On Mon, Apr 13, 2015 at 7:32 AM, Tejun Heo <tj@xxxxxxxxxx> wrote: > On Fri, Apr 10, 2015 at 01:15:29PM -0700, Matthew Garrett wrote: >> Intel publish a document on designing energy efficient SATA devices at >> http://www.intel.com/content/dam/doc/reference-guide/sata-devices-implementation-recommendations.pdf >> which recommends that ALPE be set, ASPE be cleared and that DIPM be enabled >> on the device. Right now we have no policy that matches that - medium_power >> does not enable DIPM and min_power sets ASPE. Add a new low_power policy to >> implement these recommendations. I've left devslp disabled because I'm not >> yet sure what Intel do in that case. With luck this will provide reasonable >> power savings without causing the device breakages we occasionally see with >> the min_power policy. > > I suspect the aggressive methods actually don't buy us much, except > for the obsessive mode switchings, in terms of power saving compared > to something more reasonable provided via DIPM and I'm not sure it's a > good idea to introduce yet another mode. I'd be all in for converting > min_power mode to DIPM for cases where we know this actually works > rather than introducing yet another mode. Or if there's a clear power > consumption disadvantage to DIPM, let's conver medium_power to that. Ok - my only real concern there was that we might end up changing the semantics of medium_power enough that it would break somebody. I'll post a patch to do that instead and I guess we can see what happens - worst case we revert it and add a new one. -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
