tools lib traceevent: Man pages for APIs used to extract common fields from a record

libtraceevent(3)

================

NAME

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tep_data_type, tep_data_pid,tep_data_preempt_count, tep_data_flags -

Extract common fields from a record.

SYNOPSIS

--------

[verse]

--

*#include <event-parse.h>*

enum *trace_flag_type* {

	_TRACE_FLAG_IRQS_OFF_,

	_TRACE_FLAG_IRQS_NOSUPPORT_,

	_TRACE_FLAG_NEED_RESCHED_,

	_TRACE_FLAG_HARDIRQ_,

	_TRACE_FLAG_SOFTIRQ_,

};

int *tep_data_type*(struct tep_handle pass:[*]_tep_, struct tep_record pass:[*]_rec_);

int *tep_data_pid*(struct tep_handle pass:[*]_tep_, struct tep_record pass:[*]_rec_);

int *tep_data_preempt_count*(struct tep_handle pass:[*]_tep_, struct tep_record pass:[*]_rec_);

int *tep_data_flags*(struct tep_handle pass:[*]_tep_, struct tep_record pass:[*]_rec_);

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DESCRIPTION

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This set of functions can be used to extract common fields from a record.

The _tep_data_type()_ function gets the event id from the record _rec_.

It reads the "common_type" field. The _tep_ argument is the trace event parser

context.

The _tep_data_pid()_ function gets the process id from the record _rec_.

It reads the "common_pid" field. The _tep_ argument is the trace event parser

context.

The _tep_data_preempt_count()_ function gets the preemption count from the

record _rec_. It reads the "common_preempt_count" field. The _tep_ argument is

the trace event parser context.

The _tep_data_flags()_ function gets the latency flags from the record _rec_.

It reads the "common_flags" field. The _tep_ argument is the trace event parser

context. Supported latency flags are:

[verse]

--

	_TRACE_FLAG_IRQS_OFF_,		Interrupts are disabled.

	_TRACE_FLAG_IRQS_NOSUPPORT_,	Reading IRQ flag is not supported by the architecture.

	_TRACE_FLAG_NEED_RESCHED_,	Task needs rescheduling.

	_TRACE_FLAG_HARDIRQ_,		Hard IRQ is running.

	_TRACE_FLAG_SOFTIRQ_,		Soft IRQ is running.

--

RETURN VALUE

------------

The _tep_data_type()_ function returns an integer, representing the event id.

The _tep_data_pid()_ function returns an integer, representing the process id

The _tep_data_preempt_count()_ function returns an integer, representing the

preemption count.

The _tep_data_flags()_ function returns an integer, representing the latency

flags. Look at the _trace_flag_type_ enum for supported flags.

All these functions in case of an error return a negative integer.

EXAMPLE

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[source,c]

--

#include <event-parse.h>

...

struct tep_handle *tep = tep_alloc();

...

void process_record(struct tep_record *record)

{

	int data;

	data = tep_data_type(tep, record);

	if (data >= 0) {

		/* Got the ID of the event */

	}

	data = tep_data_pid(tep, record);

	if (data >= 0) {

		/* Got the process ID */

	}

	data = tep_data_preempt_count(tep, record);

	if (data >= 0) {

		/* Got the preemption count */

	}

	data = tep_data_flags(tep, record);

	if (data >= 0) {

		/* Got the latency flags */

	}

}

...

--

FILES

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[verse]

--

*event-parse.h*

	Header file to include in order to have access to the library APIs.

*-ltraceevent*

	Linker switch to add when building a program that uses the library.

--

SEE ALSO

--------

_libtraceevent(3)_, _trace-cmd(1)_

AUTHOR

------

[verse]

--

*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.

*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.

--

REPORTING BUGS

--------------

Report bugs to  <linux-trace-devel@vger.kernel.org>

LICENSE

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libtraceevent is Free Software licensed under the GNU LGPL 2.1

RESOURCES

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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git