Le 13/05/2016 18:45, Rick Stevens a écrit :
On 05/13/2016 02:12 AM, François Patte wrote:
Bonjour,
The issue now is about wifi connections and usb (!!)
If I plug an external usb harddrive, the wifi connection becomes awfull: I tested the rate of transfert from one computer to my updated laptop, using this:
dd if=/dev/zero of=test bs=100M count=1; scp test me@laptop:/dev/null;
Without any usb hdd plugged, the rate begins at 4.7MB/s and falls down to 2.4MB/s which is acceptable I think.
With an usb hdd plugged (I tested with several devices), the rate quickly falls down to 100KB/s sometimes to 20KB/s and sometimes remains completely stalled. Moreover, the wifi connection is very often disconnected (even when there is no tranfert of data at all).
It is not uncommon for a laptop's wifi to be on the USB bus. My Dell laptop does precisely this (it is on one of the EHCI controllers).
Yes, it is a laptop Dell (latitude e6540)
Why do I think that it an update issue?: 1- because this behaviour did not happen before the update... 2- I have another laptop (exacttly the same, same brand, same model) which I did not update and this issue does not happen!
which of these packages could be responsible for this issue? I can exclude the kernel, because I tested the problem with the previous one (4.4.6) and NetworkManager* because I downgraded them.
There was a kernel 4.4.7-300 between 4.4.6 and 4.4.8. Did you test it? Try rebooting into as many of your older kernels as you have and do the test.
If the problem only appears on the 4.4.8 kernel, then my guess is that kernel-modules for kernel 4.4.8-300 is the issue since that's where the USB network and (some) disk drivers come from. I doubt if network manager has anything to do with the problem as it simply manages connections and has nothing to do with USB bus contention (which is what you're probably seeing).
The problem is the same with all kernels: as soon as a hdd is plugged in an usb port, the rate slows down and even the wifi connection stops. So it is not a kernel modules problem.