Messages in this thread | | | Date | Tue, 26 Dec 2006 15:40:08 +0100 | From | Pavel Machek <> | Subject | Re: USB power usage |
| |
Hi!
> > Couple of watts is not that bad, considering usb still eats 4W more > > than it should. > > The USB autosuspend mechanism has been present for a while in -mm and is > included in 2.6.20-rc (although you have to turn on CONFIG_USB_SUSPEND, > which is off by default -- it would be nice to change that). Has anybody > tried doing some real-world measurements to see if it actually makes a > significant improvement in power usage?
I did measurements while in -mm, and yes it helped. And yes, it works in 2.6.20-rc2, too:
root@amd:~# cat /proc/acpi/battery/BAT0/state ; sleep 20; cat /proc/acpi/battery/BAT0/state ; sleep 20; cat /proc/acpi/battery/BAT0/state ; sleep 20 present: yes capacity state: ok charging state: discharging present rate: 14245 mW remaining capacity: 50020 mWh present voltage: 15793 mV
(turned off bluetooth hanging off USB here).
present: yes capacity state: ok charging state: discharging present rate: 11650 mW remaining capacity: 49940 mWh present voltage: 15830 mV present: yes capacity state: ok charging state: discharging present rate: 10935 mW remaining capacity: 49870 mWh present voltage: 15826 mV root@amd:~#
As you can see, it saves ~3.5W, which is huge deal on machine that eats 11W total.
(X60 owners, get 2.6.20, and _disable that bluetooth_ while not in use). Pavel
-- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |