perf record: Generate tracking events for process forked by perf

With 'perf record --switch-output' without -a, record__synthesize() in
record__switch_output() won't generate tracking events because there's
no thread_map in evlist. Which causes newly created perf.data doesn't
contain map and comm information.

This patch creates a fake thread_map and directly call
perf_event__synthesize_thread_map() for those events.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1461178794-40467-8-git-send-email-wangnan0@huawei.com
Signed-off-by: He Kuang <hekuang@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 30 insertions, 1 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 178b49ecd05f..f3679c44d3f3 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -500,6 +500,23 @@ record__finish_output(struct record *rec)
         return;
 }
 
+static int record__synthesize_workload(struct record *rec)
+{
+        struct {
+                struct thread_map map;
+                struct thread_map_data map_data;
+        } thread_map;
+
+        thread_map.map.nr = 1;
+        thread_map.map.map[0].pid = rec->evlist->workload.pid;
+        thread_map.map.map[0].comm = NULL;
+        return perf_event__synthesize_thread_map(&rec->tool, &thread_map.map,
+                                                 process_synthesized_event,
+                                                 &rec->session->machines.host,
+                                                 rec->opts.sample_address,
+                                                 rec->opts.proc_map_timeout);
+}
+
 static int record__synthesize(struct record *rec);
 
 static int
@@ -532,9 +549,21 @@ record__switch_output(struct record *rec, bool at_exit)
                         file->path, timestamp);
 
         /* Output tracking events */
-        if (!at_exit)
+        if (!at_exit) {
                 record__synthesize(rec);
 
+                /*
+                 * In 'perf record --switch-output' without -a,
+                 * record__synthesize() in record__switch_output() won't
+                 * generate tracking events because there's no thread_map
+                 * in evlist. Which causes newly created perf.data doesn't
+                 * contain map and comm information.
+                 * Create a fake thread_map and directly call
+                 * perf_event__synthesize_thread_map() for those events.
+                 */
+                if (target__none(&rec->opts.target))
+                        record__synthesize_workload(rec);
+        }
         return fd;
 }