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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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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_hist_start, tracefs_hist_destroy, tracefs_hist_pause,
tracefs_hist_continue, tracefs_hist_reset - Pause, continue, or
clear an existing histogram
#include <tracefs.h>
int tracefs_hist_start(struct tracefs_instance *instance, struct tracefs_hist *hist);
int tracefs_hist_destroy(struct tracefs_instance *instance, struct tracefs_hist *hist);
int tracefs_hist_pause(struct tracefs_instance *instance, struct tracefs_hist *hist);
int tracefs_hist_continue(struct tracefs_instance *instance, struct tracefs_hist *hist);
int tracefs_hist_reset(struct tracefs_instance *instance, struct tracefs_hist *hist);
tracefs_hist_start() is called to actually start the histogram
hist. The instance is the instance to start the histogram in, NULL
if it should start at the top level.
tracefs_hist_pause() is called to pause the histogram hist. The
instance is the instance to pause the histogram in, NULL if it is
in the top level.
tracefs_hist_continue() is called to continue a paused histogram
hist. The instance is the instance to continue the histogram, NULL
if it is in the top level.
tracefs_hist_reset() is called to clear / reset the histogram
hist. The instance is the instance to clear the histogram, NULL if
it is in the top level.
tracefs_hist_destroy() is called to delete the histogram where it
will no longer exist. The instance is the instance to delete the
histogram from, NULL if it is in the top level.
All the return zero on success or -1 on error.
#include <stdlib.h>
#include <tracefs.h>
enum commands {
START,
PAUSE,
CONT,
RESET,
DELETE,
SHOW,
};
int main (int argc, char **argv, char **env)
{
struct tracefs_instance *instance;
struct tracefs_hist *hist;
struct tep_handle *tep;
enum commands cmd;
char *cmd_str;
int ret;
if (argc < 2) {
fprintf(stderr, "usage: %s command\n", argv[0]);
exit(-1);
}
cmd_str = argv[1];
if (!strcmp(cmd_str, "start"))
cmd = START;
else if (!strcmp(cmd_str, "pause"))
cmd = PAUSE;
else if (!strcmp(cmd_str, "cont"))
cmd = CONT;
else if (!strcmp(cmd_str, "reset"))
cmd = RESET;
else if (!strcmp(cmd_str, "delete"))
cmd = DELETE;
else if (!strcmp(cmd_str, "show"))
cmd = SHOW;
else {
fprintf(stderr, "Unknown command %s\n", cmd_str);
exit(-1);
}
tep = tracefs_local_events(NULL);
if (!tep) {
perror("Reading tracefs");
exit(-1);
}
instance = tracefs_instance_create("hist_test");
if (!instance) {
fprintf(stderr, "Failed instance create\n");
exit(-1);
}
hist = tracefs_hist_alloc_2d(tep, "kmem", "kmalloc",
"call_site",TRACEFS_HIST_KEY_SYM,
"bytes_req", 0);
if (!hist) {
fprintf(stderr, "Failed hist create\n");
exit(-1);
}
ret = tracefs_hist_add_value(hist, "bytes_alloc");
ret |= tracefs_hist_add_sort_key(hist, "bytes_req");
ret |= tracefs_hist_add_sort_key(hist, "bytes_alloc");
ret |= tracefs_hist_sort_key_direction(hist, "bytes_alloc",
TRACEFS_HIST_SORT_DESCENDING);
if (ret) {
fprintf(stderr, "Failed modifying histogram\n");
exit(-1);
}
tracefs_error_clear(instance);
switch (cmd) {
case START:
ret = tracefs_hist_start(instance, hist);
if (ret) {
char *err = tracefs_error_last(instance);
if (err)
fprintf(stderr, "\n%s\n", err);
}
break;
case PAUSE:
ret = tracefs_hist_pause(instance, hist);
break;
case CONT:
ret = tracefs_hist_continue(instance, hist);
break;
case RESET:
ret = tracefs_hist_reset(instance, hist);
break;
case DELETE:
ret = tracefs_hist_destroy(instance, hist);
break;
case SHOW: {
char *content;
content = tracefs_event_file_read(instance, "kmem", "kmalloc",
"hist", NULL);
ret = content ? 0 : -1;
if (content) {
printf("%s\n", content);
free(content);
}
break;
}
}
if (ret)
fprintf(stderr, "Failed: command\n");
exit(ret);
}
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]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
sameeruddin shaik <sameeruddin.shaik8@gmail.com[3]>
Report bugs to <linux-trace-devel@vger.kernel.org[4]>
libtracefs is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Copyright (C) 2020 VMware, Inc. 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. tz.stoyanov@gmail.com
mailto:tz.stoyanov@gmail.com
3. sameeruddin.shaik8@gmail.com
mailto:sameeruddin.shaik8@gmail.com
4. 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 1.7.0 12/22/2023 LIBTRACEFS(3)
Pages that refer to this page: tracefs_filter_pid_function(3), tracefs_filter_string_append(3), tracefs_hist_add_sort_key(3), tracefs_hist_alloc(3), tracefs_hist_start(3), tracefs_sql(3), tracefs_synth_alloc(3), tracefs_synth_create(3), tracefs_synth_echo_cmd(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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