This appears to be because upowerd calls `pm-powersave false`, which in turn activates /usr/lib/pm-utils/power.d/laptop-mode, which writes 10 and 5 to /proc/sys/vm/dirty_ratio and /proc/sys/vm/dirty_background_ratio, respectively, replacing default 20 and 10. Commenting this line in laptop-mode file works around this bug.
Now I'm not sure whether this bug is a kernel bug or a pm-utils one. It seems definitely not a upower bug. BTW, this bug doesn't appear on another machine I tested it on, with GA- I915G-MF motherboard, while it appears on the problematic motherboard MSI B85-G41 PC Mate. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1342341 Title: upowerd kills USB performance To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/upower/+bug/1342341/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
