| libtracefs(3) |
| ============= |
| |
| NAME |
| ---- |
| 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 |
| -------- |
| [verse] |
| -- |
| *#include <tracefs.h>* |
| |
| const char pass:[*]*tracefs_instance_get_name*(struct tracefs_instance pass:[*]_instance_); |
| const char pass:[*]*tracefs_instance_get_trace_dir*(struct tracefs_instance pass:[*]_instance_); |
| int *tracefs_instances_walk*(int (pass:[*]_callback_)(const char pass:[*], void pass:[*]), void pass:[*]_context)_; |
| bool *tracefs_instance_exists*(const char pass:[*]_name_); |
| size_t *tracefs_instance_get_buffer_size*(struct tracefs_instance pass:[*]_instance_, int _cpu_); |
| int *tracefs_instance_set_buffer_size*(struct tracefs_instance pass:[*]_instance_, size_t _size_, int _cpu_); |
| -- |
| |
| DESCRIPTION |
| ----------- |
| 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 |
| ------------ |
| 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 |
| ------- |
| [source,c] |
| -- |
| #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 |
| ----- |
| [verse] |
| -- |
| *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 |
| -------- |
| *libtracefs*(3), |
| *libtraceevent*(3), |
| *trace-cmd*(1) |
| |
| AUTHOR |
| ------ |
| [verse] |
| -- |
| *Steven Rostedt* <rostedt@goodmis.org> |
| *Tzvetomir Stoyanov* <tz.stoyanov@gmail.com> |
| -- |
| REPORTING BUGS |
| -------------- |
| Report bugs to <linux-trace-devel@vger.kernel.org> |
| |
| LICENSE |
| ------- |
| libtracefs is Free Software licensed under the GNU LGPL 2.1 |
| |
| RESOURCES |
| --------- |
| https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ |
| |
| COPYING |
| ------- |
| Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under |
| the terms of the GNU Public License (GPL). |
