Re: [patch 0/4] SATA power savings patches (ALPM)

[Bill Davidsen <davidsen@tmr.com>]

Kristen Carlson Accardi wrote:
> Hi Jeff,
> Here's the most recent patches for ALPM.  These are also located at:
> http://www.kernel.org/pub/linux/kernel/people/kristen/patches/SATA/alpm
>
> These patches implement Aggressive Link Power management for AHCI 
> controllers.  This feature is described in detail in the AHCI 1.x spec.
> It provides power savings of anywhere from .5-1.5 Watts depending on
> the system when it is enabled.  (a graph demonstrating power savings
> of this patch along with other power patches is located at 
> http://www.linuxpowertop.org/results.php for your enjoyment).
>
> This patch is changed from the previous version in that it incorporates all
> the feedback I've gotten on the patches to date.  It changes the default
> of the ahci driver to be max_performance rather than min_power, so userspace
> will need to explicitly enable alpm via the sysfs interface when it deems
> it an appropriate time to do this.  In addition, the patch was changed to
> allow either HIPM or DIPM as a prerequisite for enabling ALPM, rather than 
> just using HIPM.
I suspect these changes would be useful for servers as well, extending 
run time when a failover to UPS is detected.

--
Bill Davidsen <davidsen@tmr.com>
  "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot
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