LIBTRACEFS(3)

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