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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 07:26:15 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 07:26:15 +0000
commitc72e01b9ea891fa5cbbbe9876bdfb49079b55be7 (patch)
tree44c55a81a281a6c211745c0abc68352aeaf0180f /Documentation/libtracefs-hist-mod.txt
parentInitial commit. (diff)
downloadlibtracefs-c72e01b9ea891fa5cbbbe9876bdfb49079b55be7.tar.xz
libtracefs-c72e01b9ea891fa5cbbbe9876bdfb49079b55be7.zip
Adding upstream version 1.6.4.upstream/1.6.4upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+libtracefs(3)
+=============
+
+NAME
+----
+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
+--------
+[verse]
+--
+*#include <tracefs.h>*
+
+int *tracefs_hist_add_sort_key*(struct tracefs_hist pass:[*]_hist_,
+ const char pass:[*]_sort_key_);
+
+int *tracefs_hist_set_sort_key*(struct tracefs_hist pass:[*]_hist_,
+ const char pass:[*]_sort_key_, _..._);
+int *tracefs_hist_sort_key_direction*(struct tracefs_hist pass:[*]_hist_,
+ const char pass:[*]_sort_key_,
+ enum tracefs_hist_sort_direction _dir_);
+
+int *tracefs_hist_add_name*(struct tracefs_hist pass:[*]_hist_, const char pass:[*]_name_);
+
+int *tracefs_hist_append_filter*(struct tracefs_hist pass:[*]_hist_,
+ enum tracefs_filter _type_,
+ const char pass:[*]_field_,
+ enum tracefs_compare _compare_,
+ const char pass:[*]_val_);
+
+int *tracefs_hist_echo_cmd*(struct trace_seq pass:[*]_s_, struct tracefs_instance pass:[*]_instance_,
+ struct tracefs_hist pass:[*]_hist_,
+ enum tracefs_hist_command _command_);
+
+int *tracefs_hist_command*(struct tracefs_instance pass:[*]_instance_,
+ struct tracefs_hist pass:[*]_hist_,
+ enum tracefs_hist_command _command_);
+
+const char pass:[*]*tracefs_hist_get_name*(struct tracefs_hist pass:[*]_hist_);
+
+const char pass:[*]*tracefs_hist_get_event*(struct tracefs_hist pass:[*]_hist_);
+
+const char pass:[*]*tracefs_hist_get_system*(struct tracefs_hist pass:[*]_hist_);
+
+--
+
+DESCRIPTION
+-----------
+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_ <pass:[=] _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
+---------
+
+*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
+------------
+*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
+-------
+[source,c]
+--
+#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
+-----
+[verse]
+--
+*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_pause*(3),
+*tracefs_hist_continue*(3),
+*tracefs_hist_reset*(3)
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>
+*sameeruddin shaik* <sameeruddin.shaik8@gmail.com>
+--
+REPORTING BUGS
+--------------
+Report bugs to <linux-trace-devel@vger.kernel.org>
+
+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).