In my last blog post, Data Communication in MIMO Radar Systems, I gave an overview of the communication buses available in MicroTCA systems, but I left out any performance figures that can be achieved using one bus or the other. In this blog post, I’ll give you an idea of the throughputs that can possibly be achieved in a MicroTCA systems based on Nutaq’s products: the µDigitizer, the µSDR420, the PicoSDR, and the upcoming PicoDigitizer.
Gigabit Ethernet
In the first two gigabit Ethernet scenarios, a host PC is connected with a Perseus AMC through a gigabit Ethernet connection. The FPGA code loaded in the Perseus V6 FPGA is represented in the diagram below.
Figure1: First Gigabit Ethernet example diagram
Test 1: Data transfer from a Host computer to a Perseus AMC on 1 channel
|
Host Peer Scenario |
Windows 7, 64 Bits |
Linux, 64 Bits |
||
|
Host to Perseus on 1 channel |
Normal frames (1472 bytes) |
Number of packets |
102400 |
102400 |
|
Transfer size (in MB) |
143.75 |
143.75 |
||
|
Throughput (MB/s) |
12.6 |
114.0 |
||
|
Jumbo frames (8960 bytes) |
Number of packets |
16384 |
16384 |
|
|
Transfer size (in MB) |
140 |
140 |
||
|
Throughput (MB/s) |
54.7 |
116.7 |
||
Test 2: Data transfer from a Perseus AMC to a Host computer on 1 channel
|
Host Peer Scenario |
Windows 7, 64 Bits |
Linux, 64 Bits |
||
|
Perseus to host on 1 channel |
Normal frames (1472 bytes) |
Number of packets |
102400 |
102400 |
|
Transfer size (in MB) |
143.75 |
143.75 |
||
|
Frame gap used |
10000 |
0 |
||
|
Throughput (MB/s) |
13.5 |
114.0 |
||
|
Jumbo frames (8960 bytes) |
Number of packets |
16384 |
16384 |
|
|
Transfer size (in MB) |
140 |
140 |
||
|
Frame gap used |
10000 |
0 |
||
|
Throughput (MB/s) |
70.6 |
116.5 |
||
Looking at the results of the tests performed, we can easily conclude that 64-bit Linux (Fedora 17 distribution) is far more efficient than 64-bits Windows® 7 for gigabit Ethernet communications. This should be considered when designing a MicroTCA system using a host computer and the gigabit Ethernet communication link.
Test 3: Data transfer between two Perseus AMC on 1 channel
This test is independent of the OS used on the host computer setting up the transfers. Once the transfers are set, the host no longer intervenes in the communication process. Below is a diagram showing the hardware setup used and the logic loaded in the V6 FPGA of both Perseus AMCs:
Figure 2: Second Gigabit Ethernet example diagram
The results that follow show that the gigabit Ethernet link is used very efficiently when two Perseus AMCs are using it for communication purposes, since, if we don’t account for the overhead packet data, the available throughput of this bus is 125MB/s.
|
FPGA Peer Scenario |
Any Host |
||
|
Perseus to Perseus on 1 channel |
Normal frames (1472 bytes) |
Number of packets |
102400 |
|
Transfer size (in MB) |
143.75 |
||
|
Throughput (MB/s) |
114.7 |
||
|
Jumbo frames (8960 bytes) |
Number of packets |
16384 |
|
|
Transfer size (in MB) |
140 |
||
|
Throughput (MB/s) |
118.4 |
||
Conclusion
When you put together a MicroTCA system, in addition to taking into account the interconnections of the sub-systems, it is also important to evaluate the amount of data that needs to be exchanged between them. Knowing the throughput needed between specific sub-systems will allow you to choose the communications protocol that meets your needs and then make sure the backplane of the system you’re putting together implements this specific connection.