[PATCH 38/54] perf record: Generate tracking events for process forked by perf

[Wang Nan]

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@xxxxxxxxxx>
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/perf/builtin-record.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index de51134..e6a8b31 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -567,6 +567,23 @@ record__switch_output(struct record *rec, bool at_exit)
 		perf_session__create_kernel_maps(rec->session);
 		perf_session__set_id_hdr_size(rec->session);
 		record__synthesize(rec);
+
+		if (target__none(&rec->opts.target)) {
+			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;
+			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);
+		}
 	}
 	return fd;
 }
-- 
1.8.3.4