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>

diff --git a/drivers/cpufreq/cpufreq_times.c b/drivers/cpufreq/cpufreq_times.c
index 42420c5e1e6fc3369084b63c53941f282797471b..2883d675b1eb784a36b70a17fa3891bb9d1bd89f 100644 (file)
--- 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)nsec_to_clock_t(
-                                          uid_entry->time_in_state[i]));
+                       time = nsec_to_clock_t(uid_entry->time_in_state[i]);
+                       seq_put_decimal_ull(m, " ", time);
                }
                if (uid_entry->max_state)
                        seq_putc(m, '\n');