UDP Ethernet bandwidth vs global memory bandwidth usage

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UDP Ethernet bandwidth vs global memory bandwidth usage

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ericb
Contributor II

Dear all,

 

The bandwidth of the Ethernet seems to be limited by the global memory bandwidth usage!

 

Known issue:

The Ethernet bandwidth is limited to 470 Mb/s with the Imx6q.

 

My project description:

With the 3 first cores, I do a video process which uses memory and neon instructions.

With the last core, I send data through the UDP Ethernet.

 

Problem description:

More the video process uses the global memory (200 to 600 MB/s), more the Ethernet bandwidth decreases (430 to 150 Mb/s).

Note: the same video process with small part of memory (in this case, data should be in cache), doesn't decrease the Ethernet bandwidth (always 416 Mb/s) (the same cpu usage, but low global memory usage).

 

Configuration:

BoundaryDevices Nitrogen6X

Memory 1GBytes of 64-bit wide DDR3 @ 532MHz

Ubuntu L3.0.35_4.0.0_UBUNTU_RFS / LTIB 4.0.0 / or LTIB 4.1.0

 

I have written a simple test (code attached):

-    3 cores copy memory: 10 MB of data, by block of 64 kB. The memory bandwidth is measured and limited to a desired value for the test.

-    1 core sends udp packets (1472 bytes) : after 10s, the Ethernet bandwidth is calculated

 

6276_6276.jpgTestUdpCores.jpg

 

1 thread memory bandwidth (MB/s)

Threads count

Total memory bandwidth (MB/s)

Measured Ethernet bandwidth (Mb/s)

Cpu usage (%)

0

3

0

438

5

1

3

3

434

7

5

3

15

429

10

10

3

30

424

11

20

3

60

417

12

50

3

150

400

20

100

3

300

379

35

150

3

450

365

46

200

3

600

341

62

250

3

750

279

73

300

3

900

210

84

400

3

1200

151

94

max

3

max

149

98


 

 

6275_6275.pngpastedImage_19.png

 

 

Result:

The bandwidth of the Ethernet depends of the global memory bandwidth usage.

- No memory usage: Ethernet bandwidth 438 Mb/s

- Max memory usage: Ethernet bandwidth 149 Mb/s

 

For my project, I really need the max of Ethernet bandwidth. I have spent many to time to adjust socket options, threads priority, the BSP versions,…, without improvement.

Is there any idea to help me go on?

Thank you very much.

Original Attachment has been moved to: TestUdp.tar.gz

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BiyongSUN
NXP Employee
NXP Employee

Please check the Chip Errata. It is long time ago, file the errata in document.

ERR004512 ENET: 1 Gb Ethernet MAC (ENET) system limitation

Untitled.png

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YixingKong
Senior Contributor IV

Ericb

This discussion is closed since no activity. If you still need help, please feel free to reply with an update to this discussion, or create another discussion.

Thanks,

Yixing

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justinfarrellya
Contributor III

Yixing - did a solution to this problem become discovered? We are having the same issue. We have a memory to memory copy that is then ported to the Ethernet causing a slowdown in the overall bandwidth exactly as in the case described here. We need to get a fix for this.....

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ericb
Contributor II

Is someone can confirm this Ethernet problem with the imx6 ?

It will help me to know if I do something wrong or if the problem is hardware/software.

In advance thank you.

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YixingKong
Senior Contributor IV

Ericb

We have not got your response yet and will close the discussion in 3 days. If you still need help, please feel free to reply with an update to this discussion.

Thanks,

Yixing

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YixingKong
Senior Contributor IV

Ericb

We are sorry for getting back to you so late. Are you still stuck with the issue? If you have somehow to resolved the

issue, can we close the discussion? If you still need help, please feel free to reply with an update to this discussion.

Thanks,
Yixing

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