tracefs_hist_add_sort_key(3) — Linux manual page

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LIBTRACEFS(3)               libtracefs Manual              LIBTRACEFS(3)

NAME         top

       tracefs_hist_add_sort_key, tracefs_hist_set_sort_key,
       tracefs_hist_sort_key_direction, tracefs_hist_add_name,
       tracefs_hist_append_filter, tracefs_hist_echo_cmd,
       tracefs_hist_command, tracefs_hist_get_name,
       tracefs_hist_get_event, tracefs_hist_get_system - Update and
       describe an event histogram

SYNOPSIS         top

       #include <tracefs.h>

       int tracefs_hist_add_sort_key(struct tracefs_hist *hist,
                                     const char *sort_key);

       int tracefs_hist_set_sort_key(struct tracefs_hist *hist,
                                     const char *sort_key, ...);
       int tracefs_hist_sort_key_direction(struct tracefs_hist *hist,
                                           const char *sort_key,
                                           enum tracefs_hist_sort_direction dir);

       int tracefs_hist_add_name(struct tracefs_hist *hist, const char *name);

       int tracefs_hist_append_filter(struct tracefs_hist *hist,
                                      enum tracefs_filter type,
                                      const char *field,
                                      enum tracefs_compare compare,
                                      const char *val);

       int tracefs_hist_echo_cmd(struct trace_seq *s, struct tracefs_instance *instance,
                                 struct tracefs_hist *hist,
                                 enum tracefs_hist_command command);

       int tracefs_hist_command(struct tracefs_instance *instance,
                                struct tracefs_hist *hist,
                                enum tracefs_hist_command command);

       const char *tracefs_hist_get_name(struct tracefs_hist *hist);

       const char *tracefs_hist_get_event(struct tracefs_hist *hist);

       const char *tracefs_hist_get_system(struct tracefs_hist *hist);

DESCRIPTION         top

       Event histograms are created by the trigger file in the event
       directory. The syntax can be complex and difficult to get
       correct. This API handles the syntax, and facilitates the
       creation and interaction with the event histograms. See
       https://www.kernel.org/doc/html/latest/trace/histogram.html for
       more information.

       tracefs_hist_add_sort_key() will add a key to sort on. The hist
       is the histogram descriptor to add the sort key to. The sort_key
       is a string that must match either an already defined key of the
       histogram, or an already defined value. If hist already has
       sorting keys (previously added) the new sort_key will have lower
       priority(be secondary or so on) when sorting.

       tracefs_hist_set_sort_key() will reset the list of key to sort
       on. The hist is the histogram descriptor to reset the sort key
       to. The sort_key is a string that must match either an already
       defined key of the histogram, or an already defined value.
       Multiple sort keys may be added to denote a secondary, sort order
       and so on, but all sort keys must match an existing key or value,
       or be TRACEFS_HIST_HITCOUNT. The last parameter of
       tracefs_hist_add_sort_key() must be NULL.

       tracefs_hist_sort_key_direction() allows to change the direction
       of an existing sort key of hist. The sort_key is the sort key to
       change, and dir can be either TRACEFS_HIST_SORT_ASCENDING or
       TRACEFS_HIST_SORT_DESCENDING, to make the direction of the sort
       key either ascending or descending respectively.

       tracefs_hist_add_name() adds a name to a histogram. A histogram
       may be named and if the name matches between more than one event,
       and they have compatible keys, the multiple histograms with the
       same name will be merged into a single histogram (shown by either
       event’s hist file). The hist is the histogram to name, and the
       name is the name to give it.

       tracefs_hist_append_filter() creates a filter or appends to it
       for the histogram event. Depending on type, it will build a
       string of tokens for parenthesis or logic statements, or it may
       add a comparison of field to val based on compare.

       If type is: TRACEFS_FILTER_COMPARE - See below TRACEFS_FILTER_AND
       - Append "&&" to the filter TRACEFS_FILTER_OR - Append "||" to
       the filter TRACEFS_FILTER_NOT - Append "!" to the filter
       TRACEFS_FILTER_OPEN_PAREN - Append "(" to the filter
       TRACEFS_FILTER_CLOSE_PAREN - Append ")" to the filter

       field, compare, and val are ignored unless type is equal to
       TRACEFS_FILTER_COMPARE, then compare will be used for the
       following:

       TRACEFS_COMPARE_EQ - field == val

       TRACEFS_COMPARE_NE - field != val

       TRACEFS_COMPARE_GT - field > val

       TRACEFS_COMPARE_GE - field >= val

       TRACEFS_COMPARE_LT - field < val

       TRACEFS_COMPARE_LE - field <= val

       TRACEFS_COMPARE_RE - field ~ "val" : where field is a string.

       TRACEFS_COMPARE_AND - field & val : where field is a flags field.

       trace_hist_echo_cmd() prints the commands needed to create the
       given histogram in the given instance, or NULL for the top level,
       into the seq. The command that is printed is described by command
       and shows the functionality that would be done by
       tracefs_hist_command(3).

       tracefs_hist_command() is called to process a command on the
       histogram hist for its event in the given instance, or NULL for
       the top level. The cmd can be one of:

       TRACEFS_HIST_CMD_START or zero to start execution of the
       histogram.

       TRACEFS_HIST_CMD_PAUSE to pause the given histogram.

       TRACEFS_HIST_CMD_CONT to continue a paused histogram.

       TRACEFS_HIST_CMD_CLEAR to reset the values of a histogram.

       TRACEFS_HIST_CMD_DESTROY to destroy the histogram (undo a START).

       The below functions are wrappers to tracefs_hist_command() to
       make the calling conventions a bit easier to understand what is
       happening.

KEY TYPES         top

       tracefs_hist_alloc_nd() and tracefs_hist_add_key() both add a key
       and requires that key to have a type. The types may be:

       TRACEFS_HIST_KEY_NORMAL or zero (0) which is to not modify the
       type.

       TRACEFS_HIST_KEY_HEX to display the key in hex.

       TRACEFS_HIST_KEY_SYM to display the key as a kernel symbol (if
       found). If the key is an address, this is useful as it will
       display the function names instead of just a number.

       TRACEFS_HIST_KEY_SYM_OFFSET similar to TRACEFS_HIST_KEY_SYM but
       will also include the offset of the function to match the exact
       address.

       TRACEFS_HIST_KEY_SYSCALL If the key is a system call "id" (the
       number passed from user space to the kernel to tell it what
       system call it is calling), then the name of the system call is
       displayed.

       TRACEFS_HIST_KEY_EXECNAME If "common_pid" is the key (the pid of
       the executing task), instead of showing the number, show the name
       of the running task.

       TRACEFS_HIST_KEY_LOG will display the key in a binary logarithmic
       scale.

       TRACEFS_HIST_KEY_USECS for use with "common_timestamp" or
       TRACEFS_HIST_TIMESTAMP, in which case it will show the timestamp
       in microseconds instead of nanoseconds.

RETURN VALUE         top

       tracefs_hist_get_name() returns the name of the histogram or NULL
       on error. The returned string belongs to the histogram object and
       is freed with the histogram by tracefs_hist_free().

       tracefs_hist_get_event() returns the event name of the histogram
       or NULL on error. The returned string belongs to the histogram
       object and is freed with the histogram by tracefs_hist_free().

       tracefs_hist_get_system() returns the system name of the
       histogram or NULL on error. The returned string belongs to the
       histogram object and is freed with the histogram by
       tracefs_hist_free().

       tracefs_hist_alloc_nd() returns an allocated histogram descriptor
       which must be freed by tracefs_hist_free() or NULL on error.

       tracefs_hist_get_name(), tracefs_hist_get_event() and
       tracefs_hist_get_system() return strings owned by the histogram
       object.

       All the other functions return zero on success or -1 on error.

EXAMPLE         top

           #include <stdlib.h>
           #include <unistd.h>
           #include <tracefs.h>

           enum commands {
                   START,
                   PAUSE,
                   CONT,
                   RESET,
                   DELETE,
                   SHOW,
           };

           static void parse_system_event(char *group, char **system, char **event)
           {
                   *system = strtok(group, "/");
                   *event = strtok(NULL, "/");
                   if (!*event) {
                           *event = *system;
                           *system = NULL;
                   }
           }

           static int parse_keys(char *keys, struct tracefs_hist_axis **axes)
           {
                   char *sav = NULL;
                   char *key;
                   int cnt = 0;

                   for (key = strtok_r(keys, ",", &sav); key; key = strtok_r(NULL, ",", &sav)) {
                           struct tracefs_hist_axis *ax;
                           char *att;

                           ax = realloc(*axes, sizeof(*ax) * (cnt + 2));
                           if (!ax) {
                                   perror("Failed to allocate axes");
                                   exit(-1);
                           }
                           ax[cnt].key = key;
                           ax[cnt].type = 0;
                           ax[cnt + 1].key = NULL;
                           ax[cnt + 1].type = 0;

                           *axes = ax;

                           att = strchr(key, '.');
                           if (att) {
                                   *att++ = '\0';
                                   if (strcmp(att, "hex") == 0)
                                           ax[cnt].type = TRACEFS_HIST_KEY_HEX;
                                   else if (strcmp(att, "sym") == 0)
                                           ax[cnt].type = TRACEFS_HIST_KEY_SYM;
                                   else if (strcmp(att, "sym_offset") == 0)
                                           ax[cnt].type = TRACEFS_HIST_KEY_SYM_OFFSET;
                                   else if (strcmp(att, "syscall") == 0)
                                           ax[cnt].type = TRACEFS_HIST_KEY_SYSCALL;
                                   else if (strcmp(att, "exec") == 0)
                                           ax[cnt].type = TRACEFS_HIST_KEY_EXECNAME;
                                   else if (strcmp(att, "log") == 0)
                                           ax[cnt].type = TRACEFS_HIST_KEY_LOG;
                                   else if (strcmp(att, "usecs") == 0)
                                           ax[cnt].type = TRACEFS_HIST_KEY_USECS;
                                   else {
                                           fprintf(stderr, "Undefined attribute '%s'\n", att);
                                           fprintf(stderr,"  Acceptable attributes:\n");
                                           fprintf(stderr,"    hex, sym, sym_offset, syscall, exe, log, usecs\n");
                                           exit(-1);
                                   }
                           }
                           cnt++;
                   }
                   return cnt;
           }

           static void process_hist(enum commands cmd, const char *instance_name,
                                    char *group, char *keys, char *vals, char *sort,
                                    char *ascend, char *desc)
           {
                   struct tracefs_instance *instance = NULL;
                   struct tracefs_hist *hist;
                   struct tep_handle *tep;
                   struct tracefs_hist_axis *axes = NULL;
                   char *system;
                   char *event;
                   char *sav;
                   char *val;
                   int ret;
                   int cnt;

                   if (instance_name) {
                           instance = tracefs_instance_create(instance_name);
                           if (!instance) {
                                   fprintf(stderr, "Failed instance create\n");
                                   exit(-1);
                           }
                   }

                   tep = tracefs_local_events(NULL);
                   if (!tep) {
                           perror("Could not read events");
                           exit(-1);
                   }

                   parse_system_event(group, &system, &event);

                   if (cmd == SHOW) {
                           char *content;
                           content = tracefs_event_file_read(instance, system, event,
                                                             "hist", NULL);
                           if (!content) {
                                   perror("Reading hist file");
                                   exit(-1);
                           }
                           printf("%s\n", content);
                           free(content);
                           return;
                   }

                   if (!keys) {
                           fprintf(stderr, "Command needs -k option\n");
                           exit(-1);
                   }

                   cnt = parse_keys(keys, &axes);
                   if (!cnt) {
                           fprintf(stderr, "No keys??\n");
                           exit(-1);
                   }

                   /* Show examples of hist1d and hist2d */
                   switch (cnt) {
                   case 1:
                           hist = tracefs_hist_alloc(tep, system, event,
                                                     axes[0].key, axes[0].type);
                           break;
                   case 2:
                           hist = tracefs_hist_alloc_2d(tep, system, event,
                                                        axes[0].key, axes[0].type,
                                                        axes[1].key, axes[1].type);
                           break;
                   default:
                           /* Really, 1 and 2 could use this too */
                           hist = tracefs_hist_alloc_nd(tep, system, event, axes);
                   }
                   if (!hist) {
                           fprintf(stderr, "Failed hist create\n");
                           exit(-1);
                   }

                   if (vals) {
                           sav = NULL;
                           for (val = strtok_r(vals, ",", &sav); val; val = strtok_r(NULL, ",", &sav)) {
                                   ret = tracefs_hist_add_value(hist, val);
                                   if (ret) {
                                           fprintf(stderr, "Failed to add value %s\n", val);
                                           exit(-1);
                                   }
                           }
                   }

                   if (sort) {
                           sav = NULL;
                           for (val = strtok_r(sort, ",", &sav); val; val = strtok_r(NULL, ",", &sav)) {
                                   ret = tracefs_hist_add_sort_key(hist, val);
                                   if (ret) {
                                           fprintf(stderr, "Failed to add sort key/val %s\n", val);
                                           exit(-1);
                                   }
                           }
                   }

                   if (ascend) {
                           sav = NULL;
                           for (val = strtok_r(ascend, ",", &sav); val; val = strtok_r(NULL, ",", &sav)) {
                                   ret = tracefs_hist_sort_key_direction(hist, val, TRACEFS_HIST_SORT_ASCENDING);
                                   if (ret) {
                                           fprintf(stderr, "Failed to add ascending key/val %s\n", val);
                                           exit(-1);
                                   }
                           }
                   }

                   if (desc) {
                           sav = NULL;
                           for (val = strtok_r(desc, ",", &sav); val; val = strtok_r(NULL, ",", &sav)) {
                                   ret = tracefs_hist_sort_key_direction(hist, val, TRACEFS_HIST_SORT_DESCENDING);
                                   if (ret) {
                                           fprintf(stderr, "Failed to add descending key/val %s\n", val);
                                           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:
                           /* Show was already done */
                           break;
                   }
                   if (ret)
                           fprintf(stderr, "Failed: command\n");
                   exit(ret);
           }

           int main (int argc, char **argv, char **env)
           {
                   enum commands cmd;
                   char *instance = NULL;
                   char *cmd_str;
                   char *event = NULL;
                   char *keys = NULL;
                   char *vals = NULL;
                   char *sort = NULL;
                   char *desc = NULL;
                   char *ascend = NULL;

                   if (argc < 2) {
                           fprintf(stderr, "usage: %s command [-B instance][-e [system/]event][-k keys][-v vals][-s sort]\n", argv[0]);
                           fprintf(stderr, "      [-a ascending][-d descending]\n");
                           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);
                   }

                   for (;;) {
                           int c;

                           c = getopt(argc - 1, argv + 1, "e:k:v:B:s:d:a:");
                           if (c == -1)
                                   break;

                           switch (c) {
                           case 'e':
                                   event = optarg;
                                   break;
                           case 'k':
                                   keys = optarg;
                                   break;
                           case 'v':
                                   vals = optarg;
                                   break;
                           case 'B':
                                   instance = optarg;
                                   break;
                           case 's':
                                   sort = optarg;
                                   break;
                           case 'd':
                                   desc = optarg;
                                   break;
                           case 'a':
                                   ascend = optarg;
                                   break;
                           }
                   }
                   if (!event) {
                           event = "kmem/kmalloc";
                           if (!keys)
                                   keys = "call_site.sym,bytes_req";
                           if (!vals)
                                   vals = "bytes_alloc";
                           if (!sort)
                                   sort = "bytes_req,bytes_alloc";
                           if (!desc)
                                   desc = "bytes_alloc";
                   }
                   process_hist(cmd, instance, event, keys, vals, sort, ascend, desc);
           }

FILES         top

           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         top

       libtracefs(3), libtraceevent(3), trace-cmd(1),
       tracefs_hist_pause(3), tracefs_hist_continue(3),
       tracefs_hist_reset(3)

AUTHOR         top

           Steven Rostedt <rostedt@goodmis.org[1]>
           Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
           sameeruddin shaik <sameeruddin.shaik8@gmail.com[3]>

REPORTING BUGS         top

       Report bugs to <linux-trace-devel@vger.kernel.org[4]>

LICENSE         top

       libtracefs is Free Software licensed under the GNU LGPL 2.1

RESOURCES         top

       https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ 

COPYING         top

       Copyright (C) 2020 VMware, Inc. Free use of this software is
       granted under the terms of the GNU Public License (GPL).

NOTES         top

        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

COLOPHON         top

       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)

Pages that refer to this page: tracefs_filter_string_append(3)tracefs_hist_add_sort_key(3)tracefs_hist_start(3)tracefs_sql(3)tracefs_synth_alloc(3)tracefs_synth_create(3)tracefs_synth_echo_cmd(3)