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.

 Gigabit Ethernet example diagram

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:

 

Diagram hardware setup V6 FPGA 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.