1LIBTRACEEVENT(3) libtraceevent Manual LIBTRACEEVENT(3)
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6 tep_get_header_page_size, tep_get_header_timestamp_size,
7 tep_is_old_format - Get the data stored in the header page, in kernel
8 context.
9
11 #include <event-parse.h>
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13 int tep_get_header_page_size(struct tep_handle *tep);
14 int tep_get_header_timestamp_size(struct tep_handle *tep);
15 bool tep_is_old_format(struct tep_handle *tep);
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18 These functions retrieve information from kernel context, stored in
19 tracefs events/header_page. Old kernels do not have header page info,
20 so default values from user space context are used.
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22 The tep_get_header_page_size() function returns the size of a long
23 integer, in kernel context. The tep argument is trace event parser
24 context. This information is retrieved from tracefs events/header_page,
25 "commit" field.
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27 The tep_get_header_timestamp_size() function returns the size of
28 timestamps, in kernel context. The tep argument is trace event parser
29 context. This information is retrieved from tracefs events/header_page,
30 "timestamp" field.
31
32 The tep_is_old_format() function returns true if the kernel predates
33 the addition of events/header_page, otherwise it returns false.
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36 The tep_get_header_page_size() function returns the size of a long
37 integer, in bytes.
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39 The tep_get_header_timestamp_size() function returns the size of
40 timestamps, in bytes.
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42 The tep_is_old_format() function returns true, if an old kernel is used
43 to generate the tracing data, which has no event/header_page. If the
44 kernel is new, or tep is NULL, false is returned.
45
47 #include <event-parse.h>
48 ...
49 struct tep_handle *tep = tep_alloc();
50 ...
51 int longsize;
52 int timesize;
53 bool old;
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55 longsize = tep_get_header_page_size(tep);
56 timesize = tep_get_header_timestamp_size(tep);
57 old = tep_is_old_format(tep);
58
59 printf ("%s kernel is used to generate the tracing data.\n",
60 old?"Old":"New");
61 printf("The size of a long integer is %d bytes.\n", longsize);
62 printf("The timestamps size is %d bytes.\n", timesize);
63 ...
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66 event-parse.h
67 Header file to include in order to have access to the library APIs.
68 -ltraceevent
69 Linker switch to add when building a program that uses the library.
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72 libtraceevent(3), trace-cmd(1)
73
75 Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
76 Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.
77
79 Report bugs to <linux-trace-devel@vger.kernel.org[3]>
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82 libtraceevent is Free Software licensed under the GNU LGPL 2.1
83
85 https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
86
88 1. rostedt@goodmis.org
89 mailto:rostedt@goodmis.org
90
91 2. tz.stoyanov@gmail.com
92 mailto:tz.stoyanov@gmail.com
93
94 3. linux-trace-devel@vger.kernel.org
95 mailto:linux-trace-devel@vger.kernel.org
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99libtraceevent 1.1.1 02/08/2021 LIBTRACEEVENT(3)