perf lock: Implement cpu and task filters for BPF

Add -a/--all-cpus and -C/--cpu options for cpu filtering.  Also -p/--pid
and --tid options are added for task filtering.  The short -t option is
taken for --threads already.  Tracking the command line workload is
possible as well.

  $ sudo perf lock contention -a -b sleep 1

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220729200756.666106-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 40 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 5d1c7641223f..67d46533e518 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -54,8 +54,47 @@ struct {
 	__uint(max_entries, MAX_ENTRIES);
 } lock_stat SEC(".maps");
 
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u8));
+	__uint(max_entries, 1);
+} cpu_filter SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u8));
+	__uint(max_entries, 1);
+} task_filter SEC(".maps");
+
 /* control flags */
 int enabled;
+int has_cpu;
+int has_task;
+
+static inline int can_record(void)
+{
+	if (has_cpu) {
+		__u32 cpu = bpf_get_smp_processor_id();
+		__u8 *ok;
+
+		ok = bpf_map_lookup_elem(&cpu_filter, &cpu);
+		if (!ok)
+			return 0;
+	}
+
+	if (has_task) {
+		__u8 *ok;
+		__u32 pid = bpf_get_current_pid_tgid();
+
+		ok = bpf_map_lookup_elem(&task_filter, &pid);
+		if (!ok)
+			return 0;
+	}
+
+	return 1;
+}
 
 SEC("tp_btf/contention_begin")
 int contention_begin(u64 *ctx)
@@ -63,7 +102,7 @@ int contention_begin(u64 *ctx)
 	struct task_struct *curr;
 	struct tstamp_data *pelem;
 
-	if (!enabled)
+	if (!enabled || !can_record())
 		return 0;
 
 	curr = bpf_get_current_task_btf();