mysql> grant all on performance_schema.* to 'testuser'@'%';
ERROR 1044 (42000): Access denied for user 'root'@'localhost' to database 'performance_schema'
mysql> grant all on information_schema.* to 'testuser'@'%';
ERROR 1044 (42000): Access denied for user 'root'@'localhost' to database 'information_schema'
mysql> grant select on information_schema.* to 'testuser'@'%';
ERROR 1044 (42000): Access denied for user 'root'@'localhost' to database 'information_schema'
mysql> grant select on performance_schema.* to 'testuser'@'%';
Query OK, 0 rows affected (0.00 sec)
mysql> grant drop on performance_schema.* to 'testuser'@'%';
Query OK, 0 rows affected (0.00 sec)
mysql> grant drop on information_schema.* to 'testuser'@'%';
ERROR 1044 (42000): Access denied for user 'root'@'localhost' to database 'information_schema'
总结：
information_schema所有用户默认就有权限，相当于oracle的user_*视图，目测不支持（也无需）显示授权，包括select。
performance_schema默认等同于普通db，唯一的区别在于不支持all权限，需要显示授予select/drop等权限（要truncate必须有drop权限）。