perf lock contention: Add --lock-cgroup option

The --lock-cgroup option shows lock contention stats break down by
cgroups.

Add LOCK_AGGR_CGROUP mode and use it instead of use_cgroup field.

  $ sudo ./perf lock con -ab --lock-cgroup sleep 1
   contended   total wait     max wait     avg wait   cgroup

           8     15.70 us      6.34 us      1.96 us   /
           2      1.48 us       747 ns       738 ns   /user.slice/.../app.slice/app-gnome-google\x2dchrome-6442.scope
           1       848 ns       848 ns       848 ns   /user.slice/.../session.slice/org.gnome.Shell@x11.service
           1       220 ns       220 ns       220 ns   /user.slice/.../session.slice/pipewire-pulse.service

For now, the cgroup mode only works with BPF (-b).

Committer notes:

Remove -g as it is used in the other tools with a clear meaning of
collect/show callchains. As agreed with Namhyung off list.

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230906174903.346486-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 30 insertions, 1 deletions

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 8d3cfbb3cc65..823354999022 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -118,6 +118,9 @@ int needs_callstack;
 int stack_skip;
 int lock_owner;
 
+int use_cgroup_v2;
+int perf_subsys_id = -1;
+
 /* determine the key of lock stat */
 int aggr_mode;
 
@@ -130,6 +133,29 @@ int data_fail;
 int task_map_full;
 int data_map_full;
 
+static inline __u64 get_current_cgroup_id(void)
+{
+	struct task_struct *task;
+	struct cgroup *cgrp;
+
+	if (use_cgroup_v2)
+		return bpf_get_current_cgroup_id();
+
+	task = bpf_get_current_task_btf();
+
+	if (perf_subsys_id == -1) {
+#if __has_builtin(__builtin_preserve_enum_value)
+		perf_subsys_id = bpf_core_enum_value(enum cgroup_subsys_id,
+						     perf_event_cgrp_id);
+#else
+		perf_subsys_id = perf_event_cgrp_id;
+#endif
+	}
+
+	cgrp = BPF_CORE_READ(task, cgroups, subsys[perf_subsys_id], cgroup);
+	return BPF_CORE_READ(cgrp, kn, id);
+}
+
 static inline int can_record(u64 *ctx)
 {
 	if (has_cpu) {
@@ -364,10 +390,13 @@ int contention_end(u64 *ctx)
 			key.stack_id = pelem->stack_id;
 		break;
 	case LOCK_AGGR_ADDR:
-		key.lock_addr = pelem->lock;
+		key.lock_addr_or_cgroup = pelem->lock;
 		if (needs_callstack)
 			key.stack_id = pelem->stack_id;
 		break;
+	case LOCK_AGGR_CGROUP:
+		key.lock_addr_or_cgroup = get_current_cgroup_id();
+		break;
 	default:
 		/* should not happen */
 		return 0;