Altera Stratix V Avalon-ST User Manual
Page 23
Parameter
Value
Description
• Minimum RX Buffer credit allocation—configures the
minimum PCIe specification allowed for non-posted and
posted request credits, leaving most of the RX Buffer space
for received completion header and data. Select this option
for variations where application logic generates many read
requests and only infrequently receives single requests
from the PCIe link.
• Low—configures a slightly larger amount of RX Buffer
space for non-posted and posted request credits, but still
dedicates most of the space for received completion header
and data. Select this option for variations where application
logic generates many read requests and infrequently
receives small bursts of requests from the PCIe link. This
option is recommended for typical endpoint applications
where most of the PCIe traffic is generated by a DMA
engine that is located in the endpoint application layer
logic.
• Balanced—configures approximately half the RX Buffer
space to received requests and the other half of the RX
Buffer space to received completions. Select this option for
variations where the received requests and received
completions are roughly equal.
• High—configures most of the RX Buffer space for received
requests and allocates a slightly larger than minimum
amount of space for received completions. Select this
option where most of the PCIe requests are generated by
the other end of the PCIe link and the local application
layer logic only infrequently generates a small burst of read
requests. This option is recommended for typical root port
applications where most of the PCIe traffic is generated by
DMA engines located in the endpoints.
• Maximum—configures the minimum PCIe specification
allowed amount of completion space, leaving most of the
RX Buffer space for received requests. Select this option
when most of the PCIe requests are generated by the other
end of the PCIe link and the local application layer logic
never or only infrequently generates single read requests.
This option is recommended for control and status
endpoint applications that don't generate any PCIe
requests of their own and only are the target of write and
read requests from the root complex.
UG-01097_sriov
2014.12.15
System Settings
3-3
Parameter Settings
Altera Corporation