mirror of https://gitee.com/openkylin/linux.git
119 lines
2.9 KiB
Plaintext
119 lines
2.9 KiB
Plaintext
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libtraceevent(3)
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================
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NAME
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----
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tep_find_common_field, tep_find_field, tep_find_any_field -
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Search for a field in an event.
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SYNOPSIS
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--------
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[verse]
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--
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*#include <event-parse.h>*
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struct tep_format_field pass:[*]*tep_find_common_field*(struct tep_event pass:[*]_event_, const char pass:[*]_name_);
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struct tep_format_field pass:[*]*tep_find_field*(struct tep_event_ormat pass:[*]_event_, const char pass:[*]_name_);
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struct tep_format_field pass:[*]*tep_find_any_field*(struct tep_event pass:[*]_event_, const char pass:[*]_name_);
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--
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DESCRIPTION
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-----------
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These functions search for a field with given name in an event. The field
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returned can be used to find the field content from within a data record.
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The _tep_find_common_field()_ function searches for a common field with _name_
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in the _event_.
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The _tep_find_field()_ function searches for an event specific field with
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_name_ in the _event_.
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The _tep_find_any_field()_ function searches for any field with _name_ in the
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_event_.
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RETURN VALUE
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------------
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The _tep_find_common_field(), _tep_find_field()_ and _tep_find_any_field()_
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functions return a pointer to the found field, or NULL in case there is no field
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with the requested name.
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EXAMPLE
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-------
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[source,c]
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--
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#include <event-parse.h>
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...
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void get_htimer_info(struct tep_handle *tep, struct tep_record *record)
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{
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struct tep_format_field *field;
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struct tep_event *event;
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long long softexpires;
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int mode;
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int pid;
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event = tep_find_event_by_name(tep, "timer", "hrtimer_start");
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field = tep_find_common_field(event, "common_pid");
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if (field == NULL) {
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/* Cannot find "common_pid" field in the event */
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} else {
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/* Get pid from the data record */
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pid = tep_read_number(tep, record->data + field->offset,
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field->size);
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}
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field = tep_find_field(event, "softexpires");
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if (field == NULL) {
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/* Cannot find "softexpires" event specific field in the event */
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} else {
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/* Get softexpires parameter from the data record */
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softexpires = tep_read_number(tep, record->data + field->offset,
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field->size);
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}
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field = tep_find_any_field(event, "mode");
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if (field == NULL) {
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/* Cannot find "mode" field in the event */
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} else
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{
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/* Get mode parameter from the data record */
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mode = tep_read_number(tep, record->data + field->offset,
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field->size);
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}
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}
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...
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--
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FILES
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-----
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[verse]
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--
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*event-parse.h*
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Header file to include in order to have access to the library APIs.
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*-ltraceevent*
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Linker switch to add when building a program that uses the library.
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--
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SEE ALSO
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--------
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_libtraceevent(3)_, _trace-cmd(1)_
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AUTHOR
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------
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[verse]
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--
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*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
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*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
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--
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REPORTING BUGS
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--------------
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Report bugs to <linux-trace-devel@vger.kernel.org>
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LICENSE
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-------
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libtraceevent is Free Software licensed under the GNU LGPL 2.1
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RESOURCES
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---------
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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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