sys@GZKNEW_SQL> select sid,event,P1TEXT,state from v$session_wait where event not in ('SQL*Net message from client');
SID EVENT P1TEXT STATE
------- ------------------------------ ------------------------------ -------------------
…………………………………………
2719 rdbms ipc message timeout WAITING
2720 rdbms ipc message timeout WAITING
2724 rdbms ipc message timeout WAITING
2725 ASM background timer WAITING
2729 rdbms ipc message timeout WAITING
2731 rdbms ipc message timeout WAITING
2733 rdbms ipc message timeout WAITING
…………………………………………
通过以上sql查询到大量rdbms ipc message timeout等待，此事件是空闲事件，解释如下：
The background processes (LGWR, DBWR, LMS0) use this event to indicate that they are idle and are waiting for the foreground processes to send them an IPC message to do some work.
Wait Time: Up to 3 seconds. The parameter timeout shows the true sleep time.