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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_trace_is_on, tracefs_trace_on, tracefs_trace_off,
tracefs_trace_on_get_fd, tracefs_trace_on_fd,
tracefs_trace_off_fd - Functions to enable or disable tracing.
#include <tracefs.h>
int tracefs_trace_is_on(struct tracefs_instance *instance);
int tracefs_trace_on(struct tracefs_instance *instance);
int tracefs_trace_off(struct tracefs_instance *instance);
int tracefs_trace_on_get_fd(struct tracefs_instance *instance);
int tracefs_trace_on_fd(int fd);
int tracefs_trace_off_fd(int fd);
This set of functions can be used to check, enable or disable
writing to the ring buffer in the given trace instance. The
tracing is enabled when writing to the ring buffer is enabled.
The tracefs_trace_is_on() function checks if tracing is enabled
for the given instance. If instance is NULL, the top instance is
used.
The tracefs_trace_on() and tracefs_trace_off() functions set the
tracing in the instance to enable or disable state. If instance
is NULL, the top instance is used.
The tracefs_trace_on_get_fd() function returns a file descriptor
to the "tracing_on" file from the given instance. If instance is
NULL, the top trace instance is used. The returned descriptor can
be used for fast enabling or disabling the tracing of the
instance.
The tracefs_trace_on_fd() and tracefs_trace_off_fd() functions
set the tracing state to enable or disable using the given fd.
This file descriptor must be opened for writing with
tracefs_trace_on_get_fd(3) of the desired trace instance. These
functions are faster than tracefs_trace_on and tracefs_trace_off.
The tracefs_trace_is_on() function returns 0 if tracing is
disable, 1 if it is enabled or -1 in case of an error.
The tracefs_trace_on_get_fd() function returns a file descriptor
to "tracing_on" file for reading and writing, which must be
closed wuth close(). In case of an error -1 is returned.
The tracefs_trace_on(), tracefs_trace_off(),
tracefs_trace_on_fd() and tracefs_trace_off_fd() functions return
-1 in case of an error or 0 otherwise.
#include <tracefs.h>
int ret;
ret = tracefs_trace_is_on(NULL);
if (ret == 0) {
/* Tracing is disabled in the top instance */
} else if (ret == 1) {
/* Tracing is enabled in the top instance */
} else {
/* Error getting tracing state of the top instance */
}
...
if (!tracefs_trace_on(NULL)) {
/* Enabled tracing in the top instance */
...
if (!tracefs_trace_off(NULL)) {
/* Disabled tracing in the top instance */
} else {
/* Error disabling tracing in the top instance */
}
} else {
/* Error enabling tracing in the top instance */
}
...
int fd = tracefs_trace_on_get_fd(NULL);
if (fd < 0) {
/* Error opening tracing_on file */
}
...
if (!tracefs_trace_on_fd(fd)) {
/* Enabled tracing in the top instance */
...
if (!tracefs_trace_off_fd(fd)) {
/* Disabled tracing in the top instance */
} else {
/* Error disabling tracing in the top instance */
}
} else {
/* Error enabling tracing in the top instance */
}
...
close(fd);
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)
Steven Rostedt <[email protected][1]>
Tzvetomir Stoyanov <[email protected][2]>
Report bugs to <[email protected][3]>
libtracefs is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Copyright (C) 2021 VMware, Inc. Free use of this software is
granted under the terms of the GNU Public License (GPL).
1. [email protected]
mailto:[email protected]
2. [email protected]
mailto:[email protected]
3. [email protected]
mailto:[email protected]
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
2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2024-05-17.) 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 [email protected]
libtracefs 1.7.0 12/22/2023 LIBTRACEFS(3)
Pages that refer to this page: tracefs_trace_is_on(3)
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HTML rendering created 2024-06-26 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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