perf record: Synthesize namespace events for current processes

Synthesize PERF_RECORD_NAMESPACES events for processes that were running prior
to invocation of perf record. The data for this is taken from /proc/$PID/ns.
These changes make way for analyzing events with regard to namespaces.

Committer notes:

Check if 'tool' is NULL in perf_event__synthesize_namespaces(), as in the
test__mmap_thread_lookup case, i.e. 'perf test Lookup mmap thread".

Testing it:

  # ps axH > /tmp/allthreads
  # perf record -a --namespaces usleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 1.169 MB perf.data (8 samples) ]
  # perf report -D | grep PERF_RECORD_NAMESPACES | wc -l
  602
  # wc -l /tmp/allthreads
  601 /tmp/allthreads
  # tail /tmp/allthreads
  16951 pts/4    T      0:00 git rebase -i a033bf1bfacdaa25642e6bcc857a7d0f67cc3c92^
  16952 pts/4    T      0:00 /bin/sh /usr/libexec/git-core/git-rebase -i a033bf1bfacdaa25642e6bcc857a7d0f67cc3c92^
  17176 pts/4    T      0:00 git commit --amend --no-post-rewrite
  17204 pts/4    T      0:00 vim /home/acme/git/linux/.git/COMMIT_EDITMSG
  18939 ?        S      0:00 [kworker/2:1]
  18947 ?        S      0:00 [kworker/3:0]
  18974 ?        S      0:00 [kworker/1:0]
  19047 ?        S      0:00 [kworker/0:1]
  19152 pts/6    S+     0:00 weechat
  19153 pts/7    R+     0:00 ps axH
  # perf report -D | grep PERF_RECORD_NAMESPACES | tail
  0 0 0x125068 [0xa0]: PERF_RECORD_NAMESPACES 17176/17176 - nr_namespaces: 7
  0 0 0x1255b8 [0xa0]: PERF_RECORD_NAMESPACES 17204/17204 - nr_namespaces: 7
  0 0 0x125df0 [0xa0]: PERF_RECORD_NAMESPACES 18939/18939 - nr_namespaces: 7
  0 0 0x125f00 [0xa0]: PERF_RECORD_NAMESPACES 18947/18947 - nr_namespaces: 7
  0 0 0x126010 [0xa0]: PERF_RECORD_NAMESPACES 18974/18974 - nr_namespaces: 7
  0 0 0x126120 [0xa0]: PERF_RECORD_NAMESPACES 19047/19047 - nr_namespaces: 7
  0 0 0x126230 [0xa0]: PERF_RECORD_NAMESPACES 19152/19152 - nr_namespaces: 7
  0 0 0x129330 [0xa0]: PERF_RECORD_NAMESPACES 19154/19154 - nr_namespaces: 7
  0 0 0x12a1f8 [0xa0]: PERF_RECORD_NAMESPACES 19155/19155 - nr_namespaces: 7
  0 0 0x12b0b8 [0xa0]: PERF_RECORD_NAMESPACES 19155/19155 - nr_namespaces: 7
  #

Humm, investigate why we got two record for the 19155 pid/tid...

Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/148891931111.25309.11073854609798681633.stgit@hbathini.in.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 25 insertions, 4 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 99562c7242b6..04faef79a548 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -986,6 +986,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 	 */
 	if (forks) {
 		union perf_event *event;
+		pid_t tgid;
 
 		event = malloc(sizeof(event->comm) + machine->id_hdr_size);
 		if (event == NULL) {
@@ -999,10 +1000,30 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 		 * cannot see a correct process name for those events.
 		 * Synthesize COMM event to prevent it.
 		 */
-		perf_event__synthesize_comm(tool, event,
-					    rec->evlist->workload.pid,
-					    process_synthesized_event,
-					    machine);
+		tgid = perf_event__synthesize_comm(tool, event,
+						   rec->evlist->workload.pid,
+						   process_synthesized_event,
+						   machine);
+		free(event);
+
+		if (tgid == -1)
+			goto out_child;
+
+		event = malloc(sizeof(event->namespaces) +
+			       (NR_NAMESPACES * sizeof(struct perf_ns_link_info)) +
+			       machine->id_hdr_size);
+		if (event == NULL) {
+			err = -ENOMEM;
+			goto out_child;
+		}
+
+		/*
+		 * Synthesize NAMESPACES event for the command specified.
+		 */
+		perf_event__synthesize_namespaces(tool, event,
+						  rec->evlist->workload.pid,
+						  tgid, process_synthesized_event,
+						  machine);
 		free(event);
 
 		perf_evlist__start_workload(rec->evlist);