NAME

       tep_get_header_page_size, tep_get_header_timestamp_size, tep_is_old_format - Get the data
       stored in the header page, in kernel context.

SYNOPSIS

       #include <event-parse.h>

       int tep_get_header_page_size(struct tep_handle *tep);
       int tep_get_header_timestamp_size(struct tep_handle *tep);
       bool tep_is_old_format(struct tep_handle *tep);

DESCRIPTION

       These functions retrieve information from kernel context, stored in tracefs
       events/header_page. Old kernels do not have header page info, so default values from user
       space context are used.

       The tep_get_header_page_size() function returns the size of a long integer, in kernel
       context. The tep argument is trace event parser context. This information is retrieved
       from tracefs events/header_page, "commit" field.

       The tep_get_header_timestamp_size() function returns the size of timestamps, in kernel
       context. The tep argument is trace event parser context. This information is retrieved
       from tracefs events/header_page, "timestamp" field.

       The tep_is_old_format() function returns true if the kernel predates the addition of
       events/header_page, otherwise it returns false.

RETURN VALUE

       The tep_get_header_page_size() function returns the size of a long integer, in bytes.

       The tep_get_header_timestamp_size() function returns the size of timestamps, in bytes.

       The tep_is_old_format() function returns true, if an old kernel is used to generate the
       tracing data, which has no event/header_page. If the kernel is new, or tep is NULL, false
       is returned.

EXAMPLE

           #include <event-parse.h>
           ...
           struct tep_handle *tep = tep_alloc();
           ...
                   int longsize;
                   int timesize;
                   bool old;

                   longsize = tep_get_header_page_size(tep);
                   timesize = tep_get_header_timestamp_size(tep);
                   old = tep_is_old_format(tep);

                   printf ("%s kernel is used to generate the tracing data.\n",
                           old?"Old":"New");
                   printf("The size of a long integer is %d bytes.\n", longsize);
                   printf("The timestamps size is %d bytes.\n", timesize);
           ...

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