2009/310 Disk IO PM Enhancement 1999/388 2005/250 2008/465

[Pawel Wojcik]

On 05/19/09 06:23 PM, Edward Pilatowicz wrote:
> On Tue, May 19, 2009 at 10:37:45AM -0700, Terry Whatley wrote:
>   
>>      4.3.4 disk power attribute driver properties
>>
>> 	sd(7D) will export a set of driver properties to indicate a disk's
>> 	power attributes. See Table-2.
>>
>> 	Table-1 Disk Power Attribute Properties (array properties are indexed
>> 		by power state in order of ascending power levels)
>> 	------------------------------------------------------------------------
>> 	Prop Name            Prop Type    | Prop Description
>> 	------------------------------------------------------------------------
>> 	"pm-resource-type"      String    | "resource-spindle-disk" for the
>>                                           | spindle disks
>> 	------------------------------------------------------------------------
>> 	"pm-perf" Integer array           | array of average R/W
>>                                           | performance percentages
>> 	------------------------------------------------------------------------
>> 	"pm-pwr-saving"  Integer array    | array of average power saving in
>>                                           | units of 0.1watt
>> 	------------------------------------------------------------------------
>> 	"pm-latency"     Integer array    | array of time to first data in units
>>                                           | of 100ms
>> 	------------------------------------------------------------------------
>>
>>     
>
> exporting performance statistics via device properties seems weird to
> me.  is there a precedent for this?  why isn't this information being
> exported via kstats?  do we really want to train users to start using
> prtconf -v to get performance data?
>
> ed
>   
I think these are not performance statistics. I believe that these are 
static arrays that are specific for a device type (most likely Sun disks 
only), that correlate specific power level with performance and power 
savings. These properties, I believe, are to be used by a storage power 
manager to decide at what power level disk should run at given time.
Jane Chu may correct me here...
-Pawel