Since the posting was on a private list, I'm putting a link into the results and spreadsheet data that covers the analysis:
Results: http://zinc.canonical.com/~cking/power-benchmarking/pm-utils-results/results.txt Data: http://zinc.canonical.com/~cking/power-benchmarking/pm-utils-results/pm-tests.ods == Journal-commit == script: power.d/journal-commit For ext3/ext4 file systems this sets the journal commit time to 600 seconds(!) when on battery power. Test: build busybox Results: NO power savings on HDD drives, with biggest loss of 1.5% on SSD based netbook. Recommendation: We remove this script for two reasons: 1) It is shown not to save power on a busy system 2) It is a dangerous option - pushing the commit timeout to 10 minutes increases the likely of filesystem errors on a system hang. == Readahead === script: power.d/readahead This script tries to trade off the number of times we spin up a drive to read for potentially wasted cache. For AC power, set to 256KB, for battery power, set to 3072KB. Test: build busybox Results: All systems fail to show any power savings, in fact SSD loses ~1.7% more power with this enabled. Recommendation: Remove this script Please refer to the pm-tests.ods for the results from some thorough testing on 3 representative machines. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/900923 Title: pm-utils: readahead and journal-commit waste power To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pm-utils/+bug/900923/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
