Linux powersaving tunables

Linux offers many powersaving features but you have to know where to look to enable these features. There is a wealth of information over at LessWatts.org. I have greatly reduced my power consumption by implementing many of their tips. The first place you should start is by enabling cpufreq. This is probably the number one powersaving feature. I would also enable dynticks in the kernel. To get a better idea of how much power you are using make sure to enable the powertop interface in the kernel. Then there are many tunable powersaving features that you can manipulate from userland. Here are examples that I have used.

hal-disable-polling --device /dev/hda

Disables polling of your cdrom drive but without it most drives will not automatically recognize when a CD/DVD is inserted.

echo 5 > /sys/bus/pci/drivers/iwl3945/0000\:03\:00.0/power_level

Turns on powersaving features of the intel 3945 wireless card. Some people have reported that it can cause problems with staying connected to access points. I haven't had much trouble with it.

hdparm -B 1 -S 12 /dev/sda

Enables aggressive powersaving on the hard drive.

echo 1 > /sys/devices/system/cpu/sched_mc_power_savings

Increases CPU idle time which allows you to acheive lower power states.

echo min_power > /sys/class/scsi_host/host0/link_power_management_policy

Enables power managment for SATA.

echo 1500 > /proc/sys/vm/dirty_writeback_centisecs

Increases dirty VM writeback time which allows your HDD to stay spun down for longer periods of time.

In addition to these features the cpufreqd, laptop-mode, and powersave daemons all can help lower your wattage.

Linux powersaving tunables

Linux offers many powersaving features but you have to know where to look to enable these features. There is a wealth of information over at LessWatts.org. I have greatly reduced my power consumption by implementing many of their tips. The first place you should start is by enabling cpufreq. This is probably the number one powersaving feature. I would also enable dynticks in the kernel. To get a better idea of how much power you are using make sure to enable the powertop interface in the kernel. Then there are many tunable powersaving features that you can manipulate from userland. Here are examples that I have used.

hal-disable-polling --device /dev/hda

Disables polling of your cdrom drive but without it most drives will not automatically recognize when a CD/DVD is inserted.

echo 5 > /sys/bus/pci/drivers/iwl3945/0000\:03\:00.0/power_level

Turns on powersaving features of the intel 3945 wireless card. Some people have reported that it can cause problems with staying connected to access points. I haven't had much trouble with it.

hdparm -B 1 -S 12 /dev/sda

Enables aggressive powersaving on the hard drive.

echo 1 > /sys/devices/system/cpu/sched_mc_power_savings

Increases CPU idle time which allows you to acheive lower power states.

echo min_power > /sys/class/scsi_host/host0/link_power_management_policy

Enables power managment for SATA.

echo 1500 > /proc/sys/vm/dirty_writeback_centisecs

Increases dirty VM writeback time which allows your HDD to stay spun down for longer periods of time.

In addition to these features the cpufreqd, laptop-mode, and powersave daemons all can help lower your wattage.