On Tue, 31 Jul 2007 15:27:34 +0900 Tejun Heo <htejun@xxxxxxxxx> wrote: > Jeff Garzik wrote: > > Any chance the SCSI peeps could ACK this, and then let me include it in > > the ALPM patchset in the libata tree? > > ATA link PS is pretty complex with HIPM, DIPM and AHCI ALPM. I'm not > sure whether this three level knob would be sufficient. It might be > good enough if we're gonna develop extensive in-kernel black/white list > specifying which method works on which combination but my gut tells me > that it's best left to userland (probably in the form of per-notebook PS > profile). I think what you are saying is that you'd like a way to use your HIPM and DIPM without ALPM on the AHCI driver. Fine - it's really easy to add these levels later - if they don't make sense at the sysfs interface we can add module params to specify the definition of "min_power" as being performed via HIPM and DIPM instead of ALPM - although as of yet we have no evidence what so ever that this method actually adds value over ALPM. > > Adding to the fun, there are quite a few broken devices out there which > act weirdly when link PS actions are taken. OK - this is why I added the blacklist for this feature. > > Also, I generally don't think AHCI ALPM is a good idea. It doesn't have > 'cool down' period before entering PS state which unnecessarily hampers > performance and might increase chance of device malfunction. "might increase"? How about some actual examples of where you've shown this to be a problem? I can assert that I think ALPM is a good idea, because I've never had a report of it causing problems. Windows has been using this feature for a very long time - and you have to admit that they have a pretty large market share. Nobody is complaining about ALPM increasing device malfunction, so unless you have proof it seems insane to nak due to this. - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
