Le 13/05/2016 23:53, Rick Stevens a écrit : > On 05/13/2016 02:33 PM, François Patte wrote: >> 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) > Ok, it could (and I mean "_could_") be a firmware issue with the > underlying USB hardware. I can only suggest two things at this point. > > Item 1: See if you can plug the HDD into a port that's on a different > USB device on the machine. You can use the "lsusb -t" utility (as root) > to show you a tree of what's on the USB ports. Mine looks like: > > [root@golem4 ~]# lsusb -t > /: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M > /: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M > /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M > |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M > |__ Port 5: Dev 3, If 0, Class=Wireless, Driver=btusb, 12M > |__ Port 5: Dev 3, If 1, Class=Wireless, Driver=btusb, 12M > |__ Port 6: Dev 4, If 0, Class=Vendor Specific Class, Driver=, 480M > /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M > |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M > |__ Port 4: Dev 4, If 0, Class=Video, Driver=uvcvideo, 480M > |__ Port 4: Dev 4, If 1, Class=Video, Driver=uvcvideo, 480M > > The first ehci device has both the bluetooth and wifi on it. The second > ehci device has the webcam on it. Try to plug the HDD into a port > that's not shared with the "wireless" stuff (verify with the lsusb > command). If you can find one, see if that helps. I get exactly the same answer as yours for lsusb -t and the problem remains regardless the usb port where I plug the hdd. But now the problem become worse: with or without a hdd plugged, the wifi connection is unusable because the bitrate falls down in a few seconds (from 4MB/s to 20KB/s and, after that, remains stalled for a long time)... Could it be a hardware problem and, if yes, is there a way to test the integrity of the wifi card? Thank you -- François Patte UFR de mathématiques et informatique Laboratoire CNRS MAP5, UMR 8145 Université Paris Descartes 45, rue des Saints Pères F-75270 Paris Cedex 06 Tél. +33 (0)1 8394 5849 http://www.math-info.univ-paris5.fr/~patte
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