Teledyne LeCroy Summit T3-16 PCIe Multi-lane Protocol Analyzer User Manual - Manual (Page 226)

Teledyne LeCroy Show Metrics in the Bus Utilization Window
214 Summit T3‐16 PCI Express Multi‐Lane Protocol Analyzer User Manual
10.18.1 Unit-Based Averaging
The Analyzer builds metric graphs using unit‐based averaging (as opposed to time‐based
averaging). For the total duration of a certain request (or Memory Write transaction), the
graph value is assumed equal to the corresponding metric for this request (transaction). If
there are overlapping operations for a certain time period, then the value is calculated as
an average of metric values for all the overlapped requests (transactions).
It is important to remember that the Analyzer uses unit‐based averaging rather than
time‐based averaging. Time‐based averaging can be misleading in some situations. For
example, consider the Throughput Per Transaction graph. Sometimes, while many
outstanding requests are in progress, latency (and response time) grows for each of the
transactions, resulting in a lower throughput per transaction over time (which is reflected
in the graph). This happens even though aggregated throughput across all the
transactions is constant.
10.18.2 Bus Utilization Window Features
For the seven Split‐ and Transaction‐level graphs listed, all Bus Utilization window
features are available, such as zooming in/out, changing scale type, scrolling, context‐
sensitive status, and graph synchronization. See Bus Utilization and Bus Utilization
Buttons for more on these features.
Note: Clicking a certain place within a graph area repositions the CATC Trace display at the Link or Split
transaction level to the transaction that was in progress at that time.