By default, Streamline records samples at an interval determined by the sample rate. You can override this behavior by selecting event-based sampling (EBS) instead.
With EBS, Streamline records samples only on context switches and when the selected event has been triggered a number of times equal to the Threshold value in the Counter Configuration dialog box. It does so for each core on your target. For standard, non-EBS captures, Streamline samples counters on every context switch and at the frequency specified in the Sample Rate drop-down menu in the Capture & Analysis Options dialog box.
For example, to trigger a sample every time a core causes 500 L2 cache misses, select L2 miss from the Events to Collect list and enter 500 in the Threshold field. Given an adequate capture session, the Samples statistic contained in many of the Streamline reports indicates which processes and functions are the potential cause of inefficient caching.