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SubjectRe: [patch 0/3] AHCI Link Power Management
Arjan van de Ven wrote:
> Tejun Heo wrote:
>> Kristen Carlson Accardi wrote:
>>> Hi,
>>> This series of patches enables Aggressive Link Power Management for
>>> AHCI devices, as documented in the AHCI spec. On my laptop (a Lenovo
>>> X60), this
>>> saves me a full watt of power. On other systems, reported power savings
>>> range from .5-1.5 Watts. It has been tested by the kind folks at
>>> #powertop
>>> with similar results. Please give it a try and let me know what you
>>> think.
>>
>> I'm not sure about this. We need better PM framework to support
>> powersaving in other controllers and some ahcis don't save much when
>> only link power management is used,
>
> do you have data to support this? The data we have from this patch is
> that it saves typically a Watt of power (depends on the machine of
> course, but the range is 0.5W to 1.5W). If you want to also have an even
> more agressive thing where you want to start disabling the entire
> controller... I don't see how this is in conflict with saving power on
> the link level by "just" enabling a hardware feature ....

SATA standard defines lower power phy states. So the same argument
you're using for AHCI applies there too -- "just" enabling an existing
hardware feature.

Jeff


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