aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/trace
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2009-06-10 22:53:40 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-10 22:53:40 -0400
commit862366118026a358882eefc70238dbcc3db37aac (patch)
tree4eb62bc10327a5afac064a95a091ea05ecd2acc1 /Documentation/trace
parent57eee9ae7bbcfb692dc96c739a5184adb6349733 (diff)
parent511b01bdf64ad8a38414096eab283c7784aebfc4 (diff)
Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (244 commits) Revert "x86, bts: reenable ptrace branch trace support" tracing: do not translate event helper macros in print format ftrace/documentation: fix typo in function grapher name tracing/events: convert block trace points to TRACE_EVENT(), fix !CONFIG_BLOCK tracing: add protection around module events unload tracing: add trace_seq_vprint interface tracing: fix the block trace points print size tracing/events: convert block trace points to TRACE_EVENT() ring-buffer: fix ret in rb_add_time_stamp ring-buffer: pass in lockdep class key for reader_lock tracing: add annotation to what type of stack trace is recorded tracing: fix multiple use of __print_flags and __print_symbolic tracing/events: fix output format of user stack tracing/events: fix output format of kernel stack tracing/trace_stack: fix the number of entries in the header ring-buffer: discard timestamps that are at the start of the buffer ring-buffer: try to discard unneeded timestamps ring-buffer: fix bug in ring_buffer_discard_commit ftrace: do not profile functions when disabled tracing: make trace pipe recognize latency format flag ...
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/events.txt90
-rw-r--r--Documentation/trace/ftrace.txt2
-rw-r--r--Documentation/trace/power.txt17
3 files changed, 108 insertions, 1 deletions
diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
new file mode 100644
index 000000000000..f157d7594ea7
--- /dev/null
+++ b/Documentation/trace/events.txt
@@ -0,0 +1,90 @@
1 Event Tracing
2
3 Documentation written by Theodore Ts'o
4 Updated by Li Zefan
5
61. Introduction
7===============
8
9Tracepoints (see Documentation/trace/tracepoints.txt) can be used
10without creating custom kernel modules to register probe functions
11using the event tracing infrastructure.
12
13Not all tracepoints can be traced using the event tracing system;
14the kernel developer must provide code snippets which define how the
15tracing information is saved into the tracing buffer, and how the
16tracing information should be printed.
17
182. Using Event Tracing
19======================
20
212.1 Via the 'set_event' interface
22---------------------------------
23
24The events which are available for tracing can be found in the file
25/debug/tracing/available_events.
26
27To enable a particular event, such as 'sched_wakeup', simply echo it
28to /debug/tracing/set_event. For example:
29
30 # echo sched_wakeup >> /debug/tracing/set_event
31
32[ Note: '>>' is necessary, otherwise it will firstly disable
33 all the events. ]
34
35To disable an event, echo the event name to the set_event file prefixed
36with an exclamation point:
37
38 # echo '!sched_wakeup' >> /debug/tracing/set_event
39
40To disable all events, echo an empty line to the set_event file:
41
42 # echo > /debug/tracing/set_event
43
44To enable all events, echo '*:*' or '*:' to the set_event file:
45
46 # echo *:* > /debug/tracing/set_event
47
48The events are organized into subsystems, such as ext4, irq, sched,
49etc., and a full event name looks like this: <subsystem>:<event>. The
50subsystem name is optional, but it is displayed in the available_events
51file. All of the events in a subsystem can be specified via the syntax
52"<subsystem>:*"; for example, to enable all irq events, you can use the
53command:
54
55 # echo 'irq:*' > /debug/tracing/set_event
56
572.2 Via the 'enable' toggle
58---------------------------
59
60The events available are also listed in /debug/tracing/events/ hierarchy
61of directories.
62
63To enable event 'sched_wakeup':
64
65 # echo 1 > /debug/tracing/events/sched/sched_wakeup/enable
66
67To disable it:
68
69 # echo 0 > /debug/tracing/events/sched/sched_wakeup/enable
70
71To enable all events in sched subsystem:
72
73 # echo 1 > /debug/tracing/events/sched/enable
74
75To eanble all events:
76
77 # echo 1 > /debug/tracing/events/enable
78
79When reading one of these enable files, there are four results:
80
81 0 - all events this file affects are disabled
82 1 - all events this file affects are enabled
83 X - there is a mixture of events enabled and disabled
84 ? - this file does not affect any event
85
863. Defining an event-enabled tracepoint
87=======================================
88
89See The example provided in samples/trace_events
90
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index e362f50c496f..2a82d8602944 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -179,7 +179,7 @@ Here is the list of current tracers that may be configured.
179 179
180 Function call tracer to trace all kernel functions. 180 Function call tracer to trace all kernel functions.
181 181
182 "function_graph_tracer" 182 "function_graph"
183 183
184 Similar to the function tracer except that the 184 Similar to the function tracer except that the
185 function tracer probes the functions on their entry 185 function tracer probes the functions on their entry
diff --git a/Documentation/trace/power.txt b/Documentation/trace/power.txt
new file mode 100644
index 000000000000..cd805e16dc27
--- /dev/null
+++ b/Documentation/trace/power.txt
@@ -0,0 +1,17 @@
1The power tracer collects detailed information about C-state and P-state
2transitions, instead of just looking at the high-level "average"
3information.
4
5There is a helper script found in scrips/tracing/power.pl in the kernel
6sources which can be used to parse this information and create a
7Scalable Vector Graphics (SVG) picture from the trace data.
8
9To use this tracer:
10
11 echo 0 > /sys/kernel/debug/tracing/tracing_enabled
12 echo power > /sys/kernel/debug/tracing/current_tracer
13 echo 1 > /sys/kernel/debug/tracing/tracing_enabled
14 sleep 1
15 echo 0 > /sys/kernel/debug/tracing/tracing_enabled
16 cat /sys/kernel/debug/tracing/trace | \
17 perl scripts/tracing/power.pl > out.sv