perf evlist: Add --trace-fields option to show trace fields

To use dynamic sort keys, it might be good to add an option to see the
list of field names.

  $ perf evlist -i perf.data.sched
  sched:sched_switch
  sched:sched_stat_wait
  sched:sched_stat_sleep
  sched:sched_stat_iowait
  sched:sched_stat_runtime
  sched:sched_process_fork
  sched:sched_wakeup
  sched:sched_wakeup_new
  sched:sched_migrate_task
  # Tip: use 'perf evlist --trace-fields' to show fields for tracepoint events

  $ perf evlist -i perf.data.sched --trace-fields
  sched:sched_switch: trace_fields: prev_comm,prev_pid,prev_prio,prev_state,next_comm,next_pid,next_prio
  sched:sched_stat_wait: trace_fields: comm,pid,delay
  sched:sched_stat_sleep: trace_fields: comm,pid,delay
  sched:sched_stat_iowait: trace_fields: comm,pid,delay
  sched:sched_stat_runtime: trace_fields: comm,pid,runtime,vruntime
  sched:sched_process_fork: trace_fields: parent_comm,parent_pid,child_comm,child_pid
  sched:sched_wakeup: trace_fields: comm,pid,prio,success,target_cpu
  sched:sched_wakeup_new: trace_fields: comm,pid,prio,success,target_cpu
  sched:sched_migrate_task: trace_fields: comm,pid,prio,orig_cpu,dest_cpu

Committer notes:

For another file, in verbose mode:

  # perf evlist -v --trace-fields
  sched:sched_switch: type: 2, size: 112, config: 0x10b, { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|PERIOD|RAW, disabled: 1, inherit: 1, mmap: 1, comm: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, trace_fields: prev_comm,prev_pid,prev_prio,prev_state,next_comm,next_pid,next_prio
  #

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1452125549-1511-5-git-send-email-namhyung@kernel.org
[ Replaced 'trace_fields=' with 'trace_fields: ' to make the output consistent in -v mode ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 37 insertions, 1 deletions

diff --git a/tools/perf/Documentation/perf-evlist.txt b/tools/perf/Documentation/perf-evlist.txt
index 1ceb3700ffbb..6f7200fb85cf 100644
--- a/tools/perf/Documentation/perf-evlist.txt
+++ b/tools/perf/Documentation/perf-evlist.txt
@@ -32,6 +32,9 @@ OPTIONS
 --group::
         Show event group information.
 
+--trace-fields::
+        Show tracepoint field names.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-list[1],
diff --git a/tools/perf/builtin-evlist.c b/tools/perf/builtin-evlist.c
index 08a7d36a2cf8..8a31f511e1a0 100644
--- a/tools/perf/builtin-evlist.c
+++ b/tools/perf/builtin-evlist.c
@@ -26,14 +26,22 @@ static int __cmd_evlist(const char *file_name, struct perf_attr_details *details
                 .mode = PERF_DATA_MODE_READ,
                 .force = details->force,
         };
+        bool has_tracepoint = false;
 
         session = perf_session__new(&file, 0, NULL);
         if (session == NULL)
                 return -1;
 
-        evlist__for_each(session->evlist, pos)
+        evlist__for_each(session->evlist, pos) {
                 perf_evsel__fprintf(pos, details, stdout);
 
+                if (pos->attr.type == PERF_TYPE_TRACEPOINT)
+                        has_tracepoint = true;
+        }
+
+        if (has_tracepoint && !details->trace_fields)
+                printf("# Tip: use 'perf evlist --trace-fields' to show fields for tracepoint events\n");
+
         perf_session__delete(session);
         return 0;
 }
@@ -49,6 +57,7 @@ int cmd_evlist(int argc, const char **argv, const char *prefix __maybe_unused)
         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[] = {
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 544e4400de13..cdbaf9b51e42 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2298,6 +2298,29 @@ int perf_evsel__fprintf(struct perf_evsel *evsel,
                 printed += comma_fprintf(fp, &first, " %s=%" PRIu64,
                                          term, (u64)evsel->attr.sample_freq);
         }
+
+        if (details->trace_fields) {
+                struct format_field *field;
+
+                if (evsel->attr.type != PERF_TYPE_TRACEPOINT) {
+                        printed += comma_fprintf(fp, &first, " (not a tracepoint)");
+                        goto out;
+                }
+
+                field = evsel->tp_format->format.fields;
+                if (field == NULL) {
+                        printed += comma_fprintf(fp, &first, " (no trace field)");
+                        goto out;
+                }
+
+                printed += comma_fprintf(fp, &first, " trace_fields: %s", field->name);
+
+                field = field->next;
+                while (field) {
+                        printed += comma_fprintf(fp, &first, "%s", field->name);
+                        field = field->next;
+                }
+        }
 out:
         fputc('\n', fp);
         return ++printed;
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 5ded1fc0341e..8e75434bd01c 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -369,6 +369,7 @@ struct perf_attr_details {
         bool verbose;
         bool event_group;
         bool force;
+        bool trace_fields;
 };
 
 int perf_evsel__fprintf(struct perf_evsel *evsel,