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| -rw-r--r-- | Documentation/libtracefs-events-tep.txt | 148 |
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diff --git a/Documentation/libtracefs-events-tep.txt b/Documentation/libtracefs-events-tep.txt new file mode 100644 index 0000000..22d3dd5 --- /dev/null +++ b/Documentation/libtracefs-events-tep.txt @@ -0,0 +1,148 @@ +libtracefs(3) +============= + +NAME +---- +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 +-------- +[verse] +-- +*#include <tracefs.h>* + +struct tep_handle pass:[*]*tracefs_local_events*(const char pass:[*]_tracing_dir_); +struct tep_handle pass:[*]*tracefs_local_events_system*(const char pass:[*]_tracing_dir_, const char pass:[*] const pass:[*]_sys_names_); +int *tracefs_fill_local_events*(const char pass:[*]_tracing_dir_, struct tep_handle pass:[*]_tep_, int pass:[*]_parsing_failures_); +int *tracefs_load_cmdlines*(const char pass:[*]_tracing_dir_, struct tep_handle pass:[*]_tep_); +-- + +DESCRIPTION +----------- +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 +------------ +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 +------- +[source,c] +-- +#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 +----- +[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). |