# libtraceevent(3) Manual Page

## NAME

tep_print_event - Writes event information into a trace sequence.

## SYNOPSIS

    #include <event-parse.h>
    #include <trace-seq.h>

    void tep_print_event(struct tep_handle *tep, struct trace_seq*s, struct tep_record *record, const char *fmt, …)

## DESCRIPTION

The tep_print_event() function parses the event information of the given record and writes it into the trace sequence s, according to the format string fmt. The desired information is specified after the format string. The fmt is printf-like format string, following arguments are supported:

            TEP_PRINT_PID, "%d"  - PID of the event.
            TEP_PRINT_CPU, "%d"  - Event CPU.
            TEP_PRINT_COMM, "%s" - Event command string.
            TEP_PRINT_NAME, "%s" - Event name.
            TEP_PRINT_LATENCY, "%s" - Latency of the event. It prints 4 or more
                            fields - interrupt state, scheduling state,
                            current context, and preemption count.
                            Field 1 is the interrupt enabled state:
                                    d : Interrupts are disabled
                                    . : Interrupts are enabled
                                    X : The architecture does not support this
                                        information
                            Field 2 is the "need resched" state.
                                    N : The task is set to call the scheduler when
                                        possible, as another higher priority task
                                        may need to be scheduled in.
                                    . : The task is not set to call the scheduler.
                            Field 3 is the context state.
                                    . : Normal context
                                    s : Soft interrupt context
                                    h : Hard interrupt context
                                    H : Hard interrupt context which triggered
                                        during soft interrupt context.
                                    z : NMI context
                                    Z : NMI context which triggered during hard
                                        interrupt context
                            Field 4 is the preemption count.
                                    . : The preempt count is zero.
                            On preemptible kernels (where the task can be scheduled
                            out in arbitrary locations while in kernel context), the
                            preempt count, when non zero, will prevent the kernel
                            from scheduling out the current task. The preempt count
                            number is displayed when it is not zero.
                            Depending on the kernel, it may show other fields
                            (lock depth, or migration disabled, which are unique to
                            specialized kernels).
            TEP_PRINT_TIME, %d - event time stamp. A divisor and precision can be
                            specified as part of this format string:
                            "%precision.divisord". Example:
                            "%3.1000d" - divide the time by 1000 and print the first
                            3 digits before the dot. Thus, the time stamp
                            "123456000" will be printed as "123.456"
            TEP_PRINT_INFO, "%s" - event information.
            TEP_PRINT_INFO_RAW, "%s" - event information, in raw format.

## EXAMPLE

    #include <event-parse.h>
    #include <trace-seq.h>
    ...
    struct trace_seq seq;
    trace_seq_init(&seq);
    struct tep_handle *tep = tep_alloc();
    ...
    void print_my_event(struct tep_record *record)
    {
            trace_seq_reset(&seq);
            tep_print_event(tep, s, record, "%16s-%-5d [%03d] %s %6.1000d %s %s",
                            TEP_PRINT_COMM, TEP_PRINT_PID, TEP_PRINT_CPU,
                            TEP_PRINT_LATENCY, TEP_PRINT_TIME, TEP_PRINT_NAME,
                            TEP_PRINT_INFO);
    }
    ...

## FILES

    event-parse.h
            Header file to include in order to have access to the library APIs.
    trace-seq.h
            Header file to include in order to have access to trace sequences related APIs.
            Trace sequences are used to allow a function to call several other functions
            to create a string of data to use.
    -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>, 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

libtraceevent is Free Software licensed under the GNU LGPL 2.1

## RESOURCES

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