Altera V-Series Avalon-MM DMA User Manual
Page 122
Taking into account the overhead from TLP headers, this throughput is approximately 99% of the
maximum theoretical performance.
Using a 64-byte payload, the maximum theoretical throughput is far less due to the increased proportion
of the bandwidth that taken by the TLP headers. The DMA achieves the following throughput:
• 2.0 GBytes/sec back-to-back TX memory write completion
• 2.0 GBytes/sec back-to-back RX read completion throughput
• 2.0 GBytes/sec simultaneous reads and writes
Note: A 64-byte packet is worst-case packet size for Ethernet.
You can choose to include the DMA Descriptor Controller in the Avalon-MM bridge as shown in the
following example. Embedding the DMA Descriptor simplifies the design. Altera recommends that you
embed the DMA Descriptor Controller in the Avalon-MM bridge if you do not plan to modify it. Refer to
Getting Started with the V-Series Avalon-MM DMA for an example that includes the embedded DMA
Descriptor Controller.
Figure 8-4: Avalon-MM DMA Block Diagram with Embedded DMA Descriptor Controller
PCIe Avalon-MM Bridge
Hard IP for PCIe Using Avalon-MM Interface
Altera FPGA
Qsys System
with Internal Descriptor Controller
Memory
Read DMA
Write DMA
Hard IP
for PCIe
RX Master
TX Slave
DMA
Descriptor
Controller
Avalon-MM Burst
Master 256 Bits
Avalon-MM Burst
Master 256 Bits
Avalon-MM Master
Avalon-MM Slave Single DWORD
Avalon-ST Control/Status
Avalon-ST
256 Bits
FIFO
Internal Conduit
UG-01154
2014.12.18
V-Series Avalon-MM DMA for PCI Express
8-9
IP Core Architecture
Altera Corporation