Re: [patch 2/4] Expose Power Management Policy option to users
Tejun Heo <htejun <at> gmail.com>
2007-08-01 03:20:24 GMT
Kristen Carlson Accardi wrote:
> So at current rate of development and kernel release schedule, the best
> possible scenario is still 6 months away - whereas this patchset is already
> tested and ready for merging now.
The best possible scenario is .24-rc1 merge window with or without
waiting. With waiting, the best possible scenario is harder to achieve tho.
> Out of tree patches don't work. Nobody tests them. A module parameter
> will not work - we need to be able to expose the sysfs interface so that
> users may chose to turn the feature off and on at will - mainly according
> to their usage. For example, at boot time - you want ALPM off to maximize
> performance. Lets say when you are plugged into the wall socket, you leave
> it off, but then when you go on battery power you would want to enable it.
You can turn on and off dynamically using a module parameter. Although
it's not a pretty interface, it should work as an interim solution if we
absolutely must merge ALPM now.
>> Due to the generosity of the ATA committee, we have, by default, at
>> least two ways to achieve link PS - HIPS and DIPS. I dunno why but
>> someone thought we needed two. And then, ahci people thought automatic
> They thought we needed two because sometimes the device knows when it
> will be idle faster than the host can. this is why ALPM can determine
> idleness faster than any software algorithm on the host cpu can. You
> can use ALPM without having HIPM. You can also use it without having
I see. I get that one way is better than another in some way. I'm just