linux/tools/perf/builtin-evlist.c
Kan Liang 9953807c9e perf evlist: Print hint for group
An event group is a critical relationship. There is a -g option that can
display the relationship. But it's hard for a user to know when should
this option be applied.

If there is an event group in the perf record, print a hint to suggest
the user apply the -g to display the group information.

With the patch,

  $ perf record -e "{cycles,instructions},instructions" sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.024 MB perf.data (4 samples) ]
  $

  $ perf evlist
  cycles
  instructions
  instructions
  # Tip: use 'perf evlist -g' to show group information

  $ perf evlist -g
  {cycles,instructions}
  instructions
  $

Committer testing:

So for a perf.data file _with_ a group:

  root@number:~# perf evlist -g
  {cpu_core/branch-instructions/pp,cpu_core/branches/}
  dummy:u
  root@number:~# perf evlist
  cpu_core/branch-instructions/pp
  cpu_core/branches/
  dummy:u
  # Tip: use 'perf evlist -g' to show group information
  root@number:~#

Then for something _without_ a group, no hint:

  root@number:~# perf record ls
  <SNIP>
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.035 MB perf.data (7 samples) ]
  root@number:~# perf evlist
  cpu_atom/cycles/P
  cpu_core/cycles/P
  dummy:u
  root@number:~#

No suggestion, good.

Suggested-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Closes: https://lore.kernel.org/lkml/ZttgvduaKsVn1r4p@x1/
Link: https://lore.kernel.org/r/20240908202847.176280-1-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2024-09-11 13:08:45 -03:00

102 lines
2.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Builtin evlist command: Show the list of event selectors present
* in a perf.data file.
*/
#include "builtin.h"
#include <linux/list.h>
#include "util/evlist.h"
#include "util/evsel.h"
#include "util/evsel_fprintf.h"
#include "util/parse-events.h"
#include <subcmd/parse-options.h>
#include "util/session.h"
#include "util/data.h"
#include "util/debug.h"
#include <linux/err.h>
#include "util/tool.h"
#include "util/util.h"
static int process_header_feature(struct perf_session *session __maybe_unused,
union perf_event *event __maybe_unused)
{
session_done = 1;
return 0;
}
static int __cmd_evlist(const char *file_name, struct perf_attr_details *details)
{
struct perf_session *session;
struct evsel *pos;
struct perf_data data = {
.path = file_name,
.mode = PERF_DATA_MODE_READ,
.force = details->force,
};
struct perf_tool tool;
bool has_tracepoint = false, has_group = false;
perf_tool__init(&tool, /*ordered_events=*/false);
/* only needed for pipe mode */
tool.attr = perf_event__process_attr;
tool.feature = process_header_feature;
session = perf_session__new(&data, &tool);
if (IS_ERR(session))
return PTR_ERR(session);
if (data.is_pipe)
perf_session__process_events(session);
evlist__for_each_entry(session->evlist, pos) {
evsel__fprintf(pos, details, stdout);
if (pos->core.attr.type == PERF_TYPE_TRACEPOINT)
has_tracepoint = true;
if (!evsel__is_group_leader(pos))
has_group = true;
}
if (has_tracepoint && !details->trace_fields)
printf("# Tip: use 'perf evlist --trace-fields' to show fields for tracepoint events\n");
if (has_group && !details->event_group)
printf("# Tip: use 'perf evlist -g' to show group information\n");
perf_session__delete(session);
return 0;
}
int cmd_evlist(int argc, const char **argv)
{
struct perf_attr_details details = { .verbose = false, };
const struct option options[] = {
OPT_STRING('i', "input", &input_name, "file", "Input file name"),
OPT_BOOLEAN('F', "freq", &details.freq, "Show the sample frequency"),
OPT_BOOLEAN('v', "verbose", &details.verbose,
"Show all event attr details"),
OPT_BOOLEAN('g', "group", &details.event_group,
"Show event group information"),
OPT_BOOLEAN('f', "force", &details.force, "don't complain, do it"),
OPT_BOOLEAN(0, "trace-fields", &details.trace_fields, "Show tracepoint fields"),
OPT_END()
};
const char * const evlist_usage[] = {
"perf evlist [<options>]",
NULL
};
argc = parse_options(argc, argv, options, evlist_usage, 0);
if (argc)
usage_with_options(evlist_usage, options);
if (details.event_group && (details.verbose || details.freq)) {
usage_with_options_msg(evlist_usage, options,
"--group option is not compatible with other options\n");
}
return __cmd_evlist(input_name, &details);
}