Provided by: libtracefs-doc_1.4.2-1_all 
NAME
tracefs_hist_start, tracefs_hist_destroy, tracefs_hist_pause, tracefs_hist_continue,
tracefs_hist_reset - Pause, continue, or clear an existing histogram
SYNOPSIS
#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);
DESCRIPTION
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.
RETURN VALUE
All the return zero on success or -1 on error.
EXAMPLE
#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);
}
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), 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)
AUTHOR
Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
sameeruddin shaik <sameeruddin.shaik8@gmail.com[3]>
REPORTING BUGS
Report bugs to <linux-trace-devel@vger.kernel.org[4]>
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
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