[SOLVED] Wireless slower on battery power?

Deemoney14 · 2011-08-07 00:33:44

My laptop's wireless internet seems to run fine, but when it's on battery power it becomes significantly slower. Like, I can try to load a website on battery, wait a couple of seconds, plug it into AC and reload and it will pop up in a second or less.

I'm afraid this is some stupid built-in power saving feature that's in the BIOS that I don't know how to change, or if I can even change it. If anyone knows what's going on here, I'd appreciate the enlightenment.

For the record, my laptop is a Dell Inspiron N4110, very new.

Some hopefully helpful outputs:

$ lspci
00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 6 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #2 (rev 05)
00:1b.0 Audio device: Intel Corporation 6 Series Chipset Family High Definition Audio Controller (rev 05)
00:1c.0 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 1 (rev b5)
00:1c.2 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 3 (rev b5)
00:1c.4 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 5 (rev b5)
00:1c.5 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 6 (rev b5)
00:1d.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #1 (rev 05)
00:1f.0 ISA bridge: Intel Corporation HM67 Express Chipset Family LPC Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 6 Series Chipset Family 6 port SATA AHCI Controller (rev 05)
00:1f.3 SMBus: Intel Corporation 6 Series Chipset Family SMBus Controller (rev 05)
01:00.0 Network controller: Intel Corporation Centrino Wireless-N 1030 (rev 34)
02:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev 05)

$ iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

wlan0     IEEE 802.11bgn  ESSID:"SLCR"  
          Mode:Managed  Frequency:2.427 GHz  Access Point: 00:1A:70:33:98:AD   
          Bit Rate=54 Mb/s   Tx-Power=15 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=47/70  Signal level=-63 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:1  Invalid misc:779   Missed beacon:0

$ ifconfig
eth0      Link encap:Ethernet  HWaddr 14:FE:B5:B4:AB:00  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:46 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:180 errors:0 dropped:0 overruns:0 frame:0
          TX packets:180 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:14048 (13.7 Kb)  TX bytes:14048 (13.7 Kb)

wlan0     Link encap:Ethernet  HWaddr BC:77:37:DA:5F:7F  
          inet addr:192.168.20.221  Bcast:192.168.20.255  Mask:255.255.255.0
          inet6 addr: fe80::be77:37ff:feda:5f7f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:231192 errors:0 dropped:2219 overruns:0 frame:0
          TX packets:61754 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:140941000 (134.4 Mb)  TX bytes:6792218 (6.4 Mb)

These were all taken while on AC power. At first glance, I don't see any marked changes in the iwconfig or ifconfig output when I unplug the AC adapter. Again, any suggestions are appreciated.

UPDATE: I am an idiot. Apologies, I've been really busy and didn't mean to act like a Help Vampire.

There's a significant difference in the iwconfig when unplugged. Above you see the line:

Power Management:off

When unplugged it becomes:

Power Management:on

Good job me not Googling this problem first and finding a page that links to a page that has a fix for it.

To summarize what I found: pm-utils has a script for wireless management at /usr/lib/pm-utils/power.d/wireless that runs whenever the power state changes. If you create your own "copy" of the file in a different location, like so:

$ sudo touch /etc/pm/power.d/wireless

It will effectively override the wireless power management. In the interest of full disclosure, the answer I found was from people running Ubuntu, I imagine if you're more daring you could just delete the original file outright or neuter it or something, but I like this way since in case my battery life goes to hell I can just delete that file and be back to normal.

Last edited by Deemoney14 (2011-08-07 01:01:25)

Arch Linux

#1 2011-08-07 00:33:44

[SOLVED] Wireless slower on battery power?

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