Flow Control- Examples - Keysight Technologies U4301 User Manual

11 Viewing Offline Performance Summary
Flow Control Chart
The flow control chart displayed in the Charts pane (example shown above) has flow control Credits
plotted on Y-axis. For Header flow control, the Y-axis represents the number of headers available as
credits. The Data flow control is computed in Bytes. Therefore, the value charted on the Credits Y-
Axis for Data flow control is Bytes/16 (an FC Credit represents 16 bytes or 4 DWords). If the byte
value is not a multiple of 16, the result is rounded up to the next integer as Credits can be consumed
only in unit quantities.
NOTE

Flow Control- Examples

The following examples elaborate the usage of the Flow Control feature:
Example -1
The flow control charts represent the computed flow control credit level, which is meant for how
many bytes the receiver is ready to receive. When the data is sent in a higher volume than the
receiving capacity of the receiver, there will be a continuous slow movement of data from transmitter
to receiver. This sometimes also leads to data loss. In such scenarios, you can use the Flow Control
feature to display the credit limits of the data to be sent and the data received by the receiver.
176
In a flow control chart, the default colors used for:
- Downstream Header flow control credits is yellow.
- Downstream Data flow control credits is orange.
- Upstream Header flow control credits is green.
- Upstream Data flow control is blue.
If needed, you can change these colors using the Performance Overview Setup dialog
box. See
"Defining Chart Settings"
on page 163.
Keysight U4301 PCIe Gen3 Analyzer User's Guide