LIBTRACEEVENT(3)             libtraceevent Manual             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

libtraceevent                     01/13/2024                  LIBTRACEEVENT(3)