tep_get_header_page_size - Man Page

#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);

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​.

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​.

#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);
​.​.​.

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​.

libtraceevent(3), trace-cmd(1)

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

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

libtraceevent is Free Software licensed under the GNU LGPL 2​.1

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

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