Difference between revisions of "Laptop"

Revision as of 06:09, 20 February 2013

zh-CN:Laptop

Setting Up For Laptops

This page should contain links to pages needed for configuring a laptop for the best experience. Setting up a laptop is in many ways the same as setting up a desktop. However, there are a few key differences. When setting up a laptop with Arch Linux, the following points should be taken into consideration:

• #Power Management Power Management for laptops refers to optimizing the system to last as long as possible on a single battery charge. This can be accomplished by a variety of tweaks.
  • #Suspend and Hibernate : the operating system can be manually suspended either to memory or to disk, allowing for an (almost) complete shutdown of other hardware.
  • Hard drive spindown : the system can be configured to automatically turn off the hard disk after a specified interval of inactivity.
  • Screen shut off : the laptop screen can be configured to automatically turn off after a specified interval of inactivity (not just blanked with a screensaver but completely shut off).
  • CPU frequency scaling : the processor(s) can be configured to automatically step down to a lower frequency at lower loads.

• #Screen brightness. How do I manage screen brightness?
• Network and wireless setup is described in Wireless Setup.
• Media buttons can be configured as described in Extra Keyboard Keys.
• #Touchpad sensitivity, acceleration, button function and scroll borders can be configured for some (Synaptics or Alps) touchpads.
• #Hard disk shock protection

All of these points are important to take into consideration when getting a laptop set up the way you like. Fortunately, Arch Linux provides all the tools and programs necessary to take complete control of your laptop. These programs and utilities are highlighted below, with appropriate tips tutorials.

Power Management

Power management is very important for anyone who wishes to make good use of their battery capacity. The following tools and programs help to increase battery life and keep your laptop cool and quiet.

Battery State

Udev events

When battery charges/discharges it sends events which can be handled by udev. Example of how it could be used is presented below.

Low charge action

By default, system won't do anything if your laptop's battery is going to discharge. In order not to lose all unsaved work this example udev rule could be used:

/etc/udev/rules.d/lowbat.rules

## SLEEP IF BATTERY IS LOW
SUBSYSTEM=="power_supply", ATTR{status}=="Discharging", ATTR{capacity}=="2", RUN+="/usr/bin/systemctl suspend"

Likewise, the rule can be customized to perform other action on different status.

Utilities

Battery state can be read using ACPI utilities from the terminal. ACPI command line utilities are provided via the acpi package. A simple battery monitor that sits in the system tray is batterymon-clone^AUR which can be found in the AUR.

• batti is a simple battery monitor for the system tray, similar to batterymon-clone. Unlike the latter batti uses UPower, and if that is missing DeviceKit.Power, for it's power information.

Suspend and Hibernate

Manually suspending the operating system, either to memory (standby) or to disk (hibernate) sometimes provides the most efficient way to optimize battery life, depending on the usage pattern of the laptop. While there is relatively straightforward support in the linux kernel to support these operations, typically some adjustments have to be made before initiating these operations (typically due to problematic drivers, modules or hardware). The following tools provide wrappers around the kernel interfaces to suspend/resume :

• Acpid
• Pm-utils
• Uswsusp

which are described in more detail in Suspend.

Power saving

See the main article, power saving.

Automatic tweaks for battery life

As opposed to manually initiated actions like suspend/hibernate, a number of tweaks can be made to prolong the battery life of the laptop under low/idle usage.

• CPU Frequency Scaling is a technology used primarily by notebooks which enables the OS to scale the CPU frequency up or down, depending on the current system load and/or power scheme.
• Laptop Mode Tools provides a comprehensive suite of tools to tweak a large number of power saving settings through well documented configuration files.
• Powertop is a handy utility from Intel that displays which hardware/processes are using the most power on your system, and provides instructions on how to stop or remove power-wasting services. Works great for mobile Intel CPUs; provides the current CPU state and suggestions for power saving. Also works on AMD systems, but does not provide as much information about the CPU state.

The following options are specific to certain laptop types:

• Lapsus is a set of programs providing easy access to many features of various laptops. It currently supports most features provided by asus-laptop kernel module from ACPI4Asus project, such as additional LEDs, hotkeys, backlight control etc. It also has support for some IBM laptops features provided by IBM ThinkPad ACPI Extras Driver and NVRAM device.
• Battery tweaks for Thinkpads can be found in the tp_smapi article.
• TLP for Thinkpads is a set of scripts, which set many powersaving options according to the current Powersource. TLP is intended to be used on Thinkpads, but most settings should work on other laptops too.

PCI-e ASPM

On some laptops, powertop suggests enabling the CONFIG_PCIEASPM kernel option. It can be found under "Bus options (PCI etc.)"->"PCI Express ASPM support". This option is marked as experimental in the current kernel (2.6.35) and allows the PCI-e links to enter a power saving state.

According to [1], this option might degrade performance a bit, but on an Acer 3820TG laptop, it can reduce power consumption by about one third or even more.

More experience with this setting would be appreciated, so please share them here!

It seems like the option is going to be enabled by default in kernel 2.6.36; if so, the information here will be obsolete soon. However, if your system should be able to make use of this power management feature but you are receiving messages like like the following (check /var/log/everything.log*):

disabling ASPM on pre-1.1 PCI-e device.  You can enable it with 'pcie_aspm=force'

then add pcie_aspm=force to your kernel command line.

Granola

Granola is a daemon that monitors the cpu usage and uses the cpufreq-userspace module to lessen power usage without any noticeable difference in performance. To use it, first install from the AUR:[2], the default settings will work for most setups. You will need to load the cpufreq_userspace module, as well as the cpufreq scaling governor for your CPU at startup. Edit /etc/rc.conf: For most generic cpus:

 MODULES=( ... cpufreq_userspace acpi-cpufreq ... )

For Intel Atom or Pentium 4 cpus:

 MODULES=( ... cpufreq_userspace p4_clockmod ... )

Then add Granola to the DAEMONS array:

 DAEMONS=( ... granola ... )

and reboot.

To test if it worked, run:

 cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
 #OR
 cpufreq-info #if you have cpufreq-utils installed

and check that the cpu frequency is below maximum.

WLAN-device

When often en route working with your Notebook without WLAN-Access around, it might be expedient to add a little script to your system startup that automatically turns off your WLAN-Hardware to keep it from searching for Access Points and wasting power on this, when not connected:

#!/bin/bash

essid="`iwconfig wlan0 | grep ESSID | awk {'print $4'}`"
	if [ "$essid" == "ESSID:off/any" ] ; then
		sudo iwconfig wlan0 txpower off
	fi

[edit, if wlan0 is not your WLAN-device]

Start the script according to your DE/WM options by '(sleep xx && /path/to/script)' depending on how long it usually takes to connect to your Access Point, 60 seconds are a good default value. It will check if you're connected, turning off the device if not.

sudo iwconfig wlan0 txpower on

will bring it back up, as, of course, a reboot will.

Disk-related tweaks

Disable file access time: every time you access (read) a file the filesystem writes an access time to the file metadata. You can disable this on individual files by using the chattr command, or you can enable it on an entire disk by setting the noatime option in your fstab, as follows:

/dev/sda1          /          ext3          defaults,noatime          1  2

Source

To allow the CD/DVD rom to spin down after a while using udisks:

# udisks --inhibit-polling /dev/sr0

More tweaks

These are some generic suggestions that will work with most laptops.

Add the following to /etc/modprobe.d/modprobe.conf:

options usbcore autosuspend=1

Add the following to /etc/sysctl.conf

vm.dirty_writeback_centisecs=1500
vm.laptop_mode=5

Add the following to /etc/rc.local (and make sure it gets executed at boot time)

/usr/sbin/iwpriv your_wireless_interface set_power 5

Source: here

Hard drive spin down problem

Documented here

To prevent your laptop hard drive from spinning down too often (result of too aggressive APM defaults) do the following:

Add the following to /etc/rc.local

hdparm -B 254 /dev/sdX where X is your hard drive device

You can also set it to 255 to completely disable spinning down. You may wish to set a lower value if you move your laptop around as lower values park the heads more often and reduce the chance of damage to your hard disk while it is being moved. If you do not move your laptop at all when you are using it, then 255 or 254 is probably best. If you do, then you might want to try a lower value. A value like 128 might be a good middle-ground.

Add the following to /etc/pm/sleep.d/50-hdparm_pm

#!/bin/sh
 
if [ -n "$1" ] && ([ "$1" = "resume" ] || [ "$1" = "thaw" ]); then
	hdparm -B 254 /dev/your-hard-drive > /dev/null
fi

and run chmod +x /etc/pm/sleep.d/50-hdparm_pm to make sure it resets after suspend. Again, you can change the value 254 as you see fit.

Now the APM level should be set for your hard drive.

For some laptops, the option -S to hdparm can also be relevant (sets the spindown time for the drive). Note that all these options can also be configured using the laptop-mode tools. This will allow you to set a high value when on AC and a lower value when you are running on battery power.

Using a script and an udev rule

Since systemd users can suspend and hibernate through systemctl suspend or systemctl hibernate and handle acpi events with /etc/systemd/logind.conf, it might be interesting to remove pm-utils and acpid. Now, there's just one thing systemd can't do (at this time of writing): powermanagement, depending on whether the system is running on AC or battery. To fill this gap, one can create a single udev rule that launches a script when the laptop is unplugged and plugged:

/etc/udev/rules.d/powersave

SUBSYSTEM=="power_supply", ATTR{online}=="0", RUN+="/path/to/your/script true"
SUBSYSTEM=="power_supply", ATTR{online}=="1", RUN+="/path/to/your/script false"

Examples of powersave scripts can be found here: [3] (or in aur: powerdown^AUR), here: [4] and there: [5].

The above udev rule should work as expected, but if your power settings aren't updated after a suspend or hibernate cycle, you should add a script in /usr/lib/systemd/system-sleep/ with the following contents:

/usr/lib/systemd/system-sleep/00powersave

#!/bin/sh

case $1 in
    pre) /path/to/your/script false ;;
    post)       
	if cat /sys/class/power_supply/AC0/online | grep 0 > /dev/null 2>&1
	then
    		/path/to/your/script true	
	else
    		/path/to/your/script false
	fi
    ;;
esac'
exit 0

Don't forget to make it executable!

Now you don't need pm-utils anymore. Depending on your configuration, it may be a dependency of some other package. If you wish to remove it anyway, run pacman -Rdd pm-utils.

Screen brightness

To change your display brightness, first check /sys/class/backlight:

   # ls /sys/class/backlight/
   intel_backlight

So this particular backlight is managed by an Intel card. Keep in mind that different cards might manage this differently! It is called acpi_video0 on an ATI card, for instance.

Check current value:

   $ cat /sys/class/backlight/intel_backlight/brightness

In this case, the backlight managed by echoing values into /sys/class/backlight/intel_backlight/brightness:

   # echo "400" > /sys/class/backlight/intel_backlight/brightness

If you get a response along the lines of "invalid argument" then you didn't honor the maximum brightness. Obviously you cannot go any higher than your screens maximum brightness. The values for maximum brightness and brightness in general vary wildly among cards. This Intel card, for instance, can go up to 976 while the ATI can go up 9. Obviously these values don't say anything about maximum effective brightness.

Check your maximum brightness:

   $ cat /sys/class/backlight/intel_backlight/max_brightness

If your laptop's Fn keys don't work or Gnome/KDE fail to correctly set the brightness using their power daemons, you can try appending acpi_backlight=vendor to your kernel line in your bootloader.

setpci fallback method

On some laptops, the above methods do not actually change screen brightness. If this is the case for your laptop, first find the domain and bus using lspci:

   $ lspci
   (...)
   00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09)
   (...)

Now use setpci to change the value at slot F4 to, say, a0:

   # setpci -s 00:02.0 f4.b=a0

The .b indicates a byte value; this runs in hexadecimal from 00 to ff. ff Is usually the brightest, although this may be reversed. See here for a script which can be used with brightness keys.

Touchpad

To get your touchpad working properly, see the Touchpad Synaptics page. Note that your laptop may have an ALPS touchpad (such as the DELL Inspiron 6000), and not a Synaptics touchpad. In either case, see the link above.

Hard disk shock protection

There are several laptops from different vendors featuring shock protection capabilities. As manufacturers have refused to support open source development of the required software components so far, Linux support for shock protection varies considerably between different hardware implementations.

Currently, two projects, named HDAPS and hpfall, support this kind of protection. HDAPS is for IBM/Lenovo Thinkpads and hpfall for HP/Compaq laptops

Just Check Hard Disk Active Protection System. hpfall^AUR can be installed from the AUR.

Network Time Syncing

For a laptop, it may be a good idea to use Chrony as an alternative to NTPd to sync your clock over the network. Chrony is designed to work well even on systems with no permanent network connection (such as laptops), and is capable of much faster time synchronisation than standard ntp. Chrony has several advantages when used in systems running on virtual machines, such as a larger range for frequency correction to help correct quickly drifting clocks, and better response to rapid changes in the clock frequency. It also has a smaller memory footprint and no unnecessary process wakeups, improving power efficiency.

See also

• http://www.linux-on-laptops.com/
• http://www.linlap.com/