Fedora Linux

#OPTS='$OPTS -s 0 -i 10 -r'
# uncomment and modify this to check the state of the AC adapter
#OPTS='$OPTS -a /proc/acpi/ac_adapter/*/state'
# uncomment and modify this to check the system temperature
#OPTS='$OPTS -t /proc/acpi/thermal_zone/*/temperature 75'

Usually the DRIVER, VMAJOR, and VMINOR lines should not be changed. 

Uncomment the OPTS lines that contain additional options you wish to use. The pre-configured lines have these meanings:

-n

Allow processes that have been marked as low priority using the nice command to run at full speed. The default is to slow down the processor when only low-priority processes are running.

-s 0 -i 10 -r

Manages only CPU 0 ( -s 0 ), making speed change decisions once a second instead of the default of once every two seconds ( -i 10 ), and restore the original speed when cpuspeed exits ( -r ).

-a /proc/acpi/ac_adapter/*/state

Monitors the AC adapter and switches to minimum speed when AC power is removed. Adding -C will force the system to operate at maximum speed when AC power is connected.

-t /proc/acpi/thermal_zone/*/temperature 75

Watches the system temperature and slows down the CPU when the temperature exceeds 75 degrees Celsius (167 degrees Fahrenheit).

To see a list of all available options, run this command:

$ /usr/sbin/cpuspeed --help 2>&1|less

After editing /etc/cpuspeed , restart the cpuspeed service:

# service cpuspeed restart
Stopping cpuspeed: [ OK ]
Starting cpuspeed: [ OK ]

You can monitor the CPU speed by installing a monitor on your panel. Right-click on your GNOME panel, then select 'Add to Panel.' Choose the CPU Frequency Scaling Monitor and click Add. The icon shown in Figure 3-5 will appear; the bar graph will rise and fall as the CPU clock speed is adjusted, and hovering your mouse cursor over the display will show the current frequency setting (the box that appears below the icon in Figure 3-5).

Figure 3-5. CPU Frequency Scaling Monitor

3.1.1.4. Managing power from the command line

If you are using your system through a text-mode console, you can still access the important power- management tools.

To suspend the system, execute the pm-suspend script:

$ pm-suspend

To hibernate, use the pm-hibernate script:

$ pm-hibernate

To view the battery status, access ACPI through the /proc filesystem:

$ cat /proc/acpi/battery/*/state
present: yes
capacity state: ok
charging state: charging
present rate: 3079 mA
remaining capacity: 2912 mAh
present voltage: 16273 mV

Battery details are also available from ACPI:

$ cat /proc/acpi/battery/*/info
present: yes
design capacity: 6450 mAh
last full capacity: 5154 mAh
battery technology: rechargeable
design voltage: 14800 mV
design capacity warning: 515 mAh
design capacity low: 156 mAh
capacity granularity 1: 5 mAh
capacity granularity 2: 5 mAh
model number: DELL 0017F
serial number: 14639
battery type: LION
OEM info: Sony

By dividing the last full capacity by the design capacity, you can determine the condition of the battery. In this case, the battery can presently store 5154/6450 mAh, or about 80 percent of its design capacity, indicating that it's in reasonably good condition.

3.1.1.5. Other ways to extend battery life

To further reduce power consumption:

? Dim your screen as much as the ambient lighting conditions will allow. The backlight for the screen draws a huge amount of power; one of my systems draws 31 percent more power in total when the screen is at maximum brightness than when it is set to minimum brightness.

? Turn off all unneeded services, reducing CPU and disk activity.

? Use a lightweight desktop environment such as Xfce instead of GNOME or KDE.