On Tuesday, May 06, 2014 6:15:46 pm Ian Lepore wrote: > On Tue, 2014-05-06 at 16:37 -0400, John Baldwin wrote: > > On Tuesday, May 06, 2014 2:08:35 pm Adrian Chadd wrote: > > > On 5 May 2014 13:57, John Baldwin <j...@freebsd.org> wrote: > > > > > > > The user in question found this on 9-stable with the existing defaults > > > > as the > > > > HPET was just plain broken on their system and that was unrelated to Cx > > > > states. > > > > (Rather, Cx states were only involved because worries about them are > > > > why the > > > > system chose to use HPET. Had Cx states been enabled by default, they > > > > would > > > > have had to disable those as well in addition to forcing LAPIC instead > > > > of > > > > HPET.) > > > > > > Hm. Sounds uncomfortable. How does Windows run on systems like this? > > > Do the windows drivers just disable HPET and use LAPIC or worse for > > > timing, and just ignore anything lower than C1? > > > > I have no idea. Maybe they use the RTC. :-/ Maybe the HPET on these > > systems > > works if you use it "sparingly". I believe OS X might have only used the > > HPET > > to provide the "missing" LAPIC wakeups when entering Cx for example. (Our > > current > > eventtimer system wants to always use whichever timer it picks, not switch > > off > > between them.) > > > > The eventtimer code is happy to switch between timers on the fly, but > iirc the only interface to that feature is sysctl. I found it fairly > easy to add an in-kernel API for changing the frequency of the current > timer on the fly. I think it would be just as easy to add a kernel > call to change timers as well.
Ah. Well, if it's only a small slice of time where machines need this, I'd be fine with those machines just having to disable C1E and forcing use of LAPIC rather than adding a lot of goop to do LAPIC + HPET and then hoping the HPET works well enough. -- John Baldwin _______________________________________________ freebsd-acpi@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-acpi To unsubscribe, send any mail to "freebsd-acpi-unsubscr...@freebsd.org"
