perf lock: Print wait times with unit

Currently it only prints the time in nsec but it's a bit hard to read
and takes longer in the screen.  We can change it to use different units
and keep the number small to save the space.

Before:

  $ perf lock report

                Name   acquired  contended   avg wait (ns) total wait (ns)   max wait (ns)   min wait (ns)

        jiffies_lock        433         32            2778           88908           13570             692
   &lruvec->lru_lock        747          5           11254           56272           18317            1412
      slock-AF_INET6          7          1           23543           23543           23543           23543
    &newf->file_lock        706         15            1025           15388            2279             618
      slock-AF_INET6          8          1           10379           10379           10379           10379
         &rq->__lock       2143          5            2037           10185            3462             939

After:
                Name   acquired  contended     avg wait   total wait     max wait     min wait

        jiffies_lock        433         32      2.78 us     88.91 us     13.57 us       692 ns
   &lruvec->lru_lock        747          5     11.25 us     56.27 us     18.32 us      1.41 us
      slock-AF_INET6          7          1     23.54 us     23.54 us     23.54 us     23.54 us
    &newf->file_lock        706         15      1.02 us     15.39 us      2.28 us       618 ns
      slock-AF_INET6          8          1     10.38 us     10.38 us     10.38 us     10.38 us
         &rq->__lock       2143          5      2.04 us     10.19 us      3.46 us       939 ns
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220615163222.1275500-2-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-lock.c

@@ -251,6 +251,31 @@ struct lock_key {
 	struct list_head	list;
 };
 
+static void lock_stat_key_print_time(unsigned long long nsec, int len)
+{
+	static const struct {
+		float base;
+		const char *unit;
+	} table[] = {
+		{ 1e9 * 3600, "h " },
+		{ 1e9 * 60, "m " },
+		{ 1e9, "s " },
+		{ 1e6, "ms" },
+		{ 1e3, "us" },
+		{ 0, NULL },
+	};
+
+	for (int i = 0; table[i].unit; i++) {
+		if (nsec < table[i].base)
+			continue;
+
+		pr_info("%*.2f %s", len - 3, nsec / table[i].base, table[i].unit);
+		return;
+	}
+
+	pr_info("%*llu %s", len - 3, nsec, "ns");
+}
+
 #define PRINT_KEY(member)						\
 static void lock_stat_key_print_ ## member(struct lock_key *key,	\
 					   struct lock_stat *ls)	\
@@ -258,11 +283,18 @@ static void lock_stat_key_print_ ## member(struct lock_key *key,	\
 	pr_info("%*llu", key->len, (unsigned long long)ls->member);	\
 }
 
+#define PRINT_TIME(member)						\
+static void lock_stat_key_print_ ## member(struct lock_key *key,	\
+					   struct lock_stat *ls)	\
+{									\
+	lock_stat_key_print_time((unsigned long long)ls->member, key->len);	\
+}
+
 PRINT_KEY(nr_acquired)
 PRINT_KEY(nr_contended)
-PRINT_KEY(avg_wait_time)
-PRINT_KEY(wait_time_total)
-PRINT_KEY(wait_time_max)
+PRINT_TIME(avg_wait_time)
+PRINT_TIME(wait_time_total)
+PRINT_TIME(wait_time_max)
 
 static void lock_stat_key_print_wait_time_min(struct lock_key *key,
 					      struct lock_stat *ls)
@@ -272,7 +304,7 @@ static void lock_stat_key_print_wait_time_min(struct lock_key *key,
 	if (wait_time == ULLONG_MAX)
 		wait_time = 0;
 
-	pr_info("%*"PRIu64, key->len, wait_time);
+	lock_stat_key_print_time(wait_time, key->len);
 }
 
 
@@ -291,10 +323,10 @@ static const char		*output_fields;
 struct lock_key keys[] = {
 	DEF_KEY_LOCK(acquired, "acquired", nr_acquired, 10),
 	DEF_KEY_LOCK(contended, "contended", nr_contended, 10),
-	DEF_KEY_LOCK(avg_wait, "avg wait (ns)", avg_wait_time, 15),
-	DEF_KEY_LOCK(wait_total, "total wait (ns)", wait_time_total, 15),
-	DEF_KEY_LOCK(wait_max, "max wait (ns)", wait_time_max, 15),
-	DEF_KEY_LOCK(wait_min, "min wait (ns)", wait_time_min, 15),
+	DEF_KEY_LOCK(avg_wait, "avg wait", avg_wait_time, 12),
+	DEF_KEY_LOCK(wait_total, "total wait", wait_time_total, 12),
+	DEF_KEY_LOCK(wait_max, "max wait", wait_time_max, 12),
+	DEF_KEY_LOCK(wait_min, "min wait", wait_time_min, 12),
 
 	/* extra comparisons much complicated should be here */
 	{ }