Broadcom wireless very slow connection speed when on battery power

Captain Quor · 2010-09-11 11:23:24

I've just recently got Arch set up on my laptop (Dell Vostro 1510).

I've got the wireless up and running using the broadcom-wl package from AUR and NetworkManager, it all functions perfectly when the laptop is on mains power but as soon as I unplug the adapter and it switches to battery power my internet connection speed drops sharply, giving me around 0.40Mb/s download instead of the usual 5-6ish, I've looked all over for reports of a similar problem and can't find anything, help!

My card is a Broadcom BCM4312 802.11b/g (rev 01).

Captain Quor · 2010-09-11 14:16:29

Any ideas anyone? I'm assuming it's down to the driver's power management but I have no clue how I can turn it off or alter the way the power management stuff works.

Last edited by Captain Quor (2010-09-13 10:30:48)

Captain Quor · 2010-09-13 10:31:23

*bump*

I'm at a bit of a loss here, any ideas anyone?

stefanwilkens · 2010-09-13 11:06:35

hmm, you can set the power level through iwconfig

you'll have to install wireless_tools:

$ sudo pacman -S wireless_tools

then set the TX power level through iwconfig:

sudo iwconfig eth1 txpower X

you can request the currently set power level with:

sudo iwlist eth1 txpower

stefanwilkens · 2010-09-13 11:10:47

additionally, you can disable power menagement for your wireless card completely through iwconfig's power option. I suggest you read the manpage for iwconfig, I have quotes the 2 related options for you.

txpower
For cards supporting multiple transmit powers, sets the transmit power in dBm. If W is the power in Watt, the power in dBm is P = 30 + 10.log(W). If the value is postfixed by mW, it will be automatically converted to dBm.
In addition, on and off enable and disable the radio, and auto and fixed enable and disable power control (if those features are available).
Examples :
iwconfig eth0 txpower 15
iwconfig eth0 txpower 30mW
iwconfig eth0 txpower auto
iwconfig eth0 txpower off

power
Used to manipulate power management scheme parameters and mode.
To set the period between wake ups, enter period 'value'. To set the timeout before going back to sleep, enter timeout 'value'. You can also add the min and max modifiers. By default, those values are in seconds, append the suffix m or u to specify values in milliseconds or microseconds. Sometimes, those values are without units (number of beacon periods, dwell or similar).
off and on disable and reenable power management. Finally, you may set the power management mode to all (receive all packets), unicast (receive unicast packets only, discard multicast and broadcast) and multicast (receive multicast and broadcast only, discard unicast packets).
Examples :
iwconfig eth0 power period 2
iwconfig eth0 power 500m unicast
iwconfig eth0 power timeout 300u all
iwconfig eth0 power off
iwconfig eth0 power min period 2 power max period 4

website with the current manpage:
http://linux.die.net/man/8/iwconfig

or simply:

$ man iwconfig

Last edited by stefanwilkens (2010-09-13 11:11:37)

Captain Quor · 2010-09-14 07:58:15

I get the following result from sudo iwlist eth1 txpower:

eth1 2 available transmit-powers :
0 dBm (1 mW)
25 dBm (255 mW)
Current Tx-Power:24 dBm (200 mW)

It seems to stay identical when switching between battery and mains power so I'm not sure that this is the problem.

One thing I have noticed is that when connected to the wireless network at work, the overall Mb/s doesn't drop much at all (unlike my home wireless) but my ping goes up by about 60ms or so.

sati · 2010-09-27 00:07:27

I am too experiencing this problem with my wireless card: Broadcom BCM4322.

It has been this way for quite a while now and I have a hunch that it may of occurred during a (fairly) recent kernel update.

I haven't rolled back to an earlier kernel yet to clarify this..if I do I will report back here.

EDIT: Suggest editing /etc/laptop-mode/conf.d/wireless-power.conf & changing WIRELESS_BATT_POWER_SAVING=1 to WIRELESS_BATT_POWER_SAVING=0 and then restart laptop-mode (or reboot).

Seemed to solve the problem for myself..

Last edited by sati (2010-09-27 00:29:22)

agon · 2011-07-12 22:50:25

sati wrote:

EDIT: Suggest editing /etc/laptop-mode/conf.d/wireless-power.conf & changing WIRELESS_BATT_POWER_SAVING=1 to WIRELESS_BATT_POWER_SAVING=0 and then restart laptop-mode (or reboot).

Did the job for me too

EDIT: Woops. Just pumped up an old thread. I'm very sorry!

Last edited by agon (2011-07-12 22:51:36)

Arch Linux

#1 2010-09-11 11:23:24

Broadcom wireless very slow connection speed when on battery power

#2 2010-09-11 14:16:29

Re: Broadcom wireless very slow connection speed when on battery power

#3 2010-09-13 10:31:23

Re: Broadcom wireless very slow connection speed when on battery power

#4 2010-09-13 11:06:35

Re: Broadcom wireless very slow connection speed when on battery power

#5 2010-09-13 11:10:47

Re: Broadcom wireless very slow connection speed when on battery power

#6 2010-09-14 07:58:15

Re: Broadcom wireless very slow connection speed when on battery power

#7 2010-09-27 00:07:27

Re: Broadcom wireless very slow connection speed when on battery power

#8 2011-07-12 22:50:25

Re: Broadcom wireless very slow connection speed when on battery power

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