1LIBTRACEEVENT(3) libtraceevent Manual LIBTRACEEVENT(3)
2
6 tep_print_event - Writes event information into a trace sequence.
7
9 #include <event-parse.h>
10 #include <trace-seq.h>
11 void tep_print_event(struct tep_handle *tep, struct trace_seq*s, struct tep_record *record, const char *fmt, ...)
13
15 The tep_print_event() function parses the event information of the
16 given record and writes it into the trace sequence s, according to the
17 format string fmt. The desired information is specified after the
18 format string. The fmt is printf-like format string, following
19 arguments are supported:
20 TEP_PRINT_PID, "%d" - PID of the event.
22 TEP_PRINT_CPU, "%d" - Event CPU.
23 TEP_PRINT_COMM, "%s" - Event command string.
24 TEP_PRINT_NAME, "%s" - Event name.
25 TEP_PRINT_LATENCY, "%s" - Latency of the event. It prints 4 or more
26 fields - interrupt state, scheduling state,
27 current context, and preemption count.
28 Field 1 is the interrupt enabled state:
29 d : Interrupts are disabled
30 . : Interrupts are enabled
31 X : The architecture does not support this
32 information
33 Field 2 is the "need resched" state.
34 N : The task is set to call the scheduler when
35 possible, as another higher priority task
36 may need to be scheduled in.
37 . : The task is not set to call the scheduler.
38 Field 3 is the context state.
39 . : Normal context
40 s : Soft interrupt context
41 h : Hard interrupt context
42 H : Hard interrupt context which triggered
43 during soft interrupt context.
44 z : NMI context
45 Z : NMI context which triggered during hard
46 interrupt context
47 Field 4 is the preemption count.
48 . : The preempt count is zero.
49 On preemptible kernels (where the task can be scheduled
50 out in arbitrary locations while in kernel context), the
51 preempt count, when non zero, will prevent the kernel
52 from scheduling out the current task. The preempt count
53 number is displayed when it is not zero.
54 Depending on the kernel, it may show other fields
55 (lock depth, or migration disabled, which are unique to
56 specialized kernels).
57 TEP_PRINT_TIME, %d - event time stamp. A divisor and precision can be
58 specified as part of this format string:
59 "%precision.divisord". Example:
60 "%3.1000d" - divide the time by 1000 and print the first
61 3 digits before the dot. Thus, the time stamp
62 "123456000" will be printed as "123.456"
63 TEP_PRINT_INFO, "%s" - event information.
64 TEP_PRINT_INFO_RAW, "%s" - event information, in raw format.
65
67 #include <event-parse.h>
68 #include <trace-seq.h>
69 ...
70 struct trace_seq seq;
71 trace_seq_init(&seq);
72 struct tep_handle *tep = tep_alloc();
73 ...
74 void print_my_event(struct tep_record *record)
75 {
76 trace_seq_reset(&seq);
77 tep_print_event(tep, s, record, "%16s-%-5d [%03d] %s %6.1000d %s %s",
78 TEP_PRINT_COMM, TEP_PRINT_PID, TEP_PRINT_CPU,
79 TEP_PRINT_LATENCY, TEP_PRINT_TIME, TEP_PRINT_NAME,
80 TEP_PRINT_INFO);
81 }
82 ...
83
85 event-parse.h
86 Header file to include in order to have access to the library APIs.
87 trace-seq.h
88 Header file to include in order to have access to trace sequences related APIs.
89 Trace sequences are used to allow a function to call several other functions
90 to create a string of data to use.
91 -ltraceevent
92 Linker switch to add when building a program that uses the library.
93
95 libtraceevent(3), trace-cmd(1)
96
98 Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
99 Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.
100
102 Report bugs to <linux-trace-devel@vger.kernel.org[3]>
103
105 libtraceevent is Free Software licensed under the GNU LGPL 2.1
106
108 https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
109
111 1. rostedt@goodmis.org
112 mailto:rostedt@goodmis.org
113 2. tz.stoyanov@gmail.com
115 mailto:tz.stoyanov@gmail.com
116 3. linux-trace-devel@vger.kernel.org
118 mailto:linux-trace-devel@vger.kernel.org
119libtraceevent 1.1.1 02/08/2021 LIBTRACEEVENT(3)