| 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 |
