This set of APIs can be used to get and check current ftrace
options. Supported ftrace options may depend on the kernel
version and the kernel configuration.
The tracefs_options_get_supported() function gets all ftrace
options supported by the system in the given instance. If
instance is NULL, supported options of the top trace instance are
returned. The set of supported options is the same in all created
trace instances, but may be different than the top trace
instance.
The *tracefs_option_is_supported()/ function checks if the option
with given id is supported by the system in the given instance.
If instance is NULL, the top trace instance is used. If an option
is supported at the top trace instance, it it may not be
supported in a created trace instance.
The tracefs_options_get_enabled() function gets all ftrace
options, currently enabled in the given instance. If instance is
NULL, enabled options of the top trace instance are returned.
The tracefs_option_is_enabled() function checks if the option
with given id is enabled in the given instance. If instance is
NULL, the top trace instance is used.
The tracefs_option_mask_is_set() function checks if the bit,
corresponding to the option with id is set in the options bitmask
returned from tracefs_option_get_enabled() and
tracefs_option_is_supported().
The tracefs_option_id() converts an option name into its
corresponding id, if it is found. This allows to find the option
id to use in the other functions if only the name is known.
ЗНАЧЕНИЕ ВОЗВРАТА
The tracefs_options_get_supported() and
tracefs_options_get_enabled() functions, on success, return a
pointer to the bitmask within the instance, or a global bitmask
for the top level, or NULL in case of an error. As the returned
bitmask is part of the instance structure (or a global variable)
and must not be freed or modified.
The tracefs_option_is_supported() and tracefs_option_is_enabled()
functions return true if the option in supported / enabled, or
false otherwise.
The tracefs_option_mask_is_set() returns true if the
corresponding option is set in the mask or false otherwise.
The tracefs_option_id() returns the corresponding id defined by
tracefs_options(3) from the given name. If the name can not be
found, then TRACEFS_OPTION_INVALID is returned.
ПРИМЕР
#include <tracefs.h>
...
const struct tracefs_options_mask *options;
...
options = tracefs_options_get_supported(NULL);
if (!options) {
/* Failed to get supported options */
} else {
...
}
...
options = tracefs_options_get_enabled(NULL);
if (!options) {
/* Failed to get options, enabled in the top instance */
} else {
...
}
if (tracefs_options_mask_is_set(options, TRACEFS_OPTION_LATENCY_FORMAT)) {
...
}
...
if (tracefs_option_is_supported(NULL, TRACEFS_OPTION_LATENCY_FORMAT)) {
/* Latency format option is supprted */
}
...
if (tracefs_option_is_enabled(NULL, TRACEFS_OPTION_STACKTRACE)) {
/* Stacktrace option is enabled in the top instance */
}
ФАЙЛЫ
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.
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 man-pages@man7.org
libtracefs 1.7.0 12/22/2023 LIBTRACEFS(3)
