Teledyne LeCroy Summit T3-16 PCIe Multi-lane Protocol Analyzer User Manual - Manual (Page 221)

Summit T3‐16 PCI Express Multi‐Lane Protocol Analyzer User Manual 209
Using Unit Metrics Teledyne LeCroy
Figure 10.29: Configuration Space Editor Dialog
10.14 Using Unit Metrics
For every protocol unit at the Link or Split transaction level, PETracer™ calculates and
displays a set of metrics. Metrics are measurements of key operating parameters. You can
use metrics to evaluate performance of traffic in the CATC Trace stream.
You can view metrics information in the CATC Trace display, the Traffic Summary window,
and the Bus Utilization window.
PETracer defines different metrics for Link and Split transactions.
10.15 Metrics Defined for Link Transactions
 Number of Packets: The total number of packets that compose this Link transac‐
tion.
 Payload: The number of data payload bytes this Link transaction transferred.
 Response Time: The time it took to transmit this Link transaction on the PE link,
from the beginning of the first packet in the transaction to the end of the last
packet in the transaction.
 Data Throughput: The payload divided by response time, expressed in mega‐
bytes per second.
Note: Usually, the Number of Packets metric for a link transaction is two (in case of explicit
acknowledge) or one (in case of implicit acknowledge). However if Naks/link level retries are
involved, this metric might be higher. As a result, the Number of Packets metric is useful in
highlighting unusual link transactions.
10.15.1 Metrics Defined for Split Transactions
The following types of metrics currently are defined for Split transactions:
Number of Link Transactions: The total number of Link transactions that compose this
Split transaction.
Payload: The number of payload bytes this Split transaction transferred.
Response Time: The time it took to transmit this Split transaction on the PE link, from the
beginning of the first packet in the Split transaction to the end of the last packet in the
Split transaction;