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2010-06-03tracing: Remove ftrace_preempt_disable/enableSteven Rostedt
The ftrace_preempt_disable/enable functions were to address a recursive race caused by the function tracer. The function tracer traces all functions which makes it easily susceptible to recursion. One area was preempt_enable(). This would call the scheduler and the schedulre would call the function tracer and loop. (So was it thought). The ftrace_preempt_disable/enable was made to protect against recursion inside the scheduler by storing the NEED_RESCHED flag. If it was set before the ftrace_preempt_disable() it would not call schedule on ftrace_preempt_enable(), thinking that if it was set before then it would have already scheduled unless it was already in the scheduler. This worked fine except in the case of SMP, where another task would set the NEED_RESCHED flag for a task on another CPU, and then kick off an IPI to trigger it. This could cause the NEED_RESCHED to be saved at ftrace_preempt_disable() but the IPI to arrive in the the preempt disabled section. The ftrace_preempt_enable() would not call the scheduler because the flag was already set before entring the section. This bug would cause a missed preemption check and cause lower latencies. Investigating further, I found that the recusion caused by the function tracer was not due to schedule(), but due to preempt_schedule(). Now that preempt_schedule is completely annotated with notrace, the recusion no longer is an issue. Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-17tracing: switch function prints from %pf to %psSteven Rostedt
For direct function pointers (like what mcount provides) PowerPC64 requires the use of %ps, otherwise nothing is printed. This patch converts all prints of functions retrieved through mcount to use the %ps format from the %pf. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-07-18Merge branch 'linus' into tracing/coreIngo Molnar
Merge reason: tracing/core was on an older, pre-rc1 base. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-17tracing/function: Cleanup for function tracerXiao Guangrong
We can directly use %pf input format instead of kallsyms_lookup() and %s input format Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2009-07-16tracing/function: Fix the return value of ftrace_trace_onoff_callback()Xiao Guangrong
ftrace_trace_onoff_callback() will return an error even if we do the right operation, for example: # echo _spin_*:traceon:10 > set_ftrace_filter -bash: echo: write error: Invalid argument # cat set_ftrace_filter #### all functions enabled #### _spin_trylock_bh:traceon:count=10 _spin_unlock_irq:traceon:count=10 _spin_unlock_bh:traceon:count=10 _spin_lock_irq:traceon:count=10 _spin_unlock:traceon:count=10 _spin_trylock:traceon:count=10 _spin_unlock_irqrestore:traceon:count=10 _spin_lock_irqsave:traceon:count=10 _spin_lock_bh:traceon:count=10 _spin_lock:traceon:count=10 We want to set _spin_*:traceon:10 to set_ftrace_filter, it complains with "Invalid argument", but the operation is successful. This is because ftrace_process_regex() returns the number of functions that matched the pattern. If the number is not 0, this value is returned by ftrace_regex_write() whereas we want to return the number of bytes virtually written. Also the file offset pointer is not updated in this case. If the number of matched functions is lower than the number of bytes written by the user, this results to a reprocessing of the string given by the user with a lower size, leading to a malformed ftrace regex and then a -EINVAL returned. So, this patch fixes it by returning 0 if no error occured. The fix also applies on 2.6.30 Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: stable@kernel.org Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2009-06-25ftrace: Remove duplicate newlineLi Zefan
Before: # echo 'sys_open:traceon:' > set_ftrace_filter # echo 'sys_close:traceoff:5' > set_ftrace_filter # cat set_ftrace_filter #### all functions enabled #### sys_open:traceon:unlimited sys_close:traceoff:count=0 After: # cat set_ftrace_filter #### all functions enabled #### sys_open:traceon:unlimited sys_close:traceoff:count=0 Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4A4313A7.7030105@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-06-20tracing/urgent: fix unbalanced ftrace_start_upFrederic Weisbecker
Perfcounter reports the following stats for a wide system profiling: # # (2364 samples) # # Overhead Symbol # ........ ...... # 15.40% [k] mwait_idle_with_hints 8.29% [k] read_hpet 5.75% [k] ftrace_caller 3.60% [k] ftrace_call [...] This snapshot has been taken while neither the function tracer nor the function graph tracer was running. With dynamic ftrace, such results show a wrong ftrace behaviour because all calls to ftrace_caller or ftrace_graph_caller (the patched calls to mcount) are supposed to be patched into nop if none of those tracers are running. The problem occurs after the first run of the function tracer. Once we launch it a second time, the callsites will never be nopped back, unless you set custom filters. For example it happens during the self tests at boot time. The function tracer selftest runs, and then the dynamic tracing is tested too. After that, the callsites are left un-nopped. This is because the reset callback of the function tracer tries to unregister two ftrace callbacks in once: the common function tracer and the function tracer with stack backtrace, regardless of which one is currently in use. It then creates an unbalance on ftrace_start_up value which is expected to be zero when the last ftrace callback is unregistered. When it reaches zero, the FTRACE_DISABLE_CALLS is set on the next ftrace command, triggering the patching into nop. But since it becomes unbalanced, ie becomes lower than zero, if the kernel functions are patched again (as in every further function tracer runs), they won't ever be nopped back. Note that ftrace_call and ftrace_graph_call are still patched back to ftrace_stub in the off case, but not the callers of ftrace_call and ftrace_graph_caller. It means that the tracing is well deactivated but we waste a useless call into every kernel function. This patch just unregisters the right ftrace_ops for the function tracer on its reset callback and ignores the other one which is not registered, fixing the unbalance. The problem also happens is .30 Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: stable@kernel.org
2009-02-18tracing/core: use appropriate waiting on trace_pipeFrederic Weisbecker
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>
2009-02-17ftrace: show unlimited when traceon or traceoff has no counterSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com>
2009-02-17ftrace: rename _hook to _probeSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com>
2009-02-17ftrace: clean up coding styleSteven Rostedt
Ingo Molnar pointed out some coding style issues with the recent ftrace updates. This patch cleans them up. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-16ftrace: add pretty print function for traceon and traceoff hooksSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com>
2009-02-16ftrace: add traceon traceoff commands to enable/disable the buffersSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com>
2009-02-06trace: Call tracing_reset_online_cpus before tracer->init()Arnaldo Carvalho de Melo
Impact: cleanup To make it easy for ftrace plugin writers, as this was open coded in the existing plugins Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Frédéric Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-05trace: Remove unused trace_array_cpu parameterArnaldo Carvalho de Melo
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>
2009-01-16ftrace: remove static from function tracer functionsSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-16ftrace: combine stack trace in function callSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-16ftrace: move function tracer functions out of trace.cSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-16ftrace: add stack trace to function tracerSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-19ftrace: introduce tracing_reset_online_cpus() helperPekka J Enberg
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: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-16tracing/ftrace: change the type of the init() callbackFrederic Weisbecker
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>
2008-11-08ftrace: remove trace array ctrlSteven Rostedt
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>
2008-11-08ftrace: remove ctrl_update methodSteven Rostedt
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>
2008-11-06ftrace: restructure tracing start/stop infrastructureSteven Rostedt
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>
2008-10-20ftrace: rename the ftrace tracer to functionSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-14ftrace: make work with new ring bufferSteven Rostedt
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>
2008-07-11ftrace: use current CPU for function startupSteven Rostedt
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: 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>
2008-05-26ftrace: fix up cmdline recordingSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23ftrace: fix comm on function trace outputSteven Rostedt
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: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23ftrace: remove notraceIngo Molnar
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>
2008-05-23ftrace: build fixIngo Molnar
Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23ftrace: timestamp syncing, prepareIngo Molnar
rename and uninline now() to ftrace_now(). Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23ftrace: add self-testsSteven Rostedt
Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-23ftrace: function tracerSteven Rostedt
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: Ingo 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: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>