tracefs_instance_get_name(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_instance_get_name, tracefs_instance_get_trace_dir,
       tracefs_instances_walk, tracefs_instance_exists,
       tracefs_instance_get_buffer_size,
       tracefs_instance_set_buffer_size - Helper functions for working
       with tracing instances.

SYNOPSIS         top

       #include <tracefs.h>

       const char *tracefs_instance_get_name(struct tracefs_instance *instance);
       const char *tracefs_instance_get_trace_dir(struct tracefs_instance *instance);
       int tracefs_instances_walk(int (*callback)(const char *, void *), void *context);
       bool tracefs_instance_exists(const char *name);
       size_t tracefs_instance_get_buffer_size(struct tracefs_instance *instance, int cpu);
       int tracefs_instance_set_buffer_size(struct tracefs_instance *instance, size_t size, int cpu);

DESCRIPTION         top

       Helper functions for working with trace instances.

       The tracefs_instance_get_name() function returns the name of the
       given instance. Note that the top instance has no name, the
       function returns NULL for it.

       The tracefs_instance_get_trace_dir() function returns the tracing
       directory, where the given instance is configured.

       The tracefs_instances_walk() function walks through all
       configured tracing instances in the system and calls callback for
       each one of them. The context argument is passed to the callback,
       together with the instance name. If the callback returns
       non-zero, the iteration stops. Note, the callback is not called
       for the top top instance.

       The tracefs_instance_exists() function checks if an instance with
       the given name exists in the system.

       The tracefs_instace_get_buffer_size() returns the size of the
       ring buffer. If cpu is negative, it returns the total size of all
       the per CPU ring buffers, otherwise it returns the size of the
       per CPU ring buffer for cpu.

       The tracefs_instance_set_buffer_size() function sets the size of
       the ring buffer. If cpu is negative, then it sets all the per CPU
       ring buffers to size (note the total size is the number of CPUs *
       size). If cpu is specified, then it only sets the size of the per
       CPU ring buffer.

RETURN VALUE         top

       The tracefs_instance_get_name() returns a string or NULL in case
       of the top instance. The returned string must not be freed.

       The tracefs_instance_get_trace_dir() returns a string or NULL in
       case of an error. The returned string must not be freed.

       The tracefs_instances_walk() function returns 0, if all instances
       were iterated, 1 if the iteration was stopped by the callback, or
       -1 in case of an error.

       The tracefs_instance_exists() returns true if an instance with
       the given name exists in the system or false otherwise.

       The tracefs_instance_get_buffer_size() returns the size of the
       ring buffer depending on the cpu value passed in, or -1 on error.

       The tracefs_instance_set_buffer_size() returns zero on success
       and -1 on error.

EXAMPLE         top

           #include <tracefs.h>

           struct tracefs_instance *inst;
           ....
           char *name = tracefs_instance_get_name(inst);
                   if(name) {
                           /* Got name of the instance */
                   }
           char *dir = tracefs_instance_get_trace_dir(inst);
                   if(dir) {
                           /* Got tracing directory of the instance */
                   }
           ...
           static int instance_walk(char *name, void *context)
           {
                   /* Got instance with name */
                   return 0;
           }
           ...
                   if (tracefs_instances_walk(instance_walk, NULL) < 0) {
                           /* Error walking through the instances */
                   }
           ...
                   if (tracefs_instance_exists("foo")) {
                           /* There is instance with name foo in the system */
                   } else {
                           /* There is no instance with name foo in the system */
                   }

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 <[email protected][1]>
           Tzvetomir Stoyanov <[email protected][2]>

REPORTING BUGS         top

       Report bugs to <[email protected][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. [email protected]
           mailto:[email protected]

        2. [email protected]
           mailto:[email protected]

        3. [email protected]
           mailto:[email protected]

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 [email protected]

libtracefs 1.7.0               12/22/2023                  LIBTRACEFS(3)