On Wed 2008-03-05 09:40:23, Pierre Ossman wrote: > On Wed, 5 Mar 2008 07:02:01 +0100 > Pierre Ossman <drzeus-list@xxxxxxxxx> wrote: > > > > > I tried using predicted_us and last_measured_us, and those didn't work (see the #if 0 code in my last patch). And since cpuidle_get_last_residency() is part of predicted_us, I don't think it is reporting useful values. > > > > I take this back. They might be working just fine. It seems I've been looking at a too small piece of the puzzle. This machine has a dual core processor, and the governors control each core independently. Unfortunately it's the power fluctuations of the entire socket that causes noise, not just each processor. > > So I need to build some global algorithm instead of one per core. Ideas are welcome. > > From what I can tell, disabling one core makes the noise go away. So I guess both cores need to go into C3 (or perhaps one C2 and one C3) at the same time to cause the problem. I'm not 100% sure of this as the damn noise comes and goes, but I've been running for an hour or so now with one core disabled and without my anti-noise patch. > Actually, there are more uncertaininties. Suspecting some machines seemed to produce noise whenever they were in low-power state. Not with fluctuations: when I forced them to low-power, it just produced steady beep. (Thinkpad 560X and toshiba 4030cdt, IIRC). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
