| libtraceevent(3) | |
| ================ | |
| 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 | |
| -------- | |
| [verse] | |
| -- | |
| *#include <event-parse.h>* | |
| int *tep_get_header_page_size*(struct tep_handle pass:[*]_tep_); | |
| int *tep_get_header_timestamp_size*(struct tep_handle pass:[*]_tep_); | |
| bool *tep_is_old_format*(struct tep_handle pass:[*]_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 | |
| ------- | |
| [source,c] | |
| -- | |
| #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 | |
| ----- | |
| [verse] | |
| -- | |
| *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 | |
| ------ | |
| [verse] | |
| -- | |
| *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/linux/kernel/git/torvalds/linux.git |