On 03/08/12 17:05, Mathieu Baudier wrote:
As per http://www.williambrownstreet.net/blog/?p=387, add the following kernel arguments to the GRUB boot configuration:
pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1 i915.i915_enable_fbc=1
As measured using PowerTop, this made the power consumption decrease from 20W to 11W ! (I had already decreased it from 25W to 20W with the usual tips of disabling hardware, shutting down services, switching tuned profiles, etc.)
Thanks for the tips. I've got a X220 and power consumption is typically less than 10W, with various powertop tweaks on Fedora 17, giving me 8-9hrs of battery life.
The biggest win was setting i915.i915_enable_rc6=1 on the kernel command line, although I've read that this can cause some instability, depending on you kernel and usage -- had a couple of crashes/freezes a 6 months ago, but it seems pretty stable now. The benefits for a laptop definitely out-weigh the inconvenience or a few rare freezes, but it would be different for a server.
Might try out the other kernel line options and see if I can do better :-)
Here's my /etc/rc.d/rc.local file in case you are interested: ------------------------------------- #!/bin/bash
echo 5 > /proc/sys/vm/laptop_mode echo 0 > /proc/sys/kernel/nmi_watchdog echo 1 > /sys/devices/system/cpu/sched_mc_power_savings echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor echo 1500 > /proc/sys/vm/dirty_writeback_centisecs for i in /sys/bus/usb/devices/*/power/autosuspend; do echo 1 > $i; done for i in /sys/bus/usb/devices/*/power/level; do echo auto > $i; done echo min_power > /sys/class/scsi_host/host0/link_power_management_policy echo min_power > /sys/class/scsi_host/host1/link_power_management_policy echo Y > /sys/module/snd_hda_intel/parameters/power_save_controller echo 1 > /sys/module/snd_hda_intel/parameters/power_save for i in /sys/bus/{pci,i2c}/devices/*/power/control; do echo auto > $i; done
iwconfig wlan0 power on -------------------------------------
Cheers,
Kal