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.
| Parameter | Description |
|---|---|
| timeout | The amount of time that the session waits for an IPC message |
Oracle Database Internal Mechanism 