TIMED_OS_STATISTICS specifies the interval (in seconds) at which Oracle collects operating system (OS) statistics when a request is made from the client to the server or a request completes.
On dedicated servers, Oracle collects OS statistics at user logon and after each subsequent client invocation through the OCI into the Oracle server as a remote procedure call message.
On multi-threaded servers, Oracle collects statistics when client calls to Oracle are processed.
A value of zero specifies that OS statistics are not gathered. To collect statistics, set a value meaningful for your application and site needs.
Note: Gathering OS statistics is very expensive. Oracle Corporation recommends that you set this parameter in an ALTERSYSTEM statement rather than in the initialization parameter file, and that you reset the value to zero as soon as the needed statistics have been gathered.