perf lock contention: Add -l/--lock-addr option

The -l/--lock-addr option is to implement per-lock-instance contention
stat using LOCK_AGGR_ADDR.  It displays lock address and optionally
symbol name if exists.

  $ sudo ./perf lock con -abl sleep 1
   contended   total wait     max wait     avg wait            address   symbol

           1     36.28 us     36.28 us     36.28 us   ffff92615d6448b8
           9     10.91 us      1.84 us      1.21 us   ffffffffbaed50c0   rcu_state
           1     10.49 us     10.49 us     10.49 us   ffff9262ac4f0c80
           8      4.68 us      1.67 us       585 ns   ffffffffbae07a40   jiffies_lock
           3      3.03 us      1.45 us      1.01 us   ffff9262277861e0
           1       924 ns       924 ns       924 ns   ffff926095ba9d20
           1       436 ns       436 ns       436 ns   ffff9260bfda4f60
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Blake Jones <blakejones@google.com>
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: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20221209190727.759804-4-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-lock.txt

@@ -168,6 +168,10 @@ CONTENTION OPTIONS
 --entries=<value>::
 	Display this many entries.
 
+-l::
+--lock-addr::
+	Show lock contention stat by address
+
 
 SEE ALSO
 --------

tools/perf/builtin-lock.c

@@ -56,6 +56,7 @@ static struct rb_root		thread_stats;
 
 static bool combine_locks;
 static bool show_thread_stats;
+static bool show_lock_addrs;
 static bool use_bpf;
 static unsigned long bpf_map_entries = 10240;
 static int max_stack_depth = CONTENTION_STACK_DEPTH;
@@ -999,13 +1000,32 @@ static int report_lock_contention_begin_event(struct evsel *evsel,
 	ls = lock_stat_find(key);
 	if (!ls) {
 		char buf[128];
-		const char *caller = buf;
+		const char *name = "";
 		unsigned int flags = evsel__intval(evsel, sample, "flags");
+		struct machine *machine = &session->machines.host;
+		struct map *kmap;
+		struct symbol *sym;
 
+		switch (aggr_mode) {
+		case LOCK_AGGR_ADDR:
+			/* make sure it loads the kernel map to find lock symbols */
+			map__load(machine__kernel_map(machine));
+
+			sym = machine__find_kernel_symbol(machine, key, &kmap);
+			if (sym)
+				name = sym->name;
+			break;
+		case LOCK_AGGR_CALLER:
+			name = buf;
 			if (lock_contention_caller(evsel, sample, buf, sizeof(buf)) < 0)
-			caller = "Unknown";
+				name = "Unknown";
+			break;
+		case LOCK_AGGR_TASK:
+		default:
+			break;
+		}
 
-		ls = lock_stat_findnew(key, caller, flags);
+		ls = lock_stat_findnew(key, name, flags);
 		if (!ls)
 			return -ENOMEM;
 
@@ -1460,10 +1480,19 @@ static void print_contention_result(struct lock_contention *con)
 		list_for_each_entry(key, &lock_keys, list)
 			pr_info("%*s ", key->len, key->header);
 
-		if (show_thread_stats)
+		switch (aggr_mode) {
+		case LOCK_AGGR_TASK:
 			pr_info("  %10s   %s\n\n", "pid", "comm");
-		else
+			break;
+		case LOCK_AGGR_CALLER:
 			pr_info("  %10s   %s\n\n", "type", "caller");
+			break;
+		case LOCK_AGGR_ADDR:
+			pr_info("  %16s   %s\n\n", "address", "symbol");
+			break;
+		default:
+			break;
+		}
 	}
 
 	bad = total = printed = 0;
@@ -1471,6 +1500,9 @@ static void print_contention_result(struct lock_contention *con)
 		bad = bad_hist[BROKEN_CONTENDED];
 
 	while ((st = pop_from_result())) {
+		struct thread *t;
+		int pid;
+
 		total += use_bpf ? st->nr_contended : 1;
 		if (st->broken)
 			bad++;
@@ -1480,18 +1512,24 @@ static void print_contention_result(struct lock_contention *con)
 			pr_info(" ");
 		}
 
-		if (show_thread_stats) {
-			struct thread *t;
-			int pid = st->addr;
-
-			/* st->addr contains tid of thread */
+		switch (aggr_mode) {
+		case LOCK_AGGR_CALLER:
+			pr_info("  %10s   %s\n", get_type_str(st), st->name);
+			break;
+		case LOCK_AGGR_TASK:
+			pid = st->addr;
 			t = perf_session__findnew(session, pid);
 			pr_info("  %10d   %s\n", pid, thread__comm_str(t));
-			goto next;
+			break;
+		case LOCK_AGGR_ADDR:
+			pr_info("  %016llx   %s\n", (unsigned long long)st->addr,
+				st->name ? : "");
+			break;
+		default:
+			break;
 		}
 
-		pr_info("  %10s   %s\n", get_type_str(st), st->name);
-		if (verbose) {
+		if (aggr_mode == LOCK_AGGR_CALLER && verbose) {
 			struct map *kmap;
 			struct symbol *sym;
 			char buf[128];
@@ -1508,7 +1546,6 @@ static void print_contention_result(struct lock_contention *con)
 			}
 		}
 
-next:
 		if (++printed >= print_nr_entries)
 			break;
 	}
@@ -1616,7 +1653,6 @@ static int __cmd_contention(int argc, const char **argv)
 		.map_nr_entries = bpf_map_entries,
 		.max_stack = max_stack_depth,
 		.stack_skip = stack_skip,
-		.aggr_mode = show_thread_stats ? LOCK_AGGR_TASK : LOCK_AGGR_CALLER,
 	};
 
 	session = perf_session__new(use_bpf ? NULL : &data, &eops);
@@ -1627,6 +1663,9 @@ static int __cmd_contention(int argc, const char **argv)
 
 	con.machine = &session->machines.host;
 
+	con.aggr_mode = aggr_mode = show_thread_stats ? LOCK_AGGR_TASK :
+		show_lock_addrs ? LOCK_AGGR_ADDR : LOCK_AGGR_CALLER;
+
 	/* for lock function check */
 	symbol_conf.sort_by_name = true;
 	symbol__init(&session->header.env);
@@ -1907,6 +1946,7 @@ int cmd_lock(int argc, const char **argv)
 		    "Set the number of stack depth to skip when finding a lock caller, "
 		    "Default: " __stringify(CONTENTION_STACK_SKIP)),
 	OPT_INTEGER('E', "entries", &print_nr_entries, "display this many functions"),
+	OPT_BOOLEAN('l', "lock-addr", &show_lock_addrs, "show lock stats by address"),
 	OPT_PARENT(lock_options)
 	};
 
@@ -1976,6 +2016,16 @@ int cmd_lock(int argc, const char **argv)
 			argc = parse_options(argc, argv, contention_options,
 					     contention_usage, 0);
 		}
+
+		if (show_thread_stats && show_lock_addrs) {
+			pr_err("Cannot use thread and addr mode together\n");
+			parse_options_usage(contention_usage, contention_options,
+					    "threads", 0);
+			parse_options_usage(NULL, contention_options,
+					    "lock-addr", 0);
+			return -1;
+		}
+
 		rc = __cmd_contention(argc, argv);
 	} else {
 		usage_with_options(lock_usage, lock_options);

tools/perf/util/bpf_lock_contention.c

@@ -137,11 +137,15 @@ int lock_contention_read(struct lock_contention *con)
 		thread__set_comm(idle, "swapper", /*timestamp=*/0);
 	}
 
+	/* make sure it loads the kernel map */
+	map__load(maps__first(machine->kmaps));
+
 	prev_key = NULL;
 	while (!bpf_map_get_next_key(fd, prev_key, &key)) {
 		struct map *kmap;
 		struct symbol *sym;
 		int idx = 0;
+		s32 stack_id;
 
 		/* to handle errors in the loop body */
 		err = -1;
@@ -160,24 +164,31 @@ int lock_contention_read(struct lock_contention *con)
 			st->avg_wait_time = data.total_time / data.count;
 
 		st->flags = data.flags;
+		st->addr = key.aggr_key;
 
 		if (con->aggr_mode == LOCK_AGGR_TASK) {
 			struct contention_task_data task;
 			struct thread *t;
-
-			st->addr = key.stack_or_task_id;
+			int pid = key.aggr_key;
 
 			/* do not update idle comm which contains CPU number */
 			if (st->addr) {
-				bpf_map_lookup_elem(task_fd, &key, &task);
-				t = __machine__findnew_thread(machine, /*pid=*/-1,
-							      key.stack_or_task_id);
+				bpf_map_lookup_elem(task_fd, &pid, &task);
+				t = __machine__findnew_thread(machine, /*pid=*/-1, pid);
 				thread__set_comm(t, task.comm, /*timestamp=*/0);
 			}
 			goto next;
 		}
 
-		bpf_map_lookup_elem(stack, &key, stack_trace);
+		if (con->aggr_mode == LOCK_AGGR_ADDR) {
+			sym = machine__find_kernel_symbol(machine, st->addr, &kmap);
+			if (sym)
+				st->name = strdup(sym->name);
+			goto next;
+		}
+
+		stack_id = key.aggr_key;
+		bpf_map_lookup_elem(stack, &stack_id, stack_trace);
 
 		/* skip lock internal functions */
 		while (machine__is_lock_function(machine, stack_trace[idx]) &&

tools/perf/util/bpf_skel/lock_contention.bpf.c

@@ -168,11 +168,20 @@ int contention_end(u64 *ctx)
 
 	duration = bpf_ktime_get_ns() - pelem->timestamp;
 
-	if (aggr_mode == LOCK_AGGR_CALLER) {
-		key.stack_or_task_id = pelem->stack_id;
-	} else {
-		key.stack_or_task_id = pid;
+	switch (aggr_mode) {
+	case LOCK_AGGR_CALLER:
+		key.aggr_key = pelem->stack_id;
+		break;
+	case LOCK_AGGR_TASK:
+		key.aggr_key = pid;
 		update_task_data(pid);
+		break;
+	case LOCK_AGGR_ADDR:
+		key.aggr_key = pelem->lock;
+		break;
+	default:
+		/* should not happen */
+		return 0;
 	}
 
 	data = bpf_map_lookup_elem(&lock_stat, &key);

tools/perf/util/bpf_skel/lock_data.h

@@ -4,7 +4,7 @@
 #define UTIL_BPF_SKEL_LOCK_DATA_H
 
 struct contention_key {
-	s32 stack_or_task_id;
+	u64 aggr_key;  /* can be stack_id, pid or lock addr */
 };
 
 #define TASK_COMM_LEN  16