142 lines
4.3 KiB
Plaintext
142 lines
4.3 KiB
Plaintext
libtracefs(3)
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=============
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NAME
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----
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tracefs_instance_get_name, tracefs_instance_get_trace_dir, tracefs_instances_walk, tracefs_instance_exists,
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tracefs_instance_get_buffer_size, tracefs_instance_set_buffer_size - Helper functions for working with tracing instances.
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SYNOPSIS
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--------
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[verse]
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--
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*#include <tracefs.h>*
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const char pass:[*]*tracefs_instance_get_name*(struct tracefs_instance pass:[*]_instance_);
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const char pass:[*]*tracefs_instance_get_trace_dir*(struct tracefs_instance pass:[*]_instance_);
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int *tracefs_instances_walk*(int (pass:[*]_callback_)(const char pass:[*], void pass:[*]), void pass:[*]_context)_;
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bool *tracefs_instance_exists*(const char pass:[*]_name_);
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size_t *tracefs_instance_get_buffer_size*(struct tracefs_instance pass:[*]_instance_, int _cpu_);
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int *tracefs_instance_set_buffer_size*(struct tracefs_instance pass:[*]_instance_, size_t _size_, int _cpu_);
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--
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DESCRIPTION
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-----------
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Helper functions for working with trace instances.
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The *tracefs_instance_get_name()* function returns the name of the given _instance_.
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Note that the top instance has no name, the function returns NULL for it.
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The *tracefs_instance_get_trace_dir()* function returns the tracing directory, where
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the given _instance_ is configured.
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The *tracefs_instances_walk()* function walks through all configured tracing
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instances in the system and calls _callback_ for each one of them. The _context_
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argument is passed to the _callback_, together with the instance name. If the
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_callback_ returns non-zero, the iteration stops. Note, the _callback_ is not
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called for the top top instance.
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The *tracefs_instance_exists()* function checks if an instance with the given
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_name_ exists in the system.
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The *tracefs_instace_get_buffer_size()* returns the size of the ring buffer. If _cpu_
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is negative, it returns the total size of all the per CPU ring buffers, otherwise
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it returns the size of the per CPU ring buffer for _cpu_.
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The *tracefs_instance_set_buffer_size()* function sets the size of the ring buffer.
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If _cpu_ is negative, then it sets all the per CPU ring buffers to _size_ (note
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the total size is the number of CPUs * _size_). If _cpu_ is specified, then it only
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sets the size of the per CPU ring buffer.
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RETURN VALUE
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------------
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The *tracefs_instance_get_name()* returns a string or NULL in case of the top
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instance. The returned string must _not_ be freed.
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The *tracefs_instance_get_trace_dir()* returns a string or NULL in case of an error.
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The returned string must _not_ be freed.
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The *tracefs_instances_walk()* function returns 0, if all instances were iterated, 1
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if the iteration was stopped by the _callback_, or -1 in case of an error.
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The *tracefs_instance_exists()* returns true if an instance with the given _name_
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exists in the system or false otherwise.
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The *tracefs_instance_get_buffer_size()* returns the size of the ring buffer depending on
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the _cpu_ value passed in, or -1 on error.
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The *tracefs_instance_set_buffer_size()* returns zero on success and -1 on error.
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EXAMPLE
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-------
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[source,c]
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--
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#include <tracefs.h>
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struct tracefs_instance *inst;
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....
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char *name = tracefs_instance_get_name(inst);
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if(name) {
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/* Got name of the instance */
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}
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char *dir = tracefs_instance_get_trace_dir(inst);
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if(dir) {
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/* Got tracing directory of the instance */
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}
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...
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static int instance_walk(char *name, void *context)
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{
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/* Got instance with name */
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return 0;
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}
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...
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if (tracefs_instances_walk(instance_walk, NULL) < 0) {
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/* Error walking through the instances */
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}
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...
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if (tracefs_instance_exists("foo")) {
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/* There is instance with name foo in the system */
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} else {
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/* There is no instance with name foo in the system */
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}
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--
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FILES
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-----
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[verse]
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--
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*tracefs.h*
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Header file to include in order to have access to the library APIs.
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*-ltracefs*
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Linker switch to add when building a program that uses the library.
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--
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SEE ALSO
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--------
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*libtracefs*(3),
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*libtraceevent*(3),
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*trace-cmd*(1)
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AUTHOR
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------
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[verse]
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--
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*Steven Rostedt* <rostedt@goodmis.org>
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*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>
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--
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REPORTING BUGS
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--------------
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Report bugs to <linux-trace-devel@vger.kernel.org>
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LICENSE
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-------
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libtracefs is Free Software licensed under the GNU LGPL 2.1
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RESOURCES
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---------
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https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
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COPYING
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-------
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Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under
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the terms of the GNU Public License (GPL).
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