Teledyne LeCroy Summit T24 PCIe Multi-lane Protocol Analyzer User Manual - Manual (Page 205)

Summit T24 PCI Express Multi‐Lane Protocol Analyzer User Manual 193
Metrics Defined for Link Transactions Teledyne LeCroy
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;
Data Throughput: The transaction payload divided by response time, expressed in
megabytes per second.
Latency Time: The time measured from the end of the request transaction to the first
completion transmitted in response to the request within this Split transaction.
Note:
The Number Of Link Transactions metric for a Split Transaction usually is two for a Configuration
or IO request. It can be bigger then two for a Memory Read request.
10.16 Show Metrics in the CATC Trace Display
In the CATC Trace view display of Link Transaction or Split Transaction levels, all metrics
information applicable to a specific protocol unit is displayed in a Metrics header. The
header is located close to the end of the unit, in front of the Time cell. You can expand and
collapse the header to show or hide the metrics information.
10.16.1 Collapsed Metrics Header Display
Following is a collapsed metrics display for a unit of Link Transaction. The collapsed
header display shows only the metrics cell representing the Number of Packets (see the
following figure).