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Diffstat (limited to 'Documentation/trace/events.rst')
| -rw-r--r-- | Documentation/trace/events.rst | 78 |
1 files changed, 39 insertions, 39 deletions
diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst index c47f381d0c00..8b33850b8bf9 100644 --- a/Documentation/trace/events.rst +++ b/Documentation/trace/events.rst @@ -24,27 +24,27 @@ tracing information should be printed. --------------------------------- The events which are available for tracing can be found in the file -/sys/kernel/debug/tracing/available_events. +/sys/kernel/tracing/available_events. To enable a particular event, such as 'sched_wakeup', simply echo it -to /sys/kernel/debug/tracing/set_event. For example:: +to /sys/kernel/tracing/set_event. For example:: - # echo sched_wakeup >> /sys/kernel/debug/tracing/set_event + # echo sched_wakeup >> /sys/kernel/tracing/set_event .. Note:: '>>' is necessary, otherwise it will firstly disable all the events. To disable an event, echo the event name to the set_event file prefixed with an exclamation point:: - # echo '!sched_wakeup' >> /sys/kernel/debug/tracing/set_event + # echo '!sched_wakeup' >> /sys/kernel/tracing/set_event To disable all events, echo an empty line to the set_event file:: - # echo > /sys/kernel/debug/tracing/set_event + # echo > /sys/kernel/tracing/set_event To enable all events, echo ``*:*`` or ``*:`` to the set_event file:: - # echo *:* > /sys/kernel/debug/tracing/set_event + # echo *:* > /sys/kernel/tracing/set_event The events are organized into subsystems, such as ext4, irq, sched, etc., and a full event name looks like this: <subsystem>:<event>. The @@ -53,29 +53,29 @@ file. All of the events in a subsystem can be specified via the syntax ``<subsystem>:*``; for example, to enable all irq events, you can use the command:: - # echo 'irq:*' > /sys/kernel/debug/tracing/set_event + # echo 'irq:*' > /sys/kernel/tracing/set_event 2.2 Via the 'enable' toggle --------------------------- -The events available are also listed in /sys/kernel/debug/tracing/events/ hierarchy +The events available are also listed in /sys/kernel/tracing/events/ hierarchy of directories. To enable event 'sched_wakeup':: - # echo 1 > /sys/kernel/debug/tracing/events/sched/sched_wakeup/enable + # echo 1 > /sys/kernel/tracing/events/sched/sched_wakeup/enable To disable it:: - # echo 0 > /sys/kernel/debug/tracing/events/sched/sched_wakeup/enable + # echo 0 > /sys/kernel/tracing/events/sched/sched_wakeup/enable To enable all events in sched subsystem:: - # echo 1 > /sys/kernel/debug/tracing/events/sched/enable + # echo 1 > /sys/kernel/tracing/events/sched/enable To enable all events:: - # echo 1 > /sys/kernel/debug/tracing/events/enable + # echo 1 > /sys/kernel/tracing/events/enable When reading one of these enable files, there are four results: @@ -126,7 +126,7 @@ is the size of the data item, in bytes. For example, here's the information displayed for the 'sched_wakeup' event:: - # cat /sys/kernel/debug/tracing/events/sched/sched_wakeup/format + # cat /sys/kernel/tracing/events/sched/sched_wakeup/format name: sched_wakeup ID: 60 @@ -215,19 +215,19 @@ to the 'filter' file for the given event. For example:: - # cd /sys/kernel/debug/tracing/events/sched/sched_wakeup + # cd /sys/kernel/tracing/events/sched/sched_wakeup # echo "common_preempt_count > 4" > filter A slightly more involved example:: - # cd /sys/kernel/debug/tracing/events/signal/signal_generate + # cd /sys/kernel/tracing/events/signal/signal_generate # echo "((sig >= 10 && sig < 15) || sig == 17) && comm != bash" > filter If there is an error in the expression, you'll get an 'Invalid argument' error when setting it, and the erroneous string along with an error message can be seen by looking at the filter e.g.:: - # cd /sys/kernel/debug/tracing/events/signal/signal_generate + # cd /sys/kernel/tracing/events/signal/signal_generate # echo "((sig >= 10 && sig < 15) || dsig == 17) && comm != bash" > filter -bash: echo: write error: Invalid argument # cat filter @@ -258,7 +258,7 @@ file. To clear the filters for all events in a subsystem, write a '0' to the subsystem's filter file. -5.3 Subsystem filters +5.4 Subsystem filters --------------------- For convenience, filters for every event in a subsystem can be set or @@ -277,7 +277,7 @@ above points: Clear the filters on all events in the sched subsystem:: - # cd /sys/kernel/debug/tracing/events/sched + # cd /sys/kernel/tracing/events/sched # echo 0 > filter # cat sched_switch/filter none @@ -287,7 +287,7 @@ Clear the filters on all events in the sched subsystem:: Set a filter using only common fields for all events in the sched subsystem (all events end up with the same filter):: - # cd /sys/kernel/debug/tracing/events/sched + # cd /sys/kernel/tracing/events/sched # echo common_pid == 0 > filter # cat sched_switch/filter common_pid == 0 @@ -298,14 +298,14 @@ Attempt to set a filter using a non-common field for all events in the sched subsystem (all events but those that have a prev_pid field retain their old filters):: - # cd /sys/kernel/debug/tracing/events/sched + # cd /sys/kernel/tracing/events/sched # echo prev_pid == 0 > filter # cat sched_switch/filter prev_pid == 0 # cat sched_wakeup/filter common_pid == 0 -5.4 PID filtering +5.5 PID filtering ----------------- The set_event_pid file in the same directory as the top events directory @@ -313,7 +313,7 @@ exists, will filter all events from tracing any task that does not have the PID listed in the set_event_pid file. :: - # cd /sys/kernel/debug/tracing + # cd /sys/kernel/tracing # echo $$ > set_event_pid # echo 1 > events/enable @@ -409,14 +409,14 @@ The following commands are supported: specifies that this enablement happens only once:: # echo 'enable_event:kmem:kmalloc:1' > \ - /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger + /sys/kernel/tracing/events/syscalls/sys_enter_read/trigger The following trigger causes kmalloc events to stop being traced when a read system call exits. This disablement happens on every read system call exit:: # echo 'disable_event:kmem:kmalloc' > \ - /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/trigger + /sys/kernel/tracing/events/syscalls/sys_exit_read/trigger The format is:: @@ -426,10 +426,10 @@ The following commands are supported: To remove the above commands:: # echo '!enable_event:kmem:kmalloc:1' > \ - /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger + /sys/kernel/tracing/events/syscalls/sys_enter_read/trigger # echo '!disable_event:kmem:kmalloc' > \ - /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/trigger + /sys/kernel/tracing/events/syscalls/sys_exit_read/trigger Note that there can be any number of enable/disable_event triggers per triggering event, but there can only be one trigger per @@ -448,13 +448,13 @@ The following commands are supported: kmalloc tracepoint is hit:: # echo 'stacktrace' > \ - /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger + /sys/kernel/tracing/events/kmem/kmalloc/trigger The following trigger dumps a stacktrace the first 5 times a kmalloc request happens with a size >= 64K:: # echo 'stacktrace:5 if bytes_req >= 65536' > \ - /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger + /sys/kernel/tracing/events/kmem/kmalloc/trigger The format is:: @@ -463,16 +463,16 @@ The following commands are supported: To remove the above commands:: # echo '!stacktrace' > \ - /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger + /sys/kernel/tracing/events/kmem/kmalloc/trigger # echo '!stacktrace:5 if bytes_req >= 65536' > \ - /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger + /sys/kernel/tracing/events/kmem/kmalloc/trigger The latter can also be removed more simply by the following (without the filter):: # echo '!stacktrace:5' > \ - /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger + /sys/kernel/tracing/events/kmem/kmalloc/trigger Note that there can be only one stacktrace trigger per triggering event. @@ -488,20 +488,20 @@ The following commands are supported: capture those events when the trigger event occurred:: # echo 'snapshot if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger To only snapshot once:: # echo 'snapshot:1 if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger To remove the above commands:: # echo '!snapshot if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger # echo '!snapshot:1 if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger Note that there can be only one snapshot trigger per triggering event. @@ -519,20 +519,20 @@ The following commands are supported: trigger event:: # echo 'traceoff:1 if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger To always disable tracing when nr_rq > 1:: # echo 'traceoff if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger To remove the above commands:: # echo '!traceoff:1 if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger # echo '!traceoff if nr_rq > 1' > \ - /sys/kernel/debug/tracing/events/block/block_unplug/trigger + /sys/kernel/tracing/events/block/block_unplug/trigger Note that there can be only one traceon or traceoff trigger per triggering event. |