perf top: Add --all-cgroups option

The --all-cgroups option is to enable cgroup profiling support.  It
tells kernel to record CGROUP events in the ring buffer so that 'perf
top' can identify task/cgroup association later.

Committer testing:

Use:

  # perf top --all-cgroups -s cgroup_id,cgroup,pid
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200325124536.2800725-9-namhyung@kernel.org
Link: http://lore.kernel.org/lkml/20200402015249.3800462-1-namhyung@kernel.org
[ Extracted the HAVE_FILE_HANDLE from the followup patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-top.txt

@@ -272,6 +272,10 @@ Default is to monitor all CPUS.
 	Record events of type PERF_RECORD_NAMESPACES and display it with the
 	'cgroup_id' sort key.
 
+--all-cgroups::
+	Record events of type PERF_RECORD_CGROUP and display it with the
+	'cgroup' sort key.
+
 --switch-on EVENT_NAME::
 	Only consider events after this event is found.
 

tools/perf/builtin-top.c

@@ -1246,6 +1246,14 @@ static int __cmd_top(struct perf_top *top)
 
 	if (opts->record_namespaces)
 		top->tool.namespace_events = true;
+	if (opts->record_cgroup) {
+#ifdef HAVE_FILE_HANDLE
+		top->tool.cgroup_events = true;
+#else
+		pr_err("cgroup tracking is not supported.\n");
+		return -1;
+#endif
+	}
 
 	ret = perf_event__synthesize_bpf_events(top->session, perf_event__process,
 						&top->session->machines.host,
@@ -1253,6 +1261,11 @@ static int __cmd_top(struct perf_top *top)
 	if (ret < 0)
 		pr_debug("Couldn't synthesize BPF events: Pre-existing BPF programs won't have symbols resolved.\n");
 
+	ret = perf_event__synthesize_cgroups(&top->tool, perf_event__process,
+					     &top->session->machines.host);
+	if (ret < 0)
+		pr_debug("Couldn't synthesize cgroup events.\n");
+
 	machine__synthesize_threads(&top->session->machines.host, &opts->target,
 				    top->evlist->core.threads, false,
 				    top->nr_threads_synthesize);
@@ -1545,6 +1558,8 @@ int cmd_top(int argc, const char **argv)
 			"number of thread to run event synthesize"),
 	OPT_BOOLEAN(0, "namespaces", &opts->record_namespaces,
 		    "Record namespaces events"),
+	OPT_BOOLEAN(0, "all-cgroups", &opts->record_cgroup,
+		    "Record cgroup events"),
 	OPTS_EVSWITCH(&top.evswitch),
 	OPT_END()
 	};