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 -- Kahlil (Kal) Hodgson GPG: C9A02289 Head of Technology (m) +61 (0) 4 2573 0382 DealMax Pty Ltd (w) +61 (0) 3 9008 5281 Suite 1415 401 Docklands Drive Docklands VIC 3008 Australia "All parts should go together without forcing. You must remember that the parts you are reassembling were disassembled by you. Therefore, if you can't get them together again, there must be a reason. By all means, do not use a hammer." -- IBM maintenance manual, 1925