NAME¶

tracefs_local_events, tracefs_local_events_system, tracefs_fill_local_events - Initialize a tep handler with trace events from the local system.

SYNOPSIS¶

#include <tracefs.h>
struct tep_handle *tracefs_local_events(const char *tracing_dir);
struct tep_handle *tracefs_local_events_system(const char *tracing_dir, const char * const *sys_names);
int tracefs_fill_local_events(const char *tracing_dir, struct tep_handle *tep, int *parsing_failures);

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.

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.

EXAMPLE¶

#include <tracefs.h>
struct tep_event *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 */


        }
...


        tep_free(tep);

FILES¶

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¶

Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>

REPORTING BUGS¶

Report bugs to <linux-trace-devel@vger.kernel.org[3]>

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).

NOTES¶

1.

rostedt@goodmis.org

2.

tz.stoyanov@gmail.com

3.

linux-trace-devel@vger.kernel.org