Hi. I have a Lenovo ThinkPad X61s and for me low power consumption is _the_ most important feature there is.
When Hardy was released I decided to do some idle discharge testing. What I did was to install a plain Ubuntu desktop (i386), do no modifications except installing a few additional packages (of which only NFS support started extra background processes), charge the battery to 100% and then pulled the plug to see for how long it could go. I was connected to a wired ethernet (configured by Network Manager with DHCP), and had a NFS mounted on which there was a file I appended the output of "date;acpi" to every 30 seconds. When the laptop had turned off I simply compared the first time stamp where it was on battery to the last one in the file, and then I had the total battery life plus/minus 30 seconds. The laptop is supposed to have a battery life of 3,1 hours, according to Lenovo's web pages. My test gave me a life time of 2 hours and 23 minutes. The LCD was dimmed immediately (however not as much as possible - from 15 to 10 according to /sys/class/backlight/acpi_video1/brightness) when I pulled the plug, after two minutes it was dimmed further - all the way down to 0 (but as I found out later, it would have been restored to 10 if I had touched the laptop), then it was blanked (8 minutes later), and five minutes after that again turned off completely. It didn't suspend or hibernate when the battery went critically low - it kept going until the very end. I also noticed (another time) that if I touched the pointer after the screen had turned off completely, it was turned back on with max brightness (15) instead of the 10/15 it was set to immediately after the power cord was yanked. For the next few tries I thought I'd do something that seemed obvious to me, namely shutting of the unused radio transmitters. Doing "echo disable > /proc/acpi/ibm/bluetooth" immediately after unplugging the power gave me another 18 minutes of battery life - a 12,6% improvement. The next try I also disabled the wireless (echo 1 > /sys/class/net/wmaster0/device/rf_kill), which gave me 21 more minutes of uptime - a 14,7% improvement compared to the original 2h23m. Total uptime was now 3 hours and 2 minutes, not yet what Lenovo claims is possible but I guess they know how to brag... After this I got a bit bored and batched up my three next adjustments into one, all relating to keeping the hard drive idle as much as possible, by adding the following three commands to the script I ran after cutting power (first two suggested by PowerTOP): echo 1500 > /proc/sys/vm/dirty_writeback_centisecs for f in /sys/class/scsi_host/host*/link_power_management_policy; do echo min_power > $f; done hdparm -B 1 /dev/sda Another 18 minutes gained - total uptime was now 3 hours and 20 minutes, a whopping 40% increase over the default install! I didn't test more than that, but I'll be glad to do some more of it if there's any interest. I'd sure like to help out make Ubuntu the number #1 distro for use on laptops... I kinda regret that I nuked the Windows installation that came pre-installed, would've been fun to compare the results above to a discharge test of that one... Anyway. To sum up, my list of suggested improvements are as follows: * Don't crash - when the machine is critically low on battery, suspend to disk. * Always dim the LCD as much as possible. I can always increase it manually myself if need to (harder to remember to turn un-needed brightness down to conserve battery). * Don't blank the screen - there's no savings to be had by displaying only black pixels. Turn it off all the way, always. There's no noticable power-up delay anyway. * Feel free to turn it off after 5 minutes of idling (or less) instead of 15, too... * Don't re-instate max brightness after turning the LCD back on! At the very least it should not be more than what it tuned down to immediately after power was cut (10/15). * Deactivate unused radios. * Activate power savings in SATA ALPM and hard-drive APM, and increase the dirty_writeback_centisecs setting to keep the disk from being woken up to often. I'm on the lookout for more watts to save, so if there's any other things you'd like me to try, let me know! Tore -- Bad battery runtime in Ubuntu https://bugs.launchpad.net/bugs/195768 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
