HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. |  |
NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |EXAMPLE |FILES |SEE ALSO |AUTHOR |REPORTING BUGS |LICENSE |RESOURCES |COPYING |NOTES |COLOPHON | |
LIBTRACEFS(3) libtracefs ManualLIBTRACEFS(3)tracefs_local_events, tracefs_local_events_system, tracefs_fill_local_events, tracefs_load_cmdlines, tracefs_load_headers - Initialize a tep handler with trace events from the local system.
#include <tracefs.h> struct tep_handle *tracefs_local_events(const char *tracing_dir); struct tep_handle *tracefs_local_events_system(const char *tracing_dir, const char * const *sys_names); inttracefs_fill_local_events(const char *tracing_dir, struct tep_handle *tep, int *parsing_failures); inttracefs_load_cmdlines(const char *tracing_dir, struct tep_handle *tep); inttracefs_load_headers(const char *tracing_dir, struct tep_handle *tep);
Functions for initializing a tep handler with trace events from the local system. Thetracefs_local_events()function allocates a newtep handler and initializes it with events from all trace systems, located in the giventracing_dir directory. This could be NULL or the location of the tracefs mount point for the trace systems of the local machine, or it may be a path to a copy of the tracefs directory from another machine. Thetracefs_local_events_system()function allocates a newtep handler and initializes it with events from specified trace systemssys_names, located in the giventracing_dir directory. This could be NULL or the location of the tracefs mount point for the trace systems of the local machine, or it may be a path to a copy of the tracefs directory from another machine. Thesys_names argument is an array of trace system names, that will be used fortep handler initialization. The last element in that array must be a NULL pointer. Thetracefs_fill_local_events()function initializes already allocatedtep handler with events from all trace systems, located in the giventracing_dir directory. This could be NULL or the location of the tracefs mount point for the trace systems of the local machine, or it may be a path to a copy of the tracefs directory from another machine. Thetep argument must be a pointer to already allocated tep handler, that is going to be initialized. Theparsing_failures argument could be NULL or a pointer to an integer, where the number of failures while parsing the event files are returned. The above functions will also load the mappings between pids and the process command line names. In some cases thetep handle is created with one of the above before tracing begins. As the mappings get updated during the trace, there may be a need to read the mappings again after the trace. Thetracefs_load_cmdlines() does just that. Thetracing_dir is the directory of the mount point to load from, or NULL to use the mount point of the tracefs file system. Thetracefs_load_headers()will reade the "header_page" of the events directory that will update thetep handle with information on how to parse the tracing ring buffer sub-buffer.
Thetracefs_local_events()andtracefs_local_events_system() functions return pointer to allocated and initializedtep handler, or NULL in case of an error. The returnedtep handler must be freed withtep_free(3). Thetracefs_fill_local_events()function returns -1 in case of an error or 0 otherwise. Thetracefs_load_cmdlines()function returns -1 in case of an error, or 0 otherwise.
#include <tracefs.h> struct tep_handle *tep; ... tep = tracefs_local_events(NULL); if (!tep) { /* Failed to initialise tep handler with local events from top instance */ ... } ... tep_free(tep); ... const char *systems[] = {"ftrace", "irq", NULL}; tep = tracefs_local_events_system(NULL, systems); if (!tep) { /* Failed to initialise tep handler with local events from * ftrace and irq systems in top instance. */ ... } ... tep_free(tep); ... int parsing_failures; tep = tep_alloc(); if (!tep) { /* Failed to allocate a tep handler */ ... } if (tracefs_fill_local_events(NULL, tep, &parsing_failures) < 0) { /* Failed to initialise tep handler with local events from top instance */ } tracefs_load_cmdlines(NULL, tep); ... tep_free(tep);tracefs.h Header file to include in order to have access to the library APIs.-ltracefs Linker switch to add when building a program that uses the library.
libtracefs(3),libtraceevent(3),trace-cmd(1)
Steven Rostedt<rostedt@goodmis.org[1]>Tzvetomir Stoyanov<tz.stoyanov@gmail.com[2]>
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
libtracefs is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Copyright (C) 2020 VMware, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).
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
This page is part of thelibtracefs (Linux kernel trace file system library) project. Information about the project can be found at ⟨https://www.trace-cmd.org/⟩. If you have a bug report for this manual page, see ⟨https://www.trace-cmd.org/⟩. This page was obtained from the project's upstream Git repository ⟨https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-06-02.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orglibtracefs 1.8.1 01/02/2025LIBTRACEFS(3)Pages that refer to this page:tracefs_hist_alloc(3), tracefs_iterate_raw_events(3), tracefs_synth_alloc(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |