slackware power management on laptops
 

I've got a new netbook - Dell Inspiron mini 1011. I have installed slackware 13 on it. According to dell's website its battery should last up to 9 hours:
I understand that it depends on a variety of factors and these are just testing estimations that will probably never be achieved IRL.

For 95% of the time I don't run X on it. Just emacs (gnus), nethack, elinks. If I do run X, it's fluxbox. The average battery time is 2hrs - 2.5hrs. I understand that Slackware 13 is not designed specifically for netbooks, but 2hrs is way off the 9-hour estimation. Either the battery is faulty, or it's the power management issue.
Before I deal with the battery, I'd like to ask you for some suggestions on improving the power management.
The acpi and acpid are installed on the system. Are there any packages that would improve the battery performance? Or perhaps some config options?
I believe that recompiling the kernel would improve it, wouldn't it? What options I'd have to set/unset?

P.S.Unfortunately, once I checked the netbook is ok, I removed WinXP that came with it, so can't compare with it.

Thank you

Try what happens if you run X for a while... KDE and XFCE come wih a power management daemon which should give you better battery time. If indeed that is what you will see, then at least you know that it is possible. Next step would be to look into tweaking power management from the console. Two hours is way too low, you should be able to get around the same battery time in Slackware 13.0 as with Windows.

Eric

Thanks for your reply. I started X with xfce (I didn't install KDE) Before I unplugged the power cable, I checked and the battery was 100% charged. After unplugging the cable, the battery said: Estimated time left 2hrs 25 minutes.

Hi,
You might look into powertop as a place to start.

I believe the Xfce or KDE power management daemons will revise their estimate as time goes on, so I would do a full charge, start Xfce, and then use the laptop for while and see if it really runs down at 2:25. I would also recommend powertop to reduce power usage.

Ultimately, the laptop and BIOS manufacturers tweak things specifically for Windows, and Microsoft/Windows has access to proprietary hardware and BIOS information that Linux does not, so there are some software tweaks in Windows that improve battery life. As a result, I have generally found that Windows' battery life is longer than that on Linux and there's not much that can be done unless those manufacturers openly release that same info.

I am beginning to think that your battery actually is lasting for 2.5 hours only after a full charge. The web site may be incorrect about the battery - you can check the capacity which is written on the battery (mAh value) and report that here. Perhaps your netbook is equipped with a smaller-capacity battery than you thought.

Eric

Thanks for all your answers.

After leaving it for a minute or so it actually increased by 10 minutes. I haven't checked the powertop software yet, as I am afraid it wouldn't help much. I borrowed a windows XP CD from my neighbour and installed it along with any drivers/utilities for this netbook from dell's website. It also said 2.5hrs!!!
I'm afraid it might be the case. The battery says 11.1V Capacity 24Wh, min. 2.1Ah.
The output of acpi -V is as follows:
What does it mean for me?

It appears you have the smaller 24 Wh 3 cell battery and 2 to 2 1/2 hrs is about right for those. According to my Google-fu, Dell also sells a larger capacity 56Wh battery that provides about 8 hrs life for that particular model but by default, it ships with the 3 cell battery.

Well, you could turn on CPU frequency scaling.

echo ondemand > /sys/devices/system/cpu0/cpufreq/scaling_governor
echo ondemand > /sys/devices/system/cpu1/cpufreq/scaling_governor
...

Do it for each CPU you find in /sys/devices/system.

If the cpufreq directories don't exist, then you need to load the appropriate kernel module. It's acpi-cpufreq for Intel's CPUs and powernow-k8 for AMD's.

Crafty ba...rds!!! I bought it in store and remember the tag did say up to 8 hrs. There was a discount on this netbook, though. Now I know why.

Thanks for your help.

It is tricky to separate the marketing hype from the truth as I discovered when shopping last year for a netbook for my wife. The "standard" battery is usually a smaller capacity than the advertised optimal specifications. Buyer beware and all that. These days, KDE/XFCE etc with the newer 2.6.x kernels do a much better job if you do a bit of tweaking. On the MSI netbook (Atom CPU, intel GPU) I can get about 70-80% of rated battery life (WinXP or Slack32) and on my work Dell Latitude (Dual core Intel, intel GPU) I average about 2.5-3 hrs (about 70% of rated time). With either laptop, with either OS, to get anywhere near the advertised battery life, I have to turn off bluetooth, turn off wifi, turn off/dim the LCD backlight, and make sure the CPU is throttled back (of turn off one core) and pretty much not use it!.

So when I read the battery specification claims, I just chuckle. In real world usage, you'll be lucky to get 50% of the rated life. Although, to be fair, the MSI netbook does a fair job as it does get 6-7 hrs in use (rated at 9 hrs.).

Just my 2 cents.

Thanks, I have appended it to those file. Upon rebooting the system it doesn't seem to make any difference.

At work I've got an HP laptop (some business model, don't remember now) running XP - its battery is a real beast - On a few occasions I did almost a full day of work on battery.

Nevermind, I'll go to the store and try to argue the case.

I have the same computer

The Inspiron 1011 is actually the Mini 10v, not the Mini 10.
If you have the 3-cell battery, then 2 1/2 hours is normal (on both Linux and Windows)

An easy way to tell if you have the 3-Cell battery is your Mini 10v will lay flat when you set it down. The 6-cell battery sticks out a little and acts like a mini stand:
http://mattsshack.com/wp-content/upl.../Profile-2.jpg

Thanks for the photo. Yep, definitely I've got a 3-cell battery:(