149 lines
4.7 KiB
Plaintext
149 lines
4.7 KiB
Plaintext
libtracefs(3)
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=============
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NAME
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----
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tracefs_local_events, tracefs_local_events_system, tracefs_fill_local_events,
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tracefs_load_cmdlines -
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Initialize a tep handler with trace events from the local system.
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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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struct tep_handle pass:[*]*tracefs_local_events*(const char pass:[*]_tracing_dir_);
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struct tep_handle pass:[*]*tracefs_local_events_system*(const char pass:[*]_tracing_dir_, const char pass:[*] const pass:[*]_sys_names_);
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int *tracefs_fill_local_events*(const char pass:[*]_tracing_dir_, struct tep_handle pass:[*]_tep_, int pass:[*]_parsing_failures_);
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int *tracefs_load_cmdlines*(const char pass:[*]_tracing_dir_, struct tep_handle pass:[*]_tep_);
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--
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DESCRIPTION
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-----------
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Functions for initializing a tep handler with trace events from the local system.
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The *tracefs_local_events()* function allocates a new _tep_ handler and
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initializes it with events from all trace systems, located in the given
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_tracing_dir_ directory. This could be NULL or the location of the tracefs
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mount point for the trace systems of the local machine, or it may be a path
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to a copy of the tracefs directory from another machine.
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The *tracefs_local_events_system()* function allocates a new _tep_ handler
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and initializes it with events from specified trace systems _sys_names_,
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located in the given _tracing_dir_ directory. This could be NULL or the
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location of the tracefs mount point for the trace systems of the local
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machine, or it may be a path to a copy of the tracefs directory from another
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machine. The _sys_names_ argument is an array of trace system names, that
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will be used for _tep_ handler initialization. The last element in that
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array must be a NULL pointer.
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The *tracefs_fill_local_events()* function initializes already allocated _tep_
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handler with events from all trace systems, located in the given _tracing_dir_
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directory. This could be NULL or the location of the tracefs mount point
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for the trace systems of the local machine, or it may be a path to a copy
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of the tracefs directory from another machine. The _tep_ argument must be
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a pointer to already allocated tep handler, that is going to be initialized.
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The _parsing_failures_ argument could be NULL or a pointer to an integer,
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where the number of failures while parsing the event files are returned.
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The above functions will also load the mappings between pids and the process
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command line names. In some cases the _tep_ handle is created with one
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of the above before tracing begins. As the mappings get updated during the
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trace, there may be a need to read the mappings again after the trace.
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The *tracefs_load_cmdlines()* does just that. The _tracing_dir_ is
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the directory of the mount point to load from, or NULL to use the
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mount point of the tracefs file system.
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RETURN VALUE
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------------
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The *tracefs_local_events()* and *tracefs_local_events_system()* functions
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return pointer to allocated and initialized _tep_ handler, or NULL in
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case of an error. The returned _tep_ handler must be freed with *tep_free*(3).
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The *tracefs_fill_local_events()* function returns -1 in case of an error or
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0 otherwise.
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The *tracefs_load_cmdlines()* function returns -1 in case of an error, or
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0 otherwise.
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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 tep_handle *tep;
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...
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tep = tracefs_local_events(NULL);
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if (!tep) {
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/* Failed to initialise tep handler with local events from top instance */
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...
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}
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...
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tep_free(tep);
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...
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const char *systems[] = {"ftrace", "irq", NULL};
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tep = tracefs_local_events_system(NULL, systems);
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if (!tep) {
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/* Failed to initialise tep handler with local events from
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* ftrace and irq systems in top instance.
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*/
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...
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}
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...
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tep_free(tep);
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...
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int parsing_failures;
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tep = tep_alloc();
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if (!tep) {
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/* Failed to allocate a tep handler */
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...
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}
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if (tracefs_fill_local_events(NULL, tep, &parsing_failures) < 0) {
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/* Failed to initialise tep handler with local events from top instance */
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}
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tracefs_load_cmdlines(NULL, tep);
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...
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tep_free(tep);
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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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