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I’m using Ubuntu 12.10 with 3.5.0-26-generic kernel version. today a system error occurred and the only thing about the error code I can remember was something about power.d.

Since this error occurred, the wifi connection is extremely slow, but only in battery mode. after some research I found that:

sudo iwconfig eth1 power off

... solves the problem, but only for the current session; after a reboot the same error is still there.

Is there any other solution to fix this problem permanently?

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Some days ago, I found the solution for this problem. I changed the following lines in the wireless script in /usr/lib/pm-utils/power.d and it works fine. But since I've made these changes, it seems that the battery did not last as long as before (and not just for 10 minutes...). Is there any other solution? Is there any documentation for the power values that are used in the script?

case $driver in
    ipw2100) iwpriv_ac="set_power 0"
        iwpriv_batt="set_power 0"
        iwconfig_ac="power on"
        iwconfig_batt="power on";;
        iwpriv_ac="set_power 6"
        iwpriv_batt="set_power 6";;
    iwl*) if [ -f "/sys/class/net/$1/device/power_level" ]; then
             iwconfig_ac="power off"
             iwconfig_batt="power off"
    *) iwconfig_ac="power off"
       iwconfig_batt="power off";;

best regards

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You can put an equivalent command into /etc/rc.local, and it will be executed at every boot:

iw dev eth1 set power_save off

As an aside, your command, sudo iwconfig eth1 power off turns off wireless power management for network interface eth1, but requires root permissions. The command that I gave you does the same thing, but does not require root and is hence better for script use.

To test my solution, reboot your laptop and run iwconfig and see if eth1's Power Management field is set to off, like so:

eth2      IEEE 802.11abg  ESSID:"287LyonSt."  
          Mode:Managed  Frequency:2.437 GHz  Access Point: F8:D1:11:9B:89:81   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
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