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Good afternoon, I recently installed Debian Wheezy (7.0) on a freescale board (SABRE MCIMX6Q / iMX6Q) and discovered some disturbing lags for all network communications.

What I have tried so far was to set the network configuration in /etc/network/interfaces to static values instead of DHCP and I checked the OS load as well:

13:20:51 up 31 min, 2 users, load average: 4.75, 4.67, 3.89

The top command may consume up to 15% CPU which seems very high as well. For the OS installation we used a pre-built u-boot.bin, uImage and a Wheezy RootFS (Hard-Float).

Kernel which was compiled for wrong hardware by any chance?

Whereas other network members have low response times, this one lags even when pinging a machine on the same network, here is a short excerpt of the output of a ping command:

enter image description here

And below is the board, perhaps it's a specific problem.

enter image description here

Full size image here: https://i.sstatic.net/EWvR7.jpg

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    Is the load always so high? a 4+ load seems awfully high for such a little device. Seems like it's doing something else, which might be why the network is slow.
    – slm
    Commented Aug 28, 2013 at 16:23
  • Shortly after the boot (5-10 minutes) it goes up quite a lot yes. What came into my mind was probably it's sort of caching on the SD card that slows down the entire OS? The file system is some older EXT2. Do you have an idea what else I could check in order to find the root of my problem? Btw: It was said this board has a dual-core CPU, so in theory it's way more powerful to the other boards we installed in the past few weeks, but I never encountered such massive lags.
    – beta
    Commented Aug 28, 2013 at 21:27
  • 05:25:46 up 3 min, 1 user, load average: 4.61, 2.38, 0.96
    – beta
    Commented Aug 29, 2013 at 5:26

1 Answer 1

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I found this thread in the freescale community forums titled: Slow Network on SABRE iMX6Q. The thread suggested trying the following:

(adding "enable_wait_mode=off" in the bootargs of U-boot)

That thread also referenced another one titled: i.MX6Q SabreSD Catastrophic Ethernet Latencies, which sounds like exactly the issue you're having. Several people in the 2nd thread reported that this fixed the latency issue, so hopefully it will work for you as well.

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  • Oh wow this did the trick - Thanks a bunch!
    – beta
    Commented Aug 29, 2013 at 12:53
  • Absolutely, I added the board's name to the first post. Thanks again!
    – beta
    Commented Aug 29, 2013 at 13:08

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