LIBTRACEEVENT(3)

NAME
tep_data_type, tep_data_pid, tep_data_preempt_count, tep_data_flags - 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