On 2007.05.20 20:55:35 +0200, Andi Kleen wrote: > Björn Steinbrink <[EMAIL PROTECTED]> writes: > > > > Ok, it seems that ipw2200 is just a trigger for the problem here. AFAICT > > the cause of the worse C state usage is that after ipw2200 has woken the > > cpu, acpi_processor_idle() chooses C2 (due to dma? bm? I have no > > idea...) as the prefered sleep state. Now without NO_HZ or when I hold > > down a key, there are interrupts that wake up the CPU and when > > acpi_processor_idle() is called again the promotion to C3/C4 happens. > > But with NO_HZ, there are no such interrupts, most wakeups are caused by > > ipw2200 and so the processor doesn't go any deeper than C2 most of the > > time and thus wastes lots of power. > > The cpuidle governour code Venki is working on is supposed to address this. > There have been also earlier prototype patches by Adam Belay and > Thomas Renninger.
Venki (at least I think it was him) also told me about cpuidle and the menu governor on #powertop. Unfortunately, cpuidle seems to be gone from acpi-test (or I'm simply still too stupid for git/gitweb). I manually added the cpuidle and menu governor patches on top of my 2.6.22-rc1-hrt8 kernel, but that broke C-state duration accounting. On the bright side of things is power usage though, which is down to an incredible 13.9W in idle+ipw2200 :) Thanks, Björn - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
