WSL2-Linux-Kernel/kernel/trace/Kconfig

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#
# Architectures that offer an FTRACE implementation should select HAVE_FTRACE:
#
config HAVE_FTRACE
bool
ftrace: latency tracer infrastructure This patch adds the latency tracer infrastructure. This patch does not add anything that will select and turn it on, but will be used by later patches. If it were to be compiled, it would add the following files to the debugfs: The root tracing directory: /debugfs/tracing/ This patch also adds the following files: available_tracers list of available tracers. Currently no tracers are available. Looking into this file only shows "none" which is used to unregister all tracers. current_tracer The trace that is currently active. Empty on start up. To switch to a tracer simply echo one of the tracers that are listed in available_tracers: example: (used with later patches) echo function > /debugfs/tracing/current_tracer To disable the tracer: echo disable > /debugfs/tracing/current_tracer tracing_enabled echoing "1" into this file starts the ftrace function tracing (if sysctl kernel.ftrace_enabled=1) echoing "0" turns it off. latency_trace This file is readonly and holds the result of the trace. trace This file outputs a easier to read version of the trace. iter_ctrl Controls the way the output of traces look. So far there's two controls: echoing in "symonly" will only show the kallsyms variables without the addresses (if kallsyms was configured) echoing in "verbose" will change the output to show a lot more data, but not very easy to understand by humans. echoing in "nosymonly" turns off symonly. echoing in "noverbose" turns off verbose. 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>
2008-05-12 23:20:42 +04:00
config HAVE_DYNAMIC_FTRACE
bool
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>
2008-05-12 23:20:42 +04:00
config TRACER_MAX_TRACE
bool
ftrace: latency tracer infrastructure This patch adds the latency tracer infrastructure. This patch does not add anything that will select and turn it on, but will be used by later patches. If it were to be compiled, it would add the following files to the debugfs: The root tracing directory: /debugfs/tracing/ This patch also adds the following files: available_tracers list of available tracers. Currently no tracers are available. Looking into this file only shows "none" which is used to unregister all tracers. current_tracer The trace that is currently active. Empty on start up. To switch to a tracer simply echo one of the tracers that are listed in available_tracers: example: (used with later patches) echo function > /debugfs/tracing/current_tracer To disable the tracer: echo disable > /debugfs/tracing/current_tracer tracing_enabled echoing "1" into this file starts the ftrace function tracing (if sysctl kernel.ftrace_enabled=1) echoing "0" turns it off. latency_trace This file is readonly and holds the result of the trace. trace This file outputs a easier to read version of the trace. iter_ctrl Controls the way the output of traces look. So far there's two controls: echoing in "symonly" will only show the kallsyms variables without the addresses (if kallsyms was configured) echoing in "verbose" will change the output to show a lot more data, but not very easy to understand by humans. echoing in "nosymonly" turns off symonly. echoing in "noverbose" turns off verbose. 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>
2008-05-12 23:20:42 +04:00
config TRACING
bool
select DEBUG_FS
select STACKTRACE
ftrace: latency tracer infrastructure This patch adds the latency tracer infrastructure. This patch does not add anything that will select and turn it on, but will be used by later patches. If it were to be compiled, it would add the following files to the debugfs: The root tracing directory: /debugfs/tracing/ This patch also adds the following files: available_tracers list of available tracers. Currently no tracers are available. Looking into this file only shows "none" which is used to unregister all tracers. current_tracer The trace that is currently active. Empty on start up. To switch to a tracer simply echo one of the tracers that are listed in available_tracers: example: (used with later patches) echo function > /debugfs/tracing/current_tracer To disable the tracer: echo disable > /debugfs/tracing/current_tracer tracing_enabled echoing "1" into this file starts the ftrace function tracing (if sysctl kernel.ftrace_enabled=1) echoing "0" turns it off. latency_trace This file is readonly and holds the result of the trace. trace This file outputs a easier to read version of the trace. iter_ctrl Controls the way the output of traces look. So far there's two controls: echoing in "symonly" will only show the kallsyms variables without the addresses (if kallsyms was configured) echoing in "verbose" will change the output to show a lot more data, but not very easy to understand by humans. echoing in "nosymonly" turns off symonly. echoing in "noverbose" turns off verbose. 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>
2008-05-12 23:20:42 +04:00
ftrace: function tracer 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>
2008-05-12 23:20:42 +04:00
config FTRACE
bool "Kernel Function Tracer"
depends on HAVE_FTRACE
ftrace: function tracer 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>
2008-05-12 23:20:42 +04:00
select FRAME_POINTER
select TRACING
select CONTEXT_SWITCH_TRACER
ftrace: function tracer 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>
2008-05-12 23:20:42 +04:00
help
Enable the kernel to trace every kernel function. This is done
by using a compiler feature to insert a small, 5-byte No-Operation
instruction to the beginning of every kernel function, which NOP
sequence is then dynamically patched into a tracer call when
tracing is enabled by the administrator. If it's runtime disabled
(the bootup default), then the overhead of the instructions is very
small and not measurable even in micro-benchmarks.
ftrace: trace irq disabled critical timings This patch adds latency tracing for critical timings (how long interrupts are disabled for). "irqsoff" is added to /debugfs/tracing/available_tracers Note: tracing_max_latency also holds the max latency for irqsoff (in usecs). (default to large number so one must start latency tracing) tracing_thresh threshold (in usecs) to always print out if irqs off is detected to be longer than stated here. If irq_thresh is non-zero, then max_irq_latency is ignored. Here's an example of a trace with ftrace_enabled = 0 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 Signed-off-by: Ingo Molnar <mingo@elte.hu> -------------------------------------------------------------------- latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1d.s3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1d.s3 100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1d.s3 100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= And this is a trace with ftrace_enabled == 1 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 -------------------------------------------------------------------- latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1dNs3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000]) swapper-0 1dNs3 46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000]) swapper-0 1dNs3 47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000]) swapper-0 1dNs3 47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47) swapper-0 1dNs3 97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50) swapper-0 1dNs3 98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000]) swapper-0 1dNs3 99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000]) swapper-0 1dNs3 101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 23:20:42 +04:00
config IRQSOFF_TRACER
bool "Interrupts-off Latency Tracer"
default n
depends on TRACE_IRQFLAGS_SUPPORT
depends on GENERIC_TIME
depends on HAVE_FTRACE
ftrace: trace irq disabled critical timings This patch adds latency tracing for critical timings (how long interrupts are disabled for). "irqsoff" is added to /debugfs/tracing/available_tracers Note: tracing_max_latency also holds the max latency for irqsoff (in usecs). (default to large number so one must start latency tracing) tracing_thresh threshold (in usecs) to always print out if irqs off is detected to be longer than stated here. If irq_thresh is non-zero, then max_irq_latency is ignored. Here's an example of a trace with ftrace_enabled = 0 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 Signed-off-by: Ingo Molnar <mingo@elte.hu> -------------------------------------------------------------------- latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1d.s3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1d.s3 100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1d.s3 100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= And this is a trace with ftrace_enabled == 1 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 -------------------------------------------------------------------- latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1dNs3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000]) swapper-0 1dNs3 46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000]) swapper-0 1dNs3 47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000]) swapper-0 1dNs3 47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47) swapper-0 1dNs3 97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50) swapper-0 1dNs3 98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000]) swapper-0 1dNs3 99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000]) swapper-0 1dNs3 101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 23:20:42 +04:00
select TRACE_IRQFLAGS
select TRACING
select TRACER_MAX_TRACE
help
This option measures the time spent in irqs-off critical
sections, with microsecond accuracy.
The default measurement method is a maximum search, which is
disabled by default and can be runtime (re-)started
via:
echo 0 > /debugfs/tracing/tracing_max_latency
(Note that kernel size and overhead increases with this option
enabled. This option and the preempt-off timing option can be
used together or separately.)
config PREEMPT_TRACER
bool "Preemption-off Latency Tracer"
default n
depends on GENERIC_TIME
depends on PREEMPT
depends on HAVE_FTRACE
select TRACING
select TRACER_MAX_TRACE
help
This option measures the time spent in preemption off critical
sections, with microsecond accuracy.
The default measurement method is a maximum search, which is
disabled by default and can be runtime (re-)started
via:
echo 0 > /debugfs/tracing/tracing_max_latency
(Note that kernel size and overhead increases with this option
enabled. This option and the irqs-off timing option can be
used together or separately.)
config SYSPROF_TRACER
bool "Sysprof Tracer"
depends on X86
select TRACING
help
This tracer provides the trace needed by the 'Sysprof' userspace
tool.
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>
2008-05-12 23:20:42 +04:00
config SCHED_TRACER
bool "Scheduling Latency Tracer"
depends on HAVE_FTRACE
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>
2008-05-12 23:20:42 +04:00
select TRACING
select CONTEXT_SWITCH_TRACER
select TRACER_MAX_TRACE
help
This tracer tracks the latency of the highest priority task
to be scheduled in, starting from the point it has woken up.
config CONTEXT_SWITCH_TRACER
bool "Trace process context switches"
depends on HAVE_FTRACE
select TRACING
select MARKERS
help
This tracer gets called from the context switch and records
all switching of tasks.
ftrace: dynamic enabling/disabling of function calls This patch adds a feature to dynamically replace the ftrace code with the jmps to allow a kernel with ftrace configured to run as fast as it can without it configured. The way this works, is on bootup (if ftrace is enabled), a ftrace function is registered to record the instruction pointer of all places that call the function. Later, if there's still any code to patch, a kthread is awoken (rate limited to at most once a second) that performs a stop_machine, and replaces all the code that was called with a jmp over the call to ftrace. It only replaces what was found the previous time. Typically the system reaches equilibrium quickly after bootup and there's no code patching needed at all. e.g. call ftrace /* 5 bytes */ is replaced with jmp 3f /* jmp is 2 bytes and we jump 3 forward */ 3: When we want to enable ftrace for function tracing, the IP recording is removed, and stop_machine is called again to replace all the locations of that were recorded back to the call of ftrace. When it is disabled, we replace the code back to the jmp. Allocation is done by the kthread. If the ftrace recording function is called, and we don't have any record slots available, then we simply skip that call. Once a second a new page (if needed) is allocated for recording new ftrace function calls. A large batch is allocated at boot up to get most of the calls there. Because we do this via stop_machine, we don't have to worry about another CPU executing a ftrace call as we modify it. But we do need to worry about NMI's so all functions that might be called via nmi must be annotated with notrace_nmi. When this code is configured in, the NMI code will not call notrace. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 23:20:42 +04:00
config DYNAMIC_FTRACE
bool "enable/disable ftrace tracepoints dynamically"
depends on FTRACE
depends on HAVE_DYNAMIC_FTRACE
ftrace: dynamic enabling/disabling of function calls This patch adds a feature to dynamically replace the ftrace code with the jmps to allow a kernel with ftrace configured to run as fast as it can without it configured. The way this works, is on bootup (if ftrace is enabled), a ftrace function is registered to record the instruction pointer of all places that call the function. Later, if there's still any code to patch, a kthread is awoken (rate limited to at most once a second) that performs a stop_machine, and replaces all the code that was called with a jmp over the call to ftrace. It only replaces what was found the previous time. Typically the system reaches equilibrium quickly after bootup and there's no code patching needed at all. e.g. call ftrace /* 5 bytes */ is replaced with jmp 3f /* jmp is 2 bytes and we jump 3 forward */ 3: When we want to enable ftrace for function tracing, the IP recording is removed, and stop_machine is called again to replace all the locations of that were recorded back to the call of ftrace. When it is disabled, we replace the code back to the jmp. Allocation is done by the kthread. If the ftrace recording function is called, and we don't have any record slots available, then we simply skip that call. Once a second a new page (if needed) is allocated for recording new ftrace function calls. A large batch is allocated at boot up to get most of the calls there. Because we do this via stop_machine, we don't have to worry about another CPU executing a ftrace call as we modify it. But we do need to worry about NMI's so all functions that might be called via nmi must be annotated with notrace_nmi. When this code is configured in, the NMI code will not call notrace. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 23:20:42 +04:00
default y
help
This option will modify all the calls to ftrace dynamically
(will patch them out of the binary image and replaces them
with a No-Op instruction) as they are called. A table is
created to dynamically enable them again.
This way a CONFIG_FTRACE kernel is slightly larger, but otherwise
has native performance as long as no tracing is active.
The changes to the code are done by a kernel thread that
wakes up once a second and checks to see if any ftrace calls
were made. If so, it runs stop_machine (stops all CPUS)
and modifies the code to jump over the call to ftrace.
config FTRACE_SELFTEST
bool
config FTRACE_STARTUP_TEST
bool "Perform a startup test on ftrace"
depends on TRACING
select FTRACE_SELFTEST
help
This option performs a series of startup tests on ftrace. On bootup
a series of tests are made to verify that the tracer is
functioning properly. It will do tests on all the configured
tracers of ftrace.