tep_data_type - Man Page

Extract common fields from a record.

Synopsis

#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 *tep, struct tep_record *rec);
int tep_data_pid(struct tep_handle *tep, struct tep_record *rec);
int tep_data_preempt_count(struct tep_handle *tep, struct tep_record *rec);
int tep_data_flags(struct tep_handle *tep, struct tep_record *rec);

Description

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:

        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

#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

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

Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.

Reporting Bugs

Report bugs to <linux-trace-devel@vger.kernel.org[3]>

License

libtraceevent is Free Software licensed under the GNU LGPL 2.1

Resources

https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/

Notes

  1. rostedt@goodmis.org
    mailto:rostedt@goodmis.org
  2. tz.stoyanov@gmail.com
    mailto:tz.stoyanov@gmail.com
  3. linux-trace-devel@vger.kernel.org
    mailto:linux-trace-devel@vger.kernel.org

Referenced By

The man pages tep_data_flags(3), tep_data_pid(3) and tep_data_preempt_count(3) are aliases of tep_data_type(3).

02/08/2021 libtraceevent 1.1.1 libtraceevent Manual