On Tue, Aug 21, 2012 at 11:42:04AM +0200, Ingo Molnar wrote: > * Matthew Garrett <mj...@srcf.ucam.org> wrote: > > [...] Putting this kind of policy in the kernel is an awful > > idea. [...] > > A modern kernel better know what state the system is in: on > battery or on AC power.
That's a fundamentally uninteresting thing for the kernel to know about. AC/battery is just not an important power management policy input when compared to various other things. > > [...] It should never be altering policy itself, [...] > > The kernel/scheduler simply offers sensible defaults where it > can. User-space can augment/modify/override that in any which > way it wishes to. > > This stuff has not been properly sorted out in the last 10+ > years since we have battery driven devices, so we might as well > start with the kernel offering sane default behavior where it > can ... Userspace has been doing a perfectly reasonable job of determining policy here. > > [...] because it'll get it wrong and people will file bugs > > complaining that it got it wrong and the biggest case where > > you *need* to be able to handle switching between performance > > and power optimisations (your rack management unit just told > > you that you're going to have to drop power consumption by > > 20W) is one where the kernel doesn't have all the information > > it needs to do this. So why bother at all? > > The point is to have a working default mechanism. Your suggestions aren't a working default mechanism. -- Matthew Garrett | mj...@srcf.ucam.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
