SATA Aggressive Link Power Management (ALPM) - call for testing
tim.gardner at canonical.com
Tue Dec 6 17:14:33 UTC 2011
On 12/06/2011 06:25 AM, Colin Ian King wrote:
> Hi there,
> Aggressive Link Power Management (ALPM) is a mechanism where a SATA AHCI
> controller can put the SATA link that connects to the disk into a very
> low power mode during periods of zero I/O activity and into an active
> power state when work needs to be done. Tests show that this can save
> around 0.5-1.5 Watts of power on a typical system.
> ALPM is now available in several SATA controllers that use the Advanced
> Host Controller Interface (AHCI). However, there is some anecdotal
> evidence that some controllers may go into a low power state incorrectly
> and this ends up causing data loss. Ubuntu has the ability to use ALPM
> but it it disabled by default since it can cause data loss on some
> We are looking for (brave?) volunteers to test ALPM for 2 reasons:
> 1) help to identify typical power savings on a range of machines
> 2) help to identify chipsets (and machines) where ALPM works reliably
> and also where it is broken and needs fixing.
> An ALPM crowd-sourcing testing Wiki page has been created that describes
> a testing methodology and has a table for test results:
> Please note that there is a possibility that ALPM MAY CAUSE DATA LOSS on
> some machines, so please ensure you have backed up your data or don't
> mind the risk in losing your data.
How about screen backlight management? I've noticed that my screen at
full brightness consumes about 4W compared to screen off. Should we at
least be measuring that ?
Tim Gardner tim.gardner at canonical.com
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