On Tue, Aug 21, 2012 at 05:19:10PM +0200, Ingo Molnar wrote: > * Matthew Garrett <mj...@srcf.ucam.org> wrote: > > [...] AC/battery is just not an important power management > > policy input when compared to various other things. > > Such as?
The scheduler's behaviour is going to have a minimal impact on power consumption on laptops. Other things are much more important - backlight level, ASPM state, that kind of thing. So why special case the scheduler? This is going to be hugely more important on multi-socket systems, where your policy is usually going to be dictated by the specific workload that you're running at the time. The exception is in cases where your rack is overcommitted for power and your rack management unit is telling you to reduce power consumption since otherwise it's going to have to cut the power to one of the machines in the rack in the next few seconds. > The thing is, when I use Linux on a laptop then AC/battery is > *the* main policy input. And it's already well handled from userspace, as it has to be. > > Userspace has been doing a perfectly reasonable job of > > determining policy here. > > Has it properly switched the scheduler's balancing between > power-effient and performance-maximizing strategies when for > example a laptop's AC got unplugged/replugged? No, because sched_mt_powersave usually crippled performance more than it saved power and nobody makes multi-socket laptops. -- 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/
