ANDROID: cpufreq: times: optimize proc files

The majority of the time spent reading /proc/uid_time_in_state is due
to seq_printf calls. Use the faster seq_put_* variations instead.

Also skip empty hash buckets in uid_seq_next for a further performance
improvement.

Bug: 111216804
Test: Read /proc/uid_time_in_state and confirm output is sane
Test: Compare read times to confirm performance improvement
Change-Id: If8783b498ed73d2ddb186a49438af41ac5ab9957
Signed-off-by: Connor O'Brien <connoro@google.com>

1 files changed, 20 insertions, 14 deletions

diff --git a/drivers/cpufreq/cpufreq_times.c b/drivers/cpufreq/cpufreq_times.c
index ceddc4f43189..a181de57b8d1 100644
--- a/drivers/cpufreq/cpufreq_times.c
+++ b/drivers/cpufreq/cpufreq_times.c
@@ -193,10 +193,12 @@ static void *uid_seq_start(struct seq_file *seq, loff_t *pos)
 
 static void *uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
-	(*pos)++;
+	do {
+		(*pos)++;
 
-	if (*pos >= HASH_SIZE(uid_hash_table))
-		return NULL;
+		if (*pos >= HASH_SIZE(uid_hash_table))
+			return NULL;
+	} while (hlist_empty(&uid_hash_table[*pos]));
 
 	return &uid_hash_table[*pos];
 }
@@ -220,7 +222,8 @@ static int uid_time_in_state_seq_show(struct seq_file *m, void *v)
 				if (freqs->freq_table[i] ==
 				    CPUFREQ_ENTRY_INVALID)
 					continue;
-				seq_printf(m, " %d", freqs->freq_table[i]);
+				seq_put_decimal_ull(m, " ",
+						    freqs->freq_table[i]);
 			}
 		}
 		seq_putc(m, '\n');
@@ -229,13 +232,16 @@ static int uid_time_in_state_seq_show(struct seq_file *m, void *v)
 	rcu_read_lock();
 
 	hlist_for_each_entry_rcu(uid_entry, (struct hlist_head *)v, hash) {
-		if (uid_entry->max_state)
-			seq_printf(m, "%d:", uid_entry->uid);
+		if (uid_entry->max_state) {
+			seq_put_decimal_ull(m, "", uid_entry->uid);
+			seq_putc(m, ':');
+		}
 		for (i = 0; i < uid_entry->max_state; ++i) {
+			u64 time;
 			if (freq_index_invalid(i))
 				continue;
-			seq_printf(m, " %lu", (unsigned long)cputime_to_clock_t(
-					   uid_entry->time_in_state[i]));
+			time = cputime_to_clock_t(uid_entry->time_in_state[i]);
+			seq_put_decimal_ull(m, " ", time);
 		}
 		if (uid_entry->max_state)
 			seq_putc(m, '\n');
@@ -256,13 +262,13 @@ static int concurrent_time_seq_show(struct seq_file *m, void *v,
 	hlist_for_each_entry_rcu(uid_entry, (struct hlist_head *)v, hash) {
 		atomic64_t *times = get_times(uid_entry->concurrent_times);
 
-		seq_put_decimal_ull(m, 0, (u64)uid_entry->uid);
+		seq_put_decimal_ull(m, "", (u64)uid_entry->uid);
 		seq_putc(m, ':');
 
 		for (i = 0; i < num_possible_cpus; ++i) {
 			u64 time = cputime_to_clock_t(atomic64_read(&times[i]));
 
-			seq_put_decimal_ull(m, ' ', time);
+			seq_put_decimal_ull(m, " ", time);
 		}
 		seq_putc(m, '\n');
 	}
@@ -280,7 +286,7 @@ static inline atomic64_t *get_active_times(struct concurrent_times *times)
 static int concurrent_active_time_seq_show(struct seq_file *m, void *v)
 {
 	if (v == uid_hash_table) {
-		seq_printf(m, "cpus: %d", num_possible_cpus());
+		seq_put_decimal_ull(m, "cpus: ", num_possible_cpus());
 		seq_putc(m, '\n');
 	}
 
@@ -306,18 +312,18 @@ static int concurrent_policy_time_seq_show(struct seq_file *m, void *v)
 				continue;
 			if (freqs != last_freqs) {
 				if (last_freqs) {
-					seq_printf(m, ": %d", cnt);
+					seq_put_decimal_ull(m, ": ", cnt);
 					seq_putc(m, ' ');
 					cnt = 0;
 				}
-				seq_printf(m, "policy%d", i);
+				seq_put_decimal_ull(m, "policy", i);
 
 				last_freqs = freqs;
 			}
 			cnt++;
 		}
 		if (last_freqs) {
-			seq_printf(m, ": %d", cnt);
+			seq_put_decimal_ull(m, ": ", cnt);
 			seq_putc(m, '\n');
 		}
 	}