⊙ 响应时间

我们知道系统的响应时间等于ＣＰＵ服务的时间＋等待时间

 

Response Time = Service Time + Wait Time

 

服务时间代表的是“ CPU used by this session”,是CPU服务会话所花费的所有时间

 

分两种。

1. 实例级。

 

select a.value "Total CPU time"
from v$sysstat a
where a.name = 'CPU used by this session';

 

2. 会话级

SQL> select statistic# from v$statname where name = 'CPU used by this session';

STATISTIC#
----------
        12
SQL> select sid,a.value "Total CPU time"
  2  from v$sesstat a
  3  where a.statistic# = 12
  4  /

Service Time　＝　SQL解析时间　＋　递归调用时间　＋　其它时间

select a.value "Total parse CPU time" from v$sysstat a where a.name = 'parse time cpu'

recursive cpu usage  == ‘递归调用时间’

其他时间===>

select a.value "Total CPU",
b.value "Parse CPU",
c.value "Recusive CPU",
a.value - b.value - c.value "Other"
from v$sysstat a, v$sysstat b, v$sysstat c
where a.name = 'CPU used by this session'
and b.name = 'parse time cpu'
and c.name = 'recusive cpu usage'

等待事件

select EVENT,TIME_WAITED,AVERAGE_WAIT
from v$system_event
where event not in ('pmon timer',
                    'smon timer',
                    'rdbms ipc message',
                    'parallel dequeue wait',
                    'virtual circuit',
                    'SQL*Net message from client',
                    'client message',
                    'NULL event') order by time_waited desc;