View Full Version : [ubuntu] Disable ethernet port

July 8th, 2009, 12:37 AM
Hi, I am currently troubleshooting a warmer laptop since the upgrade to jaunty. I posted about this in http://ubuntuforums.org/showthread.php?p=7577819#post7577819 but thought i might need its own thread as I think its a separate issue to everyone else there.

I used powertop to see what was using all my power as I have seen reduction in battery life since the upgrade. I get the following

Wakeups-from-idle per second : 175.2 interval: 10.0s
no ACPI power usage estimate available

Top causes for wakeups:
38.2% (100.6) <interrupt> : eth0
16.4% ( 43.2) <kernel IPI> : Rescheduling interrupts
15.9% ( 41.9) firefox-3.5 : futex_wait (hrtimer_wakeup)
10.9% ( 28.6) <interrupt> : extra timer interrupt
4.0% ( 10.5) <interrupt> : pata_amd
3.2% ( 8.4) <interrupt> : PS/2 keyboard/mouse/touchpad
2.4% ( 6.4) <interrupt> : eth1
2.3% ( 6.0) wpa_supplicant : wl_add_timer (wl_timer)
2.2% ( 5.8) <kernel core> : hrtimer_start (tick_sched_timer)
1.0% ( 2.7) compiz.real : schedule_hrtimeout_range (hrtimer_wakeup)
0.7% ( 1.8) <interrupt> : sata_nv, mmc0

As you can see eth0 is the main cause of the wake ups. This is my ethernet port and my wireless is eth1. I want to disable eth0 to see if this reduces the extra heating.

I tried

chris@skint-laptop:~$ sudo ifdown eth0
[sudo] password for chris:
ifdown: interface eth0 not configured

yet it works if i plug in a cable. I have tried the package ifplugd but this does not have an effect either. Looking around on google brought me to http://www.linuxquestions.org/questions/linux-newbie-8/howto-disable-eth0-at-boot-time-65768/ but ubuntu does not seem to have a /etc/sysconfig folder so I am lost. Any ideas how to cut the power to eth0 or at least reduce the wake-ups

July 8th, 2009, 01:07 AM
Btw my current /etc/network/interfaces looks like this

auto lo
iface lo inet loopback

if i could manually disable it from here that would be great