lock_acquire+0x51/0xd0
>  [<c01276c6>] ? ftrace_call+0x5/0x8
>  [<c0613d4f>] _spin_lock_irqsave+0x5f/0xa0
>  [<c01a8d45>] ? ftrace_record_ip+0xf5/0x220
>  [<c02d5413>] ? debug_locks_off+0x3/0x50
>  [<c01a8d45>] ftrace_record_ip+0xf5/0x220
>  [<c01276af>] mcount_call+0x5/0xa
>  [<c02d5418>] ? debug_locks_off+0x8/0x50
>  [<c017ff27>] check_flags+0xf7/0x160
>  [<c0183e61>] lock_acquire+0x51/0xd0
>  [<c01276c6>] ? ftrace_call+0x5/0x8
>  [<c0613d4f>] _spin_lock_irqsave+0x5f/0xa0
>  [<c01affcd>] ? wakeup_tracer_call+0x6d/0xf0
>  [<c01625e2>] ? _local_bh_enable+0x62/0xb0
>  [<c0158ddd>] ? sub_preempt_count+0xd/0xf0
>  [<c01affcd>] wakeup_tracer_call+0x6d/0xf0
>  [<c0162724>] ? __do_softirq+0xf4/0x110
>  [<c01afff1>] ? wakeup_tracer_call+0x91/0xf0
>  [<c01276c6>] ftrace_call+0x5/0x8
>  [<c0162724>] ? __do_softirq+0xf4/0x110
>  [<c0158de2>] ? sub_preempt_count+0x12/0xf0
>  [<c01625e2>] _local_bh_enable+0x62/0xb0
>  [<c0162724>] __do_softirq+0xf4/0x110
>  [<c01627ed>] do_softirq+0xad/0xb0
>  [<c0162a15>] irq_exit+0xa5/0xb0
>  [<c013a506>] smp_apic_timer_interrupt+0x66/0xa0
>  [<c02d3fac>] ? trace_hardirqs_off_thunk+0xc/0x10
>  [<c0127449>] apic_timer_interrupt+0x2d/0x34
>  [<c018007b>] ? find_usage_backwards+0xb/0xf0
>  [<c0613a09>] ? _spin_unlock_irqrestore+0x69/0x80
>  [<c014ef32>] tg_shares_up+0x132/0x1d0
>  [<c014d2a2>] walk_tg_tree+0x62/0xa0
>  [<c014ee00>] ? tg_shares_up+0x0/0x1d0
>  [<c014a860>] ? tg_nop+0x0/0x10
>  [<c015499d>] update_shares+0x5d/0x80
>  [<c0154a2f>] try_to_wake_up+0x6f/0x280
>  [<c01a8b90>] ? __ftrace_modify_code+0x0/0xc0
>  [<c01a8b90>] ? __ftrace_modify_code+0x0/0xc0
>  [<c0154c94>] wake_up_process+0x14/0x20
>  [<c01725f6>] kthread_create+0x66/0xb0
>  [<c0195400>] ? do_stop+0x0/0x200
>  [<c0195320>] ? __stop_machine_run+0x30/0xb0
>  [<c0195340>] __stop_machine_run+0x50/0xb0
>  [<c0195400>] ? do_stop+0x0/0x200
>  [<c01a8b90>] ? __ftrace_modify_code+0x0/0xc0
>  [<c061242d>] ? mutex_unlock+0xd/0x10
>  [<c01953cc>] stop_machine_run+0x2c/0x60
>  [<c01a94d3>] unregister_ftrace_function+0x103/0x180
>  [<c01b0517>] stop_wakeup_tracer+0x17/0x60
>  [<c01b056f>] wakeup_tracer_ctrl_update+0xf/0x30
>  [<c01ab8d5>] trace_selftest_startup_wakeup+0xb5/0x130
>  [<c01ab950>] ? trace_wakeup_test_thread+0x0/0x70
>  [<c01aadf5>] register_tracer+0x135/0x1b0
>  [<c0877d02>] init_wakeup_tracer+0xd/0xf
>  [<c085d437>] kernel_init+0x1a9/0x2ce
>  [<c061397b>] ? _spin_unlock_irq+0x3b/0x60
>  [<c02d3f9c>] ? trace_hardirqs_on_thunk+0xc/0x10
>  [<c0877cf5>] ? init_wakeup_tracer+0x0/0xf
>  [<c0182646>] ? trace_hardirqs_on_caller+0x126/0x180
>  [<c02d3f9c>] ? trace_hardirqs_on_thunk+0xc/0x10
>  [<c01269c8>] ? restore_nocheck_notrace+0x0/0xe
>  [<c085d28e>] ? kernel_init+0x0/0x2ce
>  [<c085d28e>] ? kernel_init+0x0/0x2ce
>  [<c01275fb>] kernel_thread_helper+0x7/0x10
>  =======================
> ---[ end trace a7919e7f17c0a725 ]---
> irq event stamp: 579530
> hardirqs last  enabled at (579528): [<c01826ab>] trace_hardirqs_on+0xb/0x10
> hardirqs last disabled at (579529): [<c01814eb>] trace_hardirqs_off+0xb/0x10
> softirqs last  enabled at (579530): [<c0162724>] __do_softirq+0xf4/0x110
> softirqs last disabled at (579517): [<c01627ed>] do_softirq+0xad/0xb0
> irq event stamp: 579530
> hardirqs last  enabled at (579528): [<c01826ab>] trace_hardirqs_on+0xb/0x10
> hardirqs last disabled at (579529): [<c01814eb>] trace_hardirqs_off+0xb/0x10
> softirqs last  enabled at (579530): [<c0162724>] __do_softirq+0xf4/0x110
> softirqs last disabled at (579517): [<c01627ed>] do_softirq+0xad/0xb0
> PASSED
>
> Incidentally, the kernel also hung while I was typing in this report.

Things get weird between lockdep and ftrace because ftrace can be called
within lockdep internal code (via the mcount pointer) and lockdep can be
called with ftrace (via spin_locks).

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Tested-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 13:47:15 +02:00
Steven Rostedt ad591240ce ftrace: start wakeup tracing after setting function tracer
Enabling the wakeup tracer before enabling the function tracing causes
some strange results due to the dynamic enabling of the functions.

Signed-off-by: Steven 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: Ingo Molnar <mingo@elte.hu>
2008-07-11 15:49:20 +02:00
Steven Rostedt 7e18d8e701 ftrace: add function tracing to wake up tracing
This patch adds function tracing to the functions that are called
on the CPU of the task being traced.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: pq@iki.fi
Cc: proski@gnu.org
Cc: sandmann@redhat.com
Cc: a.p.zijlstra@chello.nl
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-26 22:51:22 +02:00
Mathieu Desnoyers 5b82a1b08a Port ftrace to markers
Porting ftrace to the marker infrastructure.

Don't need to chain to the wakeup tracer from the sched tracer, because markers
support multiple probes connected.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 22:29:25 +02:00
Steven Rostedt 4fe8c3048c ftrace: printk and trace irqsoff and wakeups
printk called from wakeup critical timings and irqs off can
cause deadlocks since printk might do a wakeup itself. If the
call to printk happens with the runqueue lock held, it can
deadlock.

This patch protects the printk from being called in trace irqs off
with a test to see if the runqueue for the current CPU is locked.
If it is locked, the printk is skipped.

The wakeup always holds the runqueue lock, so the printk is
simply removed.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:13:02 +02:00
Ingo Molnar 8ac0fca4cc ftrace: sched tracer fix
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:04:28 +02:00
Ingo Molnar 57422797dc ftrace: add wakeup events to sched tracer
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 21:04:06 +02:00
Ingo Molnar e309b41dd6 ftrace: remove notrace
now that we have a kbuild method for notrace, no need to pollute the
C code with the annotations.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:58:28 +02:00
Steven Rostedt 6fb44b717c ftrace: add trace_function api for other tracers to use
A new check was added in the ftrace function that wont trace if the CPU
trace buffer is disabled.  Unfortunately, other tracers used ftrace() to
write to the buffer after they disabled it. The new disable check makes
these calls into a nop.

This patch changes the __ftrace that is called without the check into a
new api for the other tracers to use, called "trace_function". The other
tracers use this interface instead when the trace CPU buffer is already
disabled.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:55:55 +02:00
Ingo Molnar 750ed1a407 ftrace: timestamp syncing, prepare
rename and uninline now() to ftrace_now().

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:42:31 +02:00
Ingo Molnar c7aafc5497 ftrace: cleanups
factor out code and clean it up.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:40:46 +02:00
Steven Rostedt 60a11774b3 ftrace: add self-tests
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:40:36 +02:00
Steven Rostedt 352ad25aa4 ftrace: tracer for scheduler wakeup latency
This patch adds the tracer that tracks the wakeup latency of the
highest priority waking task.

  "wakeup" is added to /debugfs/tracing/available_tracers

Also added to /debugfs/tracing

  tracing_max_latency
     holds the current max latency for the wakeup

  wakeup_thresh
     if set to other than zero, a log will be recorded
     for every wakeup that takes longer than the number
     entered in here (usecs for all counters)
     (deletes previous trace)

Examples:

  (with ftrace_enabled = 0)

============
preemption latency trace v1.1.5 on 2.6.24-rc8
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
 latency: 26 us, #2/2, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
    -----------------
    | task: migration/0-3 (uid:0 nice:-5 policy:1 rt_prio:99)
    -----------------

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
   quilt-8551  0d..3    0us+: wake_up_process+0x15/0x17 <ffffffff80233e80> (sched_exec+0xc9/0x100 <ffffffff80235343>)
   quilt-8551  0d..4   26us : sched_switch_callback+0x73/0x81 <ffffffff80338d2f> (schedule+0x483/0x6d5 <ffffffff8048b3ee>)

vim:ft=help
============

  (with ftrace_enabled = 1)

============
preemption latency trace v1.1.5 on 2.6.24-rc8
--------------------------------------------------------------------
 latency: 36 us, #45/45, CPU#0 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
    -----------------
    | task: migration/1-5 (uid:0 nice:-5 policy:1 rt_prio:99)
    -----------------

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
    bash-10653 1d..3    0us : wake_up_process+0x15/0x17 <ffffffff80233e80> (sched_exec+0xc9/0x100 <ffffffff80235343>)
    bash-10653 1d..3    1us : try_to_wake_up+0x271/0x2e7 <ffffffff80233dcf> (sub_preempt_count+0xc/0x7a <ffffffff8023309e>)
    bash-10653 1d..2    2us : try_to_wake_up+0x296/0x2e7 <ffffffff80233df4> (update_rq_clock+0x9/0x20 <ffffffff802303f3>)
    bash-10653 1d..2    2us : update_rq_clock+0x1e/0x20 <ffffffff80230408> (__update_rq_clock+0xc/0x90 <ffffffff80230366>)
    bash-10653 1d..2    3us : __update_rq_clock+0x1b/0x90 <ffffffff80230375> (sched_clock+0x9/0x29 <ffffffff80214529>)
    bash-10653 1d..2    4us : try_to_wake_up+0x2a6/0x2e7 <ffffffff80233e04> (activate_task+0xc/0x3f <ffffffff8022ffca>)
    bash-10653 1d..2    4us : activate_task+0x2d/0x3f <ffffffff8022ffeb> (enqueue_task+0xe/0x66 <ffffffff8022ff66>)
    bash-10653 1d..2    5us : enqueue_task+0x5b/0x66 <ffffffff8022ffb3> (enqueue_task_rt+0x9/0x3c <ffffffff80233351>)
    bash-10653 1d..2    6us : try_to_wake_up+0x2ba/0x2e7 <ffffffff80233e18> (check_preempt_wakeup+0x12/0x99 <ffffffff80234f84>)
[...]
    bash-10653 1d..5   33us : tracing_record_cmdline+0xcf/0xd4 <ffffffff80338aad> (_spin_unlock+0x9/0x33 <ffffffff8048d3ec>)
    bash-10653 1d..5   34us : _spin_unlock+0x19/0x33 <ffffffff8048d3fc> (sub_preempt_count+0xc/0x7a <ffffffff8023309e>)
    bash-10653 1d..4   35us : wakeup_sched_switch+0x65/0x2ff <ffffffff80339f66> (_spin_lock_irqsave+0xc/0xa9 <ffffffff8048d08b>)
    bash-10653 1d..4   35us : _spin_lock_irqsave+0x19/0xa9 <ffffffff8048d098> (add_preempt_count+0xe/0x77 <ffffffff8023311a>)
    bash-10653 1d..4   36us : sched_switch_callback+0x73/0x81 <ffffffff80338d2f> (schedule+0x483/0x6d5 <ffffffff8048b3ee>)

vim:ft=help
============

The [...] was added here to not waste your email box space.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23 20:32:36 +02:00