Install Now
tracefs_hist_start, tracefs_hist_destroy, tracefs_hist_pause, tracefs_hist_continue, tracefs_hist_reset -
Contents
Copying
Copyright (C) 2020 VMware, Inc. Free use of this software is granted under the terms of the GNU Public
License (GPL).
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.
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.
License
libtracefs is Free Software licensed under the GNU LGPL 2.1
Name
tracefs_hist_start, tracefs_hist_destroy, tracefs_hist_pause, tracefs_hist_continue, tracefs_hist_reset -
Pause, continue, or clear an existing histogram
Notes
Reporting Bugs
Report bugs to <linux-trace-devel@vger.kernel.org[4]>
Resources
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Return Value
All the return zero on success or -1 on error.
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)
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);
PNG Icons