Re: RFA: acpi-support -- glue layer for translating laptop buttons, plus legacy suspend support

[Matthew Garrett <mgarrett@chiark.greenend.org.uk>]

<bjorn@mork.no> wrote:

>You'll save between 0.5 and 1.5 W by enabling SATA Aggressive Link Power
>Management according to http://www.lesswatts.org/tips/disks.php As this
>definitely is measurable, I assume that your measurements have been done
>without enabling ALPM?  Or maybe the power saving estimated by lesswatts
>is based on normal hard drive usage?

ALPM is only relevant for AHCI and native SATA drives. The majority of
native SATA drives support asynchronous notification, so in that case 
there won't be any polling.

>Could you please share the details of what you've measured?  Which type
>of drives, controllers and drivers are used in a "typical system"?  How
>about a "typical laptop" (which in my world is the only system class
>where this matters anyway)?  How about "modern laptop" (AHCI controller,
>SATA DVD)?

Standard PATA optical drives, typically connected to an Intel 
southbridge running in piix mode.

-- 
Matthew Garrett | mjg59-chiark.mail.debian.devel@srcf.ucam.org