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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | COPYING | NOTES | COLOPHON |
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LIBTRACEFS(3) libtracefs Manual LIBTRACEFS(3)
tracefs_filter_pid_function, tracefs_filter_pid_events,
tracefs_filter_pid_function_clear, tracefs_filter_pid_events_clear
- Add and remove PID filtering for functions and events
#include <tracefs.h>
int tracefs_filter_pid_function(struct tracefs_instance *instance, int pid,
bool reset, bool notrace);
int tracefs_filter_pid_function_clear(struct tracefs_instance *instance, bool notrace);
int tracefs_filter_pid_events(struct tracefs_instance *instance, int pid,
bool reset, bool notrace);
int tracefs_filter_pid_events_clear(struct tracefs_instance *instance, bool notrace);
Both events and functions can be filtered by PID, but they are
done separately. PID filtering for functions affect the function
and function_graph tracer, where as PID filtering for events
affect all events such as sched_switch and sched_waking. If the
TRACEFS_OPTION_FUNCTION_FORK is enabled (see
tracefs_option_enable(3)), any PID that is set as part of the
function PID filtering will automatically have its children added
when they are spawned, as well as the PID removed when they exit.
If the TRACEFS_OPTION_EVENT_FORK is set, the same is true for
event PID filtering. This also includes the notrace option where
the child threads and processes of PIDs that are labled as notrace
will also not be traced.
The tracefs_filter_pid_function() affects function PID filtering
and tracefs_filter_pid_events() affects the PID event filtering.
For both functions, they add a pid to be filtered in the given
instance. If reset is true, then any PIDs already being filtered
will be removed, otherwise the pid is simply added to the
filtering. If notrace is true, then the PID is added to the list
of PIDs that are not to be traced. Note, that reset only affects
the list associated with notrace. That is, if both reset and
notrace are true, then it will not affect PIDs that are to be
traced. Same is if reset is true and notrace is false, it will not
affect PIDs that are not to be traced.
The tracefs_filter_pid_function_clear() affects function PID
filtering and tracefs_filter_pid_events_clear() affects the PID
event filtering. For both functions it will clear all the PIDs
that are being filtered for the given filter. If notrace is true
it clears all the PIDs that are not to be traced otherwise if it
is false, it clears all the PIDs that are to be traced.
All the functions return 0 on success and -1 on error.
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <tracefs.h>
static void usage(char **argv)
{
fprintf(stderr, "usage: %s [-e|-f][-c|-n] pid [pid ...]\n", argv[0]);
fprintf(stderr, " -e enable event filter\n");
fprintf(stderr, " -f enable function filter\n");
fprintf(stderr, " (default is both, function and event)\n");
fprintf(stderr, " -c clear the filter\n");
fprintf(stderr, " -n notrace filter\n");
exit(-1);
}
int main (int argc, char **argv)
{
bool events = false;
bool funcs = false;
bool neg = false;
bool clear = false;
bool reset = true;
int i;
for (i = 1; i < argc && argv[i][0] == '-'; i++) {
char *arg = argv[i];
int c;
for (c = 1; arg[c]; c++) {
switch (arg[c]) {
case 'e': events = true; break;
case 'f': funcs = true; break;
case 'n': neg = true; break;
case 'c': clear = true; break;
default:
usage(argv);
}
}
if (c == 1)
usage(argv);
}
if (i == argc && !clear)
usage(argv);
if (!events && !funcs) {
events = true;
funcs = true;
}
if (clear) {
if (events)
tracefs_filter_pid_events_clear(NULL, neg);
if (funcs)
tracefs_filter_pid_function_clear(NULL, neg);
exit(0);
}
for (; i < argc; i++) {
int pid = atoi(argv[i]);
if (events)
tracefs_filter_pid_events(NULL, pid, reset, neg);
if (funcs)
tracefs_filter_pid_function(NULL, pid, reset, neg);
reset = false;
}
exit(0);
}
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.
libtracefs(3), libtraceevent(3), trace-cmd(1),
tracefs_hist_alloc(3), tracefs_hist_alloc_2d(3),
tracefs_hist_alloc_nd(3), tracefs_hist_free(3),
tracefs_hist_add_key(3), tracefs_hist_add_value(3),
tracefs_hist_add_name(3), tracefs_hist_start(3),
tracefs_hist_destory(3), tracefs_hist_add_sort_key(3),
tracefs_hist_sort_key_direction(3)
Steven Rostedt <rostedt@goodmis.org[1]>
Report bugs to <linux-trace-devel@vger.kernel.org[2]>
libtracefs is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Copyright (C) 2023 Google, LLC. Free use of this software is
granted under the terms of the GNU Public License (GPL).
1. rostedt@goodmis.org
mailto:rostedt@goodmis.org
2. linux-trace-devel@vger.kernel.org
mailto:linux-trace-devel@vger.kernel.org
This page is part of the libtracefs (Linux kernel trace file
system library) project. Information about the project can be
found at ⟨https://www.trace-cmd.org/⟩. If you have a bug report
for this manual page, see ⟨https://www.trace-cmd.org/⟩. This page
was obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-06-02.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
libtracefs 1.8.1 01/02/2025 LIBTRACEFS(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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