Re: [patch 2/3] Expose Power Management Policy option to users

From: Jeff Garzik
Date: Mon Jun 11 2007 - 16:00:48 EST

Kristen Carlson Accardi wrote:
This patch will modify the scsi and ata subsystem to allow
users to set a power management policy for the link.
libata drivers can define a function (enable_pm) that will
perform hardware specific actions to enable whatever power
management policy the user sets up if the driver supports
it. This power management policy will be activated after
all disks have been enumerated and intialized.

The scsi subsystem will create a new sysfs file for each
host in /sys/class/scsi_host called "link_power_management_policy".
This file can have 3 possible values:

Value Meaning
min_power User wishes the link to conserve power as much as
possible, even at the cost of some performance

max_performance User wants priority to be on performance, not power

medium_power User wants power savings, with less performance cost
than min_power (but less power savings as well).

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@xxxxxxxxx>

seems OK at first glance, though I request that ata and scsi portions be split into separate patches

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