1libtracefs(3) 2============= 3 4NAME 5---- 6tracefs_local_events, tracefs_local_events_system, tracefs_fill_local_events, 7tracefs_load_cmdlines - 8Initialize a tep handler with trace events from the local system. 9 10SYNOPSIS 11-------- 12[verse] 13-- 14*#include <tracefs.h>* 15 16struct tep_handle pass:[*]*tracefs_local_events*(const char pass:[*]_tracing_dir_); 17struct tep_handle pass:[*]*tracefs_local_events_system*(const char pass:[*]_tracing_dir_, const char pass:[*] const pass:[*]_sys_names_); 18int *tracefs_fill_local_events*(const char pass:[*]_tracing_dir_, struct tep_handle pass:[*]_tep_, int pass:[*]_parsing_failures_); 19int *tracefs_load_cmdlines*(const char pass:[*]_tracing_dir_, struct tep_handle pass:[*]_tep_); 20-- 21 22DESCRIPTION 23----------- 24Functions for initializing a tep handler with trace events from the local system. 25 26The *tracefs_local_events()* function allocates a new _tep_ handler and 27initializes it with events from all trace systems, located in the given 28_tracing_dir_ directory. This could be NULL or the location of the tracefs 29mount point for the trace systems of the local machine, or it may be a path 30to a copy of the tracefs directory from another machine. 31 32The *tracefs_local_events_system()* function allocates a new _tep_ handler 33and initializes it with events from specified trace systems _sys_names_, 34located in the given _tracing_dir_ directory. This could be NULL or the 35location of the tracefs mount point for the trace systems of the local 36machine, or it may be a path to a copy of the tracefs directory from another 37machine. The _sys_names_ argument is an array of trace system names, that 38will be used for _tep_ handler initialization. The last element in that 39array must be a NULL pointer. 40 41The *tracefs_fill_local_events()* function initializes already allocated _tep_ 42handler with events from all trace systems, located in the given _tracing_dir_ 43directory. This could be NULL or the location of the tracefs mount point 44for the trace systems of the local machine, or it may be a path to a copy 45of the tracefs directory from another machine. The _tep_ argument must be 46a pointer to already allocated tep handler, that is going to be initialized. 47The _parsing_failures_ argument could be NULL or a pointer to an integer, 48where the number of failures while parsing the event files are returned. 49 50The above functions will also load the mappings between pids and the process 51command line names. In some cases the _tep_ handle is created with one 52of the above before tracing begins. As the mappings get updated during the 53trace, there may be a need to read the mappings again after the trace. 54The *tracefs_load_cmdlines()* does just that. The _tracing_dir_ is 55the directory of the mount point to load from, or NULL to use the 56mount point of the tracefs file system. 57 58RETURN VALUE 59------------ 60The *tracefs_local_events()* and *tracefs_local_events_system()* functions 61return pointer to allocated and initialized _tep_ handler, or NULL in 62case of an error. The returned _tep_ handler must be freed with *tep_free*(3). 63 64The *tracefs_fill_local_events()* function returns -1 in case of an error or 650 otherwise. 66 67The *tracefs_load_cmdlines()* function returns -1 in case of an error, or 680 otherwise. 69 70EXAMPLE 71------- 72[source,c] 73-- 74#include <tracefs.h> 75 76struct tep_handle *tep; 77... 78 tep = tracefs_local_events(NULL); 79 if (!tep) { 80 /* Failed to initialise tep handler with local events from top instance */ 81 ... 82 } 83... 84 tep_free(tep); 85... 86 const char *systems[] = {"ftrace", "irq", NULL}; 87 tep = tracefs_local_events_system(NULL, systems); 88 if (!tep) { 89 /* Failed to initialise tep handler with local events from 90 * ftrace and irq systems in top instance. 91 */ 92 ... 93 } 94... 95 tep_free(tep); 96... 97 int parsing_failures; 98 tep = tep_alloc(); 99 if (!tep) { 100 /* Failed to allocate a tep handler */ 101 ... 102 } 103 if (tracefs_fill_local_events(NULL, tep, &parsing_failures) < 0) { 104 /* Failed to initialise tep handler with local events from top instance */ 105 } 106 tracefs_load_cmdlines(NULL, tep); 107... 108 tep_free(tep); 109-- 110FILES 111----- 112[verse] 113-- 114*tracefs.h* 115 Header file to include in order to have access to the library APIs. 116*-ltracefs* 117 Linker switch to add when building a program that uses the library. 118-- 119 120SEE ALSO 121-------- 122*libtracefs*(3), 123*libtraceevent*(3), 124*trace-cmd*(1) 125 126AUTHOR 127------ 128[verse] 129-- 130*Steven Rostedt* <[email protected]> 131*Tzvetomir Stoyanov* <[email protected]> 132-- 133REPORTING BUGS 134-------------- 135Report bugs to <[email protected]> 136 137LICENSE 138------- 139libtracefs is Free Software licensed under the GNU LGPL 2.1 140 141RESOURCES 142--------- 143https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ 144 145COPYING 146------- 147Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under 148the terms of the GNU Public License (GPL). 149