tracefs_local_events(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | COPYING | NOTES | COLOPHON

LIBTRACEFS(3)               libtracefs Manual              LIBTRACEFS(3)

NAME         top

       tracefs_local_events, tracefs_local_events_system,
       tracefs_fill_local_events, tracefs_load_cmdlines - Initialize a
       tep handler with trace events from the local system.

SYNOPSIS         top

       #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);
       int tracefs_fill_local_events(const char *tracing_dir, struct tep_handle *tep, int *parsing_failures);
       int tracefs_load_cmdlines(const char *tracing_dir, struct tep_handle *tep);

DESCRIPTION         top

       Functions for initializing a tep handler with trace events from
       the local system.

       The tracefs_local_events() function allocates a new tep handler
       and initializes it with events from all trace systems, located in
       the given tracing_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.

       The tracefs_local_events_system() function allocates a new tep
       handler and initializes it with events from specified trace
       systems sys_names, located in the given tracing_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. The sys_names
       argument is an array of trace system names, that will be used for
       tep handler initialization. The last element in that array must
       be a NULL pointer.

       The tracefs_fill_local_events() function initializes already
       allocated tep handler with events from all trace systems, located
       in the given tracing_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. The tep argument must be a
       pointer to already allocated tep handler, that is going to be
       initialized. The parsing_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 the tep 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. The
       tracefs_load_cmdlines() does just that. The tracing_dir is the
       directory of the mount point to load from, or NULL to use the
       mount point of the tracefs file system.

RETURN VALUE         top

       The tracefs_local_events() and tracefs_local_events_system()
       functions return pointer to allocated and initialized tep
       handler, or NULL in case of an error. The returned tep handler
       must be freed with tep_free(3).

       The tracefs_fill_local_events() function returns -1 in case of an
       error or 0 otherwise.

       The tracefs_load_cmdlines() function returns -1 in case of an
       error, or 0 otherwise.

EXAMPLE         top

           #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);

FILES         top

           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.

SEE ALSO         top

       libtracefs(3), libtraceevent(3), trace-cmd(1)

AUTHOR         top

           Steven Rostedt <rostedt@goodmis.org[1]>
           Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>

REPORTING BUGS         top

       Report bugs to <linux-trace-devel@vger.kernel.org[3]>

LICENSE         top

       libtracefs is Free Software licensed under the GNU LGPL 2.1

RESOURCES         top

       https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ 

COPYING         top

       Copyright (C) 2020 VMware, Inc. Free use of this software is
       granted under the terms of the GNU Public License (GPL).

NOTES         top

        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

COLOPHON         top

       This page is part of the libtracefs (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
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-05-17.)  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 is not part of the original
       manual page), send a mail to man-pages@man7.org

libtracefs 1.7.0               12/22/2023                  LIBTRACEFS(3)

Pages that refer to this page: tracefs_hist_alloc(3)tracefs_iterate_raw_events(3)tracefs_synth_alloc(3)