uid_sys_stats: defer io stats calulation for dead tasks

Store sum of dead task io stats in uid_entry and defer uid io
calulation until next uid proc stat change or dumpsys.

Bug: 37754877
Change-Id: I970f010a4c841c5ca26d0efc7e027414c3c952e0
Signed-off-by: Jin Qian <jinqian@google.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>

diff --git a/drivers/misc/uid_sys_stats.c b/drivers/misc/uid_sys_stats.c
index a22b3bc4f43fb91448c610aaa1217ac6a5feb783..d677b37e4804ab8ab74ebd94c4781cdc1ae92dbd 100644 (file)
--- a/drivers/misc/uid_sys_stats.c
+++ b/drivers/misc/uid_sys_stats.c
@@ -49,7 +49,8 @@ struct io_stats {
 
 #define UID_STATE_TOTAL_CURR   2
 #define UID_STATE_TOTAL_LAST   3
-#define UID_STATE_SIZE         4
+#define UID_STATE_DEAD_TASKS   4
+#define UID_STATE_SIZE         5
 
 struct uid_entry {
        uid_t uid;
@@ -221,41 +222,48 @@ static u64 compute_write_bytes(struct task_struct *task)
        return task->ioac.write_bytes - task->ioac.cancelled_write_bytes;
 }
 
-static void add_uid_io_curr_stats(struct uid_entry *uid_entry,
-                       struct task_struct *task)
+static void add_uid_io_stats(struct uid_entry *uid_entry,
+                       struct task_struct *task, int slot)
 {
-       struct io_stats *io_curr = &uid_entry->io[UID_STATE_TOTAL_CURR];
+       struct io_stats *io_slot = &uid_entry->io[slot];
 
-       io_curr->read_bytes += task->ioac.read_bytes;
-       io_curr->write_bytes += compute_write_bytes(task);
-       io_curr->rchar += task->ioac.rchar;
-       io_curr->wchar += task->ioac.wchar;
-       io_curr->fsync += task->ioac.syscfs;
+       io_slot->read_bytes += task->ioac.read_bytes;
+       io_slot->write_bytes += compute_write_bytes(task);
+       io_slot->rchar += task->ioac.rchar;
+       io_slot->wchar += task->ioac.wchar;
+       io_slot->fsync += task->ioac.syscfs;
 }
 
-static void clean_uid_io_last_stats(struct uid_entry *uid_entry,
-                       struct task_struct *task)
+static void compute_uid_io_bucket_stats(struct io_stats *io_bucket,
+                                       struct io_stats *io_curr,
+                                       struct io_stats *io_last,
+                                       struct io_stats *io_dead)
 {
-       struct io_stats *io_last = &uid_entry->io[UID_STATE_TOTAL_LAST];
+       io_bucket->read_bytes += io_curr->read_bytes + io_dead->read_bytes -
+               io_last->read_bytes;
+       io_bucket->write_bytes += io_curr->write_bytes + io_dead->write_bytes -
+               io_last->write_bytes;
+       io_bucket->rchar += io_curr->rchar + io_dead->rchar - io_last->rchar;
+       io_bucket->wchar += io_curr->wchar + io_dead->wchar - io_last->wchar;
+       io_bucket->fsync += io_curr->fsync + io_dead->fsync - io_last->fsync;
 
-       io_last->read_bytes -= task->ioac.read_bytes;
-       io_last->write_bytes -= compute_write_bytes(task);
-       io_last->rchar -= task->ioac.rchar;
-       io_last->wchar -= task->ioac.wchar;
-       io_last->fsync -= task->ioac.syscfs;
+       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;
+
+       memset(io_dead, 0, sizeof(struct io_stats));
 }
 
 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;
        uid_t uid;
 
-       BUG_ON(!rt_mutex_is_locked(&uid_lock));
-
        hash_for_each(hash_table, bkt, uid_entry, hash)
                memset(&uid_entry->io[UID_STATE_TOTAL_CURR], 0,
                        sizeof(struct io_stats));
@@ -266,72 +274,38 @@ static void update_io_stats_all_locked(void)
                uid_entry = find_or_register_uid(uid);
                if (!uid_entry)
                        continue;
-               add_uid_io_curr_stats(uid_entry, task);
+               add_uid_io_stats(uid_entry, task, UID_STATE_TOTAL_CURR);
        } while_each_thread(temp, task);
        rcu_read_unlock();
 
        hash_for_each(hash_table, bkt, uid_entry, hash) {
-               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;
+               compute_uid_io_bucket_stats(&uid_entry->io[uid_entry->state],
+                                       &uid_entry->io[UID_STATE_TOTAL_CURR],
+                                       &uid_entry->io[UID_STATE_TOTAL_LAST],
+                                       &uid_entry->io[UID_STATE_DEAD_TASKS]);
        }
 }
 
-static void update_io_stats_uid_locked(uid_t target_uid)
+static void update_io_stats_uid_locked(struct uid_entry *uid_entry)
 {
-       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();
 
-       BUG_ON(!rt_mutex_is_locked(&uid_lock));
-
-       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)
+               if (from_kuid_munged(user_ns, task_uid(task)) != uid_entry->uid)
                        continue;
-               add_uid_io_curr_stats(uid_entry, task);
+               add_uid_io_stats(uid_entry, task, UID_STATE_TOTAL_CURR);
        } 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;
+       compute_uid_io_bucket_stats(&uid_entry->io[uid_entry->state],
+                               &uid_entry->io[UID_STATE_TOTAL_CURR],
+                               &uid_entry->io[UID_STATE_TOTAL_LAST],
+                               &uid_entry->io[UID_STATE_DEAD_TASKS]);
 }
 
 static int uid_io_show(struct seq_file *m, void *v)
@@ -416,7 +390,7 @@ static ssize_t uid_procstat_write(struct file *file,
                return count;
        }
 
-       update_io_stats_uid_locked(uid);
+       update_io_stats_uid_locked(uid_entry);
 
        uid_entry->state = state;
 
@@ -456,8 +430,7 @@ static int process_notifier(struct notifier_block *self,
        uid_entry->power += task->cpu_power;
        task->cpu_power = ULLONG_MAX;
 
-       update_io_stats_uid_locked(uid);
-       clean_uid_io_last_stats(uid_entry, task);
+       add_uid_io_stats(uid_entry, task, UID_STATE_DEAD_TASKS);
 
 exit:
        rt_mutex_unlock(&uid_lock);