1*4882a593Smuzhiyunlibtraceevent(3) 2*4882a593Smuzhiyun================ 3*4882a593Smuzhiyun 4*4882a593SmuzhiyunNAME 5*4882a593Smuzhiyun---- 6*4882a593Smuzhiyuntep_get_header_page_size, tep_get_header_timestamp_size, tep_is_old_format - 7*4882a593SmuzhiyunGet the data stored in the header page, in kernel context. 8*4882a593Smuzhiyun 9*4882a593SmuzhiyunSYNOPSIS 10*4882a593Smuzhiyun-------- 11*4882a593Smuzhiyun[verse] 12*4882a593Smuzhiyun-- 13*4882a593Smuzhiyun*#include <event-parse.h>* 14*4882a593Smuzhiyun 15*4882a593Smuzhiyunint *tep_get_header_page_size*(struct tep_handle pass:[*]_tep_); 16*4882a593Smuzhiyunint *tep_get_header_timestamp_size*(struct tep_handle pass:[*]_tep_); 17*4882a593Smuzhiyunbool *tep_is_old_format*(struct tep_handle pass:[*]_tep_); 18*4882a593Smuzhiyun-- 19*4882a593SmuzhiyunDESCRIPTION 20*4882a593Smuzhiyun----------- 21*4882a593SmuzhiyunThese functions retrieve information from kernel context, stored in tracefs 22*4882a593Smuzhiyunevents/header_page. Old kernels do not have header page info, so default values 23*4882a593Smuzhiyunfrom user space context are used. 24*4882a593Smuzhiyun 25*4882a593SmuzhiyunThe _tep_get_header_page_size()_ function returns the size of a long integer, 26*4882a593Smuzhiyunin kernel context. The _tep_ argument is trace event parser context. 27*4882a593SmuzhiyunThis information is retrieved from tracefs events/header_page, "commit" field. 28*4882a593Smuzhiyun 29*4882a593SmuzhiyunThe _tep_get_header_timestamp_size()_ function returns the size of timestamps, 30*4882a593Smuzhiyunin kernel context. The _tep_ argument is trace event parser context. This 31*4882a593Smuzhiyuninformation is retrieved from tracefs events/header_page, "timestamp" field. 32*4882a593Smuzhiyun 33*4882a593SmuzhiyunThe _tep_is_old_format()_ function returns true if the kernel predates 34*4882a593Smuzhiyunthe addition of events/header_page, otherwise it returns false. 35*4882a593Smuzhiyun 36*4882a593SmuzhiyunRETURN VALUE 37*4882a593Smuzhiyun------------ 38*4882a593SmuzhiyunThe _tep_get_header_page_size()_ function returns the size of a long integer, 39*4882a593Smuzhiyunin bytes. 40*4882a593Smuzhiyun 41*4882a593SmuzhiyunThe _tep_get_header_timestamp_size()_ function returns the size of timestamps, 42*4882a593Smuzhiyunin bytes. 43*4882a593Smuzhiyun 44*4882a593SmuzhiyunThe _tep_is_old_format()_ function returns true, if an old kernel is used to 45*4882a593Smuzhiyungenerate the tracing data, which has no event/header_page. If the kernel is new, 46*4882a593Smuzhiyunor _tep_ is NULL, false is returned. 47*4882a593Smuzhiyun 48*4882a593SmuzhiyunEXAMPLE 49*4882a593Smuzhiyun------- 50*4882a593Smuzhiyun[source,c] 51*4882a593Smuzhiyun-- 52*4882a593Smuzhiyun#include <event-parse.h> 53*4882a593Smuzhiyun... 54*4882a593Smuzhiyunstruct tep_handle *tep = tep_alloc(); 55*4882a593Smuzhiyun... 56*4882a593Smuzhiyun int longsize; 57*4882a593Smuzhiyun int timesize; 58*4882a593Smuzhiyun bool old; 59*4882a593Smuzhiyun 60*4882a593Smuzhiyun longsize = tep_get_header_page_size(tep); 61*4882a593Smuzhiyun timesize = tep_get_header_timestamp_size(tep); 62*4882a593Smuzhiyun old = tep_is_old_format(tep); 63*4882a593Smuzhiyun 64*4882a593Smuzhiyun printf ("%s kernel is used to generate the tracing data.\n", 65*4882a593Smuzhiyun old?"Old":"New"); 66*4882a593Smuzhiyun printf("The size of a long integer is %d bytes.\n", longsize); 67*4882a593Smuzhiyun printf("The timestamps size is %d bytes.\n", timesize); 68*4882a593Smuzhiyun... 69*4882a593Smuzhiyun-- 70*4882a593Smuzhiyun 71*4882a593SmuzhiyunFILES 72*4882a593Smuzhiyun----- 73*4882a593Smuzhiyun[verse] 74*4882a593Smuzhiyun-- 75*4882a593Smuzhiyun*event-parse.h* 76*4882a593Smuzhiyun Header file to include in order to have access to the library APIs. 77*4882a593Smuzhiyun*-ltraceevent* 78*4882a593Smuzhiyun Linker switch to add when building a program that uses the library. 79*4882a593Smuzhiyun-- 80*4882a593Smuzhiyun 81*4882a593SmuzhiyunSEE ALSO 82*4882a593Smuzhiyun-------- 83*4882a593Smuzhiyun_libtraceevent(3)_, _trace-cmd(1)_ 84*4882a593Smuzhiyun 85*4882a593SmuzhiyunAUTHOR 86*4882a593Smuzhiyun------ 87*4882a593Smuzhiyun[verse] 88*4882a593Smuzhiyun-- 89*4882a593Smuzhiyun*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*. 90*4882a593Smuzhiyun*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page. 91*4882a593Smuzhiyun-- 92*4882a593SmuzhiyunREPORTING BUGS 93*4882a593Smuzhiyun-------------- 94*4882a593SmuzhiyunReport bugs to <linux-trace-devel@vger.kernel.org> 95*4882a593Smuzhiyun 96*4882a593SmuzhiyunLICENSE 97*4882a593Smuzhiyun------- 98*4882a593Smuzhiyunlibtraceevent is Free Software licensed under the GNU LGPL 2.1 99*4882a593Smuzhiyun 100*4882a593SmuzhiyunRESOURCES 101*4882a593Smuzhiyun--------- 102*4882a593Smuzhiyunhttps://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 103