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ANDROID: uid_sys_stats: reduce update_io_stats overhead

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Replaced read_lock with rcu_read_lock to reduce time that preemption
is disabled.

Added a function to update io stats for specific uid and moved
hash table lookup, user_namespace out of loops.

Bug: 37319300
Change-Id: I2b81b5cd3b6399b40d08c3c14b42cad044556970
Signed-off-by: Jin Qian <jinqian@google.com>
This commit is contained in:
Jin Qian 2017-04-13 17:07:58 -07:00 committed by Amit Pundir
parent f99c355d91
commit a29fcfb727
1 changed files with 51 additions and 10 deletions
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61
drivers/misc/uid_sys_stats.c
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@ -235,28 +235,28 @@ static void clean_uid_io_last_stats(struct uid_entry *uid_entry,
io_last->fsync -= task->ioac.syscfs;
}
static void update_io_stats_locked(void)
static void update_io_stats_all_locked(void)
{
struct uid_entry *uid_entry;
struct task_struct *task, *temp;
struct io_stats *io_bucket, *io_curr, *io_last;
struct user_namespace *user_ns = current_user_ns();
unsigned long bkt;
BUG_ON(!rt_mutex_is_locked(&uid_lock));
uid_t uid;
hash_for_each(hash_table, bkt, uid_entry, hash)
memset(&uid_entry->io[UID_STATE_TOTAL_CURR], 0,
sizeof(struct io_stats));
read_lock(&tasklist_lock);
rcu_read_lock();
do_each_thread(temp, task) {
uid_entry = find_or_register_uid(from_kuid_munged(
current_user_ns(), task_uid(task)));
uid = from_kuid_munged(user_ns, task_uid(task));
uid_entry = find_or_register_uid(uid);
if (!uid_entry)
continue;
add_uid_io_curr_stats(uid_entry, task);
} while_each_thread(temp, task);
read_unlock(&tasklist_lock);
rcu_read_unlock();
hash_for_each(hash_table, bkt, uid_entry, hash) {
io_bucket = &uid_entry->io[uid_entry->state];
@ -279,6 +279,47 @@ static void update_io_stats_locked(void)
}
}
static void update_io_stats_uid_locked(uid_t target_uid)
{
struct uid_entry *uid_entry;
struct task_struct *task, *temp;
struct io_stats *io_bucket, *io_curr, *io_last;
struct user_namespace *user_ns = current_user_ns();
uid_entry = find_or_register_uid(target_uid);
if (!uid_entry)
return;
memset(&uid_entry->io[UID_STATE_TOTAL_CURR], 0,
sizeof(struct io_stats));
rcu_read_lock();
do_each_thread(temp, task) {
if (from_kuid_munged(user_ns, task_uid(task)) != target_uid)
continue;
add_uid_io_curr_stats(uid_entry, task);
} while_each_thread(temp, task);
rcu_read_unlock();
io_bucket = &uid_entry->io[uid_entry->state];
io_curr = &uid_entry->io[UID_STATE_TOTAL_CURR];
io_last = &uid_entry->io[UID_STATE_TOTAL_LAST];
io_bucket->read_bytes +=
io_curr->read_bytes - io_last->read_bytes;
io_bucket->write_bytes +=
io_curr->write_bytes - io_last->write_bytes;
io_bucket->rchar += io_curr->rchar - io_last->rchar;
io_bucket->wchar += io_curr->wchar - io_last->wchar;
io_bucket->fsync += io_curr->fsync - io_last->fsync;
io_last->read_bytes = io_curr->read_bytes;
io_last->write_bytes = io_curr->write_bytes;
io_last->rchar = io_curr->rchar;
io_last->wchar = io_curr->wchar;
io_last->fsync = io_curr->fsync;
}
static int uid_io_show(struct seq_file *m, void *v)
{
struct uid_entry *uid_entry;
@ -286,7 +327,7 @@ static int uid_io_show(struct seq_file *m, void *v)
rt_mutex_lock(&uid_lock);
update_io_stats_locked();
update_io_stats_all_locked();
hash_for_each(hash_table, bkt, uid_entry, hash) {
seq_printf(m, "%d %llu %llu %llu %llu %llu %llu %llu %llu %llu %llu\n",
@ -361,7 +402,7 @@ static ssize_t uid_procstat_write(struct file *file,
return count;
}
update_io_stats_locked();
update_io_stats_uid_locked(uid);
uid_entry->state = state;
@ -399,7 +440,7 @@ static int process_notifier(struct notifier_block *self,
uid_entry->utime += utime;
uid_entry->stime += stime;
update_io_stats_locked();
update_io_stats_uid_locked(uid);
clean_uid_io_last_stats(uid_entry, task);
exit: