Squeezing the watts
Saturday, August 4th, 2007 at 3:05 pm
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I’ve written a couple of previous posts about saving power around the office and home, and have been using my Watts-Up Pro power analyzer/data logger to measure every power-enabled device that I use.
In that range, I’ve been tweaking the kernel on my Thinkpad T42p to minimize the power consumption of it during running hours. Here’s some things I’ve found:
Enable these kernel options:
# Set the kernel to only use the CPU speed that is appropriate to the load. # If you're reading email, there's no reason for your 2.4Ghz processor to # be running at that speed, so train it down to 600Mhz instead, etc. CONFIG_CPU_FREQ_GOV_ONDEMAND # Use the new, "next generation" high-performance timer instead of the # legacy 8254s. CONFIG_HPET_TIMER # The in-kernel irq balancer is obsolete and wakes the CPU up far more # than needed. CONFIG_IRQBALANCE # This is required to set longer CPU sleep times in the kernel CONFIG_NO_HZ # This enables the aggressive power-saving support of the AC97 sound # codecs. In this mode, the power-mode is dynamically controlled at each # open/close. This will save roughly ½ watt of power. CONFIG_SND_AC97_POWER_SAVE # This automatically disables UHCI USB when not in use. This saves # roughly 1 Watt of power. CONFIG_USB_SUSPEND
And add these tweaks to your startup scripts:
# Wake up the disk less often echo 1500 > /proc/sys/vm/dirty_writeback_centisecs # Enable laptop mode echo 5 > /proc/sys/vm/laptop_mode # Enable powersave mode for AC97 echo 1 > /sys/module/snd_ac97_codec/parameters/power_save
After you set these and rebuild your kernel with those options, you should now be consuming a lot less power than the “stock kernel”. Good luck!