OpenWrt/LEDE Project

  • Status Closed
  • Percent Complete
  • Task Type Bug Report
  • Category Base system
  • Assigned To
    Alexander Couzens
  • Operating System All
  • Severity Medium
  • Priority Medium
  • Reported Version Trunk
  • Due in Version Undecided
  • Due Date Undecided
  • Private
Attached to Project: OpenWrt/LEDE Project
Opened by Alexander Couzens - 20.08.2016
Last edited by Mathias Kresin - 28.07.2018

FS#105 - lantiq: high latency on adsl lines using pppo[ae]

based on the thread
[LEDE-DEV] [OpenWrt-Devel] latency on PPPoA ADSL Annex A on using Lantiq

When using ssh onto the box via adsl, there is a high latency.
The last 3.18 version of lede works. Known good:

  • 161179f40bd7899516518f3844fea28c6dd86efc r47130

Known broken versions:

  • 2795592d913ba8ba57ba537d40714407ea463426 r47131
  • 2a0e1b7f8d59f795abb29d20007822f0da232c43 r47958

mkresin also has a patch for lantiq+4.0, which also has a high latency.
blogic mentioned linux commit 7424ce65065852bdf7a040bf2490da4a8fc4b464 [atm] switch vcc_sendmsg() to copy_from_iter() could be the issue.

Also an interesting side-effect. setup a uhttpd on the device and serve a file to the internet is very slow (using 4mb file random data). it only uploads 5kb/s

Closed by  Mathias Kresin
28.07.2018 11:53
Reason for closing:  Fixed
Project Manager
Alexander Couzens commented on 21.08.2016 00:01

on 3.18 it's still slow (20kb/s) on rev47130

Anonymous Submitter commented on 21.08.2016 09:13

Noticed & posted on the forum about this a while back: The problem has been around a while :-)

Project Manager
Mathias Kresin commented on 21.08.2016 10:28

@alexander The upload from LEDE r354 to wan (HTTP, IPv6) is fine with VDSL (ptm):

5.242.880   1,10M/s   in 4,6s

Near to the theoretical maximum of my 10 MBit upload.

Project Manager
Felix Fietkau commented on 19.01.2017 13:54

Please test if the issue still exists in the latest version

Andy Botting commented on 20.01.2017 01:21

Seems much better to me on ADSL

Samuel Smith commented on 20.01.2017 10:00

@andy, what hardware and which revision are you using, because I am still experiencing problems?

Andy Botting commented on 20.01.2017 11:20

I'm using ada6d9fecaf5147db51b7f27c548eb66590d8500 (+ Enable SMP for XRX200 patch) on a TP-Link TD-W8970.

My ADSL is slow, so the difference isn't quite so great, but by SSH connection to it from over the wan is now usable. Not great, but usable.

Jim Gettys commented on 21.01.2017 14:14

Did the lantiq driver get some bufferbloat debloating love?

When I last looked at it maybe 3 years ago, it had 128 packets of buffering in its ring buffering. This can cause really large amounts of latency any time the link saturates.

DSL needs something equivalent to the BQL algorithm used on ethernet to keep the ring buffer size no more than necessary for the bandwidth. Unfortunately, it was never feasible for me to go further in and try to fix it.

Andy Botting commented on 06.02.2017 03:55

@samuel, looks like I am experiencing some latency issues connecting in via the WAN. Was had to notice before because my ADSL is slow

Project Manager
Alexander Couzens commented on 18.02.2017 16:15

@nbd: can you explain what changed or better which commit could do here any improvements?

Project Manager
Felix Fietkau commented on 18.02.2017 17:36

No idea

Anonymous Submitter commented on 19.02.2017 10:30

Is this similar to my experience reported ?

TL;DR - traffic through the router is fine, originating from router to 'internet' is severely rate limited.

If so, I have a DGN3500 here and I may be able to ask a local ISP to put it on a test ADSL line....ssh access etc if it would help anyone. Unfortunately I upgraded to VDSL2 so can no longer use my own line for testing with the device.

Project Manager
Alexander Couzens commented on 28.05.2017 03:28

i've worked on the lantiq kgdboc support. k(g)db over serial is working now.
next task: fix ftrace on lantiq. #153

Black Raven commented on 23.10.2017 10:41

I have found this thread, seems to be related to my problem.

The lag on SSH connection (every key pressed in the SSH session has noticeable lag about 500-1000 ms) makes typing very annoying.
Even loading more complex luci web pages over https like firewall configuration page is very slow and loading takes many seconds (cca 1 configuration line per second).
Let's encrypt acme service is unable to verify my domain because of timeouts.

Guys, please help me to recover full speed access to my router.

Project Manager
Alexander Couzens commented on 02.01.2018 16:00

patch is prepared to be send to the ML

Black Raven commented on 04.01.2018 06:58

Thank you very much Alexander.
Looking forward to a new release which includes the fix.

Project Manager
Alexander Couzens commented on 06.01.2018 15:30

attached patch

Project Manager
Alexander Couzens commented on 06.02.2018 20:52

The patch has been merged. Waiting one week until I want to merge it into stable.


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