Controlling SGA Sampling

Performance Analysis for Oracle

Agent Options

The StealthCollect collector process is responsible for sampling both the  memory and the underlying operating system. The light-weight sampling combined with the high-frequency capacity is the StealthCollect technological core. The sampling frequency has a tradeoff of data accuracy and application overhead. Higher sampling frequency yields more accurate data, at a cost of increased overhead on the monitored host.  

To control the memory/OS sampling frequency

The SGA Sampling Rate is modified as follows:

  • Fixed - A Fixed number of samples are performed each second, regardless of the overhead imposed on the server.

  • Automatic - The agent automatically adjusts the sampling frequency such that the imposed overhead does not exceed the given threshold (as measured in % Server CPU usage); Yet this limitation itself does not lower the sampling frequency below that specified in the second criteria of the minimal acceptable (as measured in samples per second). Clicking on either button lets you define each criteria with a more detailed resolution, consisting of the memory sampling and OS sampling components.

    The StealthCollect agent features a low-rate Dictionary Sampling  for supplementary data. Adjust the collection and refresh sampling frequency (measured in hours), as desired. Click Refresh Now to initiate an immediate collection of dictionary information