From: Arjan van de Ven <arjan at linux.intel.com>
To: powertop@lists.01.org
Subject: Re: [Powertop] USB devices get wrong power use values
Date: Sun, 13 Oct 2013 11:48:25 -0700 [thread overview]
Message-ID: <525AEAF9.5080709@linux.intel.com> (raw)
In-Reply-To: 20131013162212.GH30504@merlins.org
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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)
next reply other threads:[~2013-10-13 18:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-13 18:48 Arjan van de Ven [this message]
-- strict thread matches above, loose matches on Subject: below --
2013-10-18 0:24 [Powertop] USB devices get wrong power use values Marc MERLIN
2013-10-18 0:01 Marc MERLIN
2013-10-13 22:38 Arjan van de Ven
2013-10-13 22:10 Marc MERLIN
2013-10-13 16:22 Marc MERLIN
2013-10-13 15:33 Arjan van de Ven
2013-10-12 11:16 Sergey Senozhatsky
2013-09-22 23:54 Marc MERLIN
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