Public bug reported: The kernel allows us to save power on a range of devices - currently pm- utils power.d does not make full advantage of these power savings.
Tools like PowerTop provide advice on which devices can be set into a "Good" power management state. Analysis on a selection of representative modern mobile x86 based platforms (e.g. netbook, laptop) has shown that a subset of devices can be safely put into a power saving state. Each of the "Good/Bad" PowerTop device recommendations were measured accurately using a 6 digit digital multimeter. Each measurement was based on measuring current drain over 5 x 60 second periods on the Good and Bad settings and seeing which device shows the most promising power saving. The resulting data can be found here: http://zinc.canonical.com/~cking/power-benchmarking/powertop-good-bad- recommendations/powertop-good-bad-recommendations.ods And the write-up of the methodology and conclusions can be found here: http://zinc.canonical.com/~cking/power-benchmarking/powertop-good-bad- recommendations/results.txt >From this analysis we can draw a conclusion that the following devices behave well to power savings as follows: * Webcam * Audio * DRAM * Ethernet * Wifi * Bluetooth * SATA link * MMC/SD >From this, two pm-utils power.d scripts were written to control the power state of the above devices. The script pci_devices controls the PCI specific devices and usb_bluetooth controls USB webcams into and out of power saving modes. These were then tested by community - see: https://wiki.ubuntu.com/Kernel/PowerManagementPMUtils Power savings were calculated from the ACPI battery information. The characteristics and reliability of ACPI battery data to measure power consumption has been studied here: http://zinc.canonical.com/~cking /power-benchmarking/acpi-battery-results/results.txt - the test scripts used by the community testing use a battery power measuring tool that has been calibrated and checked using a 6 digit multimeter and calculates the average power consumption and standard deviation (to allow us to discriminate against unreliable samples). >From these results, I discarded data where the standard deviation was rather high and also results where the savings or losses were smaller than the standard deviation. This left me with a set of results where we have conclusive data showing us power savings or losses with these new scripts. The conclusion is that the vast majority of machines save power. Also, users tested their machines to see if the devices behaved correctly. On the samples of machines I have (Dell Inspirion 6400, Lenovo X220i, HP Mini 210 + HP Mini 10) I see no regressions. I therefore am requesting that the two new pm-utils/power.d scripts are added to pm-utils. Typical savings: 0.38 W per machine with some machines seeing > 1-2W savings. Attached to this bug report are the two new scripts for pm-utils/power.d ** Affects: pm-utils (Ubuntu) Importance: Undecided Status: New ** Tags: battery-power-consumption -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/911325 Title: pm-utils: additonal power.d scripts to save power To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pm-utils/+bug/911325/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
