Re: [Powertop] USB devices get wrong power use values
Arjan van de Ven <arjan at linux.intel.com>
| Newsgroups | dev.linux.lists.powertop |
|---|---|
| Message-ID | <[email protected]> |
On 10/13/2013 9:22 AM, Marc MERLIN wrote: >> having a USB device active also generally makes the CPU/etc use much more power, >> which Powertop "charges" to the USB device in question. >> >> 8 Watts sounds entirely reasonable for that to me... > > Aah, if the CPU gets involved, then yes, it's a bit more possible. > So, a simple USB keyboard that's unused can keep one core awake and burn 8 > watts if something else goes wrong in the kernel to cause that? a bad USB keyboard can keep the processor out of deep package C states.. not a lot the software can do about that... but yet it can be THAT much power delta. (we've seen for example on some servers that a cheap keyboard makes > 15 Watts difference, but measured at the wall socket, so after the power supply/etc)