Re: [Discuss] Speedstep on Celeron SU2300 - 20% more battery lifetime on Windows

[Arjan van de Ven <arjan@linux.intel.com>]

  On 9/6/2010 3:03 PM, Tiago Marques wrote:
> On Mon, Sep 6, 2010 at 4:47 PM, Arjan van de Ven<arjan@linux.intel.com>  wrote:
>>   On 9/6/2010 1:35 AM, Thomas Renninger wrote:
>>> Hi,
>>>
>>> I am adding lesswatts.org and linux-pm list.
>>> I expect you found out why you do not get frequency/P- states and it
>>> seem to be correct. On these lists, people can help you further
>>> to find out Linux vs Windows battery drain differences.
>>>
>>> If you have the same backlight settings, I expect C-state or graphics
>>> card must be the reason. There is nothing else than CPU or GPU
>>> that drains so much energy for being the reason of
>>> 20% more battery life time.
>>> Which graphics card and driver do you use (for nvidia/ati, trying the
>>> binary one for comparison, might show a big difference on a recent
>>> card)?
>>> Which C-state driver do you use (there is an acpi and intel_idle one
>>> with latest kernels):
>>> cat /sys/devices/system/cpu/cpuidle/current_driver
>>> I hope to be able to provide a c-state tool soon, for now you have to
>>> go through:
>>> cat /sys/devices/system/cpu/cpu*/cpuidle/state*
>>> to check which and how often/efficient C-states are used.
>> powertop will tell you exactly this
>>
> Thank you. Please see my previous e-mail. C0, C1 and C4. Do you know
> of any way to force the intermediate ones for debugging?

intel_idle driver is the only way that's reasonable in amount of work.

for anything else you depend on the grace of the bios.